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EVALUATION AND RESEARCH OF ENVIRONMENTAL IMPACTS OF MECHANICAL HARVESTING IN

lAKE OKEECHOBEE MID-COURSE SUMMARY

REPORT

South Florida Water Management District

3301 Gun Club Road West Palm Beach FL 33416-4680

Mote Marine Laboratory 1600 City Island Park Sarasota Florida 34236 (813) 388-4441

L Kellie Dixon Senior Chemist Principal Investigator

Selvakumaran Mahadevan PhD Director Mote Marine Laboratory

March 11 1988

MML 87-335

TABLE OF CONTENTS

I EXECUTIVE SUMMARY MID COURSE REPORT 1 - 1

II LAKE OKEECHOBEE LITERATURE REVIEW 2 - 1

III BIOMASS - MID-COURSE SUMMARY 3 - 1

IV WATER QUALITY SURVEYS 4 - 1

V PHYTOPLANKTONPRIMARY PRODUCTIVITY STUDIES 5- 1

VI COMMUNITY METABOLISM 6 - 1

VII SEDIMENT CHEMISTRY 7 - 1

VIII BENTHIC FAUNA IMPACTS 8- 1

IX LARVALJUVENILE FISH TASK 9 - 1

X BENEFITCOST ANALYSIS 10 - 1

EVALUATION AND RESEARCH OF IMPACTS

OF MECHAN I CAL WEED HARVEST I NG I N LAKE OKEECHOBEE

I EXECUT IVE SUMMARY - MID-COLIRSE REPORT

Mote Mari ne Laboratory assi sted by DSA

Envi ronmental Qual i ty Laboratory i s mi dway through

research project conducted for the South Fl ori da

Grou p I nc and

an eval uat i on and

Water Management

D i str i ct to assess the envi ronmental i mpacts of mechani cal harvest i ng of

Hydri l l a The harvest i ng and subsequent upl and d i sposal of materi al are

be i ng performed as a demonstrat i on project to eval uate the nutri ent

( part i cul arl y phosphorus ) removal potent i al and operati onal costs of th i s

techn i que The study s i te ( F i gure 1 1) i s on the northwestern shore of

Lake Okeechobee where approxi mate ly 1000 acres of Hydri 1 1 a are to be

harvested by I nternat i onal Sc i ence and Technol ogy I nc together wi th

L a ke Weed Cutt i ng Serv i ce I nc Spec i f i c i mpacts and s i te

characteri stics to be eval uated incl ude s i te b i omass water qual i ty

phytopl ankton and pri mary product i v i ty cOlMlun i ty metabol i sm sed i ment

chemi stry benth i c i nfauna and ep i phyte commun i t i es and l arval and

juven i l e f i sh popu l at i on s In add i tion a cost benefi t anal ysi s i s to be

performed address i ng the harvest i ng vari abl es and poss i bl e products to

opt i m i ze the cost effect i veness of harvesti ng A l i terature survey of

pert i nent top i cs i s al so i ncl uded as a separate tas k and the enti re

project i s conducted under the auspi ces of a Qual i ty Assurance program

des i gned to ensure the prec i s i on accuracy representat i veness and

compl eteness of al l data

The l i terature survey i s compl ete and over 400 annotated documents

have been comp i l ed i nto a cOlMlercial l y avai l abl e b i bl i ograph i c retri eval

system by key words Task members are abl e to request searches of th i s

database for i nformati on on top i cs spec i f i c to the i r tas k I n add i t i on

summari es o f i nformat i on on sel ected keywords such as Hydri l l a

phosphorous and others have been prepared a s Lake Fact Sheetsmiddot

The bi omass sampl i ng (August 19B7) was del i beratel y conducted i n

a wide range of growth cond i t i ons for eval uat i on of Hvdri l l a dens i t i es

and nutri ent content A cond i t i on i ndex was devel oped to eval uate pl ant

1-1

maturi ty Hvdri l l a senescence and peri phyton i nfestat i on was accompan i ed

by an areal decl i ne i n both bi omass and nutri ent content Max i mum

n i trogen and phosphorus t i ssue concentrat i ons were associ ated with ful l y

mature pl ants pri or t o senescence The presence o f other macrophytes was

respons i bl e for most wi thi n- stati on vari ati on Th i s task i nc i dental l y

d i scovered l arge seasonal d i fferences i n Hydr i l l a phosphorus and n i trogen

content Sampl es col l ected at the study s i te by ISampT duri ng J anuary

1988 were roughly f i ve t i mes h i gher i n phosphorus content than the

materi al col l ected by thi s project duri ng August 1987

Water qual i ty wi thi n the s i te represented an extremel y dynami c

system The i n fl uence of the Ki s s immee Ri ver and any other l ocal

d i sch arges produced d i l ut i on grad i ents across the s i te Vari at i ons i n

qual i ty were apparent between sampl i ng dates Numerous v i ol at i ons of the

i nstantaneous d i ssol ved oxygen cri ter ion (5 0 mgl ) were recorded

part i cu l arl y near the lake bottom Damp i ng of d i urnal oxygen extremes

was observed i n the harvested transects Al l n i trogen spec i es and total

phosphorous were h igher i n the unharvested transect waters than i n the

harvested transect The d i fference may be due e i ther to nutri ent

ut i l i zat i on i n the regrowth areas or to the rel ease of nutri ents from the

senescent Hydr i l l a mat present i n harvested areas The ent i re study s i te

was n i trogen l i mi ted wi th N P rat i os ( by we i ght ) of 3 0 i n the harvested

areas and 9 4 i n the unharvested control s

li ght penetrati on of the water at al l harvested stat i ons was

demonstrated to be s i gn i fi cantl y h i gher than at the unharvested control s

duri ng September onl y By January regrowth of Hvdri l l a produced

s l i ghtl y smal l er compensat i on depths on the harvested transect

Grad i ents i n l i ght penetrat i on were al so apparent wi th i n the experi mental

transect and may be rel ated to t ime s i nce harvest Vert i cal grad i ents

for in 1i1Y data were part i cul arly apparent at the weeded stat i ons

Bl ue-green al gae were the domi nant phytopl an kton taxa at al l

stat i ons d uri ng the September sampl i ngs Thi s domi nance was much reduced

duri ng J anuary when more green al gae were present Di vers i ty and number

of tax a i ncreased at four of the s i x stat i ons i n January but no

cons i stent pattern was apparent for e i ther harvested or control stat i ons

I n add i t i on there were no systemat ic d i fferences between harvested and

1 - 2

unharvested areas on the bas i s of spec i es compos i t i on Vari at i ons i n

chl orophyl l content al so were affected more by seasonal cond i t i ons than

by harvest i ng

The conunun i ty metabol i sm measurements conducted durlng September

1 987 i nd i cate probabl e d i fferences i n oxygen budgets for control and

harvested areas al though i n i t i al stat i st i cal methods d i d not establ i sh

the s i gni f i cance of such d i fferences Th i s was attri buted to anomal ous

data col l ected at a stat i on with unusual sed iment character i s t i cs ( h i ghly

organ i c unconsol idated f i ne grai ned mater i al in contrast to f i ne

grai ned sand ) Add i t i onal data analyses wi l l excl ude thi s stat i on from

cons i derat i on and future sampl i ngs wi l l be conducted at al ternate

l ocat i ons Di fferences by treatment duri ng the January sampl i ng were not

as pronounced as i n September and i nd i cate that regrowth of Hvdri 1 1 a with i n t hat peri od had offset harvest i ng e ffects

Sed i ment heterogenei ty was marked wi th i n the s i te with organ i c

w ith nutri ent content were fa i rl y l ow Organ i c content averaged 0 7

n i trogen 0 27 mgg total phosphorous 0 08 mgg and potass i um 0 49 mgg

on a dry we ight basi s Ni trate-n i tri te -n i trogen concentrati ons were l ess

than 1 of the total present Total n i trogen tota1 phosphorous rat i os

averaged 3 1 and were markedl y l ower than comparabl e rat i os i n e i ther t he

water col umn or the bi omass sampl es refl ect i ng a preferenti al

mobi l i zati on of n i trogen from s i te sed iments Few stat i st i cal l y

s i gn i f i cant d i fferences were detected a s a resul t o f w ith i n - stat i on

vari ati ons and the col l ect i on of more total phosphorus and total n i trogen

val ues are proposed for the second effort of th i s tas k

Data anal yses t o date for benth i c i nfauna i ncl ude preharvest and

postharvest cond i t i ons duri ng August and October respect i vel y The

August fauna was notabl y depauperate both i n taxa and numbers of

i nd i v i dual s wh i l e pronounced i ncreases in both were observed for

October D i urnal l y oxygen - poor cond i t i ons part i cul arl y duri ng August

may l i mi t benth i c fauna Spati al grad i ents were al so noted w ith

decreas i ng s pec i es ri chness and faunal dens i ti es at the southern end of

the study area Experimental and control stat i ons exh i bi ted s i mi l ar

faunal densi t i es and spec i es richness pri or to harvest wh i l e both

1 -3

parameters were substant i al ly greater at the harvested stat i ons duri ng

the October sampl i ng

Based on sampl i ngs i n September and J anuary the l arval and

juven i l e f i sh task col l ected 44 ( 2 1 ) of al l spec i es prev i ously reported

for Lake Okeechobee F i ve habi tats represent i ng both natural and

harvested edges and open water as wel l as heav i ly vegetated areas

were sampl ed Heterandria formosa LeDomi s sp and Gambus i a aff i nis

were the most abundant spec i es Centrarch i ds were the most abundant eggs

recovered The col l ect i on methods were f a i rly specif i c for part i cul ar

l i fe stage juven i l es were taken primari ly i n l i g ht trap sampl es whereas

postl arvae and eggs were taken i n pl ankton tows and Hvdri l l a sampl es

col l ected by the harvester LeDomi s s p appears to ut i l i ze al l fi ve

hab i tats dependent on l i festage No vert i cal strat i fi cat i on of organ i sms

was detected i n the weeded hab i tat and spec i es d i vers i t i es were

equ i val ent at both natural and harvested RedgesR of the Hydri l l a mat No

stat i s t i ca l ly s i gn i f i cant short term i mpacts of harvesti ng on spec i es

abundance or d i str i buti on are apparent

The cost-benefi t analys i s i s restri cted to eval uati ng mechan i cal

harvest i ng al one Benefi ts of thi s techni que wi th the except i on of

sal eabl e byproducts or costs assoc i ated wi th harvested mater i al are

pr i mari l y non -quanti fi abl e ( i mproved habi tat and water qual i ty boater

access nutri ent removal ) Therefore ranges of econom i c parameters wi l l

be ut i 1 i zed together wi th operat i ona 1 data from harvest i ng and

env i ronmental vari abl es from th i s project to present an economi cal l y

opt im i zed harvest i ng pl an to the Di stri ct

I n sunvnary no catastroph i c impacts due to mechan ical harvest i ng

have been detected i n the foregoi ng categori es al though subtl e

d i fferences have been determi ned by the study des ign Harvest i ng reduces

the amount of oxygen stress i n the study area and the nutri ent content of

the water col umn i s l ower i n the harvested than the unharvested areas

The s i te i s n i trogen l i mi ted based on water col umn sed i ment and pl ant

t i ssue anal yses Seasonal vari at i ons are l arge wi th respect to

d i fferences between harvested and unharvested areas for a l gal and l arval

fi sh popUl at i ons Spati al grad i ents were apparent i n many parameters

1 -4

The qual i ty assurance program associ ated wi th thi s project has

thus far conducted a systems aud i t for the pl an of study and at l east one

performance aud i t on f i e l dwork A Qual i ty Assurance Project Pl an has

been prepared and i s i n use as a project control document Aud i ts of

data management and anal ysi s are pl anned for the fi nal report i ng phase

At mi d -course sampl i ng anal yses and del i verabl es are on

schedul e and the project is operati ng wi th i n the budget No probl ems are

foreseen to prevent t imely compl eti on of the remai nder of the schedul ed

work Where al terati ons to speci f ic tasks have been recommended the

support for these efforts wi l l be obtai ned by real l ocati on of funds

wi th i n the project rather than by add i t i onal fund i ng

1-5

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lAKE (J(EECH08EE

Figure 11 Stu dy site l ocation Evaluation and research of impacts o f mechanical harves ting in Lake Okeechobee

I

I I LAKE OKEECHOBEE LITERATURE REV I EW

I I A INTRODUCTION

A 1 i terature rev i ew was conducted as a d i screte task of the

research project The Eval uat i on and Research of Impacts of Aquat i c Weed

Harvest i ng Demonstrat i on i n Lake Okeechobee cond ucted by Mote Mari ne

Laboratory The purpose of the l i terature rev i ew was to provide project

team members wi th economi c geol og i c hydrol og i c chemi cal and

b i ol og i cal i nformat i on on Lake Okeechobee wi th part i cu l ar emphas i s on

water qual i ty probl ems concern i ng phosphorus storage and cycl i ng between

the water col umn sed i ments and aquat i c weeds

I I B METHODS

Three techn i cal el ements were undertaken i n compl et i ng the

l i terature rev i ew 1) ident i fy i ng and search i ng i nformat i on 2) creat i ng

f i l es and 3 ) devel opi ng outputs

I nformati on was obtai ned by rev i ewi ng journal s for art i cl es

search i ng card catal ogs of area l i brar ies contact i ng major authors

conduct i ng research and request i ng key word searches of avai l abl e

computer l i brari es Journal s searched i ncl uded The Journal of Aquat i c

Pl ant Management Quarterly Journal o f the Fl ori da Academy o f Sci ences

( and Fl ori da Sc i ent i st ) L i mnol ogy and Oceanography Hydrobi ol og i a and

North Amer i can Journal of F i sher i es Management L i brari es vi s i ted

i ncl uded Un i vers i ty of South Fl or ida Uni vers i ty of Fl orid a Mote Mari ne

Laboratory Southwest Fl or ida Reg i onal Pl ann i ng Counci l South Fl ori da

Water Management D i str i c t and the Okeechobee off i ce of the Fl ori da Game

and Freshwater Fi sh Commi ss i on Key word l i terature searches were

c o n d u c t e d on d i qu at Lake O keechobee Hyd r i l l a and

nutr i entsaquat i c pl ants u s i ng searches avai l abl e from the Fl ori da

Department of Env i ronmental Regul at i on the Un i vers i ty of Fl ori da Aquati c

Weed Program and the U S Fi sh and Wi l d l i fe Servi ce

2-1

I I C PRODUCT

After rev i ew each publ icat i on was cited keyworded and annotated

u s i ng ARTF I LE vers i on 3 02 software for l i brar i es and b i bl i ographic

storage

Two outputs were devel oped from the comp i l ed i nformat i on 1 )

annotated c i tation s of each i nd i v i dual report and 2 ) Lake Fact Sheets

wh ich summari ze ava i l abl e i nformat i on on a spec i fic top ic requested by

members of t he study team Lake Fact Sheets and keyword b i bl i ographies

were d i stri buted t hroughout the course of the study as requested by

i nd i vi dual project members Lake Fact Sheets and a key word l i st

fol l ow Annotated c i tat i ons appear i n Append i x 2 A

2-2

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on AQUATIC PLANTS

Entri es i n Bi bl i ography 69

( For more deta i l s on spec i fic top ics pl ease see other fact sheets i e

hydri l l a b i omass harvest i ng etc )

Types of stud i es noted

- -Aquat ic pl ant ecol ogy (Moss 1980 23 Lugo and Snedaker 1971 113

Bl ackburn n 11 1968 128 Canfi el d et J 1983 260 Cassan i and

Caton 1985 352 Marshal l 1984 386)

- -Informat i on on aquat i c pl ant communi t i e s as habi tat (Wi l ey etI 1984

34 Durocher niI 1984 38 Mi l l eson nI 1980 40 Watki ns et I

1983 45 Ager and Kerce 1974 190 Sav i no et il 1985 196 Richard

n iI 1985 262)

- -Aquatic pl ant and sed i ment rel ati onsh i ps (Engel and N ichol s 1984 44

Barko and Smart 1986 106 Barko et 11 1983 147 L i et I 1974

108)

- -Aquat i c p l ant management ( Fl or ida DER nI 1986 415)

- - Nutrjent removal by aquat i c pl ants ( Reddy and DeBusk 1985 132)

- -Stud i es on harvest i ng aquat i c pl ants and the effects of harvest i ng

( Carpenter and Adams 1978 17 Sabol 1987 37 Mi ko l 1985 41

Wi l e 1978 57 Neel n 11 1973 114 N ichol s 1974 115

Smal l et

I 1985 130 Wi l e 1975 135)

- -Stud i es on chemical and other control s of aquat i c pl ants ( H i l t i bran n

J 1972 105 Ganstad 1978 110 deNoyel l es and Kett l e 1980 118

M i l on n 11 1986 119 Smal l et I 1985 130 Sutton and Vand i ver

1986 139 Lesl i e and Kobyl i nsk i 1985 255 Langel and and DeMont

1986 227 Barrett 1981 342 Barrett and Murphy 1982 344 Cl ayton

and Tanner 1982 355 Frank and Comes 1967 364 Graham 1976 369

Hughes and McCol l 1980 377 Richard et I 1984 426)

- -Aquat i c pl ant chem i s try and phys i ol ogy ( LaLonde 1970 107 Gerl off

1978 111 Gerl off 1973 112 Bri stow and Wh i tcombe 1971 136)

- - Chl orophyl l a concentrat i ons and aquat i c macrophytes ( Canfi e l d et I

1984 263)

2-3

Produced by Mote Marine Laboratory for South Florida Water Management District

- -B i omass stud i es and methods ( Schl oesser and Manny 1984 14 Mace i n a

J il 1984 33)

- -Uses for aquat i c weed s such as cattl e s i l age ( Bagnal l n l 1978

18) and compost (Wi l e g1 Jl 1978 19)

--Stud i es concern i ng Hydrilla vertic1llata ( Bagnal l 1980 18 Bol e and

Al l an 1978 15 P i erterse J il 1984 42 Bruner and Batterson 1984

43 Bowes 11 il 1979 47 Sutton 1982 52 Sutton and Port i er 1985

53 Sutton and Port i er 1983 57 McGhehee 1979 57 Bal c i unas 1985

116 Mart i n 1983 146 Johnston n Jl 1983 36 Canfi el d et l

1983 265 Mace i n a and Shi reman 1982 281 Hodgson and Carter 1982 423)

2-4

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fa c t She e t on BIOMASS

Entri es i n B i bl i ography 14

Types of stud i es noted

- -A troph i c state i ndex for l akes based on al gal bi omass (Carl son 1977

2)

- -Chl orophyl l -b i omas s - nutri ent rel ati onsh i ps for phytopl ankton (Canfi el d

et gl 1985 4)

--An assessment of bi omass control for water qual i ty management (Wong et

li 1979 9) --Methodol og ies for est imat i ng or measuri ng bi omass (Schl oesser and

Manny 1984 14 Mace i na g1 li 1984 33)

--Effects of harvest i ng or other weed control methods on aquat i c

vegetat i on b i omass (Mi kol 1985 41 Wi l e 1978 57 Cassani and Caton

1985 352 Hughes 1974 378 Sch i l l er 1983 398)

--B i omass measurements rel ati ng seasonal and b i otype vari at i ons i n

Hydr i l l a (Bowes et 11 1979 47 Steward 1987 408)

--Seasonal b i omas s of sel ected spec i es (Bowes et li 1979 47 Dewey et

l 19a1 266)

SUMMARY

Several stud i es use b iomass as a measure of aquat i c pl ant control

and as part of overal l assessments of water qual i ty management Mi ko 1

(1985) uses total pl ant bi omass measurements to asses s the effects of

mechan i cal harvesti ng on aquat i c vegetati on Wi l e (1978) al so presents

bi omass data as part of an assessment of envi ronmental effects of

mechan i cal harvesting Cassine and Caton (1985) asses s the same for

chem i cal and b i ol og i cal weed control Mace i na et li (1984) present a

method for est i mat i ng submersed pl ant bi omass by us i ng a record i ng

fathometer The i r data showed that the tech n i que i s not equal l y rel i abl e

for al l water bod i es However accurate b iomass determi nat i ons cou l d be

obt ai ned i f fathometer traci ngs are cal i brated w i th actual b i omas s data

Add i t i onal b iomass data for aquat i c p l ants are presented by Hughes

2-5

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

( 1974) Sch i l l er ( 1983 ) and Steward ( 1987 ) Bowes n il ( 1979) and

Steward ( 1987 ) present bi omass data for Hydri l l a i n Fl ori da

Canfi e l d et il ( 1985 ) address chl orophyl l - bi omass - nutri ent

rel at i onsh i ps for n atural assembl ages of Fl ori da phytopl ankton Carl son

( 1977 ) presents a troph i c state i ndex for l akes and uses al gal b i omass as

a parameter for the i ndex

2-6

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STU DY

Fact Sheet on D IQUAT

Entr i es i n B i bl i ography 84

Types of stud i es noted

- -Taxi c i ty data ( Mayer and El l ers i eck 1986 270 Berry and Schreck

1976 346 Funderburk and Lawrence 1967 366 Howe and Wri gt 1965

376 Kam W i ng and Furtado 1977 381 Naqui et Ai 1980 390)

- - Effects of d i quat on aquat i c commun i t i es ( H i l t i bran I 1972 105

Berry sl 1964 347 Cas san i and Caton 1985 352 Cal derban k 1972

351 C l ayton 1986 356 Dan i el 1972 358 G i l derhus 1967 368

Haag 1986 370 H i l senhoff 1966 372 Hughes and McCol l 1980 377

Joyce and Thayer 1986 379 Marshal l 1984 386 M i chaud 1979 387)

- -General chem i cal control gu i des and control of spec i fi c aquat i c

pl ants (Abery 1986 339 Barrett 1981 342 Barrett and Murphy 1982

344 Barrett and Logan 1982 345 Chevron Chemi cal Corp 1978 354

Hi l t i bran 1971 373 H i mel n li 1981 375 Ki l l gore 1984 383

Mac kenz i e 1966 385 Mobl ey n il 1971 388)

- -Di quat accumul ati on i n pl ants and sed i ments ( B i rmi ngham and Colman

1983 348 Dav i s and Seaman 1968 359 Frank and Comes 1967 364

Langeland and Warner 1986 384)

- - Experi mental data on herb i c i de treatments (Bri t i sh Col umbi a 1975

350 Clayton and Tanner 1982 355 Dunn et I 1983 362 Hal l er

1982 371 K i l l gore 1981 382 Newroth and L i m 1980 392)

- -Di quat u se wi th other types of control s (Charudattan 1986 353 Frank

AI 1979 365 Ganstad 1986 367 Graham 1976 369 Newroth

1974 391)

SUMMARY

I n add i t i on to the above noted stud i es three l i terature summari es and

rev i ews prov ide good i nformat i on on d i quat stud i es

Joyce and Ramey (1986) prov ide a good annotated rev i ew of 1 i terature

concern i ng research on the fate of aquat i c herb i c i de s i n water w i th

emphas i s on Fl ori d a s freshwater ecosystems Tucker (1980) rev i ews 50

c i tat i ons on d i quat c i tat i ons and prov ides a deta i l ed summary on the

2-7

Produced by Mote Marine Laboratory for South Florida Water Management District

foll ow i ng aspects of d i quat env i ronmental chemi stry adsorpt i on by so il

and cl ay mi neral s aerob i c and anaerob i c soi l stud i es soi l stud i es under

fi el d cond i t i ons aquat i c studi es soi l l eaching stud i es rotat i onal crop

stud i es photochem i cal degradat i on stud i es and mi croorgan i sm stud i es

Langel and and DeMont ( 1986 ) prov i de a thorough rev i ew of the l i terature

on the detect i on tox i c i ty and pers i stence of d i quat endotha1 1 and

f1 uri done They al so present speci fi c data on stud i es of the pers i stence

of d i quat endothal l and f1 uridone i n North Carol i na ponds and water

movement patterns i n Lake Wheel er North Carol i na

2-8

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fact Sheet on EUTROPHICATION

Entr i es i n Bi bl i ography 12

Types of stud i es noted

- -Eval uati ons of nutri ents i n eutroph i c l akes (Canfi el d 1983 5

Schi ndl er 1971 131 Michaud n ll 1979 387 Lee and Jones 1980

175)

- -Aquati c pl ant probl ems i n eutroph i c l akes (Graham 1976 369 Hughes

and McCol l 1980 377)

--Assess i ng eutroph i cati on based on water qual i ty stud i es ( Federi co et

Al 1981 67)

--Troph i c structure assessments and changes i n eutroph i c l akes ( Gayl e

1975 181 US Envi ronmental Protect i on Agency 1975 161)

SUMMARY

A number of stud i es address eutroph i cati on i n Lake Okeechobee

US Env i ronmental Protect i on Agency (1975 161) reports on Lake

Okeechobee as part of the Nat i onal Eutroph i cat i on Survey and a number of

state gency commi ttee stud i es and eng i neeri ng reports provi de anal yses

of Lake Okeechobee eutroph i cati on (MacGl l n AI 1976 174 Bl ack Crow

Ei dsness Inc 1976 185 Lee and Jone s 1980 175)

Us i g seven years of water qual i ty data Federi co et it 1 (1981

67) i dent i fy annual and seasonal l mnet i c water qual i ty trends exami ne

the re l at i o n s hi p to t r i but ary i n fl ow s i d en tify trends and

quali tyd i scharge rel ati onsh i p s cal cul ate annual l ake materi al budgets

for each year and assess the trophi c status of the 1 ake Gayl e (1975

181) presents a systems model for understanding eutrophicat i on i n Lake

Okeechobee

2-9

Produced by Mote Marine Laboratory for South Flori da Water Management District

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on HARVESTING

Entr i es i n B i bl i ography 15

Types of stud i es noted

--Effects of harvesti ng aquat i c pl ants on nutr i ent removal ( Bol e and

Al l an 1978 15 Wi l e 1978 57 Neel et AI 1973 114)

--Compari sons of mechan ical and b i ol og i cal harvest i ng wi th herbi c i de

control ( Carpenter and Adams 1978 17 Smal l et AI 1985 130

Sch i l l er 1983 398)

--Di sposal of and uses for harvested hydri l l a ( Bagnal l et AI 1978 18

Sabol 1987 37)

--Harvest i ng effects on aquat i c fl ora and fauna (Mi kol 1985 41 Wi l e

1978 57 N i chol s 1974 115 Wi l e 1975 135 Schramm et AI 1985

212 Lesl i e and Kobyl i nsk i 1985 255)

- - Economi c s of mechani cal harvest i ng (McGhehee 1979 57)

- - Phys i cal propert i es of hydri l l a for harvesti ng ( Bagnal l 1980 59)

SUMMARY

Most of the stud i es address the effects of mechan i cal ly harvest i ng

aquat i c pl ants Bol e and Al l an (1978) report that the harvest i ng of

Hydr i l la vert i c illata woul d result i n the d i rect transfer of onl y a smal l

amount of phosphorus i n the soi l i nto the water and the organ i cal l y-bound

phosphorus removed i n harvested pl ants woul d be deri ved l argely from the

sed i ment and not the water body W i l e (1978) and Neel n AI (1973)

present data and anal yses on l ake nutri ent dynam i cs resul t i ng from

harvest i ng aquat i c pl ants W i l e (1978) al so presents data on al gae

phytopl an kton fi sh and water qual i ty changes

A number of other stud i es address harvest i ng affects on fl ora and

fauna Mi kol (1985) reports that harvest i ng pl ants al so removed from 2-

8 of the total stand i ng crop of juven i l e fi sh Lesl i e and Kobyl i ns ki

(1985) address benth i c macro i nvertebrate response to aquat i c vegetat i on

removal wh il e Sabol (1087) addresses the env i ronmental effects of aquat i c

d i sposal o f chopped hydr i l l a

2-10

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

Compar i sons of mechan i cal harvest i ng and herbi c i des address

phosphorus cycl i ng (Carpenter and Adams 1 978) and Smal l et Jl ( 1 985)

report that herbi c i des reduced aquat i c vegetat i on but d i d not el i mi nate

i t Us i ng grass carp as bi ol og i cal control s el im i nated or red uced the

vegetat i on depend i ng on the stocki ng rat i o ( Smal l et AI 1985 )

2-11

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fact Sheet on Hydrjlla vertic11l ata

Entri es i n B i bl i ography 37

Spec i fi c stud i es on hydri l l a i n Lake Okeechobee i ncl ude a

compari son of dens i ty data for Lake Okeechobee and three other areas of

Fl ori da wi th stud i es spec i fi c to the speci a l i zed reproducti ve structures

of hydri l l a (Sutton and Port i er 1985 53) and an ana lys i s of potass i um

n i trogen and phosphorus content i n hydri 11 a from Lake Okeechobee and

three other areas of Sout h Fl ori da ( Sutton and Porti er 1983 56)

Pl ants from Lake Okeechobee had the h i ghest concentrat i on s of each

Other types of stud i e s on hydri l l anoted

--Phys i cal and mechani cal propert i es of hydri l l a (Bagnal l 1980

59)

--Nutri ent uptake stud i es of hydri l l a (Bol e and Al l an 1978 15)

--Us i ng hydri l l a for s i l age ( Bagnal l et Al 1978 18)

--Methods for determi n i ng or est i mat i ng pl ant biomass (Maceina et

li 1984 33)

--Growth reproduct i on and l i fe hi story of hydril l a ( Langel and and

Sutto 1980 35 Bruner and Batterson 1984 43 Spencer et li 1987

48 Sutton 1982 52)

--Habi tat i mportance and ecol ogy of hydril l a communit i es and

al terations to hydril l a communities (Watkins et li 1983 45middot

Bowes et

li 1979 47 Bl ackburn et li 1968 128 Sutton and Vandiver 1986

139 Can f i el d n Al 1983 265 Mace i na and Sh i reman 1982 281

R i chard i1 Al 1985 396)

--Biol ogical control s of hyd ri l l a (Bal ciunas and Minno 1985 46

Bal ciunas 1985 116 Johnston et li 1983 36 Cas sani and Caton

1985 352)

--Mechanical control s of hydril l a (McGhehee 1979 57)

--Chemical control of hydri l l a (Martin 1983 146 Cassani and

Caton 1985 352 Frank et li 1979 365 Hughes 1974 378 Small et

Al 1985 404 Steward 1972 405 Steward 1982 406 Steward 1976

407 Steward 1987 408 Van 1985 419 Van et Al 1987 420)

2-12

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

SUMMARY

Most of the stud i es deal w ith ways to control Hydr i l l a

verticilJata as a nui sance weed The effects of harvest i ng Hydri l l a i s

frequent l y addressed wi th mi xed resul ts Bol e and Al l an ( 1978) report

that the harvest i ng of Hydri 1 1 a woul d resul t i n the d i rect transfer of

onl y a smal l amount of phosphorus in the so i l i nto the water and the

organ i cal ly-bound phosphorus removed i n the harvested pl ants woul d be

deri ved l argel y from the sed i ment and not the water body

Johnston g1 il ( 1 983 ) report on the recol oni zat i on of a smal l pond

wi th aquat i c vegetat i on where grass carp have been used to control

Hydrill a They demonstrate the feas i b i l i ty o f reduc i ng the compet i t i ve

advantage of Hydri l l a i n order to l l ow other spec i es to become

establ i shed but al so note that care must be exerc i sed i n sel ect i ng

repl acement spec i es Other aquat i c pl ants may grow as prol i fi cal l y as

the Hydri 1 1 a bei ng repl aced

Sabol ( 1 987) and Langel and and Sutton ( 1 980 ) report on the

regrowth of fragmented Hydri l 1 a w i th confl i ct i ng resul t s In f iel d

stud i es Sabol ( 1 987) tested the re -growth potent i al of chopped Hydri 1 1 a

and found that a very smal l port i on of fragments cou1 d produce new

g rowth Conversely Langel and and Sutton ( 1980 ) under control l ed

l aboratory and f i e l d cond i t i ons demonstrated that 40 of the pl ant

fragments wi th one or two nodes were capabl e of vegetat i ve reproduct i o n

Bagnal l 11 il ( 1984 ) eval uated the feas i b i l i ty o f us i ng Hydri l 1 a

for cattl e feed and Macei na 1 il ( 1 984 ) present a method for pred i cti ng

pl ant b i omass us i ng a record i ng fathometer

2-13

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on N ITROGEN

Entri es i n B i bl i ography 27

Types of stud i es noted

- - Land userunoff rel at i onsh i ps w i th nutri ents i ncl ud i ng n i trogen

( Feder i c o 1 977 3 )

- - Nutri ent i n fluences on aquat i c pl ants and phytopl ankton (Canfi el d et

li 1985 4 Can fi el d 1 983 5 Davi s 1980 20 Dav i s 1 982 27

P i eterse 1 984 42 Sutton and Port i er 1 983 56 Bl ac kburn et il

1 968 1 28 Reddy and DeBus k 1 985 13 2 Jones and Federi co 1 984 1 )

- - Water qual i ty stud i es that i ncl ude nitrogen parameters ( Lutz 1 977a

7 Lutz 1 977b 16 M i l ler 1 980 20 Mi l l er et li 1982 26 Dav i s

and Marshal l 1 975 65 Peverl y and Johnson 1 979 394 Jones 1 983

9 )

- - Nutri ent rel at i onsh i ps w i th the troph i c structure of l akes (Henri kson

11 il 1 980 32 Dye 11 il 1975 138)

- - N i trogen and other water qual i ty data for Lake Okeechobee ( Di c kson et

li 1978 66 Davi s and Marshal l 1975 65 Federi co g1 li 1981 67

Fre i betger 1972 69 Mi l l er 1975 70 Jones and Federi co 1984 1

Jones 1 983 9)

- -N i t rogen i nputs and l ake eutroph i cat i on ( Sch i ndl er 197 1 13 1

Feder i co et il 1981 67 Canfi el d 1 983 5 )

- -Den i tri ficat i on i n Lake Okeechobee (Messer et li 1979 1 43 Messer

and Brezon i c 1 984 1 58)

- -Geochemi cal exchanges across the sed i ment -water i nterface ( Burton et

il 1975 1 45 Messer and Brezon i c 1984 158 )

- -Model s pred i ct i ng n i t rogen concentrat i ons (Jones 1983 9 )

SUMMARY

Several stud i es prov i de data on n i trogen for Lake Okeechobee

(M i l l er 1 980 20 Di c kson et li 1978 66 ) Many of these prov ide

n i trogen data as part of l arger studies for i nstance Federi co et li

( 1981 67 ) summari ze seven years of water qual i ty data i n order to

ident i fy annual and seasonal trends cal cu l ate annual budgets and assess

2-14

Produced by Mote Marine Laboratory for South Florida Water Management District

the troph i c state of the l ake Two stud ies ( Fre i berger 1 972 69

Mi l l er 1 97 5 70) i ncl ude lake Okeechobee as part of l arger wet and dry

season nutri ent surveys of South Fl ori d a

Jones ( 1 983 9 ) eval uates the qual i ty o f d i scharges t o Lake

Okeechobee nutr i ent concentrat i ons affects of var i ous changes i n l ake

l evel s and the abi l i ty of var i ous model s to accuratel y pred i ct n i trogen

and phosphorus concentrat i ons Jones and Federi co ( 1984 I) al so apply

nutr i ent model smiddot to Lake Okeechobee Dav i s and Marshal l ( 1 975 65)

present i nformat i on on areal and seasonal vari at i on s of n i trogen l evel s

nutri ent l oad i ngs and budgets for Lake Okeechobee and other chemi stry

d ata

Sutton and Port i er ( 1 983 56) eval uate the potass i um n i trogen

and phosphorus content of Hydri l l a from fi ve l ocat i on s i n South F l ori da

Sampl es were eval uated for wi th i n 1 ocat i on vari abi l i ty and for between

l ocat i on vari abi l i ty and resul ts showed that pl ants from lake Okeechobee

had h i gher concentrat i ons of nutri ents than pl ants from other areas

2-15

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on PHOSPHORUS

Entr ies i n Bi bl i ography 135

Phosphorus stud i es speci fi c to Lake Okeechobee i ncl ude

- -An anal ys i s o f the effect o f reduced nutri ent l oad i ngs on Lake

Okeechobe chl orophyl l (Jones and Feder i co 1984 )

- -An eval u at i on of the qual i ty of d i scharges to l ake nutri ent

concentrat i on s (Jones 1983 )

- -An analys i s of the abi l i ty of vari ous model s to accurately pred i ct

phosphorus concentrat i on s (Jones 1983 )

- -A comp ari son of phosphorus content i n hydri l l a from Lake Okeechobee and

four other l ocat i ons (Sutton and Porter 1 983 )

- -Aer i a 1 and seasonal vari at i ons of phosphoru s 1 eve 1 s i n Lake Okeechobee

(Davi s and Marshal l 1975 )

-A survey of total ortho p l us aci d - hydrol yzabl e phosphorus ( P- P04)

dur i ng a peri od of h igh water and a peri od of l ow water at 1 1 stat i on s i n

Lake Okeechobee and several stat i ons el sewhere i n South Fl or1 da

(Fre i berger 1972 )

- -An anal ys i s of l i mi t i ng factors based on al gal assays on water sampl es

from 30 s i tes i n the Ki s s i mmee R i ver- Lake Okeechobee Bas i n (Dye tl AI

1 975 )

- - Stud i es on nutri ent exchange across the sed i ment-water i nterface

(Burton et il 1975 )

Add i t i onal l y spec i fi c phosphorus d ata for Lake Okeechobee and i t s

watershed are presented i n a number o f reports (Jones and Feder i co 1984

Jones 1983 Mil l er 1980 Davi s and Marshal l 1975 Fre i berger 1 972

Messer et il 1 979 Dye et il 1975 Burton et Al 1975 Lee and Jones

1975 Lutz 1 977 Mi l l er et il 1982 Di ckson et Al 1978 M i l l er 1975)

Regard i ng management pl an s for phosphorus l evel s t he Lake

Okeechobee Techni cal Commi ttee ( 1 986 ) recommended to reduce phosphorus

l oads by at l east 40 (based on the mod i fi ed Vol l enwe i der nutri ent

l oad i ng model s ) through a program of d i vers i ons and treatment

2-16

Produced by Mote Marine Laboratory for South Florida Water Management District

Stud i es out s i de the lake Okeechobee area wh i ch prov i de i nformat i on

val uabl e to the study of phosphorus i ncl ude

- - Uptake of phosphorus from sed i ment and the water col umn by pl ants ( Bol e

and Al l an 1978 Dav i s 1984 Dav i s 1982 Reddy and DeBus k 1985 Dav i s

and Harri s n d li i1 Al 1974)

- -The i nfl uence of 1 and use patterns and other control s on phosphorus

l evel s ( Federi co 1977 Mi chal ski i1 Al 1975)

- -The correl at ion of nutri ent l evel s w i th chl orophyl l and phytopl ankton

l evel s ( Canfi el d i1 Al 1985 )

- - I ndexi ng and model l i ng techn i ques for l akes us i ng phosphorus and

rel ated data ( Carl son 1977 Canfi el d 1983 Meri cas and Mal one 1984)

- - Data on removal of phosphorus by mechan i ca l l y harvest i ng pl ants

( Carpenter and Adams 1978 Wi l e 1978 )

- -Rel ati on sh i p between nutri ents and b i ol og i cal parameters ( Henri kson g1

Al 1980 Pi eterse 1984 Enn i s 197 5 Re i nertsen 1 986 )

- - Phosphorussed i ment i nteract i ons (Twi nch and Peters 1984 li et li

1 97 1

- -laboratory and other control l ed stud i es on the propert i es of phosphorus

( Shannon and lee 1966 li et li 197 1 )

--Other l i terature stud i es ( Sch i ndl er et Al 197 1 )

2-17

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on PHYTOPLANKTON

Entr i es i n B i bl i ography 8

Types of stud i es noted

- - Phytopl ankton stud i es for Lake Okeechobee (Marshal l 1977 1 2 Dav i s

and Marshal l 1975 65 Marshal l 1977 424 Jones and Federi co 1 984

1 )

- - Phytopl anktonnutri entl ake eutroph i cat i on rel at i onsh i ps (Canfi el d et

AI 1985 4 Sch i ndl er 1971 13 1 Hughes and McCol l 1 980 377 Jones

and Federi co 1 984 1 )

- - Phytopl ankton pri mary producti on methodol ogy ( Schearer et AI 1985

278)

--Phytopl ankton responses to aquat i c pl ant removal (R i chard et AI 1985

426)

SUMMARY

Dav i s and Marshal l ( 1975 65) present 2 - 12 years of

phytopl an kton dens i ty data for Lake Okeechobee as wel l as i nformat i on on

n i trogn and phosphorus l evel s ( areal and season al vari at i on s ) pri mary

product i v i ty changes in al gal popul at i on s nutr i ent l oad ings and

budgets ra i n fal l chemi stry dat a regress i on anal yses on bi ol og i cal

act i v i ty and chemi cal or phys i cal propert i e s and trophic state

Marshal l s ( 1 977 1 2 ) phytopl ankton dens i ty data for 1974 show peaks i n

May and September i n Lake Okeechobee Marshal l concl udes that Lake

Okeechobee exh i b i t s seasonal patterns and peri od i c i ty typ i cal of

temperate l akes al though the seasonal vari at i on i n den s i t i es i s typi cal

of a trop i cal l ake

Jones and Federi co ( 1984 1 ) present over four years of d ata on

chl orophyl l a pri mary product i v i ty phytopl ankton dens i t i es and domi nant

species They al so an al yze the effect of reduced nutri ent l oad i ng s on

L a ke Okeechobee chl orophyl l and concl ude that chl orophyl l and

product i v i ty l evel s have not changed substanti al l y dur i ng the study

peri od except that peak val ues were h i gher i n 1981

2-18

Produced by Mote Marine Laboratory for South Florida Water Management District

Canfi el d n li ( 1985 4) col l ected data from 165 Fl ori da l akes

and reported a s i gn i fi cant correl at i on between chl orophyl l a

concentrat i ons and phytopl ankton bi omass Mul t i pl e repress i on anal yses

i nd i cated that phytopl ankton bi omass was dependent on both the total

phosphorus and total n i trogen concentrati on Nutri ent-phytopl ankton and

Secch i - phytopl ankton rel ati onsh i ps for the Fl orida l akes had h i gher

coeffi c i ents of determi nat i on i f chl orophyl l a concentrat i ons rather than

bi omass data were used

2-19

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fa ct Sheet on PRIMARY PRODUCTIVITY

Entries in Bibl iography 11

Types of studies noted

- -General ecol ogy studies incl uding primary productivity (Fontaine and

Ewe l 1981 31)

- -Trophic studies of l akes (Henrikson it 11 1980 32)

--Nutrient infl uences on primary productivity (Davis and Harris no date

141)

- -Primary production methodol ogy (Shearer l1 11 1985 278)

--Primary production data in Fl orida (Odum 1974 169 Brezonic et 11

1979 155 Jones and Federico 1984 1 Davis and Marshal 1975 65

Marshal l 1974 424)

- -Seasonal primary productivi ty cycl es (Comita 1985 1195 Marshal l

1974 424)

SUMMARY

Severa 1 stud i es concern primary production in Lake Okeechobee

Brezonjc l1 11 (1979 155) report to the Fl orida Sugar Cane League on

factors affect i ng primary product ion n Lake Okeechobee Jones and

Federico (1984 1) present primary productivity data on Lake Okeechobee

for 1974-76 and 1979-82 as wel l as information on chl orophyl l a

phytop 1 ankton dens i ties and domi nant spec 1 es and an anal ys s of the

effect of reduced nutrient l oadings Their report concl udes that

ch l orophyl l and productivity l evel s have not c hanged substantial l y during

the study period except for peak val ues that were higher in 1981 and

overal l val ues were higher In the Lake s north end Marshal l (1974

424) add resses seasonal changes for primary productivity and

phytopl ankton He concl udes that considering primary productivity and

other factors Lake Okeechobee phytopl ankton dynamics resembl e temperate

l akes Davis and Marshal l (1975 65) present over two years of data on

chemical and biol ogical investigations of Lake Okeechobee incl uding

primary productivity

2-20

Produced by Mote Marine Laboratory for South Florida Water ManaQement District

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet o n SED IMENTS

E ntr i es i n B i bl i ography 21

Types of stud i es noted

Most of the stud i es i nvol ve sedi ment nutr i ent ava i l abi l i ty fl uxes

and uptake by pl ants These i ncl ude reports on

-- Laboratory experiments to determi ne phosphorus uptake from the

sed i ments by Myri ophyl l ym and Hydri l l a ( Bol e and Al l an 1978 1 5 )

- - Phosphate exchange i n l ake sed i ments (Twi nch and Peters 1984 295 L i

et l 197 1 1 49 li Al 1973 )

- -Ava i l ab i l i ty of sedi ment phosphorus for macrophytes ( L i et l 1974

108)

- - Phosphorus fl uxes i n south Fl ori da marshes (Dav i s and Harri s no date

143 )

- -The i mportance of den i tr i fi cati on i n lake Okeechobee (Messer et l

1979 1 43 )

- -Geochemi cal exchanges across the sed i ment -water i nterface i n the

Ki s s i mmee Ri ver- Lake Okeechobee watershed ( Burton g1 l 1975 145)

- - lak sed i ment den i tri f i cat ion model s (Messer and Brezon i c 1 984 1 58)

There are al so a number of stud i es concern i ng the rel at i onsh i p of

sedi ment type and other factors to pl ant growth ( Bruner and Batterson

1984 43 Mart i n 1983 146 Barko et il 1983 147 Engel and

N i chol s 1 984 44 Barko and Smart 1986 106) pest i c i de and other

chemi cal res i dues i n sedi ments ( Pfeuffer 1985 298 Hughes and McCol l

1980 377 S i ms i man and Chesters 1976 402 )

SUMMARY

BUrton et l ( l979) documents the rol e of sed i ments i n determi n i ng

water qual i ty i n the Ki s s immee Ri ver-lake Okeechobee watershed wi th an

emphas i s on nutri ent exchange across the sed i ment -water i nterface They

a l so prov ide survey i nformat i on on sediment d i str i but i on and transport

Mes ser et l ( 1979) summari zes the i mportance of den i tr if i cat i on i n lake

Okeechobee i ncl ud i ng a d i scuss i on on the rol e of sedi ments i n the

2-21

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

den i tr i fi cat i on process

eval uat i on o f l ake sed i ment

Lake Okeechobee

Messer and Brezon i c ( 1 984 ) present an

den i tri fi cat i on model s and i ncl ude data from

Dav i s and Harri s ( n d ) provi de est i mates of phosphorus fl uxes

wh i ch d i rectly contri bute to uptake through pl ant growth and to retent i on

through pl ant detri tus sed i mentat i on for the Evergl ades Conservat i on Area

2

2-22

LAKE OKEECHOBEE LITERATURE REVIEW

LIST OF KEY WORDS

ABUNDANCE ( 2 ) ADSORPTION ( 2 ) AGE (1) AGRICULTURE (1) ALGAE (14) ALGAL BIOASSAY (1) ALGICIDES ( 2 ) ALKALI N I TY (1) ALKALOIDS (1) ALTERNANTHERA ( 2 ) ALTERNATHERA (1) AMMONIA (1) AMPH I PODS (1) ANALYSIS OF COVARIANCE (1) ANIMAL BEHAVIOR (1) ANIMALS ( 2 ) AQUATHOL (1) AQUATIC PLANT CHEMISTRY (1) AQUATIC PLANTS (76) AQUATIC ORGANISMS ( 2 ) AQUATIC ( 1 ) AQUIFER ( 2 ) ARGULUS ( 1 ) ARTHROPODS ( 1 ) ATHERINE FISH (1) BACKPUMPING ( 2 ) BACTERIA ( 3 ) BASS (18) BEACH HAB ITATS ( 2 ) BEHAVIOR ( 2 ) BENTHOS (9 ) BEST MANAGEMENT PRACTICES (1) B IOACCUMULATION (1) BIOASSAY (1) BIOLOGICAL CONTROL (8) BIOLOGY ( 6 ) BIOMASS (15) BIOTIC ASSESSMENT (1) BIOTYPES (1) BIRDS ( 2 ) BLACK CRAPPIE (19) BLACK BULLHEADS (1) BLUEGILL ( 1 2 ) BODY FORM ( 2 ) BREEDING (1) BROMAC I L (1) BROOK SILVERSIDE (1) CABOMBA (1)

2-23

CADDISFLIES (1) CADMIUM (1) CALLITRICHE (1) CALOOSAHATCHEE RIVER (5) CANALS ( 2 ) CARBON (1) CARBONATE ROCKS (1) CARBOXYLASE (1) CAREX (1) CATTAI LS (1) CATTLE FEED (1) CENTRARCHIDS (5) CERATOPHYLLUM (5) CHAIN PICKEREL ( 1 ) CHANN ELS ( 1 ) CHAOBORUS (1) CHARA ( 6 ) CHEMICAL CONTROL ( 66 ) CHEMISTRY (10) CHIRONOMID LARVAE (1) CHIRONOMIDS (1) CHLORIDE (4) CHLORINATED HYDROCARBONS (1) CHLOROPHYLL (11) CLADIUM ( 2 ) CLASSIFICATION (1) COEFFICIENT OF DETERMINATION (1) COMMERCIAL FISHERY (2 ) COMMUNI TIES (1) COMMUNITY STRUCTURE ( 7 ) COMPETITION ( 3 ) COMPOST (1) COMPUTER MODELS (1) CONFINING BEDS (1) CONTOUR MAPPING (1) CONTROLLED RELEASE (1) COPEPODS (1) COPPER ( 9 ) COPPER SULFATE (1) CORE SAMPLER (1) COST BENEFIT ANALYSIS (1) CRUSTACEANS ( 2 ) CTENOPHARYNGODON IDE (2 ) CULTURAL CONTROL ( 2 ) CYANATRYN (1) DALAPON (4) DEGRADATION ( 3 ) DEMOGRAPHY (1)

DENITRIFICATION (1) DENSITY (6) DESORPTION (1) DETENTIONRETENTION ( 1 ) DETRITUS (1) DEVELOPMENT (2) DIATOMS (1) DICHLOBENIL (2) DIPOTASSIUM ENDOTHAL ( 1 ) DIQUAT (89) DISCHARGE ( 1 ) DISPERS ION (1) DISSOLVED OXYGEN (14) DISSO LVED SOLIDS (2) DISTRIBUTION (16) DIURNAL (1) DRAINAGE (4) DREDGING (1) DYSTROPHIC (1) EARLY DEVELOPMENT (2) ECOLOGY (15) ECONOMIC ANALYSIS (1) ECONOMICS (1) ECOSYSTEM (1) EFFLUENT REDUCTION (1) EFFLUENT (1) EGERIA (6) EICHHORNIA (13) ELODEA (20) EMBRYO ( 1 ) ENDOTHAL-POTASSIUM ( 1 ) ENDOTHALL (20) ENTRAINMENT (2) EPIPHYTES (1) EUTROPHICATION (12) EVERGLADES ( 9 ) EVERGLADES COUNTY (1) EXOGENOUS FEEDING (2) EXPLORATION (2) FAUNA (2) FEEDING ( 9 ) FEEDING RELATIONSHIPS (2) FENAC (5) FIRST YEAR SURVIVAL ( 1 ) FISH (130) FLOOD CONTROL (1) FLOODING ( 1 ) FLORIDA (31) FLORIDA EVERGLADES (1) FLORIDA LAKES (4) FLORIDA DUCK (1) FLORIDAN AQUIFER (2)

2-24

F LOW RATES (1) F LURIDONE (9) FOOD CHA I NS (1) FOOD HABITS (2) FOOD (6) FORAGE ( 1 ) FORAGING ( 1 ) FREQUENCY ANALYSIS (1) FRESHWATER SPECIES (1) FRESHWATER DISCHARGE ( 1 ) FRESHWATER (27) FRESHWATER MARSH (1) GEOLOGY ( 9 ) GERMINATION (1) GIZZARD F I SH (1) GIZZARD SHAD (2) GLADES COUNTY (9) GLYPHOSATE ( 6 ) GRAPNEL SAMPLER (3) GRASS CARP (8 ) GREAT BRITAIN ( 6 ) GROUNDWATER (5) GROWTH (11) GROWTH INHIBITORS (1) HABITAT (2) HABITAT PARTITION ING (1) HARVESTING (7) HAUL SEINE ( 1 ) HENDRY COUNTY (9) HERBICIDES (47) HEXAZINONE ( 1 ) HIGHlANDS COUNTY (1) HISTORY (3) HOST SPECIFICITY (1) HYDRILLA (42) HYDROCARBONS (1) HYDROCOTYLE (1) HYDROGEOLOGY (2) HYDROLOGY (17) HYDROPERIOD CHANGES (1) HYGROPHILA (1) HYPERmiddotEUTROPHIC (1) ICHTHYOFAUNA (1) ICHTHYOPLANKTON (2) IDENTIFICATION KEY (1) IDENTIFICATION GUIDE (10) IMAZAPYR (1) IMPOUNDMENTS (3) IMPROVING CATCH (1) INDICATOR SPECIES (1) INORGANIC PHOSPHATE (1) INSECT CONTROL (1)

INSECTS (4) INVERTEBRATES (9) IRON (2) IRON CHELATE (1) IRR IGAT ION (2) ISOPODS (1) JASM INE (1) JUNCUS (2) JUVEN ILE F ISH (5) K ISS IMMEE R IVER (11) LABORATORY STUD IES (1) LAGAROS I PHON (3) LAKE LEVELS (2) LAKE WANAKA (1) LAKE CONWAY (1) LAKE OKEECHOBEE (89) LAKE DRAWDOWN (1) LAKES (75) LAND USE (6) LARGEMOUTH BASS (16) LARVAE (1) LARVAL F ISH (25) LEAF PRODUCTION (1) LEMNA (8 ) LEPOMIS (1) L IFE HISTORY ( 9 ) L IGHT INTENSITY (1) L IGHT TRAPS (1) L IMNOLOGY (2) LI MNO PH I LA (1) L ITERATURE SURVEY (5) L ITHOLOG IC ANALYSIS (3) L ITTORAL (12) L ITTORAL ZONE (9) LOTAC (3) MACRO INVERTEBRATES (12) MACROPHYTES (18) MANAGEMENT PLAN (3) MANGANESE (3) MARION COUNTY (3) MARSH PLANTS (3) MARTIN COUNTY (27) MASS BALANCE MODEL (3) MATERIAL BUDGET (3) MATHEMAT ICAL MODELLING (3) MATHEMATICAL MODELS (3) MECHAN ICAL CONTROL (15) MECHANICAL HARVEST ING (24) METHODS ( 9 ) M ICROBES (3) MICROPTERUS (6) MINERAL RETENTION (3)

2-25

MINERAL ADSORPTION (3) M INERAL NUTRITION (3) MINERALIZATION (3) M ISS ISSI PPI S ILVERSIDE (3) MODELING (6) MODELS (12) MOLLUSKS (3) MONITOR ING (15) MORPHOLOGY (3) MORTALITY (12) MOTHS (3) MOWING (3) MYOMERE NUMBERS (3) MYR IOPHYLLUM (84) MYSIDS (3) NAIDIDAE (3) NAJAS (18) NEKTON (3) NEMATODES (3) NEOCHETINA (6) NETS (6) N ICKEL (3) N ITRATES (3) N ITROGEN (81) NORTHERN P IKE (3) NUPHAR ( 9 ) NUTR IENTS (141) OCALA GROUP (3) OKEECHOBEE COUNTY (33) OKLAWAHA R IVER (3) OL IGOCHAETES (3) OLIGOTHROPHIC (6) ORANGE LAKE (3) ORGANIC MATTER (3) OSCEOLA COUNTY (3) OXYGEN (9) PALAEOLIMNOLOGY (3) PALM BEACH COUNTY (30) PAN ICUM (67) PARAQUAT (39) PARTICULATE MATTER (3) PASPALUM (3) PATHOGENS (3) PERI PHYTON (3) PERSISTENCE (9) PESTICIDES (27) PH ( 9 ) PHOSPHATE (15) PHOSPHORUS (135) PHOTOSYNTHES IS (12) PHYS IOLOGY (12) PHYTOPLANKTON (27)

PHYTOTOXICITY (3) PIKE (3) PISCIVOROUS FISH ( 6 ) PISTIA (15) PLANKTON (15) PLANNING (3) PLANT SUCCESSION (9) PLANT HARVESTING (9) PLANT ABUNDANCE ( 6 ) PLANT DENSITY (3) PLANT COMMUNITIES (9) PLANT SURVEY TECHNIQUES (9) PLANT COMPOSITION (9) PLANT NUTRITION (3) PLANT GROWTH ( 6 ) PLANT BIOMASS (3) POLLUTION (3) POLLUTION CONTROL (3) POLYCHAETES (3) POLYMER ( 6 ) POMACEA (3) POHOXIS ( 6 ) PONAR GRAB SAMPLER (9) PONDS ( 6 ) POPULATION DYNAMICS (9) POPULATION (21) POTAMOGETON (57) POTASSIUM (9) PREDATION (3) PREDATOR - PREY (15) PRIMARY PRODUCTION (36 ) PROPAGU1ES (3) PUMP STATIONS (3) PUMPING (3) RADAR (3) RADIOPHOSPHORUS (3) RAINFALL (18) RANUNCULUS ( 6 ) RATS (3) RECLAMATION ( 3 ) RECORDING FATHOMETER (3) RECRUITMENT (3) REDBREAST SUNFISH (3) REDEAR SUNFISH (3) REFERENCES (3) REGRESSION ANALYSIS (15) RELEASE RATES (3) REMOTE SENSING (3) REPRODUCTION (12) RESERVOIRS (51) RESIDUES (27) RESOURCE PARTITIONING (9)

2-26

RESPIRATION (3) REVIEW (3) RIVERS (42) RUNOFF (33) SAGITTARIA (3 ) SALVINIA (18) SAMPLING (15) SAMPLING METHODS ( 6 ) SAMPLING GEAR (3) SCIRPUS (3) SEA LEVEL RISE (3) SEASONAL EFFECTS (12) SEASONAL SUCCESSION (3 ) SEASONAL (9) SECCHI DISK (9) SEDIMENTARY ROCKS (3 ) SEDIMENTS (78) SEEPAGE (12) SEWAGE DISCHARGES (3) SHAD (15) SHINERS (3) SHOREFLIES (3) SHORELINE AREAS (3 ) SILICA (3) SILICON (3) SIZE CLASS ( 6 ) SNAILS (3) SODIUM ALGINATE ( 6 ) SODIUM (3) SOILS (9) SOUTH FLORIDA (24) SPARGANIUM (3 ) SPAWNING (21) SPECIES DIVERSITY (3 ) SPECIES COMPOSITION (3 ) SPECIFIC CONDUCTANCE (15) SPOTTED BASS (3 ) ST LUCIE ESTUARY (3 ) ST JOHNS RIVER (3 ) ST LUCIE COUNTY (3 ) STANDING CROP (15) STOCHASTIC LAKE MODELS (3 ) STORHWATER (3) STRATIGRAPHY ( 6 ) STREAMS (9) SUNFISH (18) SURFACE DISCHARGES (3) SURFACE WATER (21) SURFACTANTS ( 6 ) SURVIVAL ( 3 ) SUSPENDED SOLIDS (3 ) SWIM PROGRAM ( 3)

TAYLOR CREEK (6) TAYLOR CREEK WATERSHED (3) TEMPERATURE (9) TENNESSEE (6) TERRESTRIAL (6) THREADFIN SHAD (15) TILAPIA (3) TOXICITY (36) TRACE METALS (3) TRANSMISSIBILITY (3) TRANSPARENCY (6) TROPHIC STRUCTURE (30) TUBER PRODUCTION (3) TUBER DENSITY (3) TURBIDITY (12) TURION (9) TYPHA (9) UPPER TAYLOR CREEK (3) USGS (3) UTILIZATION (3) UTRICULARIA (3) VALLISNERIA (15) VAUCHERIA (3) VEGETATED HABITATS (3) VEGETATION (15) VEGETATIVE PROPAGULES (3) VEGETATIVE REPRODUCTION (6) VELOCITY (3) VERTEBRATES (3) WASTELOAD ALLOCATION (6) WASTEWATER TREATMENT (6) WASTEWATER (3) WATER SUPPLY (12) WATER RECYCLING (3) WATER LEVELS (6) WATER CONSERVATION AREA 2A (3) WATER CHEMISTRY (21) WATER QUALITY (Ill) WATER MANAGEMENT (6) WATER LEVEL (9) WATER CIRCULATION (3) WATER BUDGET (3) WATERSHED ANALYSIS (3) WEIGHT DISTRIBUTION (3) WEIR BOX (3) WET AND DRY SEASON (9) WETLANDS (9) WHITE CRAPPIE (6) WILDLIFE (3) WITHLACOOCHEE RIVER (6) WOLFFIA (3) XYLENE (6)

2-27

ZINC (3) ZOOLOGY (3) ZOOPLANKTON (21)

I I I BIOMASS - M ID-COURSE SUMMARY

I I I A INTRODUCT ION

The experimental removal of Hydr i l l a vert i c i 1 1 ata R i s bei ng

conducted to prov ide removal of nutr i ents phosphorus i n part icul ar from

Lake Okeechobee as wel l as the anc i l l ary benefi ts of i ncreased fi sh

hab i tat and nav igat i onal acces s To determi ne benefi ts and costs of

removal an i ndependent est i mate of both b i omass and nutri ent content of

vert i ci l l ata has been conducted

The bi omass sampl i ng effort was conducted i n August 1987 and was

compl eted pri or to the actual harvest i ng Stat i ons were concentrated i n

the area of the Hydri l l a mat but some non -Hydr i 1 1 a spec i es were al so

col l ected Sampl i ng l ocat i ons were sel ected on the bas i s of qual i tat i ve

cl ass i ficati ons of Hydri l l a growth character i s t ics

Based on fi e l d reconna i ssance i n Aprll and Ju l y 1987 a

s ubstant i al amount of spati al nonhomogene i ty i n both weed dens i ty and

spec i es compos i t i on was observed throughout the proposed s tudy s i te A

vari ety of env i ronmental factors such as substrate compos i t i on water

qual i ty and to a l es ser degree l i ght penetrat i on and water depth may

have been respons i bl e for these observed d i fferences Any past

appl icat i on and poss i bl e res i dual effects of weed control herb ic i des may

al so be contr i buti ng envi ronmental factors As growth character i st ics

w i th i n th i s area were not un i form i t was assumed un l i ke ly that nutri ent

content was evenly d i stri buted To quanti fy these area -wi de var i ati ons

a s ampl i ng scheme emphas iz i ng the range of Hydril l a growth cond i t i ons was

des i gned

III B MATER IALS AND METHODS

I I I B 1 Sampl e Col l ecti on

Prec i s i on measurement of Hydri l l a bi omass i s h igh l y dependent upon

the representat i veness of the sampl es as wel l as evenness of growth

character i st ics wi thi n the study s i te As di fferences i n dens i ty had

3 - 1

been observed duri ng reconnai ssance surveys fi ve Hydri l l a cond i t i on

factors were establ i shed ( see Tabl e 3 1 ) Stat i ons were apport i oned

among these fi ve categor i es rat i ng sel ected s i tes accord i ng to these

cond i t i on factors to i nsure that comparabl e representat i ve sampl es were

col l ected

As a resul t fi fteen ( 1 5 ) stat i ons were establ i shed wi th i n the

weed harvest i ng area ( Fi gure 3 1 ) Sampl i ng l ocat i ons were fi xed and

recorded i n the fi e l d us i ng Loran C (Apel co model DXL -6000 ) Sampl e

col l ect i on at each stat i on con s i sted of three repl i cated cl i pped - pl ots of

Hydri l l a removed from wi thi n a 202Sm2 sampl i ng dev i ce pl aced on the

substrate The sampl i ng box was constructed of steel pl ate 3 mm th ick

The overal l des i gn was s imi l ar to that descri bed by Mart i n and Sherman

( 1979 ) The top of the box however was covered by a d i amond pattern

screen wi th an attached hook to fac i l i tate l i ft i ng the sampl er wh i ch

contai ned the Hydr i l l a sampl e i nto the boat

The sampl er was l owered to the substrate and the Hydri l l a adjacent

to the edge of the box was cut by the d i ver wi th a kn i fe The bottom

sl i d i ng pl ate was then i nserted to conta i n the Hydri l l a sampl e and the

sampl er was then retri eved to the surface

Onl y the above- substrate port i ons of the pl ant were col l ected

s i nce thi s was cons i dered to be the port i on of the pl ant subject to

removal by the mechan i cal harvester Unconsol i d ated detri tal materi al

and roots were not col l ected Any non -Hydri J 1 a macrophytes col l ected

were separated from the Hydri l l a sampl es and treated as d i screte sampl es

Each l abel l ed repl i cate sampl e was we i ghed separatel y to the nearest gram

to determ i ne fresh wet we i ght s The i nd i v i dual repl i cates were then

i ced and shi pped to the l aboratory for dry we ight and nutr i ent content

analys i s

Add i t i onal fi el d procedures i ncl uded a near-fi el d and obl i que

photograph taken at each bi omass sampl i ng stat i on

3-2

I I I B 2 Anal yt i cal Methods

Percent mo i sture was determi ned on al l sampl es Sampl es were

dri ed at 103 - 1050C and the dri ed materi al was used i n n i trogen

phosphorus and potass i um anal yses A total of 52 sampl es were processed

(45 Hydri l l a and 7 non - Hydrjl l a fract i ons ) by MML Total Kjel dahl

n i t rogen and total phosphorus were analyzed from dri ed ground pl ant

materi al Methods ut i l i zed were from the AOAC Methods of Anal ysi s 13th

Ed i t i on 1980 Kjel dahl d i gesti on i n a bl ock d i gester of l ess than O lg

pl ant materi al was fol l owed by sampl e reconst i tut i on automated d i l ut i on

and col ori metri c determi nati on o f amon i a and phosphate by Techn i con

AutoAnal yzer II The resul tant n i trogen and phosphorus concentrat i ons

were converted to a dry we i ght basi s

Procedures for the potass i um anal ysi s are deri ved from the AOAC

Methods of Ana lys i s 13th Ed i t i on 1980 Less than 0 3g of dri ed ground

p l ant materi al was d i gested wi th n i tr ic and perchl ori c ac i ds d l l utjed

wi th 1+1 hydrochl ori c ac i d and anal yzed by atomi c adsorpt i on

1 1 1 B 3 Dat a Management

B i omass data col l ected duri ng thi s study was used to generate the

fol l ow i ng types of data

o Wet and dry wei ghts of Hydri l l a expressed as gm2

o Nutri ents [n i trogen ( N ) phosphorous ( P) potas s i um (K ) ]

per we i ght of Hydri l l a

I I I C I NTERMIM RESULTS - BIOMASS

I I I C l B IOMASS ANALYSIS

Monocul tures of Hydri l l a were present except at Stat i ons 1 2 5

9 and 13 At these fi ve l ocat i ons i nc i dental col l ect i ons of

Ceratoohyl l um sp were made I n i t i al process i ng of these sampl es

cons i sted of separat i ng Hydril l a and non -Hydri l l a spec i es and anal yzi ng

and eval uati ng each fract i on as a d i screte sampl e Once the eval uati on

3 -3

was compl eted b i omass val ues from both sets of sampl es were combi ned to

represent the overal l b i omass harvested from the study are a

B i omass val ues (dry we ights a l l spec i es combi ned ) ranged from

1 9 33 gm2 ( 02 kgm2 ) to 3 1 7 67 gmm2 (0 32 kgm2 ) (Tabl e 3 2 ) The

l ower b i omass val ues were found at stat i ons 1 and 2 wh i ch were nearshore

stat i ons The h i ghest b i omass general l y occurred at the stati ons l ocated

i n the central port i ons of the Hydri 1 1 a mat The range i n wet and dry

b i omass val ues wi th i n a confi dence i nterval of 1 plusmn standard dev i at i on

( SO ) are graph i cal l y presented i n F i gures 3 2 and 3 3 The cons iderabl e

var i at i on i n b i omass val ues among the stati ons i s rel ated to onshy

shoreoff-s hore d i fferences in stat i on l ocat i on and var i at i on in b i omass

maturi ty wh i ch i s descri bed by the prev i ous ly l i sted cond i t i on factors

rhe Hydri 1 1 a cond i t i on factors have been devel oped to prov ide an

i nd i cat i on of the vari abi l i ty of pl ant maturi ty and were used to prov ide

a prel i mi nary eval uati on of the rel ati onsh i p between pl ant maturi ty and

nutrient content The cond i t i on factors recorded at each stat i on dur i ng

b i omass sampl i ng are summari zed i n Tabl e 3 3

The Hydr i 1 1 a b i omass val ues for each sampl i ng stat i on were grouped

accord i ng to the i r respecti ve cond i t i on factor and pl otted ( F i gure 3 4 )

The resul ts of th i s group i ng dep i cts a cl ear pattern of the d i stri but i on

of b i omass versus p 1 ant maturi ty or cond i t i on factor The new growth

cond i t i ons (1 and 2) had the l owest mean bi omass val ues whi l e cond i t i on

4 (mature cond i t i on ) had the h i ghest val ue and cond i t i on 5 (senescence )

i nd i cated a decl i n i ng b i omass of the Hydri 1 1 a mat at the stati on

l ocat i ons The stat i ons sampl ed and the study area were pr i mari l y

con s idered to be represented by a mature growth cond i t i on duri ng the

August col l ecti on Cond i t i on factors ( pl ant maturi ty) are al so rel ated

to nutri ent content as i s subsequently d i scussed

A gross esti mate of b i omass i n terms of areal extent was projected

us i ng the wei ghtarea rat i o for each stat i on and then averag i ng the

rat i os It shoul d be noted however that stat i on sel ect i on for thi s

task was not random and stat i ons were del i beratel y chosen wh i ch

refl ected a range of growth cond i t i ons By the same l og i c l ocat i ons of

transects to be harvested were not random and were chosen i n an attempt

to sel ect maxi mum dens i t i es of Hydri l l a Wi th these qual i fi ers the

3 -4

average b i omass sampl ed ranged from l ess than 1 to over 14 tons per acre

and averaged 7 tonsacre Esti mates for tons of b i omass i n fres h both

wet and dry cond i ti ons al so appear i n Tabl e 3 2 The wet b i omass val ues

represent we ights of the pl ant materi al after surface water has been

removed from the pl ant by bl ott i ng wi th a dry med i um Because of t h i s

handl i ng procedure a d i rect compari son wi th the harvest contractor s

fi el d est i mates (of merely dra i ned materi al ) are not val i d s i nce the

water associ ated wi th the Hydri l 1 a cou l d add a con s i derabl e but unknown

amount to the esti mated total we ight

B iomass sampl i ng i n the study area has been l i mi ted to a s i ng l e

event and the resul t s of the samp l i ng effort do not refl ect seasonal

vari at i ons However Bowes et al ( 1 979) i nvest i g ated the seasonal

Hydri lJ a b i omass product i on of three Fl ori da l akes Lake Trafford

Orange and Jackson Thei r study i ndi cated that the t i me for seasonal

peaks i n bi omass vari ed wi th the southern most 1 ake Lake Trafford

produc i ng the max i mum Hydri l l a bi omass i n August wh i l e the more northern

l akes Orange and Jackson produced more Hydri l l a b i omass i n Novernber

I 1 I C 2 NUTRI ENT REMOVAL

Phosphorus content of Hydri 1 1 a and the potent i al for removi ng

phosphorus from the l ake system was the pri mary focus of the data

anal ys i s Secondary aspects were quant i fyi ng n i trogen and potass i um as

they rel ate to the overal l nutri ent content of the study area and

prov i d i ng i nformat i on for any poss i bl e uses for the harvested materi a l

Tabl e 3 4 summari zes the analyti cal data for bi omass sampl es

col l ected Hydri l l a and total b i omass are tabul ated separatel y s i nce

Hydri l J a i s the target spec i es of the harvest i ng program and i t compri ses

the majori ty of the pl ant materi al i n the study area Inter-spec i fi c

d i fferences i n pl ant chemi cal compos i t i on are al so reported by Boyd

( 1978) as the greatest source of vari at i on i n characteri zat i on stud i es of

aquat i c macrophytes

3 - 5

I I I C 2 1 Phosphorus

Total phosphorus ranged from 9 1 mgg to 2 68 mgg for al l spec i es

comb i ned and 91 mgg to 2 67 mgg for Hvdrill a only (Tabl e 3 4) The

comb i ned data wi th confidence i nterval s ( 1plusmn SO) are shown i n F i gure 3 5

The somewhat h i gher var i at i on i n phosphorus content at Stat i on s 2 5 9

and 13 i s est imated to occur as a resul t of the presence of non -Hvdri l l a

spec i e s at these l ocat i ons Therefore the presence of other spec i es i n

the sampl es ( i f not separated ) i s ant i c i pated to produce data that have a

greater vari abi l i ty and consequently are not as rel i abl e an est i mate of

nutri ent content as des i red for management dec i s i ons

Coeffi c i ents of var i at i on I n phosphorus content were cal cul ated

and pl otted by stat i on for comb i ned pl ants and for Hydr i l l a on l y ( F i gures

3 6 and 3 7) A compari son o f F i gures 3 6 and 3 7 however i ndi cates

that a rel at i vely smal l amount of the vari at i on observed can be

attri buted to the presence of two spec i es at a s i ngl e stat i on F i gure

3 7 demonstrates an i mportant con s iderat i on for any future sampl i ng and

asses sment effort s Sampl es o f Hydri l l a from the extremes of the

cond i t i on factors i e 1 and 5 produce data that may vary from 20 to

more than 30 i n est i mates of phosphorus content

The comb inat i on of cond i t i on factors and means for phos phorous

content at each stat i on i ndi cate a rel ati onsh i p between cond i t i on i e

re l at i ve maturi ty and phosphorus content ( F i gure 3 8) Stati ons wh i ch

cons i st pr imari ly of new pl ant growth (cond i t i on 1 ) contai n the l east

amount of phosphorus on a mgg (p l ant mater i al ) bas i s wh i l e stati on s

wi th pl ants that are descri bed as bei ng i n cond i t i on 4 (mature) have the

greatest amount of phosphorous A dec 1 i ne in phosphorus content al so

apparently accompan i es pl ant senescence

RegreSS i on anal ys i s was conducted to determ i ne the rel at i onsh i p

between b i omass and phosphorus content Because onl y one i ndependent

vari abl e (b i omas s ) was used i n the regress i on mode i t is necessary to

report only the resul ts of the two-tai l ed test u s i ng Student s t shy

stat i ons The nul l hypothes i s for the two -tai l ed test i s that there i s

no rel at i onsh i p between the dependent vari abl e and a spec i fi c i ndependent

vari abl e namel y bi omas s The t -stati st ic generated by the model

3-6

i nd i cated that b i omass s i gn i fi cantly effects phosphorus content at a 43

confidence l evel That i s there i s a 57 chance of i nd i cat i ng there i s

no rel ati onsh i p between b i omass and phosphorus i f the nul l hypothes i s i s

rejected

Add i t i onal stat i st i cal model i ng and an al ys i s i nd i cated that

b i omass at stati ons categori zed as Cond i t i on 4 were s i gn i fi cant ly rel ated

to phosphorous content at onl y a 75 confi dence l evel or a 25 chance

that a re 1 at i onshi p between b i omass and phosphorous content does not

exi st The h i gher confi dence l evel provi des some support for the use of

Hydrj 1 1 a cond i t i on factors part i cul arl y cond i t i on 4 for est i mat i ng the

nutri ent content of Hydri 1 1 a

To prov i de some prel i mi nary est i mates of potent i al phosphorous

removal rel ated to Hydri 1 1 a matur i ty each sampl i ng stat i on s phosphorous

we i ght to area rat i o was determi ned (Tabl e 3 5 ) These rat ios were then

averaged by cond i t i on factor The resu1 tant overal l phosphorus content

ranged from 16 1 bacre (cond i t i on 1 ) to 3 40 1 bacre (cond i t i on 4) and

dupl i cated the trend observed i n the b i omass data ( F i gure 3 4 )

The range of Hydri 1 1 a cond i t i ons factors and the presence o f other

macrophyte spec i es wi thi n the harvest area i nd i cates that further

defi n i t i on of the nutri ent removal est i mates are requ i red Th i s further

quant i fi cati on can be accompl i shed i n part through the use of aeri al

photographs The i nter im report by 15ampT ( 1 987 ) i nd i cates that sca1 ed

true col or and fa1 se col or i nfrared photographs of the study area have

been rout i ne1 y fl own Cop i es of these photographs and vegetat i on maps

wi 1 1 be requested from 15ampT The vegetati on maps produced from these

photographs by 15ampT wi l l be computer d i g i t i zed and acreage measurements

cal cul ated I t shoul d be noted that remote resource sens i ng techn i ques

part i cul arl y stud i es i nvol v i ng submerged pl ants have l i mi tati ons rel ated

primari l y to water depth and cl ari ty These 1 im i tati ons restri ct the

quant i ficat i on of i mmature Hydri 1 1 a represent i ng cond i t i on factors 1 and

2 because i t i s unl i ke1 y these p1 ants can be detected due to thei r

submerged cond i t i on Hydri ll a exh i bi t i ng cond i t i on factors 3 4 and 5

shoul d be v i s i bl e i n the l ate summer aeri al photographs as emergent mats

The fal se col or i nfrared aeri al photographs wi l l al so be anal yzed to

3 - 7

further separate the area i nto cond i t i on factors (3 4 and 5 ) These

refi ned est imates wi l l be i ncl uded in the fi nal report

An i ntegrated seasonal data base on nutri ent content of Hydri l l a

i n Lake Okeechobee i s l acki ng However recent data ( 1 5ampT 1988 )

i nd i cates there may be a pronounced seasonal d i fference i n t he chemi cal

compos i t i on of Hydrll l a from the l ake Hydri l l a sampl es col l ected by

15ampT duri ng January 1988 had phosphorus and n i trogen val ues that were

two to t hree t i mes h igher than the val ues reported for Aug ust 1987

(Tabl e 3 6 )

Spl i t sampl es anal yzed by the same l aboratory wh i ch prov i ded the

I SampT data provi ded veri fi cati on for the August phosphorus data reported

i n th i s study Therefore i t appears to be reasonabl e to assume that an

i ncrease i n Hydri l l a nutri ent content has occurred between August 1 987

and January 1988 The spec i fi c causes for th i s i ncrease are present ly

unknown but Federi co et al 1981 have suggested a nutri ent i nput

mechan i sm for the l ake based on l ake management W i th the fal lwi nter

i ncrease i n l ake surface area nutri ents conta i ned i n the l i ttoral zone

cou l d be transported l ake-ward by the fl ood i ng of the l i ttoral zone

Water qual i ty data from the present study does i n fact i nd i cate an

i ncrease i n i norgan i c phosphorus (P04- P ) from August 1 987 to January

1988 I t may be specul ated that i ncreased nutri ent avai l ab i l i ty may have

produced t h i s i ncrease i n Hydri l l a nutri ent content I t shoul d al so be

noted however that a seasonal i ncrease i n Hydri l l a phosphorus and

n i trogen content may occur i ndependent of any l ake management reg i me

Th i s seasonal vari at i on i n Hydri l l a nutri ent content has i mportant

rami fi cat i ons for any cont i nued or future harvest i ng programs I t al so

creates some add i t i onal quest i ons For exampl e i s th i s Hydri l l a

nutri ent i ncrease a l akewi de phenomenon or i s i t a near fi el d effect that

might be rel ated to the recent harvest i ng I f th i s i s a l akewide

i ncrease i n nutri ent content does it al so produce a correspond i ng

i ncrease i n bi omass so that phosphorus removal per acre cou l d be

max i mi zed I f th i s were true then the seasonal t i m i ng of any future

harvest i ng efforts need s to be careful l y cons i dered

Converse l y i f the wi nter i ncrease i n phosphorus content i s a near

fi el d effect rel ated to harvest i ng then perhaps harvest i ng des i gn i e

3 - 8

n umber and widths of harvested l anes needs to be re -exami ned and t i mi ng

of the harvest i ng may become l ess i mportant S i nce Hydri l l a i s a

n u i s ance spec i es al l prev i ous harvest i ng strateg i es have been a i med

toward weed el i mi nat i on for n av igat i onal purposes Because of th i s

nu i sance status management strateg i es have not been dev i sed or tested to

ut i l i ze Hydrj l l a as a nutri ent removal middotcrop middot For exampl e a seri es of

narrow but cl osely spaced cuts may be v i ewed as crop th i nn i ng wh i ch may

resul t i n greater nutri ent uptake by the adjacent unthi nned port i on of

the middotcrop middot Th i s act i on cou l d al so be coord i nated wi th n av i gat i onal

concerns and where appropri ate habi tat restorat i on or ma i ntenance

1 1 1 C 2 2 Ni trogen

As previ ous l y noted n i trogen has al so been eval uated as part of

the nutri ent analys i s N i trogen (TKN) ranged from 13 45 mgg to 26 34

mgg for al l spec i es combi ned and 13 45 mgg to 26 1 5 mgg for Hydri l l a

onl y (Tabl e 3 4) I ts d i stri but i on among stat i ons ( F i gure 3 9 ) fol l owed

the pattern prev i ousl y d i scussed for phosphorus Thi s pattern i ncl uded

the h i gh vari at i on attri buted to the presence of other spec i es ( F i gures

3 10 and 3 1 1 ) as wel l as the cond i t i on factornutri ent content

rel ati onsh i p of Hydri l l a ( F i gure 3 1 2 )

1 1 1 C 2 3 Potas s i um

The rema l n l ng nutri ent i ncl uded i n the anal ys i s was potass i um

wh i ch vari ed from 10 20 mgg to 26 28 mgg for al l spec i es combi ned and

10 20 mgg to 26 28 mgg for Hydri 1 1 a (Tabl e 3 4) Wi th several mi nor

except i ons potass i um content was a more vari abl e pl ant nutri ent than

e i ther phosphorus or n i trogen ( Fi gure 3 13 ) Thi s vari abi l i ty i n

potass i um content has al so been prev i ousl y reported by Sutton and Port i er

( 1983 )

A c o n s i d erabl e amou n t of the vari abi l i ty i n potas s i um

concentrat i ons was attri buted to the presence of other spec i es ( F i gures

3 1 4 and 3 1 5 ) but even when monocul tures of Hydri l l a are con s i dered a

h i gh amount of vari abi l i ty st i l l exi sts Kl opatek ( 1978) suggests that

3 - 9

vari at i on i n potass i um l evel s i n aquat i c macrophytes may refl ect h i gh

metabol i c demand duri ng the peri od of rap i d growth and that potass i um i s

not stored by pl ants s i nce th i s nutri ent i s read i l y avai l abl e from most

soi 1 s When grouped by cond i t i on factor the h i ghest potass i IJm contents

occurred i n the new or rapi d ly growi ng pl ants (cond i t i ons 1 2 and 3 )

( F i gure 2 - 1 6 ) Potass i um content decreases i n the l atter growth stages

assoc i ated wi th cond i t i on factors 4 and 5

I I I D CONCLUS IONS

The Hydri l l a b i omassnutri ent data anal yzed to date i nd i cates that

there are several important factors to be cons idered for future or

conti nued Hydri l l a harvest i ng programs

o Recogn i t i on and categori zati on of the rel ati ve maturi ty

state (cond i t i on factor) of the Hydri l l a mat i s i mportant

to sel ect sampl i ng l ocat i ons for nutri ent ana lys i s

o Anal ysi s of the nutri ent content of Hydri l l a i s most

preci se i e l owest sampl e vari at i on when col l ected from

areas of the mature mat The extremes of growth cond i t i on

new growth and senescence produced more vari abl e data

requ i ri ng l arger numbers of sampl es for rel i abl e mean

determi nat i ons

o Further testi ng of season a 1 d i fferences i n Hydri 1 1 a

nutri ent content and coup 1 i ng wi th harvest j ng-management

strateg i es cou l d s ign i ficantl y opt i m i ze the amount of

nutri ents removed through mechan i cal harvest i ng

I I I E RECOMMENDATIONS

Based on the data col l ected and anal yzed to date the fol l owi ng i s

the recommended course of act i on

Add i t i onal quant i tat i ve sampl i ng of Hydri l l a i n Lake Okeechobee i s

recommended Th i s add i t i onal sampl i ng effort shou l d be conducted at

3 - 10

1 ocat i ons both wi th i n the present study area as wel l as some 1 ocat i ons

out s i de of the study area Th i s general i zed pl an wi l l test for near

fi el d effects i e those effects that m ight be rel ated to harvest i ng

vs l akewi de effects Th i s sampl i ng effort shou l d be conducted quarterl y

to i nvest i gate the apparent seasonal changes i n Hydri l l a nutri ent

content Sampl i ng shou l d dupl i cate earl i er efforts and shou l d be

conducted at e i ght l ocat i on s four wi th i n and four outs i de of the present

study area

I I I F QUALITY ASSURANCE RESULTS

Tabl e 3 7 deta i l s the prec i s i on and accuracy of anal yt i cal resul ts

of dr i ed pl ant t i ssue Al l data were generated i n groups wi th

sat i sfactory qual i ty assurance cri teri a

3 - 1 1

LITERATURE CITED

Bowes G A S Hol aday W T Hal l er 1979 Seasonal vari ati on i n the b i omas s tuber dens i ty and photosynthet i c metabol i sm of Hydr i l l a i n three Fl ori d a l akes J Aquat i c Pl ant Mgt 17 61-65

Boyd C E 1978 Chemi cal Compos i t i on of Wetl and Pl ants IN Freshwater Ecol ogical Processes and Management Potenti al eds R E Good D F Wh i gham R L S i mpson C G Jackson J r Academi c Pres s N Y 378p

Freder i co A C K G D i c kson C R Kratzer F E Davi s 1981 Lake Okeechobee Water Qual i ty Stud i es and Eutroph i cat i on Assessment Techn i cal Publ i cati on 181-2 May 1981 Resource Pl ann i ng Department South Fl ori da Water Management D i stri c t West Pal m Beach FL 270pp + App

Kl opatek J M 1978 Nutri ent Dynami cs of Freshwater R i ver i ne Marshes and the Rol e of Emergent Macrophytes IN Freshwater Ecol og i cal Processes and Management Potent i al eds R E Good D F Wh i gham R L S i mpson C G Jackson Jr Academi c Press N Y 378p

ISampT 1987 Letter to Mr Ed Terczak dated Sep t 3 1987 Subj ect Chemi cal Anal yses resul ts of sampl es of Hydri l l a and mi crodeus

ISampT 1988 Letter to Mr Ed Terczak dated Jan 25 1988 Subj ect Compari son of nutri ent content i n Hydri l l a and water hyaci nth sampl es from the Demonstrat i on Project study area

Sutton D L and K H Port i e r 1983 Var i ati on of n i trogen phosphorus and potass i um contents of Hydri 1 l a i n South Fl orida J Aquat i c Pl ant Mgt 2 1 87 -92

3-12

Tabl e 3 1

Cond i t i on 1

Cond i t i on 2

Cond i t i on 3

Cond i t i on 4

Cond i t i on 5

Hvdrll l a Cond i t i on Factors to Descri be Pl ant Maturi ty i n the Lake Okeechobee Study Area

Areas of new pl ant growth rooted pl ants are l ess

than a foot h i g h

Pl ant growt h i s v igorou s but does not extend to the

surface P l ant s extend from 12 to 34 of the water

col umn i n height

Pl ant growth i s v igorous reaches the surface not

matted or at l east not brown and dyi ng on the

surface

Pl ant g rowth i s matted at the surfac e fl oat i ng

pl ants trapped s i gns of earl y decompos i t i on

P l ant mats are senescent and some open water i s

evident under mat

Source DSA Group I nc 1988

T-- 3 BiJS s_ bull aty 6 Sct irg 1tilt in _ Ia1 kee--gtee OJ --l l

my WEI lOOS lOOS

station GM2 so KGM2 so ArnE GM2 so KGM2 so ArnE

1 19 33 17 10 0 02 0 02 0 09 197 00 188 04 0 20 0 19 0 88

2 32 00 12 53 0 03 0 01 0 14 364 67 127 36 0 36 0 13 1 63

3 67 00 18 19 0 07 0 02 0 30 636 00 191 01 0 64 0 19 2 84

4 155 00 72 75 0 16 0 07 0 69 1660 33 733 09 1 66 0 73 7 41

5 195 33 85 82 0 20 0 09 0 86 1757 00 720 00 176 0 72 7 84

6 166 33 37 58 0 17 0 04 0 74 1695 33 335 67 1 70 0 34 7 56

7 263 33 56 70 0 26 0 06 1 18 2158 67 538 68 2 16 0 54 9 63

8 67 33 4067 0 07 0 04 0 30 676 33 302 63 0 68 0 30 3 02

9 184 67 94 85 0 18 0 09 0 77 1765 66 719 58 1 77 0 72 7 88

10 317 67 155 28 0 32 0 16 1 42 3165 33 1379 28 3 17 1 38 14 12

11 205 67 82 37 0 21 0 08 0 92 1716 00 500 11 1 72 0 50 7 66

12 200 67 47 60 0 20 0 05 0 90 2192 00 554 43 2 19 0 55 9 78

13 188 67 49 17 0 19 0 05 0 84 2326 00 492 11 2 33 0 49 10 38

14 116 00 29 82 0 12 0 03 0 52 1228 33 334 60 123 0 33 5 48

15 234 67 66 29 0 23 0 07 1 05 1997 33 527 08 2 00 0 53 8 91

Notes GM2= Grams Per Meter Square

SD= staOOald Deviation 1lGM2= Kilograms Per Meter Square

Dlta Ioolules Nan-Hydrilla Values for lhese stations

SOlllCe DSA Group Inc 1988

Tabl e 3 3

Cond i t i on

1

2

3

4

5

Sununary of Hydr i l l a Cond i t i on Factor by stat i on for the Lake Okeechobee study area August 18- 21 1987

Hydri 1 1 a Stat i ons

lt1 h i gh 1 2

12middot34 water col umn i n hei ght 2

at surface not matted 8 1 4 1 5

matted earl y decompos i t i on 4 6 7 1 0 1 1 1 2 1 3

senescent open water 5 9

Source DSA Group I nc 1987

Table 3 4 SUImlary ot Hyt1rllla Nl11rlent conumt nan Ole JaKe UKeeCnacee -oxty AJea 11

--- --------- - - ----- - -

Hydrilla Total Hydrilla Total Hydrilla Total p P TlltN TlltN K K

station I-CG so I-CG so I-CG so I-CG so I-CG so I-CG so

1 1 20 0 35 1 20 0 35 13 45 4 66 13 45 4 66 20 78 9 78 20 78 9 78

2 1 55 0 53 1 40 0 35 15 02 4 80 16 39 2 83 2156 12 06 16 45 6 23

3 1 43 0 06 1 43 0 06 15 78 1 37 15 78 1 37 19 66 6 19 19 66 6 19

4 2 36 0 27 2 36 0 27 20 67 2 76 20 67 2 76 20 57 4 81 20 57 4 81

5 1 28 0 14 1 47 0 30 16 49 0 88 16 93 1 10 19 09 2 11 18 99 1 98

6 1 60 0 02 1 60 0 02 17 16 028 17 16 0 28 23 56 5 57 23 56 5 57

7 0 91 0 07 0 91 0 07 15 58 0 38 15 58 0 38 10 20 0 53 10 20 0 53

8 1 37 0 15 1 37 0 15 13 60 2 50 13 60 2 50 26 28 8 25 26 28 8 25

9 1 45 0 36 1 48 0 39 17 60 2 38 17 73 2 56 18 34 5 30 18 59 5 35

10 1 96 0 14 1 96 0 14 21 35 1 69 21 35 1 69 18 71 2 73 18 71 2 73

11 1 63 0 13 1 63 0 13 16 71 0 37 16 71 0 37 16 60 5 06 16 60 5 06

12 1 81 0 12 1 81 0 12 21 97 1 04 21 97 1 04 14 43 1 37 14 43 1 37

13 2 67 0 27 2 68 25 26 15 2 29 26 34 1 97 15 89 4 52 15 89 4 52

14 2 14 0 09 2 14 0 09 20 68 1 12 20 68 1 12 23 68 1 72 23 68 1 72

15 1 33 0 11 1 33 0 11 14 01 0 47 14 01 0 47 15 82 1 99 15 82 1 99

Note All Values Expressed as Milligrams Per Gram of Dry Weight

50ur0e DSA Group Inc 1988

Tabl e 3 6

Sampl i ng Peri od Pl ant

August 1987

Tops

Steins

Whol e Pl ants

August 1987

Whol e P l ants

+January 1988

Who l e Pl ants

A Compari son of Hydri l l a Nutri ent Content for Samp l i ng Periods Conducted i n August 1987 and January 1987 i n t he Lake O keechobee Study Area

N i trogen Phosphorous (mgg-dry wei ght) (mgg-dry wei ght)

19 5 3 21

10 4 1 49

16 3 1 53

13 45 - 26 15 91 - 2 67

31 2 - 35 2 6 9 - 9 2

Source IST Augu s t 1987 Source DSA HHL August 1987

+Source IST January 1988

Tabl e 3 7 Bi omass anal ys i s qual i ty assurance resul ts

Prec i s i on Accuracy Parameter ( n X RSO SO) ( n X RSO SO)

Total phosphorus 6 3 8 1 4 4 1 0 1 7 6 5

Tota l Kje l dahl n i trogen 8 3 2 2 2 4 1 06 6 1 1 2

Potas s i um 6 3 1 1 8 5 12 1 2 43 5

zB

Figure middot3- 1 BIOMASS SAMPLING LOCATIONS

_c liOn Aalill LAaoaATOAV bullbull DA OAOb INC 18 bull

EVALUATION OF AQUATIC WEED HARVESTING DEMONSTRATION

IN LAKE OKEECHOBEE

Cl M EANS

B I O MAS S WET WE IG HT GRAS METER SQUARE

5--------------------------------------------------

45

4

3 5

3

25

1 5

1

05

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

+ UPPER CONFIDENCE STATION

o LOWER COIJADENCE

re 3 2

w a 4 J a tJ) lr w-ti

o M EANS

500

450-

40

350

300

2 50

20

1 50

1 00

50

0

1 2 3 4

+ UPPER CONfIDB-JCE

_ GPnl IP INC

81 0M-ASS D RY WEIGHT CRAMS METER SQUARE

-1-5 e 7 8 sa 1 0 1 1 1 2 1 3 1 4 1 5

STAriON o LOWER (ONlDENCE

ure 3 - 3

________________________________________________________ -____ G

c- -0 (I) (I) -laquo l 0 m J 0 I-

TOTAL BI O MASS VS HYDRI LLA C ONDITIO N DRY WEIGHT GlA2

3 00--------------------------------------------

2 80

1 80

1 60

1 40

1 20

1 00

80

6 0

40

20

middot0 1 2 3

CONDITION FACTOR IS I GM2 DRY NEIGHT

4 6

Figure 3-4

J laquo It w -It 0 L-a 0 -CL lt)

o M EAtJS

M I LLI G RAM S O F TOTA L P H O S PH O RUS

3--------------------------------------------

1

1 4

1 2

1

08 -1 2 3 4

+ UPPER CONFID ENCE

5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION gt LOWER CONFlDENCE

Figure 3-

z o tr 4 gt IL o

w o b IL W o o

C O EFFI C I ENT OF VARI ATION

TOTAL PHOSFHORUS 1 00-----------------------------------------------

90

80

70

60

50

40

30

2 0

1 0-

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION

i

z o ti gt b o

w o b h W o o

CO EFFIC I ENT OF VARIATION TOTAL PHOSA-lORUS (HtDRILLA ONLY)

I OO------------------------------------------------

90

80

70

60

50

40

30

20

1 0

1

IS I CONDlllON FACTORS STATION

9 1 0 1 1 1 2 1 3 1 4 1 5

Figure 3 -7

c - t) 2 0 -1 0 I-

TOTAL PH O S PH U RS VS H YDR I LLA C O N DITI ON

3--------------------------------------------

28

2

2

1 8

1 6 1 4

1

1 2 3

CONOrTJOt FACTOR -I I MGG my yenEIGHT

4 5

ure 3-8

J laquo cr

2 2 w l-e )- 20 (( 0 b 1 8 0 (-

z 1 6 t= 1 4

1 2

1 0

8

o M EANS

M ILLIGRAMS O F TOTAL KJELDAHL NITROGEN

1 2 3 4

+ UPPER CONFDE1CE

----r f 5 bull 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION ltgt LOWER COtADENCE

-ltlilirA 3-9

z 0

gt La 0

I-Z w

0 La La w

0 0

CO EFFIC I ENT OF VARI ATION

TOTAL l1ltJtJ

4

30

2

1 0

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

IS I CONDITlON FACTOR kZ 1 CV ()

Figure 3-1 0

z o t( tr laquo gt L o

tshyZ W o L L W o o

middot

CO EFFIC I ENT O F VARIATIO N 1lltN (HfDRlliA ONLY)

1 00-----------------------------------------------

90

80

70

80

50

40-

30

20

1 0

IS I CONDlllON FACTORS STATION WJ CV(7) 3- 1 1

0 -lt- z a

I--1 0 I-

30

28

28

24

22

2

1 8

1 8

1

1

2

0 1

TOTAL TKN VS HYDRI LLA CON DITION

2 3

CONDITION FACTOR r ] GG CRY WEIGHT

3- 1 2

-oJ ( tr W gt-cr n L 0 Cl - Cl E

o M EANS

M I LL IG RA M S O F TOTAL POTASSI U M

38---------------------------------------------

2

1

8--------------------- 1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

+ UPPER CONFDENCE STATION

ltgt LCJWER CONFIDENCE

z o n 4 gt LL o

I-shyZ bJ o LL LL W o o

1 00

90

80

70

80

50

40

30

20

1 0

0 -

CO EFFIC I ENT O F VARIATION POTASSIUU

-- _-_------ ------

1 2 3 4 5 8 7 8 1

IS I CONDITION FACTOR STATION ---

l2 J cv(-)

1 4 1 5

3- 1 4

z 0 t a oC gt Iamp-0

--

It

r z w 0 lamp-Iamp-w 0 0

C O EFFIC I ENT O F VARI ATION

POTASSlUA (HfffiILLA 011 Y) 1 00 - - - - - - -- - ---- - - - -- - -- - - - ---- --- - -- - - - - - - - - - - -- - - - - -

90

80

70

60

50

40

30 -

20

-

1 0

0 - 1 2 3 4

IS I CONDIllON FACTORS

l 7

J

r t

I 10 1 1 1 2 13

STATON LUd CV ( )

3- 1 5

TOTAL P OTASS I U M VS HYD RI L LA CON DITI ON

30------------------------------------------

28

28

1 2 3

CONDfTION FACTOR 1 I GG y WEIGHT

4 5

3- 1 8

IV WATER QUALITY SURVEYS

IV A INTRODUCTION

Concerns for water qual i ty i n Lake Okeechobee are pr i mar i l y

focused on nutri ent storage and cycl i ng between the water col umn

sedi ments and bi omass and the impl i cat i ons of these processes for the

current and future troph i c state of the l ake The harvest i ng

demonstrat i on project undertaken by the South Fl ori da Water Management

Di strict and conducted by I nternat i onal Sci ence and Technol ogy I nc

( ISampT) i s one of the remed i al measures proposed to arrest the apparently

i ncreas i ng troph i c state The harvest i ng and subsequent upl and d i sposal

of Hydrj l l a i s bei ng u sed to effect the removal of total nutri ents

( phos phorus in part i cul ar) from the aquat i c system The Di str i ct s

eval u at i on and research project ( EampR) conducted by Mote Mari ne Laboratory

(MML) was des i gned to del i neate other env i ronmental i mpacts and cost

benefi ts associ ated wi th mechan i cal weed removal

The goal of the water qual i ty task of the EampR s tudy was to

del i neate changes that cou l d be attri buted to the removal of dense stands

of Hydri l l a vert i c i l l ata ( Fi gure 4 1 ) Al though the i mmed i ate i mpacts of

weed harvest i ng on water qual i ty may be substant i al those wh i ch

perS i sted over a peri od of t i me were expected to be fai rl y smal l and

l ocal i zed due to the advect i ve barri er of the Hydri l l a mat Accord i ngl y

i n order t o resol ve these changes from background vari abi l i ty grad i ents

of water qual i ty were assumed to exi st across the s i te al though they may

be wea k

The sampl i ng program was desi gned t o al l ow the stat i st i c al

eval uat i on of water qual i ty d i fferences between stat i ons at any one poi nt

i n t i me prov id i ng enough anal yt i cal data to produce mean i ngful

compari sons As a resu l t a mi n i mum of tri pl i cate col l ect i on s per

stat i on were necessary Th i s approach was preferabl e to more frequent

sampl i ngs because i t centered on quant i fy i ng i mpacts at part i cul ar

i nstances rather than on a conti nu i ng bas i s when seasonal processes i n

the study area woul d compl i cate anal yses of data

4 - 1

Water qual i ty i nformati on i s al so necessary for the i nterpretat i on

and anal ys i s of many of the other tasks Phytopl ankton and pri mary

product i v i ty stud i es i n part i cul ar are heavi l y dependent on t h i s task and

wi l l exami ne ava i l abl e nutri ents tox i c compounds ( copper) as wel l as

phys i cal data produced by thi s tas k Accord i ng l y sampl i ngs for water

qual i ty were conducted on each of the days that Envi ronmenta 1 Qual i ty

Laboratory ( EQL) depl oyed primary producti v i ty equ i pment In add i t i on

certa i n parameters (d i ssol ved s i l i cates col or and i norgan i c carbon )

were added to the analyti c al su i te at stat i ons where product i v i ty was

be i ng determi ned Water qual i ty sampl i ngs were al so conducted wi th i n 24

hours of the communi ty metabol i sm task fi el d efforts and wi th i n two weeks

of l arval and juven i l e fi sh sampl i ngs

IV B METHODS

IV B l Water Qual i tv Stat i on locat i ons

The northern 1 200-m (4000 ft ) of Transect 3 was des i gnated as the

experimental transect where a majori ty of the tasks focused the i r

efforts Th i s harvested area was sel ected based upon central 1 ocat i on

wi th i n the study s i te representati veness of the study s i te as a whol e

wi th respect to depth fetch shore proxi mi ty and speci es compos i t i on

and the dens i ty of the Hydri l l a mat of the area

Stat i on l ocat i ons for most sampl i ng s of the water qual i ty task

were i l l ustrated i n F igure 4 2 a superi mposed on the Loran C l i nes mapped

for the study s i te dur i ng the August 1 987 reconnai ssance A tabul at i on

of Loran coordi nates of these stat i ons appears i n Tabl e 4 1 Stat i ons

were establ i shed to defi ne any ex i st i ng water qual i ty grad i ents across

the s i te as wel l as i mpacts due to harvest i ng and so extend beyond the

boundari es of the area schedul ed for harvest Stat i ons 1 2 3 13 1 5

and 1 6 represented the perimeter o f the study s i te Stat i ons 7 - 9 were

l ocated on the northern hal f of Transect 3 the experi mental transect

and represented the treatment stat i ons the treatment be i ng harvest i ng

Control ( unharvested ) stat i on 10- 1 2 were adj acent to the

experi mental transect i n the unharvested l ane between Transects 3 and 4

4 -2

( Stat i ons 4 -6 were al ternate control stati ons to be used onl y i f unusual

cond i t i ons at Stat i ons 10- 1 2 i nd i cated that they woul d not represent

und i sturbed cond i t i ons These stat ions have not been occup i ed to date )

Stat i ons 7 - 1 2 were al so the same areas sampl ed for phytopl ankto n benth i c

i nfauna and sed i ment chemi stry Stat i on 1 5 was or i g i nal l y establ i s hed

beyond the southern end of Transects 6 and 7 However dense growths of

Amer i can Lotus i n the area made i t l i kel y that water exchange was

mi n i mi zed wi th the rest of the study area Th i s stat i on was accord i ng l y

moved t o the north but kept between transects s o that i t represented

unharvested cond i t i ons

I V B 2 Parameters

In liY i nstrumentat i on (Hartek Hark V I I ) was used to determi ne

depth profi l es (at 0 2 and 0 5 meter i ncrements from the surface and at

bottom) of temperature conduct i v i ty pH and ox idat i on-reduct i on

potent i a l (ORP) bull Di ssol ved oxygen ( DO) meters ( YS I 57 pol arographi c

el ectrodes equ i pped wi th st i rrers ) were used to measure DO at the same

depths Heters ( and i nstruments ava i l abl e as backup equ i pment ) had been

bench cal i brated aga i nst known standards or phys i ca l constants pri or to

each sampl i ng Cal i brat i ons of the meters empl oyed were repeated

fol l owi ng each sampl i ng L i -Cor i ntegrat i ng photometers were ut i l i zed to

quant i fy i nc i dent and penetrant l i ght Care was taken i n performi ng

these measurements to mi n i mi ze weed d i sturbance i n l oweri ng the

i nstruments and ext i nct i on coeffic i ents were cal cul ated from both the

upper ( 0 5 m) and l ower ( bottom) read i ngs to provi de est i mates of both

weed mass and water col umn l i ght attenuati on Water sampl es were

col l ected for l aboratory analys i s outs ide of the i nfl uence of any meter

d i sturbances

Sampl es were secured us i ng a non -metal l i c i mpel l er-type pump wi th

a weed excl ud i ng cage mesh s i ze of 1 mm ( F i gure 9 3 ) The cage was

l owered wi th a mi n i mum of d i sturbance to the weed mat to prevent

resuspens i on and entrai nment of l oose ly attached al ga l materi al or other

pl ant debri s Th i s col l ecti on techn i que was empl oyed for al l sampl i ngs

Chemi cal parameters i ncl uded al l standard n i trogen and phosphorus

4-3

spec i es Inorgan i c forms - -orthophosphorus ammon i a- n i trate- and

n i tri te -n i trogen - - were determi ned on fi l tered sampl es ( 0 45 micon

effect i ve pore s i ze ) to ascerta i n the ava i l abl e amounts most mean i ngfu l

for b i ol og i cal assessments Potass i um and sodi um were quant i f i ed on a

fi l tered sampl e Trace metal concentrat i ons copper ( Cu ) and i ron ( Fe )

al so were determi ned o n fi l tered sampl es due t o the affi n i ty of these

e l ements for suspended part i cul ates

Total organ i c carbon total Kjel dahl n i trogen total phosphorus

and al kal i n i t i es were determi ned on unfi l tered s ampl es as was

bi ochem ica l oxygen demand Turb i d i ty and suspended l oads were quant i fi ed

and total col i form was analyzed by the membrane fi l ter techni que The

analys i s of sampl es for sod i um chl ori de and fl uori de concentrat i ons was

performed to permi t water mass cal cul at i ons and determi nat i on of water

qual i ty grad i ents across the s i te Anal yses necessary for the pri mary

product i v i ty task were col or d i ssol ved s i l i ca and i norgan i c carbon

Water qual i ty anal yt i ca 1 methods used were those approved by the

Envi ronmental Protect ion Agency ( EPA ) and the Fl orida Department of

Envi ronmental Regul ati on ( FDER) Method references anal yt i cal hol d i ng

t i mes and preservati ves are detai l ed i n Tabl e 4 2

Lake l evel s for spec i fi c dates were obtai ned from the Di stri ct and

represent 1 ake wide averages of stage recorders operated by both the

Di stri ct and the u s Army Corps of Eng i neers

IV B 3 Sampl i ng

There were four types of water qual i ty sampl i ngs each vary i ng i n

the numbers of stat i ons sampl ed t imi ng of col l ecti ons or parameters

anal yzed The s ampl i ngs were enti tl ed basel i ne short - term impacts

quarterl y and fi el d demonstrati on Col l ect i ons were focused around the

experimental transect Analyti cal sui tes i nc l uded both phys i cal and

chemi cal parameters Sampl i ngs performed to date appear i n Tabl e 4 3

4 -4

Basel i ne Sampl i ng

Basel i ne sampl i ng was conducted on August 18 1 987 pri or to any

harves t i ng act i v i ty wi t h i n the s i te The day was cl ear hot and cal m

Average l ake l evel for the day was 4 22 m ( 13 85 ft ) A total of n i ne

( 9 ) l ocati ons ( Figure 4 2 ) was sampl ed to establ i sh a grid of control

stat i ons ( Stat i ons sampl ed were 1 2 3 10 1 1 12 13 1 5 and 16 )

These stat i ons were al l i n areas where no harvest i ng act i v i t i es were

schedul ed Stat i ons 10 1 1 and 1 2 were l ocated i n a heavi l y weeded

area whi l e the rema i n i ng control stat i ons were outs i de the area to be

harvested and were i n comparati vely open water At each stati on a total

of three separate sampl es was col l ected from a depth of 0 2 m for

l aboratory analys i s

At Stati ons 1 3 13 and 16 sampl es were al so sec ured from 0 8

of the overal l depth Water depth ranged from 0 9 to 2 0 meters at al l

stat i on s These corners of the study si te represented the spat 1 a1

extremes and water qual i ty data from surface and at depth were used as

i nd i cat i ons of verti cal gradi ents over the s i te

One add i t i onal stat i on at the mouth of the K i s s i mmee R i ver

( Stati on 20) was sampl ed at the surface (0 2m ) The effect of thi s

tri butary on l ake nutri ent l oad i ng and resul tant spat i al grad i ents may

thus be cons i dered Th i s s i ng l e sampl e however was not i ncl uded i n

stat i st i cal anal yses

A total of fourteen ( 14) stati on-depths resul ted from thi s

sampl i ng for a total of forty ( 40 ) sampl es for anal ys i s In ll1Y and

l aboratory analyses i ncl uded al l wi th the except i on of col or s i l i cates

and org an i c carbon as no phytopl ankton sampl i ng was conducted duri ng

th i s epi sod e Sampl es for total col i form were col l ected from Stat i ons

10 1 1 and 1 2 onl y ( n i ne sampl es)

Short Term Impacts Sampl i ng

Two short term impacts water qual i ty sampl i ngs were conducted

i mmed i atel y after and approx i matel y one week fol l owi ng the compl et i on

of harvest on the exper imental transect These sampl i ngs were i n

4 - 5

conjunct i on wi th and on the same day as phytopl ankton and pr i mary

product i v i ty sampl i ngs Sampl es were col l ected from Stati ons 10 1 1 and

1 2 the control stat i ons and from Stat i ons 7 8 and 9 the experi mental

stat i ons ( F1 gure 4 5 ) Experimental stat i ons were l ocated approxi mately

150m 600m 1070m ( 500 ft 2000 ft and 3500 ft ) from the northern end of

the transect and were approximate ly 75 m ( 250 ft ) from e i ther edge of the

harvested area Contro 1 stat i ons were pa i red wi th each experi mental

stat i on and were adj acent approx1mate1y mi dway between Transect 3 and 4

1 n the center o f the unharvested are a Sampl es were col l ected from 0 2m

depth onl y

Aquat i c weed harvest1 ng on the experi mental transect began

September 3 1987 and the northern 1 220 m was compl eted on September 1 7

Dur1 ng th i s and the succeed 1 ng dayt 1 me sampl i ng events the ongo i ng

harvest of weeds cont i nued nearby An MHl fi el d crew conducted sampl i ng

on September 1 7 a hot cal m and cl ear day when l ake l evel s averaged 4 13

m ( 13 56 ft ) Th 1ck Hvdri 1 1 a growth was v 1 s i b1 e at depth w1 th i n the

tran sect Another sampl i ng occurred on September 22 1987 ( l ake l evel

4 1 2 m ( 1 3 51 ft raquo under s imi l ar cond i t i ons Regrowth of Hydri 1 1 a i n the

experiment al transect was extens ive by th i s date Sampl es were col l ected

near the mouth of the Ki s s immee Ri ver on both occas i ons Seven ( 7 )

stat i on depths resul ted 1 n the col l ect1 0n o f n i neteen ( 1 9 ) sampl es on

eah date Al l in si tu parameters and l aboratory anal yses were i nc l uded

Quarterl y Sampl i ng

As wi th the i mmed i ate i mpacts sampl i ng s quarterl y sampl i ngs were

conducted i n conjunct i on wi th phytopl ankton work Stat i ons sampl ed

i nc l uded 1 2 3 7 8 9 10 1 1 1 2 13 1 5 and 16 at 0 2m depth

( F i gure 4 2 ) and Stat i ons 1 3 1 3 and 16 at 0 8m overal l dept h

S i xteen ( 16 ) stat i on depth s pl us one ri ver sampl e resul ted i n at l east

49 sampl es duri ng each of the four efforts In s i tu and 1 aboratory

parameters i ncl uded al l those l i sted wi th the except i on that total

col i form d i s sol ved s i l i cates col or and i norgan i c carbon were anal yzed

on l y on sampl es from Stat i ons 7 8 9 1 0 1 1 and 12 onl y ( the

exper i mental stat i ons and the i r control pa i rs )

4 -6

Quarterly sampl i ngs took pl ace on September 30 1 987 and January

1 3 1 988 wi th the rema i n i ng sampl i ngs schedul ed for Apr i l and June 1988

Lake l evel s were 4 1 4 and 4 90m ( 1 3 60 and 16 07 ft ) i n September and

January respect i vel y The September event was conducted o n a bl ustery

day (wi nds from the west at 5- 10 kts ) wh i ch l ater produced a dr i v i ng

rai nstorm Vi s i b i l i ty both in and above the l ake was obscured currents

were al so noted Li ght and vari abl e w i nds from the NE to W were noted

duri ng the January sampl i ng Hydrilla had regrown to t he surface i n some

cases by th i s date but otherwi se was not often vi s I b1 e due to i ncreased

l ake l evel s

The northern 180m of the experi mental transect was reharvested

duri ng December 1987 Stati ons 7 and 10 were sampl ed i n January and thus

represented a t h i rd treatment ( 1 e harvested twi ce ) In order to

ma i nta i n a bal anced des i gn for stat i st i cal anal yses however two ( 2 )

stati ons were added t o the sampl i ng schedul e The pos i t i on of Stat i on

7 5 was just south of the mowed sect i on and another control ( 10 5 ) was

added i n a comparabl e l ocat i on south of Stat i on 1 0 Stat i ons 7 5 8 and

9 then became the experimental group to be consi dered i n data analyses

F i el d Demonstrat i on Sampl i ng

Water qua 1 i ty impacts duri ng the actual harvest i ng process were

expected to be pri mari l y a product of turbul ence generated by harvest i ng

These effects were al so expected to be fa i rl y l ocal i zed due to the

dens i ty of the weed mat Any temporary resuspen s i on of organ i c detr i tus

or el evat i on of sol i ds or nutri ent concentrati ons wou l d be establ i shed by

an i ntens i ve t i me seri es wh i ch woul d exami ne the degree and durat i on of

any d i sturbance

The fi el d demonstrat i on water qual i ty samp l l ng was conducted on

October 28-29 1 987 when l ake l evel s were at 14 26 ft Three pai rs of

stat i ons approxi matel y 100 ft apart were establ i shed at the northern edge

of the wi nd fence or harvested area l ocated between Tran sects 2 and 3

( Fi gure 4 6 ) Subsequent to preharvest sampl i ng a harvester made two

passe s each approx i mately 100m l ong A smal l barri er of Hydri l l a ( ca

3m w ide ) was l eft i ntact between the harvested area of Transect 2 and the

4 - 7

RharvestedR area for th i s study Stat i ons were i dent i fi ed as Rcut R (Cl

C2 C3 ) or R uncut R (UCl UC2 UC3 ) duri ng th i s effort

Fol l owi ng the two passes of the harvester over the experi mental

swath no more harvest i ng occurred in that area for at l east 24 hours A

t i me seri es of sampl es were col l ected from -each of the s i x ( 6 ) stat i ons

Data were to be compared from each of the two stat i on types for

quant i fyi ng i mpacts and traci ng the i r durat i o n

Sampl es were col l ected a t 0 2m and 0 8m o f the overal l depth us i ng

the pump and the weed excl ud i ng cage to el imi nate the l argest Hydri l l a

fragments from the sampl e Col l ect i ons took pl ace i mmedi atel y pri or to

the passage of the harvester immedi atel y subsequent to the harvest of

the experimental stat i ons (wi th i n approxi matel y 0 5 hr) and then aga i n

at roughl y 2 5 10 and 24 h r i nterval s after the harvest Sampl es were

not col l ected i n tri pl i cate i nstead the three stat i ons i n each

treatment type formed the basi s for stati sti cal compari son A total of

twel ve ( 1 2 ) stat i on depths and s i x (6) col l ect i ons resul ted i n seventyshy

two sampl es for ana lys i s The s i x col l ect i ons were i dent i fi ed as rounds

1 -6 i n data pri ntouts In 11Y parameters to be determi ned i ncl uded al l

l i sted with the except i on of l i ght penetrat i on and secchi depth

measurements Total col i form was not anal yzed due to the extremel y short

hol d i ng t i me of that parameter nor were repet i ti ve l i ght measurements

wh i ch have a h i gh potenti al for d i sturbance of the water mass due to the

actual sampl i ng process Suspended l oad and turbi d i ty anal yses were

ut i l i zed for est imates of l i ght attenuat i on S i l i cates col or and

i norgan i c carbon were not anal yzed as no phytopl ankton work was

conducted at th i s t i me

IV C INTER IM RESULTS

Al l water qual i ty data col l ected through the m idpo i nt of thi s

project appear i n Append i x 4 A and i ncl ude in s i tu and chemi cal anal yses

from the sampl i ngs performed on August 18 September 1 7 September 22

September 30 and October 28-29 1 987 and January 13 1 988 Means of

al l parameters measured i n the study s i te are presented i n Tabl es 4 4

and 4 5 by date but wi thout regard to treatment stat i on or depth

4 -8

The most notabl e of the in ll1Y parameters i s di ssol ved oxygen

More than 32 of al l observat i ons made were i n v i ol ati on of t he 5 0 mg1

i nstantaneous d i s so 1 ved oxygen cri teri on for C1 ass I waters and 20 of

a l l observat i ons were bel ow 4 0 mg1 (Tabl e 3 4 ) Samp1 i ng t i mes were

skewed toward the morn i ng hours and were thus abl e to record the effects

of pre-dawn resp i rati on of aquat i c vegetat i on at the s i t e

Surface sampl es were al so col l ected i n the Ki s s i mmee Ri ver

approximatel y midway between the S R 78 bri dge and Lake Okeechobee i n

add i t i on t o those sampl es spec i fi ed by the scope of work (Tabl e 4 6 )

Ion content ( sod i um potass i um chl ori de al kal i n i ty s i l i cates )

typi cal l y was l ower i n the ri ver than the s i te waters and i ncreased

sod i um and chl oride concentrat i ons were observed i n the southern port i on

of the study area The ri ver was general l y l ess turbi d ( turbid i ty total

suspended sol ids ) hi gher in col or and apparent ly represented a source

of d i ssol ved i ron to the area

Both throughout the s i te and i n the Ki ss immee Ri ver d i ssol ved

copper l evel s i f detected were only sl i ghtl y above the l i m its of

detect i on The same was true of n i trite-ni trogen wi th the excepti on of

the January sampl i ng On th i s date concentrati ons at the Ki ss inunee

stat i on were h i gher (0 027 mg1 ) than the rema i nder of the stat i on s and

concentrat i on grad i ents were apparent across the study s i te Data on

col or si l i cates and i norgan i c carbon al though presented i n the

append i x wi l l not be extens i vel y analyzed i n thi s sect i on as such data

were pri mari l y col l ected for use i n i nterpretat i on of phytopl ankton

anal yses

IV D DATA REDUCTIONS

Stati sti cal anal yses of i n s i ty and chemi cal data empl oyed one and

two-way analyses of vari ance where treatment effects ( harvested non shy

harvested stat i ons depths ) were consi dered as fi xed (Model I ANOVA)

Two-way anal yses were conducted empl oyi ng the same assumpt i ons when the

rel at i ve magni tude of effects was of i nterest S ign i fi cance l evel s were

set at 0 05 ( P 95) Except where noted anal yses ut i l i zed the

untransformed val ues of the vari ous parameters Log ( base e) data

4-9

trans format i ons were usual ly used to approxi mate normal d i stri but i ons

Parameters trans formed for analys i s i ncl uded orthophosphate ammoni a

n i trate -n i tri te-n i trogen potass i um i ron BOD turbi d i ty TSS and

sod i um

When vari ances among groups were s i gni fi cant i nd i v i dual means

were contrasted us i ng e i ther Student t-tests or Tukey s Student i zed Range

Test wh i ch computes the smal l est HSD ( honestly s ig n i fi cant d i fference )

for determi n i ng d i fferences Both were ap pl i ed at the P - 95 l evel

IV E DISCUSSION

IYr E I In 1i1Y Parameters

D i ssol ved oxygen l evel s and percent s aturat i on of d i ssol ved oxygen

were expected to show the most change from harvest i ng act i v i ti es W ide

d i urna 1 swi ngs shoul d be damped by the removal of 1 arge amounts of

Hydril l a D i urnal pH cycl es and to a l esser extent ORP woul d be

expected to fol l ow thi s pattern as l ess vegetat i on woul d be present to

con sume carbon d i ox ide Seasonal cycl es were expected i n temperature

data however d i urnal cycl es and verti cal thermal grad i ents were l ess

l i kely 1 n areas where dense stands of fl oat i ng Hydri l l a had been removed

For al l parameters wi nd generated m ix i ng i n harvested areas shou ld

1 es sen the degree of al l surface-to-bottom grad i ents Any changes i n

conduct i v i ty at a part i cul ar l ocat i on as a resul t of harvesti ng woul d be

i nd i rect and woul d l i kel y refl ect al terat i ons i n current structure by

removal of the Hvdri l1a mat and the i ncreased fl ush i ng i n harvested

areas

Due to the obv ious d i fferences between sampl i ngs anal yses of i n

tliY data empl oyed two -way ANOVAs usi ng date and treatment ( harvested

Stat i ons 7 8 and 9 and non-harvested Stati ons 10 1 1 and 1 2 ) as

factors Further as vert i cal grad i ents for some parameters appeared

substant i al data sets were al so subd i v i ded i nto surface and bottom

readi ngs and exami ned separately Data were anal yzed from the sampl i ngs

of September 1 7 22 and 30 and January 13 As ant ic i pated sampl i ng

date was a h i ghl y s i gn i fi cant factor for al l i n s i tu parameters

4 - 10

conduct i v i ty ORP pH temperature DO and percent saturat i on Those

parameters exh i bi t i ng d i fferences attri butabl e to harvest i ng impact were

DO and percent saturat i on at both surface and bottom and pH at bottom

No i nteract i ve terms were s i gn i fi cant i nd icat i ng a consi stent and

pred i ctabl e pattern of d i fferences

Di ssol ved oxygen l evel s averaged between 0 5 and 3 6 mgl h i g her

i n the experi mental ( harvested ) transect than i n the adj acent control

stat i ons Th i s pattern was general ly most ev i dent from read i ngs at the

bottom of the water col umn Overal l i ncreases i n percent saturat i on were

approxi mately 20

It shoul d be noted that the majori ty of these data were col l ected

before 1000 ( EST ) and that th i s t i mi ng affected both the magni tude and

the d i rect i on of d i fferences i n DO l evel s Had sampl i ng been conducted

predomi nantly dur i ng mid- to l ate afternoon i t i s most probabl e that the

unharvested and heav i l y weeded areas would have had s i gn i fi cant ly h i gher

DO val ues than the adj acent harvested areas The observed pattern i s

cons i stent wi th an enhanced pre-dawn DO middot sag middot i n areas wi th h i gher

dens i t i es of aquati c vegetat i on (control s ) To ensure that no bi as was

i ntroduced by sequence of sampl i ng on each date stat i ons were ranked by

t i me of sampl i ng the ranks summed by treatment and compared Duri ng that

sampl i ng with the most d i screpancy between treatment rank sums September

30 DO l evel s i ndi cated that thi s was not a seri ous factor

The overal l s i gni fi cance of date i n the previ ous anal yses was due

predomi nantl y to the i ncl us i on of the January data set as can be deduced

from the means presented i n Tabl e 4 4 W i th removal of th i s data set and

reanal ys i s of the three September sampl i ngs the onl y parameters where

date was a s i g n i fi cant factor were pH and ORP I n attempt i ng to quant i fy

the i mmed i ate i mpacts of harvest i ng the removal of the January data set

can be j ust i fi ed on the bas i s that the regrowth of Hydri l l a was

essent i al l y compl ete by th i s sampl i ng and that there were no obv i ous

d i fferences between experi mental and control stat i ons The s i gn i fi cant

d i fferences between experimental and control s for DO percent saturat i on

and bottom pH however were essent i al l y the same i n th i s reanal ysi s

i mpl y i ng that the i mpacts were most marked e i ther wi th i n the th i rty days

of harves t or duri ng that part i cul ar port i on of the growi ng season

4- 1 1

The i ntens i ve fi e l d demonstrat i on sampl i ng carr i ed out on October

28 and 29 1 987 to del 1 neate the invned i ate impacts of harvest i ng was

pr i mari ly desi gned to measure turbid i ty associ ated parameters or

nutri ents rel eased from the sed iments as a resul t of the passage of the

harvester The in 1iY data co 1 1 ected however were subjected to an

ana l ys i s s i mi l ar to the above (Tabl e 4 7 ) D i fferences between harvested

and unharve sted areas were s i gn i fi cant here for a l l parameters but

pri mar i l y for the val ues at depth D i ssol ved oxygen duri ng - th i s

samp 1 1 ng however was l ower overa 1 1 i n the harvested area As water

col umn oxygen demand (BOD ) was comparabl e between transects reference to

sampl i ng t imes the majori ty after 1000 EST cl ari fy thi s apparent

d i screpancy These d i urnal cycl es are apparent i n F i gure 3 7

Duri ng the i mmedi ate impacts sampl i ng conduct i v i t i es were

s i gn i fi cant ly h i gher i n the experimental area than at the control

stat i ons wi th i n one hour of the passage of the harvester ( F i gure 4 6)

Cond i t i ons i n both areas had been comparabl e just pri or to the harvest

Th i s may i l l ustrate the rap id i ty wi th wh i ch fl ush i ng rates are i ncreased

Al l other in 1i1Y parameters wi th the except i on of percent saturat i on

exh i b i ted s ign i f i cant changes over t ime part i cul arly a t the bottom of

the water col umn These are i l l u strated for the rema i n i ng parameters i n

F i gures 3 9 through 3 1 1 where subtl e di fferences produced by harvest i ng

are superi mposed upon d i urnal cycl es The magni tude and s i gn of

d i fferences for many parameters in add i t i on to DO between harvested and

control stat i ons were heav i l y dependent on the t i me of day

Vert i cal grad i ents i n vari ous parameters were expected to be

reduced as a resul t of the removal of the advect i ve barri er of the

Hydri l l a mat and the consequent i ncrease i n wi nd -generated mi x i ng

Anal yses of vari ance of surface mi nus bottom in s i tu val ues as a s i ng l e

vari abl e were performed wi th stati ons

( harvested ) and control ( unharvested

comparat i ve ly non -weeded stat i ons ) Of

categori zed i nto experi mental

i ncl ud i ng both weeded and

the s i x sampl i ngs anal yzed i n

th i s manner surface to bottom grad i ents were most often observed for pH

DO and percent satura t i on Surface DO val ues ranged between 0 3 and 3 8

mgl h i gher (4 -46 saturat i on ) and surface pH between 0 04 and 0 2 SU

h i gher

4 - 1 2

Surface to bottom grad i ents were a 1 so apparent i n both

experi mental and control areas duri ng the immed i ate i mpacts sampl i ng of

October 28 and 29 Except for conduct i v i ty vert i cal grad i ents for these

two treatments were not stat i st i cal l y d i fferent from one another when the

fi ve post -harvest sampl i ng rounds were consi dered as a un i t Thi s

s i mi l ari ty i n grad i ents however shoul d not be confused wi t h the

d i fferences previ ousl y demonstrated between treatment areas for th i s

sampl i ng as the grad i ent anal ys i s i s concerned onl y wi th the d i fference

between surface and bottom val ues and makes no statement concern i ng the

rel ati ve posi t i ons of i nd i v i dual val ues

The fact that gradi ents were present at al l i n the harvested area

duri ng October may impl y that the d i mensi ons of the pl ot from wh i ch

HydrjJ l a was removed ( approxi matel y 6 by 1 20 meters ) were i nsuffi c i ent

for exi st i ng wi nd d i rect i on and vel oc i ty to cause substanti al mix i ng

Water depths ranged between 1 2 and I Sm These grad i ents were present

for pH DO and percent saturat i on agai n for the January sampl i ng i n both

control and experi mental transects wh i ch i s not surpri s i ng i n l i ght of

the degree of regrowth over four months s i nce harvest and the phys i cal

s imi l ari ty of stat i ons at th i s t i me

E2 Chemical Parameters

The anal ys i s of chemi cal data was desi gned to answer the fol l owi ng

questi ons for the sampl i ngs to date

o Are there detectabl e water qual i ty d i fferences between the

experimental and control stat i ons

o If there are was thi s ei ther d i rect l y or i nd i rect ly a product of

harvest i ng act i v i ty or i s i t the byproduct of stat i on l ocat i on

and the resul t of natural d i l ut i on grad i ents ( i e l oad i ng from

the Ki s s immee Ri ver or other sources )

o I f there are no s ign i fi cant d i fferences between harvested and

unharvested areas were d i fferences to be expected on the bas i s of

water mass compos i t i on

4 - 13

Where chemi cal spec i es are not d i rect ly correl ated wi th a d i st i nct

water mass or where i nputs to the water col umn are d i ffuse enough to

prevent the ma i ntenance of a spat i a 1 grad i ent or the detect i on of a

s i ngl e sourc e data analysi s i s s i mpl i fi ed to a compari son of treatment s

experimenta1 s agai nst control s Seasonal trend s i f present can be

factored i nto the stat i st i cal ana lys i s A s i mpl e compari son of harvested

aga i nst unharvested area chemi stry can al so be performed shoul d i on

content and rat i os i ndi cate that these water masses were i denti cal duri ng

sampl e col l ect i on and that d i l ut i on grad i ents can be i gnored

However when nutri ents or other spec i es are i ntroduced i nto a

system a ssoc i ated wi th a di sti nct water mass and when d i l ut i on with

ex i st i ng waters produces detectabl e gradi ents the quest i on s become more

compl ex In add i t i o n b i ol og i cal uptake wi l l produce non - l i near

rel a t i on sh i ps and the separati on of harvesti ng impacts from expected

gradi ents becomes more d i ffi cul t

The compl ex i ty of these questi ons i n the presence of d i l ut i on

grad i ents can be i l l ustrated graph i cal l y by reference to Fi gure 4 1 2

where hypotheti cal data appear In the fi rst part parameter X i s a

l i near func t i on of sod i um or i n other word s X i s a l so a con servati ve

parameter so i ts absol ute l evel i s affected onl y by d i l uti on wh i ch

mai nta i n s a constant X Sod i um rat i o Th i s regress i on would be devel oped

u s i ng one day s data from the ent i re gri d of n i ne control stat i ons across

the study s i te The hypothet ical data from a harvested stat i on (Stat i on

7 ) and the control (Stat i on 10 ) are al so pl otted It i s apparent that

wh i l e the l evel s of parameter X at the harvested and control stat i on

shown are probabl y not stat i st i cal l y d i fferent from one another the

harvested stat i on c l earl y fal l s outside of the 95 confi dence i nterval of

the X Sod i um regress ion for thi s data set and d i fferences from the l evel s

expected may refl ect harvest i ng i mpacts

In the second port i on of Figure 4 1 2 an al ternate s i tuat i on i s

i l l ustrated where the 1 eve1 s of parameter X at h arvested and control

stat i ons are shown to be c l earl y d i fferent However it i s apparent that

the water mass at the harvested stat i on i s sl i ghtl y more d i l ute and that

the correspond i ngl y l ower l evel s of parameter X are to be expected I n

4 - 14

both s i tuat i ons any b i ol og i cal processes affect i ng parameter X wi l l

produce even more compl ex rel at i onsh i ps

Sod i um and chl ori de were fi rst exami ned for i ns i g ht i nto water

mass movement and d i l ut i on processes occurri ng across the study s i te

The sum of these two i ons ( i n mi l l i equ i va1ent s ) was empl oyed a s an

approxi mat i on of total i on content They were both assumed to be

conservat i ve i e not part i ci pat i ng to any substant i al degree i n

b i ol og i cal processes where they might be sequestered or added to t he

water col umn F i gure 4 13 i l l ustrates thi s d i l ut i on process as i t occurs

across the study s i te The rat i o of sod i um to chl oride was al so

cal cul ated as an i dent i fy i ng feature of a part i cul ar stat i on

The gri d of ni ne control stat i ons was sampl ed on three occas i ons

August 1 8 September 30 1987 and January 13 1988 These data were

exami ned as t hey represented the 1 argest spat i a 1 area Anal yses of

vari ance i nd i cated that both total i on content and sod i um ch1 0r ide rati os

vari ed s ign i fi cant ly wi th respect to sampl i ng date I n l i ght of the

seasonal pattern of preci p i tat i on and the i nfl uence of ri ver d i scharge on

the area th i s was not surpri s i ng I n add i t i on however stat i on was

h i gh l y s i gn i f icant as a factor In the case of sod i um pl us chl ori de

th i s represents a change i n total i on content or d i l ut i on occurri ng

across a spat i al grad i ent ( Fi gure 4 14 ) I n the case of sod i um ch 1 0r i de

rat i os the fact that rat i os are di fferent at d i fferent stat i ons impl i es

that two or more separate water bod ies are represented across the s i te

( F i gure 4 1 5) I nteract i ve terms were al so s i gn i fi cant for each

parameter i nd i cat i ng that d i fferences were not cons i stent across t i me or

space Th i s i s apparent i n compari ng Fi gure 4 13 wi th Fi gure 4 14

As the mi xi ng of more than two water masses together woul d make

ana l ys i s of the rema i n i ng parameters extreme ly mathemat i cal l y compl ex

regress i ons of sodi um aga i n st chl ori de were performed for al l control

stat i ons on the three sampl i ng dates On each date correl at i ons for

l i near rel at ionshi ps were s ign i fi cant at pgt99 9 Th i s resul t al l owed

the use of the assumpt i on that onl y two water masses were mi x i ng across

the s i te Parameters associ ated wi th one of the two water masses coul d

therefore be detected by regress i ons on sod i um or some other conservat i ve

parameter

4 - 1 5

Anal yses of water qual i ty impacts were i n i t i al l y restri cted to

four sampl i ngs September 1 7 22 and 30 1 987 and January 13 1 988

Stat i ons 7 - 9 for experimental and Stat i ons 10 - 1 2 for control s (Stat i on

7 5 and 10 5 were used for the J anuary data set as an area wh i ch

i nc l uded Stat i on 7 had been reharvested shortl y before the sampl i ng )

S i gn i fi cant amounts of vari ati on between experi mental (Stat i on s 7

8 9 ) and control s ( Stati ons 1 0 1 1 1 2 ) as groups were found us i ng

two-way ANOVAs wi th date and treatment as factors (Tabl e 4 8 ) Al l

n i trogen and phosphorus spec i es (wi th the except i on of orthophosphate )

conta i ned s i gn i fi cant amounts of vari at i on d i stri buted between the

harvested and unharvested control stat i ons In add i t i on for BOD

turb id i ty and total suspended sol i d s d i fferences were present as wel l

As expected potassi um fl uoride chl ori de and sod i um d i d not d i spl ay

s i gn i fi cant vari ati ons between data from harvested and unharvested

stat i ons I ron copper total organ i c carbon and al kal i n i ty were al so

not s i gn i fi cant ly d i fferent between treatments

As d i scussed above however d i fferences between harvested and

unharvested areas are strai ghtforward onl y i f I water masses i n each of

the two treatment areas were identi cal or 2 the anal yzed parameter has

no s i gn i fi c ant rel ati onsh i p to a part i cul ar water mas s or to sod i um

Al though n o s ign i fi cant d i fferences i n sod i um o r chl ori de

concentrat i ons were observed between harvested and unharvested stat i ons

as a group di 1 ut i on grad i ents of these parameters were present wh i ch

paral l el ed the axi s of the harvested transects ( Fi gure 4 1 4 ) As a

resul t the data envel ope for the stati ons of a s i ngl e treatment was

l arge i n compar i son to any subtl e d i fferences between transects (F i gure

4 16 ) The fact that any di fferences were detected between experi mental

and control transects (Tabl e 4 8) impl i ed that they were substanti al

enough to overr ide the wi th i n -treatment vari abi l i ty expected from the

sod i um grad i ent S i gn i fi cance of i nteract i ve tems i n these model s

i nd i cated that d i fferences were not cons i stent from sampl i ng to sampl i ng

To d i rect l y compare harvested and non-harvested water qual i ty the

water of the two treatments must represent i dent i cal d i l ut i ons of source

and rece i v i ng waters As d i l ut i on gradi ents were roughly paral l el to the

transect axes stat i ons were pa i red and the d i fferences of experimental s

4 - 1 6

l ess control s cal cul ated for each pa i r of sod i um and chl ori de data

( Stat i ons 7 - 1 0 8- 1 1 9 - 1 2 Tabl es 4 9 4 10 ) The mean d i fferences

computed for al l sampl i ngs or for each date were on no occas i on d i fferent

from zero ( t - tests ) I n add i t i on no cons i stent pattern of d i fferences

was observed The conc1 us i on was that wh l l e di fferences 1 n the water

mass were present between stat i ons w ith i n a s i ngl e treatment harvested

stat i ons and t he i r adjacent control pai rs represented i dent i cal waters on

each date w i th respect to d i l ut i on

As water masses were i dent i cal the d i fferences i n parameter

concentrat i ons were cal cul ated for each stat i on pa i r as for sod i um and

chl ori de above These d i fferences are summari zed i n Tabl e 4 1 1 for those

parameters for wh i ch treatment was a s i gn i f icant factor i n the two-way

ANOVAs descri bed above (Tabl e 4 8 ) The magn i tudes of the d i fferences on

i nd i v i dual dates when not stat i st i cal l y equ i val ent to zero are al so

presented

Us i ng the pai red compari sons of stat i ons al l n i trogen s peci es and

total phosphorus exh i bi ted s i gn i fi cant al though subtl e d i fferences

between harvested and unharvested areas for the sampl i ngs to date (The

only date where orthophosphorus showed treatment d i fferences was on

September 22 and on th i s occas i on the magni tude was onl y 0 002 11191

1 ess than the 1 im i t of detect i on ) These d i fferences are most notabl e

for n i trate and ammon i a n i trogen and are i n add i t i on to any d i l ut i on

grad i ents across the s i te They can be presumed to refl ect the i mpacts

e i ther d i rect or i nd i rect of harvest i ng

Concentrat i ons where d i fferent were typi cal l y l arger i n the

unharvested control transect Th i s may be attri buted to e i ther uptake by

regrowth at harvested stat i ons or to the rel ease of nutri ents by

senescent macrophytes or peri phyton at the unharvested l ocat i ons

Fl oat i ng mats of Hydrj 1 1 a i n vari ous cond i t i ons were present through the

September 30 sampl i ng

B i ochemi cal oxygen demand turbi d i ty and suspended sol i d s al so

showed d i fferences us i ng stat i on pa i rs al though i n the i n stance of

suspended sol i ds concentrat i ons were sl i ghtl y h i gher at the harvested

stat i ons Wi nd -generated sed i ment resuspensi on i n harvested areas and

suspended senescent pl ant materi al i n the unharvested areas (contri but i ng

4- 1 7

to turbi d i ty and oxygen demand but wi th rel at i vely l i ttl e dry we i ght ) are

postul ated to account for these d i fferences Th i s i s supported

c i rcumstant i al l y by the l argest d i fference i n suspended sol ids be i ng

observed on September 30 when w i nd cond i t i ons were the most extreme of

any of the days sampl ed

The l argest number of parameters d i fferent between harvested and

weeded areas was al so observed on September 30 wh i l e the fewest were

seen on January 1 3 1 988 Whether th i s d i stri but i on across t ime i s a

res ul t of 1 ) vary ing nutri ent uptake rates throughout the growi ng season

2 ) the essent i al l y compl eted regrowth observed by the January s ampl i ng

3 ) the h i gher l ake l evel s and l ack of a fl oati ng mat of Hydri l l a perhaps

reduc i ng res idence t i mes of water across the s i te duri ng January or

4) the h i gher January nutri ent l evel s maki ng d i fferences more d i ff icul t

to d i scern i s i mposs i bl e to resol ve

Another techn i que for data anal ys i s was empl oyed on the September

30 and January 13 data sets for those parameters wh i ch were associ ated

wi th d i l ut i on grad i ents across the s i te Bri efl y i f the grid of control

stat i on s d i spl ayed s i gn i fi cant regress i ons with sod i um theoret ical

parameter concentrat i ons were cal cul ated for al l control and experimental

stati ons based on the observed sod i um data and that funct i on wi th the

h i ghest regress i on coeffi ci ent Res i dual s (V i - V hat) were then

compared by t - tests between means of experimental and control groups to

determi ne i f popul ati ons were the s ame (no impacts F i gure 3 1 2B) or

d i fferent ( i mpacts Fi gure 4 1 2A)

L i sted i n Tabl e 4 1 2 by date are the regres s i on types and

coeffi c i ents of the vari ous parameter concentrat i ons wi th sod i um Onl y

surface data from control stat i ons were used The vari ed nature of i nputs

to the s i te i s exempl i fi ed by F igures 4 1 7 and 4 18 dep i cti ng the vast l y

d i fferent d i stri buti ons of orthophosphorus between September and January

Whi l e rel at i vel y few parameters were apparentl y associ ated wi th

d i l ut i on duri ng the August sampl i ng the h i gher l oads i n September and

January perhaps coupl ed with sl owed uptake and growth rates duri ng the

l atter part of the year may produce l onger water col umn res idence t i mes

for nutri ent spec i es and permi t the detect i on of d i l ut i on grad i ents i n

4 - 18

these parameters Chl ori de and potas s i um and any other parameter onl y

s l ightl y affected by bi ol og i cal act i v i ty shoul d certa i nl y produce

s i gn i fi cant rel ati onsh i ps (The l ack of s i gn i fi cance of fl uor i de wi th

res pect to sod i um i s attri buted to the extremel y l ow l evel s encountered

e g concentrat i ons at or bel ow the l i mi t of detect i on for th i s

parameter )

Overal l the res i dual s anal ys i s of sod i um dependency proved l es s

sens i t i ve than that o f the pai red stat i ons anal yses O f the twenty-two

parameter-date combi nati ons where a s i gn i fi cant regress i on wi th sod i um

was obtai ned res i dual s of experimental stat i ons were s i gn i fi cant ly

d i fferent from res i dual s from control stat i ons for onl y three parameters

- - orthophosphorus and al kal i n i ty duri ng September 30 1 987 and n i tri teshy

n i trogen dur i ng January 13 1 988 Figure 4 19 superimposes the

experi mental stat i on orthophosphorus concentrati ons upon the rel at i onsh i p

devel oped for control stati ons i n September I t can be seen here that

the experimental stat i ons (X) are not evenl y d i stri buted around the

regress i on l i ne

Orthophosphorus concentrat i ons on th i s occas i on were l ower i n

the experi mental transect but onl y by 0 002 mgl l ess than the l i mi t of

detect i on Al kal i n i t i es at these stat i on s were h i gher than sod i um

concentrat i on s mi ght pred i ct by about 9 mgl as CaC03 Duri ng January

n i tri te - n i trogen was al so l ower at the harvested stat i ons than woul d be

expected on the bas i s of d i l ut i on al one but aga i n by l ess than the l imi t

of detect i on

As troph i c states and nutri ent l i mi tati ons wi thi n Lake Okeechobee

area of concern rati os of d i ssol ved and i norgan i c n i trogen to phosphorus

spec i es were cal cul ated and summari zed i n Tabl e 4 1 3 On a we ight bas i s

systems wi th rat i os l ess than 1 0 are typ i cal l y cons i dered n i trogen

1 i mi ted wh i l e phosphorus 1 im i tat i ons occur at rat i os greater than 1 7

( Sakamoto 1 966) Wi th th i s cr i teri on the waters o f the study s i te are

cl earl y n i trogen l imi ted i n contrast to al gal assays performed i n the

v i c i n i ty duri ng 1 974 and 1 975 ( Dye et al 1975 ) These resul ts have the

most consequences for phytopl ankton popul ati ons rather than macrophytes

as the rooted pl ants are capabl e of extracti ng at l east some i f not the

majori ty of thei r requ i red nutri ents from the hydroso i l

4 - 19

The stati st i cal anal yses d i scussed earl i er for the i ndi vi dual

parameters determi ned i norgan i c ni trogen spec i es to be h i gher i n the

unharvested control stat i ons and orthophosphorus to be s l i ghtl y l ower

ANaYA s of N P rat i os al so found s i gni fi cant d i fferences The treatment

( harvested or unharvested ) or stat i on was more important than date i n

account i ng for vari ati on Al l September and January sampl i ngs combi ned

produced mean N P rat i os for the harvested stat i ons ( 7 - 9 ) of 3 0 and for

the unharvested d i fferences coul d be attri buted e i ther to uptake by

act i vel y growi ng p l ants or to rel ease of nutri ents by senescent p l ant

materi a 1 Oi fferences between harvested and nonharvested areas were

l east apparent duri ng the January sampl i ng when ri s i ng l ake l evel and

Hydri l l a regrowth combi ned to i ncrease stat i on to stat i on phys i cal

s i m i l ari t i es

E 2 Bacteri ol ogi cal Parameters

Resul ts of total col i form anal yses (membrane fi l ter techn i que) of

sampl es col l ected on August 18 September 1 7 22 30 1987 and January 13

1 988 appear in Tabl es 4 1 4 After the August fi e ld effort sampl es were

col l ected i n conjuncti on wi th the phytopl ankton work and al l sampl es were

anal yzed by EQL Overal l bacteri ol ogi cal qual i ty was qu i t e good wi th

on ly a s i ngl e sampl e exceed i ng the 1000 counts per 100 ml cri teri on for

Cl ass I waters Th i s s i ngl e val ue of 5000 (Stat i on 1 1 September 30

1 987 ) was cl as sed as a stat i st i cal outl i er for the study as a whol e The

other two val ues from sampl es col l ected s i mul taneously were 900 and

100100 ml Most stat i on means were bel ow 200 countslOa ml

Stat i st i cal anal yses of these data empl oyed natural l og

transformat i on s Two way ANaYA s (by date and treatment and by date and

s t at i o n ) prod uced s i gn i fi cant terms for date and i nteract i ve

rel at i onsh i ps however nei ther harvesti ng nor stat i on accounted for

s ign i fi cant amounts of vari at i on Further anal yses cons i sted of mul t i pl e

l i near regress i ons of l og transformed total col i form counts aga i nst BOD

turb i d i ty total suspended sol i d s sod i um and chl ori de content ( as water

mass i ndi cators ) col or and s i l i cates A s i gn i fi cant regress i on model

whi ch i ncl uded BOD col or and TSS was obtai ned (r2 = 0 255 n 72) A

4 -20

d i rect rel ati onsh i p wi th BOD was not surpri s i ng The vari at i on wi th

col or val ues may be support for runoff control l ed bacteri a l evel s in the

l ake i ncreas i ng duri ng peri ods of h i gh d i scharge or backpump i ng (wh ich

are themsel ves characteri zed by i ncreased col or l evel s from t he

accumul ated surface waters An i nverse rel at i onsh i p w i th TSS l evel s was

l ess amenabl e to i nterpretat i on and i s l i kely to have been an art i fact of

some other control l i ng i nfl uence

IV E WATER QUALITY IMPACTS - QUALITY ASSURANCE OBJECTIVES

Prec i s i on and accuracy targets and resul ts for in ll1Y water

qual i ty parameters are presented in Tabl e 4 1 5 Prec i s i on est i mates were

based on dupl i cate in 1iY determi nat i ons expressed as percent rel ati ve

standard devi at i on (S RSD) Measurements at one stat i on per day were

typ i cal l y repl i cated i n thi s fash i on Prec i s i on est i mates for fi el d

measurements necessari l y i nc l uded the representati veness of the sampl i ng

as any non - homogene i ty of the s i te bei ng sampl ed appeared i n these

resul t s

Accuracy was determi ned from both pre- and post - sampl i ng

cal i brat i on of i nstrumentati on and where appl i cabl e the s i mu l taneous

col l ect i on of sampl es for l aboratory analysi s wi th al ternate procedures

or equ i pment Thi s was expressed as percent recovery ( R) of

f i el dl aboratory val ues t i mes 1 0 Col l ect i on of sampl es for

veri f icat i on was typi cal l y conducted at a rate of 1 for every 1 0 stati ons

samp l ed For th i s project di ssol ved oxygen and conducti v i ty were so

veri fi ed

Comparabi l i ty o f data was veri fi ed duri ng the pre- and postshy

sampl i ng cal i brati ons of i nstrumentat i on aga i nst standard sol ut i ons or

phys i c al constants Compl eteness of in 1iY data was esti mated to be

greater than 88 throughout the sampl i ngs to date

The qual i ty assurance object i ves for l aboratory anal yses were

anal ogous to those d i scussed for the i n s i tu parameters and are l i sted i n

Tabl e 4 14 Prec i s i on esti mates were determi ned from the anal yt i cal

resul ts and SRSD between the concentrati ons of two al i quots of a s i ng l e

conta i ner Dupl i cate analyses were performed at a rate of at l east one

4 - 2 1

for every ten sampl es The RSD between sampl es only sl i ghtly above the

l i mi t of detect i on i s often qu i te h i gh al though the analys i s i s

extremel y prec i se ( L e 0 001 and 0 002 11191 47 1 RSD ) Some mean

tRSD val ues and SD val ues are skewed by these seemi ngl y i mprec i se

dupl i cates that are actual l y wi th i n QA l i mi ts Accuracy of analyses was

assessed by the analys i s of sampl es to wh i ch known amounts of standard

materi al s had been added

IVG I NTERIM SUMMARY AND CONCLUSIONS

The study area i mmedi ately south of the entrance of the Ki s s 1mee

R i ver i nto Lake Okeechobee represents a compl ex combi nat i on of factors

wi t h regard to water qual i ty Vari at i ons with t i me were observed for

almost al l parameters measured D i ssol ved oxygen v i ol at i ons of the 5 0

11191 i nstantaneous cri teri on were common and d i urnal cycl es of DO and

rel ated parameters were apparent The skew i n sampl i ng t i mes toward the

morn i ng hours undoubtedly i ncreased the number of observed v i ol at i ons

a l though sampl i ng l ater i n the afternoon woul d i ncrease the percent

saturat i on of d i ssol ved gases and val ues i n excess of the 1 10 cri terion

wou l d have resul ted

In li1Y parameters were i n i t i al l y eval uated for stat i st i cal

d i fferences between harvested and unharvested stat i ons as a grou p

Di fferences i n DO percent saturat i on and p H were observed and were most

marked at the bottom of the water col umn and duri ng the September

sampl i ngs Pred i ct abl y harvesti ng reduced the ampl i tude of the d i urnal

DO cycl e such that DO concentrat i ons were h i gher i n the harvested

transect i n the morn i ng hours and l ower duri ng the afternoon Both the

magn i tude and the d i rect i on of the observed d i fferences were therefore a

funct i on of the t i me of sampl i ng

A rap i d change i n water masses was al so observed at harvested

stat i ons and th i s was attri buted to the i ncreased fl ush i ng potent i al

produced by Hydri l l a removal Inten s i ve surveys detected vert i cal

grad i ents of s i mi l ar magn i tudes for i n s i tu parameters at both harvested

and control stati ons The s i ze of the harvested transect may have been

too smal l to al l ow wi nd-generated vert i cal mi xi ng to be effect i ve

4-22

Bacteri ol og i cal water qual i ty at the s i te was good overal l wel l

wi th i n the 1000 1100 ml cri teri on and correl at i ons w ith col or BOD and

TSS were present Col or rel at i onshi ps i ndi cate a functi onal rel at i onsh i p

of total col i form wi th d i scharge i nto the l ake whi l e the rel at i onsh i p

wi th TSS was i nverse

Chemi cal water qual i ty d i stri but i ons at the s i te were a l so qu i te

compl ex Spat i al and d i l uti on grad i ents produced by the i nfl uence of the

K i s s i mmee Ri ver were qu i t e apparent as determi ned by conservat i ve

parameters such as sod i um and chl ori de The d i l ut i on grad i ents were

roughl y paral l el wi th the l ong axi s of the harvested transects such that

a progress i on of i ncreas i ng strengths of Lake Ri ver d i l ut i ons were

observed al ong both the experimental harvested transect and the adjacent

unharvested control transect Thi s transl ated to a h i gh wi th i n -treatment

va ri a b n i ty of water masses compared to the between- treatment

vari abi l i ty wh i ch i n turn may obscure d i fferences between harvested and

unharvested areas i n stra ightforward stat i st i cal compari sons

Overal l stat i sti cal techni ques were sat i sfactory because the

number of sampl es adequate for determi ni ng di fferences i n concentrat i ons

was at or near the analyt i cal l imi ts of detect i on The three stat i st i cal

anal yses were 1 ) d i rect compari sons (means test i ng and ANOVA s ) of

harvested to unharvested data sets 2) ana lys i s by d i fference of stat i on

pa i rs ( harvested l ess the adjacent control stati on) and whether

d i fferences were stat i sti cal l y d i fferent from zero and 3) res i dual s

anal ysi s of those parameters wi th a s ign i fi cant rel at i onsh i p w i th sod i um

and whether the popul ati on of res i dual s from control stati ons was

equ i val ent to those from the harvested stati ons

Ana lys i s of harvested versus unharvested data groups by parameter

reveal ed s i gn i fi cant d i fferences between treatments for al l n i trogen

spec i es total phosphorus BOD turb id i ty and total suspended sol i ds

These d i fferences are i n sp i te of the broad envel ope i n water qual i ty

conta i ned wi th i n each treatment type However d i rect compari sons and

correct est i mati on of the magni tude of harvest i ng impacts are poss i bl e

onl y where the water masses of the two treatments can be assumed to

represent equ i val ent po i nts on the d i l ut i on grad i ent

The d i fference i n sod i um and chl ori de concentrat i ons between each

harvested stat i on and i ts adjacent unharvested stat i on was cal cul ated

For al l dates these d i fferences were equ i val ent to zero mean i ng that

the water mass was i dent i cal at Stati ons 7 and 10 at Stat i ons 8 and 1 1

and at Stat i ons 9 and 1 2 The d i fferences i n concentrat i ons between the

stat i on pai rs cou l d then be calcul ated Al l n i trogen spec i es and total

phosphorus concentrat i ons were typ i cal l y h i gher i n the unharvested

transect On the one occas i on where orthophosphorus d i ffered between

treatments i t was s l i ghtl y h i gher i n the harvested transect Turbid i ty

and BOD were al so h i gher at the control stat i ons wh i l e total suspended

sol i ds were sl ightly l ess Uptake by macrophytes i n act i ve regrowth

rel ease o f nutri ents by senescent and matted pl ant mater i al and wi nd shy

generated resuspens i on may account for thi s pattern

Ana lys i s of those parameters associ ated wi th d i l u t i on and of those

wi th s i gn i fi cant correl at i ons wi th sod i um proved l ess sens i t i ve for

detect i ng d i fferences Al though many parameters d i spl ayed s i gn i f icant

rel at i onsh i ps the i r d i stri but i on around the regress i on l i ne was

cons i derabl e and res i dual popul at i ons were s i gn i fi cantly d i fferent

between treatments for only three parameters

The s i te as a whol e appeared to be n i t rogen 1 i mi ted based on

we i g ht r at i os of i norgan i c n i trogen forms to orthophosphorus

O i fferences between harvested and unharvested areas were apparent here

al so w i th average rat i o s of 3 0 and 9 4 respect i vely

IVG RECOMMENDATIONS - FINAL REPORT

For the rema i n i ng two quarterly sampl i ngs i n th i s task a

real l ocat i on of effort i s proposed wh i ch woul d del ete copper and fl uori de

from the anal yt i cal su i tes These two parameters were e i ther at or near

the 1 im i ts of analyt i cal detect i on for al most al l s ampl es and

stat i sti cal analyses were not effect i ve i n determi n i ng any d i fferences

attri butabl e to harvest i ng at these l ow concentrat i ons N i tri teshy

n i trogen however shoul d be reta i ned Al though l evel s were l ow they

are i mportant i n th i s n i trogen 1 i mi ted system and d i fferences between

treatments were apparent The Ki ss i mmee R i ver stat i on shou l d cont i nue to

4-24

be sampl ed and another stat i on shou l d be added to the west of Stat i on 1

toward Buckhead Ridge as an i ntermi ttent nutri ent i nput may be present

there Mon i tori ng of these two add i t i onal stat i ons shou l d cont i nue for

al l parameters In pl ace of copper and fl uor ide anal yses d i ssol ved

cal c i um i s suggested as a repl acement to prov ide a bas i s of compari son

wi th other work done prev i ously i n the l ake and to exam i ne i ts behav i or

across the s i te The poss i b i l i ty of mov i ng the exper imental and control

stat i on pai rs ( Stat i ons 7 - 1 2 ) to the most recently harvested area for the

subsequent sampl i ng i s currentl y be i ng d i scussed wi th the task l eaders of

the i nter-rel ated tasks

Future data exami nat i ons wh i ch wi 1 1 be conducted for the fi nal

report of th i s project i ncl ude the deta i l ed assessment of l i ght

penetrat i on profi l es and the effect of the weed mat upon these The data

from the 24 hour fi el d demonstrat i on sampl i ng wi l l be eval uated w ith

regard to chemi cal parameters and the i mmedi ate effects produced by

harvest i ng S i l i cates col or and i norgan i c carbon data wi l l be

processed as wi l l the rema i n i ng parameters for d i fferences between

experi mental and control stat i on s and a further anal ys i s of d i ssol ved

oxygen wi th cons i derat i ons for t i me of day vegetat i on and even sed i ment

type wi l l be conducted

4-25

LITERATURE CITED

Dye C W D A Jones L T Ros s R L Wi l l more 1 975 L imi t i ng nutri ents i n the Ki ss i llll1ee Ri ver - Lake Okeechobee Bas i n based on al gal assay techni ques Fl a Dept Envi ronmental Regul at i on Sakamoto H 1 966 Pri mary product i on by phytopl ankton conununi ty i n some Japanese l akes and i ts dependence on l ake depth Arch Hydrobi ol 62 1 - 28

4-26

Table 4 1 Mean IDran coordinates of water quality staticns

STATIOO NO

1 2 3 7 7 5 8 9 10 10 5 11 12 13 15 16

Ipound)RAN 1 JPRAN 2

14313 2 45453 2 14312 6 43449 1 14312 4 43445 9 14313 6 43449 1 14313 4 43448 2 14313 2 43447 7 14312 9 43446 1 14313 7 43448 5 14313 5 43447 7 14313 4 43447 3 14312 9 43445 7 14315 1 43444 6 14313 9 43443 2 143109 43437 8

Table 4 2 water Quality parameters methods ard holdirq times

Parameter

TeJlFerature Corrluctivity pi ORP Dissolved Oxygen Light Penetratim Secxhl laboratory 0rthqil0spl0rus (D) Total AlosJtIorus (D) AImalia-Nitrogen (D) Nitrite-Nitrogen (D) Nitrate-Nitrogen (D) Total Kjeldahl Nitrogen ium (D) Ccgler (D) Iran (D) Total OJgan1c carbon Alkalinity Biochemical Oxygen DeuanI lu1)idity SUspenled Solids Ibtal Ollifonn auoride Scdium Fluoride Color silicates (D) Inorganic Cartlon

MetbodlInstrument

Martek Mark VII Martek Mark VII Martek Mark VII Martek Mark VII YSI 57 LiOlr Secxhl Disk (LiDngtlogical)

EPA 365 1 365 3 EPA 365 3 365 4 SM 417F EPA 350 3 EPA 353 3 353 3 EPA 353 2 353 3 EPA 351 2 SM 30lA SM 303A B SM 303A B EPA 415 1 8M 403 4C EPA 3102 EPA 405 1 EPA 180 1 SM 2090 8M 908A 909A SM 4070 EPA 325 3 SM 303A EPA 3402 SM 204A B EPA 370 1 SM 425C EPA 415 1

Holdirg TimePreservative Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable

Filter iDmSdiately 48 hrs4Oc 28 daYSH2S04 to pllt2 40c Filter bImadiately 28 daYSH2S04 to pllt2 40c Filter bImadiately 48 hrsH4 to pllt2 40c Filter iDmSdiately 28 daYSH4 to pHlt2 40c 28 daYSH2S04 to pllt2 40c Filter iDmSdlately 6 1IDSIftll) to pllt2 40c Filter iDmSdiately 6 1IDSIftll) to pllt2 40c Filter inmediately 6 1IDSIftll) to pHlt2 40c 28 daYSH2S04 to pIlt2 40c 14 days4oC 48 hrs4Oc 48 hrs4Oc 7 days4Oc 6 hrs4Oc 28 days4Oc Filter inmdiately 6 lOOIlthslftll) to pIlt2 40c 28 days4Oc 48 hrs4Oc 28 days4Oc 28 days4Oc

EPA = EPA 6004-7920 Methods for OJemical Analysis of water ard wastes SM = stanIard Methods for the Examination of water ard wastewater 15th Fdition 1980 (D) = Dissolved

Tabl e 4 3

Date

Aug 18 1987

Sept 17 1987

Sept 22 1987

Sept 30 1987

Oct 28-29 1987

Jan 13 1988

Sampl i ng efforts and dates Water Qual i ty Tas k

Sampl i ng Type

Basel i ne

Short Term Impacts

Short Term Impacts

Quarterly

F i el d Demonstrat i on

Quart erly

No of Stat i ons

9

6

6

12

6

12

No of V i al s

1

1

1

1

6

1

Table 4 4 site averages of in situ parameters by sanplirg date all stations all depths

1987 1988

AU 18 SEP 17 SEP 22 SEP 30 ocr 28-29 JAN 13

n 28 18 18 36 144 68

2 SD 2 S D 2 S D S( S D S( S D 2 SD

onluctivity 0 5350 0661 0 5397 0351 0 5074 0550 0 4985 0517 0 3921 0731 0 3017 0895

ORP 493 109 441 42 298 77 293 47 295 31 247 55

Pi 8 02 0 55 8 27 0 34 7 56 027 7 47 043 7 72 0 51 7 59 0 30

lenperature 28 95 144 27 34 0 50 27 23 054 26 67 041 23 11 099 16 67 078

Dissolved Oxygen (00) 5 02 3 20 3 51 2 20 2 87 1 32 5 11 2 28 664 2 25 8 16 1 58

PeJta1t SaturatiCBl 66 1 42 9 44 4 27 9 36 3 16 7 64 0 28 6 77 8 269 84 0 16 7

00 cbs lt1 0 nql 128 318 218 336 0144 168

00 cbs lt4 0 nql 1428 U18 1318 936 14144 168

00 cbs lt5 0 ugII 1428 1218 1618 1536 41144 268

Table 4 5 Site averages of water quality parameters by sanplirg date all stations all depths

1987 l2sectsect AU 18 SEP 17 SEP 22 SEP 30 ocr 28-29 JAN 13

n 39 18 18 48 7 3 54 K SD K SD I SD K S D K SD K SD

0rthqil0sJil0 0 019 0 007 0 017 0 005 OOll 0 003 O OlS 0 014 0 033 0 011 0 082 0 045 Total rus 0 07 0 11 0 10 0 01 0 08 0 01 0 09 0 03 0 12 0 06 0 15 0 05

Anrncnia-nitrogen 0 039 0 018 0 04 5 0 042 0 017 0 012 0 012 0 017 0 040 0 029 0 04 6 0 036 Nitrite-nitrogen 0 004 0 001 0 005 0 004 0 004 0 001 0 003 0 003 0 004 0 001 0 008 0 004 Nitrate-nitrite-nitrogen 0 009 0 003 0 034 0 036 0 039 0 021 0 048 0 046 0 038 Q 019 0 190 0 039 Total Kjeldahl nitrogen 1 52 0 26 1 75 0 15 1 55 0 28 1 47 0 18 1 29 0 20 1 20 0 17 Potassium 4 4 0 9 4 7 0 3 4 5 0 3 4 2 1 0 2 9 0 5 3 9 1 0

Cqpar 0 003 0 002 0 003 0 002 0 003 0 001 0 002 0 001 0 001 0 001 0 002 0 002 Iron 0 002 0 002 0 014 0 007 0 014 0 007 0 015 0 019 0 048 0 018 0 090 0 031 ampxlium 4 8 9 7 6 47 3 4 6 46 9 4 7 49 0 9 4 31 0 8 9 28 2 8 1 Olloride 8 5 8 13 1 79 6 6 4 76 5 8 6 76 2 10 0 55 9 14 9 48 2 16 7 Fluoride 0 3 0 03 0 3 0 05 0 3 0 03 0 3 0 04 0 1 0 03 0 2 0 03 lbtal organic carlxln 2 1 7 1 6 17 9 0 9 18 1 0 8 18 4 1 0 19 7 2 5 18 4 3 0 Alkalinity 105 14 117 5 113 8 1U 10 7 3 15 68 lS Biochemical oxygen deHard 1 9 1 0 2 7 1 3 2 2 0 6 2 3 1 2 1 5 0 7 1 1 0 6 lubidi ty 2 4 1 9 4 2 0 9 4 1 1 5 4 0 2 9 3 1 2 5 3 7 2 1 Total susperded solids 3 3 3 3 6 0 2 3 5 7 2 4 6 3 4 7 4 5 3 9 3 1 4 1 Oller 61 5 66 9 81 9 113 10 silicates 12 8 2 2 13 1 2 2 12 0 3 0 5 4 0 5 Inorganic carlon 17 4 4 3 19 9 2 8 20 4 4 4 11 9 5 2

11=18

Table 4 6 site averages of water quality parameters for the KissiJulse River by sanpling date

1987 1988

AU 18 SEP 17 SEP 22 SEP 30 JAN 13

0 032 0 096 0 12 7 0 116 0 063 Total (ilcsphorus 0 09 0 18 0 20 0 20 0 12 Almalia-nitrcgen 0 021 0 036 lt0 005 0 017 0 069 Nitrite-nitrcgen lt0 005 lt0 005 lt0 005 lt0 005 0 027 Nitrate-nitrite-nitrogen 0 012 0 009 0 072 0 188 0 151 Total Kje1dahl nitrogen 0 51 1 39 1 40 1 12 1 08 Ibtassium 3 7 3 6 3 5 2 9 3 2

((gler 0 003 0 003 0 004 0 001 lt0 001 Iron 0 008 0 085 0 095 0 172 0 225 Sodium 3 3 4 2 6 5 24 2 2 1 0 15 0 Olloride 60 6 47 8 4 1 9 38 7 23 7 Fluoride 0 3 0 3 0 3 0 2 0 2 Total organic cartxn 19 6 19 5 19 9 18 8 17 4 Alkalinity 89 7 3 66 57 34 Biochemical oxygen daDaM 2 4 3 0 1 5 1 3 0 5 lJnbidity 3 0 3 9 2 7 2 3 2 3 Total suspenied solids J 9 4 8 4 0 2 5 2 0 Color 110 130 130 125 Silicates 6 58 6 42 5 67 3 17 Iooxganic carbon 4 4 9 6 7 2 1 1

Tabl e 4 7 S i g n i f icant F middot test rat i os for two-way ANOVA s by treatment and samp 1 1 ng round for in illY data co 1 1 ected duri ng fi el d demonstrat i on samp l i ng October 28-29 1987

FmiddotTET RAT IOS

TREATMENI ROUND INTERACTION (Exp vs control ) (1-5 only ) (Treatment x Round )

CONDUCTI V lTV Surface 25 99 1 14 56 Bottom 28 3 5 4 26 1 6 73

ORP Surface 2 1 10 Bottom 5 35

pH Surface 32 67 33 10 Bottom 1 1 1 5 4 5 1 4 48

Temperature Surface 104 64 Bottom 21 95 1 1 73 8 17

D i s sol ved Surface Oxygen Bottom 14 1 5 7 98 5 20

Saturat i on Surface Bottom 7 66 3 87

df df error bull 20 F 0 05 [df 20 ] bull

1

4 35

4

2 87

4

2 87

Table 4 8 Significant F-test ratios fnD two way analysis of variane by date ani treatment statiCllS 7-12 only Septedler 17 22 30 1987 ani JanJaIY 13 1988 data

rus dissolved Total pnsphorus Anroonia-nitrogen di ssolved Nitrite-nitrogen dissolved Nitrate-nitrite-nitrogen dissolved Total Kjeldahl nitrogen RltassilDU di ssel ved Cqpr di ssolved Iron dissolved Total organic car1xXl Alkalinity Biochemical oxygen demard TUlbidi ty Total suspenied solids Chloride SOdilDU Fluoride

Degrees of freedaD

Degrees freedan of error = 64

F 0 05 [df 60]

595 12 31 05

4 09 96 71 51 06 31 28

225 02 6 34

424 47 23 36 18 32 28 69

171 46 145 71

49 55

3

2 76

lREMMENl ( vs cxmR)L)

10 24 4 81

17 59 12 57

6 75

6 31 24 03 22 36

1

4 00

3 89

4 64 4 94 5 08

3

2 76

TABLE OF CONTENTS

I EXECUTIVE SUMMARY MID COURSE REPORT 1 - 1

II LAKE OKEECHOBEE LITERATURE REVIEW 2 - 1

III BIOMASS - MID-COURSE SUMMARY 3 - 1

IV WATER QUALITY SURVEYS 4 - 1

V PHYTOPLANKTONPRIMARY PRODUCTIVITY STUDIES 5- 1

VI COMMUNITY METABOLISM 6 - 1

VII SEDIMENT CHEMISTRY 7 - 1

VIII BENTHIC FAUNA IMPACTS 8- 1

IX LARVALJUVENILE FISH TASK 9 - 1

X BENEFITCOST ANALYSIS 10 - 1

EVALUATION AND RESEARCH OF IMPACTS

OF MECHAN I CAL WEED HARVEST I NG I N LAKE OKEECHOBEE

I EXECUT IVE SUMMARY - MID-COLIRSE REPORT

Mote Mari ne Laboratory assi sted by DSA

Envi ronmental Qual i ty Laboratory i s mi dway through

research project conducted for the South Fl ori da

Grou p I nc and

an eval uat i on and

Water Management

D i str i ct to assess the envi ronmental i mpacts of mechani cal harvest i ng of

Hydri l l a The harvest i ng and subsequent upl and d i sposal of materi al are

be i ng performed as a demonstrat i on project to eval uate the nutri ent

( part i cul arl y phosphorus ) removal potent i al and operati onal costs of th i s

techn i que The study s i te ( F i gure 1 1) i s on the northwestern shore of

Lake Okeechobee where approxi mate ly 1000 acres of Hydri 1 1 a are to be

harvested by I nternat i onal Sc i ence and Technol ogy I nc together wi th

L a ke Weed Cutt i ng Serv i ce I nc Spec i f i c i mpacts and s i te

characteri stics to be eval uated incl ude s i te b i omass water qual i ty

phytopl ankton and pri mary product i v i ty cOlMlun i ty metabol i sm sed i ment

chemi stry benth i c i nfauna and ep i phyte commun i t i es and l arval and

juven i l e f i sh popu l at i on s In add i tion a cost benefi t anal ysi s i s to be

performed address i ng the harvest i ng vari abl es and poss i bl e products to

opt i m i ze the cost effect i veness of harvesti ng A l i terature survey of

pert i nent top i cs i s al so i ncl uded as a separate tas k and the enti re

project i s conducted under the auspi ces of a Qual i ty Assurance program

des i gned to ensure the prec i s i on accuracy representat i veness and

compl eteness of al l data

The l i terature survey i s compl ete and over 400 annotated documents

have been comp i l ed i nto a cOlMlercial l y avai l abl e b i bl i ograph i c retri eval

system by key words Task members are abl e to request searches of th i s

database for i nformati on on top i cs spec i f i c to the i r tas k I n add i t i on

summari es o f i nformat i on on sel ected keywords such as Hydri l l a

phosphorous and others have been prepared a s Lake Fact Sheetsmiddot

The bi omass sampl i ng (August 19B7) was del i beratel y conducted i n

a wide range of growth cond i t i ons for eval uat i on of Hvdri l l a dens i t i es

and nutri ent content A cond i t i on i ndex was devel oped to eval uate pl ant

1-1

maturi ty Hvdri l l a senescence and peri phyton i nfestat i on was accompan i ed

by an areal decl i ne i n both bi omass and nutri ent content Max i mum

n i trogen and phosphorus t i ssue concentrat i ons were associ ated with ful l y

mature pl ants pri or t o senescence The presence o f other macrophytes was

respons i bl e for most wi thi n- stati on vari ati on Th i s task i nc i dental l y

d i scovered l arge seasonal d i fferences i n Hydr i l l a phosphorus and n i trogen

content Sampl es col l ected at the study s i te by ISampT duri ng J anuary

1988 were roughly f i ve t i mes h i gher i n phosphorus content than the

materi al col l ected by thi s project duri ng August 1987

Water qual i ty wi thi n the s i te represented an extremel y dynami c

system The i n fl uence of the Ki s s immee Ri ver and any other l ocal

d i sch arges produced d i l ut i on grad i ents across the s i te Vari at i ons i n

qual i ty were apparent between sampl i ng dates Numerous v i ol at i ons of the

i nstantaneous d i ssol ved oxygen cri ter ion (5 0 mgl ) were recorded

part i cu l arl y near the lake bottom Damp i ng of d i urnal oxygen extremes

was observed i n the harvested transects Al l n i trogen spec i es and total

phosphorous were h igher i n the unharvested transect waters than i n the

harvested transect The d i fference may be due e i ther to nutri ent

ut i l i zat i on i n the regrowth areas or to the rel ease of nutri ents from the

senescent Hydr i l l a mat present i n harvested areas The ent i re study s i te

was n i trogen l i mi ted wi th N P rat i os ( by we i ght ) of 3 0 i n the harvested

areas and 9 4 i n the unharvested control s

li ght penetrati on of the water at al l harvested stat i ons was

demonstrated to be s i gn i fi cantl y h i gher than at the unharvested control s

duri ng September onl y By January regrowth of Hvdri l l a produced

s l i ghtl y smal l er compensat i on depths on the harvested transect

Grad i ents i n l i ght penetrat i on were al so apparent wi th i n the experi mental

transect and may be rel ated to t ime s i nce harvest Vert i cal grad i ents

for in 1i1Y data were part i cul arly apparent at the weeded stat i ons

Bl ue-green al gae were the domi nant phytopl an kton taxa at al l

stat i ons d uri ng the September sampl i ngs Thi s domi nance was much reduced

duri ng J anuary when more green al gae were present Di vers i ty and number

of tax a i ncreased at four of the s i x stat i ons i n January but no

cons i stent pattern was apparent for e i ther harvested or control stat i ons

I n add i t i on there were no systemat ic d i fferences between harvested and

1 - 2

unharvested areas on the bas i s of spec i es compos i t i on Vari at i ons i n

chl orophyl l content al so were affected more by seasonal cond i t i ons than

by harvest i ng

The conunun i ty metabol i sm measurements conducted durlng September

1 987 i nd i cate probabl e d i fferences i n oxygen budgets for control and

harvested areas al though i n i t i al stat i st i cal methods d i d not establ i sh

the s i gni f i cance of such d i fferences Th i s was attri buted to anomal ous

data col l ected at a stat i on with unusual sed iment character i s t i cs ( h i ghly

organ i c unconsol idated f i ne grai ned mater i al in contrast to f i ne

grai ned sand ) Add i t i onal data analyses wi l l excl ude thi s stat i on from

cons i derat i on and future sampl i ngs wi l l be conducted at al ternate

l ocat i ons Di fferences by treatment duri ng the January sampl i ng were not

as pronounced as i n September and i nd i cate that regrowth of Hvdri 1 1 a with i n t hat peri od had offset harvest i ng e ffects

Sed i ment heterogenei ty was marked wi th i n the s i te with organ i c

w ith nutri ent content were fa i rl y l ow Organ i c content averaged 0 7

n i trogen 0 27 mgg total phosphorous 0 08 mgg and potass i um 0 49 mgg

on a dry we ight basi s Ni trate-n i tri te -n i trogen concentrati ons were l ess

than 1 of the total present Total n i trogen tota1 phosphorous rat i os

averaged 3 1 and were markedl y l ower than comparabl e rat i os i n e i ther t he

water col umn or the bi omass sampl es refl ect i ng a preferenti al

mobi l i zati on of n i trogen from s i te sed iments Few stat i st i cal l y

s i gn i f i cant d i fferences were detected a s a resul t o f w ith i n - stat i on

vari ati ons and the col l ect i on of more total phosphorus and total n i trogen

val ues are proposed for the second effort of th i s tas k

Data anal yses t o date for benth i c i nfauna i ncl ude preharvest and

postharvest cond i t i ons duri ng August and October respect i vel y The

August fauna was notabl y depauperate both i n taxa and numbers of

i nd i v i dual s wh i l e pronounced i ncreases in both were observed for

October D i urnal l y oxygen - poor cond i t i ons part i cul arl y duri ng August

may l i mi t benth i c fauna Spati al grad i ents were al so noted w ith

decreas i ng s pec i es ri chness and faunal dens i ti es at the southern end of

the study area Experimental and control stat i ons exh i bi ted s i mi l ar

faunal densi t i es and spec i es richness pri or to harvest wh i l e both

1 -3

parameters were substant i al ly greater at the harvested stat i ons duri ng

the October sampl i ng

Based on sampl i ngs i n September and J anuary the l arval and

juven i l e f i sh task col l ected 44 ( 2 1 ) of al l spec i es prev i ously reported

for Lake Okeechobee F i ve habi tats represent i ng both natural and

harvested edges and open water as wel l as heav i ly vegetated areas

were sampl ed Heterandria formosa LeDomi s sp and Gambus i a aff i nis

were the most abundant spec i es Centrarch i ds were the most abundant eggs

recovered The col l ect i on methods were f a i rly specif i c for part i cul ar

l i fe stage juven i l es were taken primari ly i n l i g ht trap sampl es whereas

postl arvae and eggs were taken i n pl ankton tows and Hvdri l l a sampl es

col l ected by the harvester LeDomi s s p appears to ut i l i ze al l fi ve

hab i tats dependent on l i festage No vert i cal strat i fi cat i on of organ i sms

was detected i n the weeded hab i tat and spec i es d i vers i t i es were

equ i val ent at both natural and harvested RedgesR of the Hydri l l a mat No

stat i s t i ca l ly s i gn i f i cant short term i mpacts of harvesti ng on spec i es

abundance or d i str i buti on are apparent

The cost-benefi t analys i s i s restri cted to eval uati ng mechan i cal

harvest i ng al one Benefi ts of thi s techni que wi th the except i on of

sal eabl e byproducts or costs assoc i ated wi th harvested mater i al are

pr i mari l y non -quanti fi abl e ( i mproved habi tat and water qual i ty boater

access nutri ent removal ) Therefore ranges of econom i c parameters wi l l

be ut i 1 i zed together wi th operat i ona 1 data from harvest i ng and

env i ronmental vari abl es from th i s project to present an economi cal l y

opt im i zed harvest i ng pl an to the Di stri ct

I n sunvnary no catastroph i c impacts due to mechan ical harvest i ng

have been detected i n the foregoi ng categori es al though subtl e

d i fferences have been determi ned by the study des ign Harvest i ng reduces

the amount of oxygen stress i n the study area and the nutri ent content of

the water col umn i s l ower i n the harvested than the unharvested areas

The s i te i s n i trogen l i mi ted based on water col umn sed i ment and pl ant

t i ssue anal yses Seasonal vari at i ons are l arge wi th respect to

d i fferences between harvested and unharvested areas for a l gal and l arval

fi sh popUl at i ons Spati al grad i ents were apparent i n many parameters

1 -4

The qual i ty assurance program associ ated wi th thi s project has

thus far conducted a systems aud i t for the pl an of study and at l east one

performance aud i t on f i e l dwork A Qual i ty Assurance Project Pl an has

been prepared and i s i n use as a project control document Aud i ts of

data management and anal ysi s are pl anned for the fi nal report i ng phase

At mi d -course sampl i ng anal yses and del i verabl es are on

schedul e and the project is operati ng wi th i n the budget No probl ems are

foreseen to prevent t imely compl eti on of the remai nder of the schedul ed

work Where al terati ons to speci f ic tasks have been recommended the

support for these efforts wi l l be obtai ned by real l ocati on of funds

wi th i n the project rather than by add i t i onal fund i ng

1-5

o 18 bullbull UNnar tllllllllI UINL UNnan

_ bull 0111 II wilD LlMi

lAKE (J(EECH08EE

Figure 11 Stu dy site l ocation Evaluation and research of impacts o f mechanical harves ting in Lake Okeechobee

I

I I LAKE OKEECHOBEE LITERATURE REV I EW

I I A INTRODUCTION

A 1 i terature rev i ew was conducted as a d i screte task of the

research project The Eval uat i on and Research of Impacts of Aquat i c Weed

Harvest i ng Demonstrat i on i n Lake Okeechobee cond ucted by Mote Mari ne

Laboratory The purpose of the l i terature rev i ew was to provide project

team members wi th economi c geol og i c hydrol og i c chemi cal and

b i ol og i cal i nformat i on on Lake Okeechobee wi th part i cu l ar emphas i s on

water qual i ty probl ems concern i ng phosphorus storage and cycl i ng between

the water col umn sed i ments and aquat i c weeds

I I B METHODS

Three techn i cal el ements were undertaken i n compl et i ng the

l i terature rev i ew 1) ident i fy i ng and search i ng i nformat i on 2) creat i ng

f i l es and 3 ) devel opi ng outputs

I nformati on was obtai ned by rev i ewi ng journal s for art i cl es

search i ng card catal ogs of area l i brar ies contact i ng major authors

conduct i ng research and request i ng key word searches of avai l abl e

computer l i brari es Journal s searched i ncl uded The Journal of Aquat i c

Pl ant Management Quarterly Journal o f the Fl ori da Academy o f Sci ences

( and Fl ori da Sc i ent i st ) L i mnol ogy and Oceanography Hydrobi ol og i a and

North Amer i can Journal of F i sher i es Management L i brari es vi s i ted

i ncl uded Un i vers i ty of South Fl or ida Uni vers i ty of Fl orid a Mote Mari ne

Laboratory Southwest Fl or ida Reg i onal Pl ann i ng Counci l South Fl ori da

Water Management D i str i c t and the Okeechobee off i ce of the Fl ori da Game

and Freshwater Fi sh Commi ss i on Key word l i terature searches were

c o n d u c t e d on d i qu at Lake O keechobee Hyd r i l l a and

nutr i entsaquat i c pl ants u s i ng searches avai l abl e from the Fl ori da

Department of Env i ronmental Regul at i on the Un i vers i ty of Fl ori da Aquati c

Weed Program and the U S Fi sh and Wi l d l i fe Servi ce

2-1

I I C PRODUCT

After rev i ew each publ icat i on was cited keyworded and annotated

u s i ng ARTF I LE vers i on 3 02 software for l i brar i es and b i bl i ographic

storage

Two outputs were devel oped from the comp i l ed i nformat i on 1 )

annotated c i tation s of each i nd i v i dual report and 2 ) Lake Fact Sheets

wh ich summari ze ava i l abl e i nformat i on on a spec i fic top ic requested by

members of t he study team Lake Fact Sheets and keyword b i bl i ographies

were d i stri buted t hroughout the course of the study as requested by

i nd i vi dual project members Lake Fact Sheets and a key word l i st

fol l ow Annotated c i tat i ons appear i n Append i x 2 A

2-2

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on AQUATIC PLANTS

Entri es i n Bi bl i ography 69

( For more deta i l s on spec i fic top ics pl ease see other fact sheets i e

hydri l l a b i omass harvest i ng etc )

Types of stud i es noted

- -Aquat ic pl ant ecol ogy (Moss 1980 23 Lugo and Snedaker 1971 113

Bl ackburn n 11 1968 128 Canfi el d et J 1983 260 Cassan i and

Caton 1985 352 Marshal l 1984 386)

- -Informat i on on aquat i c pl ant communi t i e s as habi tat (Wi l ey etI 1984

34 Durocher niI 1984 38 Mi l l eson nI 1980 40 Watki ns et I

1983 45 Ager and Kerce 1974 190 Sav i no et il 1985 196 Richard

n iI 1985 262)

- -Aquatic pl ant and sed i ment rel ati onsh i ps (Engel and N ichol s 1984 44

Barko and Smart 1986 106 Barko et 11 1983 147 L i et I 1974

108)

- -Aquat i c p l ant management ( Fl or ida DER nI 1986 415)

- - Nutrjent removal by aquat i c pl ants ( Reddy and DeBusk 1985 132)

- -Stud i es on harvest i ng aquat i c pl ants and the effects of harvest i ng

( Carpenter and Adams 1978 17 Sabol 1987 37 Mi ko l 1985 41

Wi l e 1978 57 Neel n 11 1973 114 N ichol s 1974 115

Smal l et

I 1985 130 Wi l e 1975 135)

- -Stud i es on chemical and other control s of aquat i c pl ants ( H i l t i bran n

J 1972 105 Ganstad 1978 110 deNoyel l es and Kett l e 1980 118

M i l on n 11 1986 119 Smal l et I 1985 130 Sutton and Vand i ver

1986 139 Lesl i e and Kobyl i nsk i 1985 255 Langel and and DeMont

1986 227 Barrett 1981 342 Barrett and Murphy 1982 344 Cl ayton

and Tanner 1982 355 Frank and Comes 1967 364 Graham 1976 369

Hughes and McCol l 1980 377 Richard et I 1984 426)

- -Aquat i c pl ant chem i s try and phys i ol ogy ( LaLonde 1970 107 Gerl off

1978 111 Gerl off 1973 112 Bri stow and Wh i tcombe 1971 136)

- - Chl orophyl l a concentrat i ons and aquat i c macrophytes ( Canfi e l d et I

1984 263)

2-3

Produced by Mote Marine Laboratory for South Florida Water Management District

- -B i omass stud i es and methods ( Schl oesser and Manny 1984 14 Mace i n a

J il 1984 33)

- -Uses for aquat i c weed s such as cattl e s i l age ( Bagnal l n l 1978

18) and compost (Wi l e g1 Jl 1978 19)

--Stud i es concern i ng Hydrilla vertic1llata ( Bagnal l 1980 18 Bol e and

Al l an 1978 15 P i erterse J il 1984 42 Bruner and Batterson 1984

43 Bowes 11 il 1979 47 Sutton 1982 52 Sutton and Port i er 1985

53 Sutton and Port i er 1983 57 McGhehee 1979 57 Bal c i unas 1985

116 Mart i n 1983 146 Johnston n Jl 1983 36 Canfi el d et l

1983 265 Mace i n a and Shi reman 1982 281 Hodgson and Carter 1982 423)

2-4

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fa c t She e t on BIOMASS

Entri es i n B i bl i ography 14

Types of stud i es noted

- -A troph i c state i ndex for l akes based on al gal bi omass (Carl son 1977

2)

- -Chl orophyl l -b i omas s - nutri ent rel ati onsh i ps for phytopl ankton (Canfi el d

et gl 1985 4)

--An assessment of bi omass control for water qual i ty management (Wong et

li 1979 9) --Methodol og ies for est imat i ng or measuri ng bi omass (Schl oesser and

Manny 1984 14 Mace i na g1 li 1984 33)

--Effects of harvest i ng or other weed control methods on aquat i c

vegetat i on b i omass (Mi kol 1985 41 Wi l e 1978 57 Cassani and Caton

1985 352 Hughes 1974 378 Sch i l l er 1983 398)

--B i omass measurements rel ati ng seasonal and b i otype vari at i ons i n

Hydr i l l a (Bowes et 11 1979 47 Steward 1987 408)

--Seasonal b i omas s of sel ected spec i es (Bowes et li 1979 47 Dewey et

l 19a1 266)

SUMMARY

Several stud i es use b iomass as a measure of aquat i c pl ant control

and as part of overal l assessments of water qual i ty management Mi ko 1

(1985) uses total pl ant bi omass measurements to asses s the effects of

mechan i cal harvesti ng on aquat i c vegetati on Wi l e (1978) al so presents

bi omass data as part of an assessment of envi ronmental effects of

mechan i cal harvesting Cassine and Caton (1985) asses s the same for

chem i cal and b i ol og i cal weed control Mace i na et li (1984) present a

method for est i mat i ng submersed pl ant bi omass by us i ng a record i ng

fathometer The i r data showed that the tech n i que i s not equal l y rel i abl e

for al l water bod i es However accurate b iomass determi nat i ons cou l d be

obt ai ned i f fathometer traci ngs are cal i brated w i th actual b i omas s data

Add i t i onal b iomass data for aquat i c p l ants are presented by Hughes

2-5

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

( 1974) Sch i l l er ( 1983 ) and Steward ( 1987 ) Bowes n il ( 1979) and

Steward ( 1987 ) present bi omass data for Hydri l l a i n Fl ori da

Canfi e l d et il ( 1985 ) address chl orophyl l - bi omass - nutri ent

rel at i onsh i ps for n atural assembl ages of Fl ori da phytopl ankton Carl son

( 1977 ) presents a troph i c state i ndex for l akes and uses al gal b i omass as

a parameter for the i ndex

2-6

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STU DY

Fact Sheet on D IQUAT

Entr i es i n B i bl i ography 84

Types of stud i es noted

- -Taxi c i ty data ( Mayer and El l ers i eck 1986 270 Berry and Schreck

1976 346 Funderburk and Lawrence 1967 366 Howe and Wri gt 1965

376 Kam W i ng and Furtado 1977 381 Naqui et Ai 1980 390)

- - Effects of d i quat on aquat i c commun i t i es ( H i l t i bran I 1972 105

Berry sl 1964 347 Cas san i and Caton 1985 352 Cal derban k 1972

351 C l ayton 1986 356 Dan i el 1972 358 G i l derhus 1967 368

Haag 1986 370 H i l senhoff 1966 372 Hughes and McCol l 1980 377

Joyce and Thayer 1986 379 Marshal l 1984 386 M i chaud 1979 387)

- -General chem i cal control gu i des and control of spec i fi c aquat i c

pl ants (Abery 1986 339 Barrett 1981 342 Barrett and Murphy 1982

344 Barrett and Logan 1982 345 Chevron Chemi cal Corp 1978 354

Hi l t i bran 1971 373 H i mel n li 1981 375 Ki l l gore 1984 383

Mac kenz i e 1966 385 Mobl ey n il 1971 388)

- -Di quat accumul ati on i n pl ants and sed i ments ( B i rmi ngham and Colman

1983 348 Dav i s and Seaman 1968 359 Frank and Comes 1967 364

Langeland and Warner 1986 384)

- - Experi mental data on herb i c i de treatments (Bri t i sh Col umbi a 1975

350 Clayton and Tanner 1982 355 Dunn et I 1983 362 Hal l er

1982 371 K i l l gore 1981 382 Newroth and L i m 1980 392)

- -Di quat u se wi th other types of control s (Charudattan 1986 353 Frank

AI 1979 365 Ganstad 1986 367 Graham 1976 369 Newroth

1974 391)

SUMMARY

I n add i t i on to the above noted stud i es three l i terature summari es and

rev i ews prov ide good i nformat i on on d i quat stud i es

Joyce and Ramey (1986) prov ide a good annotated rev i ew of 1 i terature

concern i ng research on the fate of aquat i c herb i c i de s i n water w i th

emphas i s on Fl ori d a s freshwater ecosystems Tucker (1980) rev i ews 50

c i tat i ons on d i quat c i tat i ons and prov ides a deta i l ed summary on the

2-7

Produced by Mote Marine Laboratory for South Florida Water Management District

foll ow i ng aspects of d i quat env i ronmental chemi stry adsorpt i on by so il

and cl ay mi neral s aerob i c and anaerob i c soi l stud i es soi l stud i es under

fi el d cond i t i ons aquat i c studi es soi l l eaching stud i es rotat i onal crop

stud i es photochem i cal degradat i on stud i es and mi croorgan i sm stud i es

Langel and and DeMont ( 1986 ) prov i de a thorough rev i ew of the l i terature

on the detect i on tox i c i ty and pers i stence of d i quat endotha1 1 and

f1 uri done They al so present speci fi c data on stud i es of the pers i stence

of d i quat endothal l and f1 uridone i n North Carol i na ponds and water

movement patterns i n Lake Wheel er North Carol i na

2-8

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fact Sheet on EUTROPHICATION

Entr i es i n Bi bl i ography 12

Types of stud i es noted

- -Eval uati ons of nutri ents i n eutroph i c l akes (Canfi el d 1983 5

Schi ndl er 1971 131 Michaud n ll 1979 387 Lee and Jones 1980

175)

- -Aquati c pl ant probl ems i n eutroph i c l akes (Graham 1976 369 Hughes

and McCol l 1980 377)

--Assess i ng eutroph i cati on based on water qual i ty stud i es ( Federi co et

Al 1981 67)

--Troph i c structure assessments and changes i n eutroph i c l akes ( Gayl e

1975 181 US Envi ronmental Protect i on Agency 1975 161)

SUMMARY

A number of stud i es address eutroph i cati on i n Lake Okeechobee

US Env i ronmental Protect i on Agency (1975 161) reports on Lake

Okeechobee as part of the Nat i onal Eutroph i cat i on Survey and a number of

state gency commi ttee stud i es and eng i neeri ng reports provi de anal yses

of Lake Okeechobee eutroph i cati on (MacGl l n AI 1976 174 Bl ack Crow

Ei dsness Inc 1976 185 Lee and Jone s 1980 175)

Us i g seven years of water qual i ty data Federi co et it 1 (1981

67) i dent i fy annual and seasonal l mnet i c water qual i ty trends exami ne

the re l at i o n s hi p to t r i but ary i n fl ow s i d en tify trends and

quali tyd i scharge rel ati onsh i p s cal cul ate annual l ake materi al budgets

for each year and assess the trophi c status of the 1 ake Gayl e (1975

181) presents a systems model for understanding eutrophicat i on i n Lake

Okeechobee

2-9

Produced by Mote Marine Laboratory for South Flori da Water Management District

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on HARVESTING

Entr i es i n B i bl i ography 15

Types of stud i es noted

--Effects of harvesti ng aquat i c pl ants on nutr i ent removal ( Bol e and

Al l an 1978 15 Wi l e 1978 57 Neel et AI 1973 114)

--Compari sons of mechan ical and b i ol og i cal harvest i ng wi th herbi c i de

control ( Carpenter and Adams 1978 17 Smal l et AI 1985 130

Sch i l l er 1983 398)

--Di sposal of and uses for harvested hydri l l a ( Bagnal l et AI 1978 18

Sabol 1987 37)

--Harvest i ng effects on aquat i c fl ora and fauna (Mi kol 1985 41 Wi l e

1978 57 N i chol s 1974 115 Wi l e 1975 135 Schramm et AI 1985

212 Lesl i e and Kobyl i nsk i 1985 255)

- - Economi c s of mechani cal harvest i ng (McGhehee 1979 57)

- - Phys i cal propert i es of hydri l l a for harvesti ng ( Bagnal l 1980 59)

SUMMARY

Most of the stud i es address the effects of mechan i cal ly harvest i ng

aquat i c pl ants Bol e and Al l an (1978) report that the harvest i ng of

Hydr i l la vert i c illata woul d result i n the d i rect transfer of onl y a smal l

amount of phosphorus i n the soi l i nto the water and the organ i cal l y-bound

phosphorus removed i n harvested pl ants woul d be deri ved l argely from the

sed i ment and not the water body W i l e (1978) and Neel n AI (1973)

present data and anal yses on l ake nutri ent dynam i cs resul t i ng from

harvest i ng aquat i c pl ants W i l e (1978) al so presents data on al gae

phytopl an kton fi sh and water qual i ty changes

A number of other stud i es address harvest i ng affects on fl ora and

fauna Mi kol (1985) reports that harvest i ng pl ants al so removed from 2-

8 of the total stand i ng crop of juven i l e fi sh Lesl i e and Kobyl i ns ki

(1985) address benth i c macro i nvertebrate response to aquat i c vegetat i on

removal wh il e Sabol (1087) addresses the env i ronmental effects of aquat i c

d i sposal o f chopped hydr i l l a

2-10

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

Compar i sons of mechan i cal harvest i ng and herbi c i des address

phosphorus cycl i ng (Carpenter and Adams 1 978) and Smal l et Jl ( 1 985)

report that herbi c i des reduced aquat i c vegetat i on but d i d not el i mi nate

i t Us i ng grass carp as bi ol og i cal control s el im i nated or red uced the

vegetat i on depend i ng on the stocki ng rat i o ( Smal l et AI 1985 )

2-11

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fact Sheet on Hydrjlla vertic11l ata

Entri es i n B i bl i ography 37

Spec i fi c stud i es on hydri l l a i n Lake Okeechobee i ncl ude a

compari son of dens i ty data for Lake Okeechobee and three other areas of

Fl ori da wi th stud i es spec i fi c to the speci a l i zed reproducti ve structures

of hydri l l a (Sutton and Port i er 1985 53) and an ana lys i s of potass i um

n i trogen and phosphorus content i n hydri 11 a from Lake Okeechobee and

three other areas of Sout h Fl ori da ( Sutton and Porti er 1983 56)

Pl ants from Lake Okeechobee had the h i ghest concentrat i on s of each

Other types of stud i e s on hydri l l anoted

--Phys i cal and mechani cal propert i es of hydri l l a (Bagnal l 1980

59)

--Nutri ent uptake stud i es of hydri l l a (Bol e and Al l an 1978 15)

--Us i ng hydri l l a for s i l age ( Bagnal l et Al 1978 18)

--Methods for determi n i ng or est i mat i ng pl ant biomass (Maceina et

li 1984 33)

--Growth reproduct i on and l i fe hi story of hydril l a ( Langel and and

Sutto 1980 35 Bruner and Batterson 1984 43 Spencer et li 1987

48 Sutton 1982 52)

--Habi tat i mportance and ecol ogy of hydril l a communit i es and

al terations to hydril l a communities (Watkins et li 1983 45middot

Bowes et

li 1979 47 Bl ackburn et li 1968 128 Sutton and Vandiver 1986

139 Can f i el d n Al 1983 265 Mace i na and Sh i reman 1982 281

R i chard i1 Al 1985 396)

--Biol ogical control s of hyd ri l l a (Bal ciunas and Minno 1985 46

Bal ciunas 1985 116 Johnston et li 1983 36 Cas sani and Caton

1985 352)

--Mechanical control s of hydril l a (McGhehee 1979 57)

--Chemical control of hydri l l a (Martin 1983 146 Cassani and

Caton 1985 352 Frank et li 1979 365 Hughes 1974 378 Small et

Al 1985 404 Steward 1972 405 Steward 1982 406 Steward 1976

407 Steward 1987 408 Van 1985 419 Van et Al 1987 420)

2-12

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

SUMMARY

Most of the stud i es deal w ith ways to control Hydr i l l a

verticilJata as a nui sance weed The effects of harvest i ng Hydri l l a i s

frequent l y addressed wi th mi xed resul ts Bol e and Al l an ( 1978) report

that the harvest i ng of Hydri 1 1 a woul d resul t i n the d i rect transfer of

onl y a smal l amount of phosphorus in the so i l i nto the water and the

organ i cal ly-bound phosphorus removed i n the harvested pl ants woul d be

deri ved l argel y from the sed i ment and not the water body

Johnston g1 il ( 1 983 ) report on the recol oni zat i on of a smal l pond

wi th aquat i c vegetat i on where grass carp have been used to control

Hydrill a They demonstrate the feas i b i l i ty o f reduc i ng the compet i t i ve

advantage of Hydri l l a i n order to l l ow other spec i es to become

establ i shed but al so note that care must be exerc i sed i n sel ect i ng

repl acement spec i es Other aquat i c pl ants may grow as prol i fi cal l y as

the Hydri 1 1 a bei ng repl aced

Sabol ( 1 987) and Langel and and Sutton ( 1 980 ) report on the

regrowth of fragmented Hydri l 1 a w i th confl i ct i ng resul t s In f iel d

stud i es Sabol ( 1 987) tested the re -growth potent i al of chopped Hydri 1 1 a

and found that a very smal l port i on of fragments cou1 d produce new

g rowth Conversely Langel and and Sutton ( 1980 ) under control l ed

l aboratory and f i e l d cond i t i ons demonstrated that 40 of the pl ant

fragments wi th one or two nodes were capabl e of vegetat i ve reproduct i o n

Bagnal l 11 il ( 1984 ) eval uated the feas i b i l i ty o f us i ng Hydri l 1 a

for cattl e feed and Macei na 1 il ( 1 984 ) present a method for pred i cti ng

pl ant b i omass us i ng a record i ng fathometer

2-13

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on N ITROGEN

Entri es i n B i bl i ography 27

Types of stud i es noted

- - Land userunoff rel at i onsh i ps w i th nutri ents i ncl ud i ng n i trogen

( Feder i c o 1 977 3 )

- - Nutri ent i n fluences on aquat i c pl ants and phytopl ankton (Canfi el d et

li 1985 4 Can fi el d 1 983 5 Davi s 1980 20 Dav i s 1 982 27

P i eterse 1 984 42 Sutton and Port i er 1 983 56 Bl ac kburn et il

1 968 1 28 Reddy and DeBus k 1 985 13 2 Jones and Federi co 1 984 1 )

- - Water qual i ty stud i es that i ncl ude nitrogen parameters ( Lutz 1 977a

7 Lutz 1 977b 16 M i l ler 1 980 20 Mi l l er et li 1982 26 Dav i s

and Marshal l 1 975 65 Peverl y and Johnson 1 979 394 Jones 1 983

9 )

- - Nutri ent rel at i onsh i ps w i th the troph i c structure of l akes (Henri kson

11 il 1 980 32 Dye 11 il 1975 138)

- - N i trogen and other water qual i ty data for Lake Okeechobee ( Di c kson et

li 1978 66 Davi s and Marshal l 1975 65 Federi co g1 li 1981 67

Fre i betger 1972 69 Mi l l er 1975 70 Jones and Federi co 1984 1

Jones 1 983 9)

- -N i t rogen i nputs and l ake eutroph i cat i on ( Sch i ndl er 197 1 13 1

Feder i co et il 1981 67 Canfi el d 1 983 5 )

- -Den i tri ficat i on i n Lake Okeechobee (Messer et li 1979 1 43 Messer

and Brezon i c 1 984 1 58)

- -Geochemi cal exchanges across the sed i ment -water i nterface ( Burton et

il 1975 1 45 Messer and Brezon i c 1984 158 )

- -Model s pred i ct i ng n i t rogen concentrat i ons (Jones 1983 9 )

SUMMARY

Several stud i es prov i de data on n i trogen for Lake Okeechobee

(M i l l er 1 980 20 Di c kson et li 1978 66 ) Many of these prov ide

n i trogen data as part of l arger studies for i nstance Federi co et li

( 1981 67 ) summari ze seven years of water qual i ty data i n order to

ident i fy annual and seasonal trends cal cu l ate annual budgets and assess

2-14

Produced by Mote Marine Laboratory for South Florida Water Management District

the troph i c state of the l ake Two stud ies ( Fre i berger 1 972 69

Mi l l er 1 97 5 70) i ncl ude lake Okeechobee as part of l arger wet and dry

season nutri ent surveys of South Fl ori d a

Jones ( 1 983 9 ) eval uates the qual i ty o f d i scharges t o Lake

Okeechobee nutr i ent concentrat i ons affects of var i ous changes i n l ake

l evel s and the abi l i ty of var i ous model s to accuratel y pred i ct n i trogen

and phosphorus concentrat i ons Jones and Federi co ( 1984 I) al so apply

nutr i ent model smiddot to Lake Okeechobee Dav i s and Marshal l ( 1 975 65)

present i nformat i on on areal and seasonal vari at i on s of n i trogen l evel s

nutri ent l oad i ngs and budgets for Lake Okeechobee and other chemi stry

d ata

Sutton and Port i er ( 1 983 56) eval uate the potass i um n i trogen

and phosphorus content of Hydri l l a from fi ve l ocat i on s i n South F l ori da

Sampl es were eval uated for wi th i n 1 ocat i on vari abi l i ty and for between

l ocat i on vari abi l i ty and resul ts showed that pl ants from lake Okeechobee

had h i gher concentrat i ons of nutri ents than pl ants from other areas

2-15

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on PHOSPHORUS

Entr ies i n Bi bl i ography 135

Phosphorus stud i es speci fi c to Lake Okeechobee i ncl ude

- -An anal ys i s o f the effect o f reduced nutri ent l oad i ngs on Lake

Okeechobe chl orophyl l (Jones and Feder i co 1984 )

- -An eval u at i on of the qual i ty of d i scharges to l ake nutri ent

concentrat i on s (Jones 1983 )

- -An analys i s of the abi l i ty of vari ous model s to accurately pred i ct

phosphorus concentrat i on s (Jones 1983 )

- -A comp ari son of phosphorus content i n hydri l l a from Lake Okeechobee and

four other l ocat i ons (Sutton and Porter 1 983 )

- -Aer i a 1 and seasonal vari at i ons of phosphoru s 1 eve 1 s i n Lake Okeechobee

(Davi s and Marshal l 1975 )

-A survey of total ortho p l us aci d - hydrol yzabl e phosphorus ( P- P04)

dur i ng a peri od of h igh water and a peri od of l ow water at 1 1 stat i on s i n

Lake Okeechobee and several stat i ons el sewhere i n South Fl or1 da

(Fre i berger 1972 )

- -An anal ys i s of l i mi t i ng factors based on al gal assays on water sampl es

from 30 s i tes i n the Ki s s i mmee R i ver- Lake Okeechobee Bas i n (Dye tl AI

1 975 )

- - Stud i es on nutri ent exchange across the sed i ment-water i nterface

(Burton et il 1975 )

Add i t i onal l y spec i fi c phosphorus d ata for Lake Okeechobee and i t s

watershed are presented i n a number o f reports (Jones and Feder i co 1984

Jones 1983 Mil l er 1980 Davi s and Marshal l 1975 Fre i berger 1 972

Messer et il 1 979 Dye et il 1975 Burton et Al 1975 Lee and Jones

1975 Lutz 1 977 Mi l l er et il 1982 Di ckson et Al 1978 M i l l er 1975)

Regard i ng management pl an s for phosphorus l evel s t he Lake

Okeechobee Techni cal Commi ttee ( 1 986 ) recommended to reduce phosphorus

l oads by at l east 40 (based on the mod i fi ed Vol l enwe i der nutri ent

l oad i ng model s ) through a program of d i vers i ons and treatment

2-16

Produced by Mote Marine Laboratory for South Florida Water Management District

Stud i es out s i de the lake Okeechobee area wh i ch prov i de i nformat i on

val uabl e to the study of phosphorus i ncl ude

- - Uptake of phosphorus from sed i ment and the water col umn by pl ants ( Bol e

and Al l an 1978 Dav i s 1984 Dav i s 1982 Reddy and DeBus k 1985 Dav i s

and Harri s n d li i1 Al 1974)

- -The i nfl uence of 1 and use patterns and other control s on phosphorus

l evel s ( Federi co 1977 Mi chal ski i1 Al 1975)

- -The correl at ion of nutri ent l evel s w i th chl orophyl l and phytopl ankton

l evel s ( Canfi el d i1 Al 1985 )

- - I ndexi ng and model l i ng techn i ques for l akes us i ng phosphorus and

rel ated data ( Carl son 1977 Canfi el d 1983 Meri cas and Mal one 1984)

- - Data on removal of phosphorus by mechan i ca l l y harvest i ng pl ants

( Carpenter and Adams 1978 Wi l e 1978 )

- -Rel ati on sh i p between nutri ents and b i ol og i cal parameters ( Henri kson g1

Al 1980 Pi eterse 1984 Enn i s 197 5 Re i nertsen 1 986 )

- - Phosphorussed i ment i nteract i ons (Twi nch and Peters 1984 li et li

1 97 1

- -laboratory and other control l ed stud i es on the propert i es of phosphorus

( Shannon and lee 1966 li et li 197 1 )

--Other l i terature stud i es ( Sch i ndl er et Al 197 1 )

2-17

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on PHYTOPLANKTON

Entr i es i n B i bl i ography 8

Types of stud i es noted

- - Phytopl ankton stud i es for Lake Okeechobee (Marshal l 1977 1 2 Dav i s

and Marshal l 1975 65 Marshal l 1977 424 Jones and Federi co 1 984

1 )

- - Phytopl anktonnutri entl ake eutroph i cat i on rel at i onsh i ps (Canfi el d et

AI 1985 4 Sch i ndl er 1971 13 1 Hughes and McCol l 1 980 377 Jones

and Federi co 1 984 1 )

- - Phytopl ankton pri mary producti on methodol ogy ( Schearer et AI 1985

278)

--Phytopl ankton responses to aquat i c pl ant removal (R i chard et AI 1985

426)

SUMMARY

Dav i s and Marshal l ( 1975 65) present 2 - 12 years of

phytopl an kton dens i ty data for Lake Okeechobee as wel l as i nformat i on on

n i trogn and phosphorus l evel s ( areal and season al vari at i on s ) pri mary

product i v i ty changes in al gal popul at i on s nutr i ent l oad ings and

budgets ra i n fal l chemi stry dat a regress i on anal yses on bi ol og i cal

act i v i ty and chemi cal or phys i cal propert i e s and trophic state

Marshal l s ( 1 977 1 2 ) phytopl ankton dens i ty data for 1974 show peaks i n

May and September i n Lake Okeechobee Marshal l concl udes that Lake

Okeechobee exh i b i t s seasonal patterns and peri od i c i ty typ i cal of

temperate l akes al though the seasonal vari at i on i n den s i t i es i s typi cal

of a trop i cal l ake

Jones and Federi co ( 1984 1 ) present over four years of d ata on

chl orophyl l a pri mary product i v i ty phytopl ankton dens i t i es and domi nant

species They al so an al yze the effect of reduced nutri ent l oad i ng s on

L a ke Okeechobee chl orophyl l and concl ude that chl orophyl l and

product i v i ty l evel s have not changed substanti al l y dur i ng the study

peri od except that peak val ues were h i gher i n 1981

2-18

Produced by Mote Marine Laboratory for South Florida Water Management District

Canfi el d n li ( 1985 4) col l ected data from 165 Fl ori da l akes

and reported a s i gn i fi cant correl at i on between chl orophyl l a

concentrat i ons and phytopl ankton bi omass Mul t i pl e repress i on anal yses

i nd i cated that phytopl ankton bi omass was dependent on both the total

phosphorus and total n i trogen concentrati on Nutri ent-phytopl ankton and

Secch i - phytopl ankton rel ati onsh i ps for the Fl orida l akes had h i gher

coeffi c i ents of determi nat i on i f chl orophyl l a concentrat i ons rather than

bi omass data were used

2-19

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fa ct Sheet on PRIMARY PRODUCTIVITY

Entries in Bibl iography 11

Types of studies noted

- -General ecol ogy studies incl uding primary productivity (Fontaine and

Ewe l 1981 31)

- -Trophic studies of l akes (Henrikson it 11 1980 32)

--Nutrient infl uences on primary productivity (Davis and Harris no date

141)

- -Primary production methodol ogy (Shearer l1 11 1985 278)

--Primary production data in Fl orida (Odum 1974 169 Brezonic et 11

1979 155 Jones and Federico 1984 1 Davis and Marshal 1975 65

Marshal l 1974 424)

- -Seasonal primary productivi ty cycl es (Comita 1985 1195 Marshal l

1974 424)

SUMMARY

Severa 1 stud i es concern primary production in Lake Okeechobee

Brezonjc l1 11 (1979 155) report to the Fl orida Sugar Cane League on

factors affect i ng primary product ion n Lake Okeechobee Jones and

Federico (1984 1) present primary productivity data on Lake Okeechobee

for 1974-76 and 1979-82 as wel l as information on chl orophyl l a

phytop 1 ankton dens i ties and domi nant spec 1 es and an anal ys s of the

effect of reduced nutrient l oadings Their report concl udes that

ch l orophyl l and productivity l evel s have not c hanged substantial l y during

the study period except for peak val ues that were higher in 1981 and

overal l val ues were higher In the Lake s north end Marshal l (1974

424) add resses seasonal changes for primary productivity and

phytopl ankton He concl udes that considering primary productivity and

other factors Lake Okeechobee phytopl ankton dynamics resembl e temperate

l akes Davis and Marshal l (1975 65) present over two years of data on

chemical and biol ogical investigations of Lake Okeechobee incl uding

primary productivity

2-20

Produced by Mote Marine Laboratory for South Florida Water ManaQement District

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet o n SED IMENTS

E ntr i es i n B i bl i ography 21

Types of stud i es noted

Most of the stud i es i nvol ve sedi ment nutr i ent ava i l abi l i ty fl uxes

and uptake by pl ants These i ncl ude reports on

-- Laboratory experiments to determi ne phosphorus uptake from the

sed i ments by Myri ophyl l ym and Hydri l l a ( Bol e and Al l an 1978 1 5 )

- - Phosphate exchange i n l ake sed i ments (Twi nch and Peters 1984 295 L i

et l 197 1 1 49 li Al 1973 )

- -Ava i l ab i l i ty of sedi ment phosphorus for macrophytes ( L i et l 1974

108)

- - Phosphorus fl uxes i n south Fl ori da marshes (Dav i s and Harri s no date

143 )

- -The i mportance of den i tr i fi cati on i n lake Okeechobee (Messer et l

1979 1 43 )

- -Geochemi cal exchanges across the sed i ment -water i nterface i n the

Ki s s i mmee Ri ver- Lake Okeechobee watershed ( Burton g1 l 1975 145)

- - lak sed i ment den i tri f i cat ion model s (Messer and Brezon i c 1 984 1 58)

There are al so a number of stud i es concern i ng the rel at i onsh i p of

sedi ment type and other factors to pl ant growth ( Bruner and Batterson

1984 43 Mart i n 1983 146 Barko et il 1983 147 Engel and

N i chol s 1 984 44 Barko and Smart 1986 106) pest i c i de and other

chemi cal res i dues i n sedi ments ( Pfeuffer 1985 298 Hughes and McCol l

1980 377 S i ms i man and Chesters 1976 402 )

SUMMARY

BUrton et l ( l979) documents the rol e of sed i ments i n determi n i ng

water qual i ty i n the Ki s s immee Ri ver-lake Okeechobee watershed wi th an

emphas i s on nutri ent exchange across the sed i ment -water i nterface They

a l so prov ide survey i nformat i on on sediment d i str i but i on and transport

Mes ser et l ( 1979) summari zes the i mportance of den i tr if i cat i on i n lake

Okeechobee i ncl ud i ng a d i scuss i on on the rol e of sedi ments i n the

2-21

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

den i tr i fi cat i on process

eval uat i on o f l ake sed i ment

Lake Okeechobee

Messer and Brezon i c ( 1 984 ) present an

den i tri fi cat i on model s and i ncl ude data from

Dav i s and Harri s ( n d ) provi de est i mates of phosphorus fl uxes

wh i ch d i rectly contri bute to uptake through pl ant growth and to retent i on

through pl ant detri tus sed i mentat i on for the Evergl ades Conservat i on Area

2

2-22

LAKE OKEECHOBEE LITERATURE REVIEW

LIST OF KEY WORDS

ABUNDANCE ( 2 ) ADSORPTION ( 2 ) AGE (1) AGRICULTURE (1) ALGAE (14) ALGAL BIOASSAY (1) ALGICIDES ( 2 ) ALKALI N I TY (1) ALKALOIDS (1) ALTERNANTHERA ( 2 ) ALTERNATHERA (1) AMMONIA (1) AMPH I PODS (1) ANALYSIS OF COVARIANCE (1) ANIMAL BEHAVIOR (1) ANIMALS ( 2 ) AQUATHOL (1) AQUATIC PLANT CHEMISTRY (1) AQUATIC PLANTS (76) AQUATIC ORGANISMS ( 2 ) AQUATIC ( 1 ) AQUIFER ( 2 ) ARGULUS ( 1 ) ARTHROPODS ( 1 ) ATHERINE FISH (1) BACKPUMPING ( 2 ) BACTERIA ( 3 ) BASS (18) BEACH HAB ITATS ( 2 ) BEHAVIOR ( 2 ) BENTHOS (9 ) BEST MANAGEMENT PRACTICES (1) B IOACCUMULATION (1) BIOASSAY (1) BIOLOGICAL CONTROL (8) BIOLOGY ( 6 ) BIOMASS (15) BIOTIC ASSESSMENT (1) BIOTYPES (1) BIRDS ( 2 ) BLACK CRAPPIE (19) BLACK BULLHEADS (1) BLUEGILL ( 1 2 ) BODY FORM ( 2 ) BREEDING (1) BROMAC I L (1) BROOK SILVERSIDE (1) CABOMBA (1)

2-23

CADDISFLIES (1) CADMIUM (1) CALLITRICHE (1) CALOOSAHATCHEE RIVER (5) CANALS ( 2 ) CARBON (1) CARBONATE ROCKS (1) CARBOXYLASE (1) CAREX (1) CATTAI LS (1) CATTLE FEED (1) CENTRARCHIDS (5) CERATOPHYLLUM (5) CHAIN PICKEREL ( 1 ) CHANN ELS ( 1 ) CHAOBORUS (1) CHARA ( 6 ) CHEMICAL CONTROL ( 66 ) CHEMISTRY (10) CHIRONOMID LARVAE (1) CHIRONOMIDS (1) CHLORIDE (4) CHLORINATED HYDROCARBONS (1) CHLOROPHYLL (11) CLADIUM ( 2 ) CLASSIFICATION (1) COEFFICIENT OF DETERMINATION (1) COMMERCIAL FISHERY (2 ) COMMUNI TIES (1) COMMUNITY STRUCTURE ( 7 ) COMPETITION ( 3 ) COMPOST (1) COMPUTER MODELS (1) CONFINING BEDS (1) CONTOUR MAPPING (1) CONTROLLED RELEASE (1) COPEPODS (1) COPPER ( 9 ) COPPER SULFATE (1) CORE SAMPLER (1) COST BENEFIT ANALYSIS (1) CRUSTACEANS ( 2 ) CTENOPHARYNGODON IDE (2 ) CULTURAL CONTROL ( 2 ) CYANATRYN (1) DALAPON (4) DEGRADATION ( 3 ) DEMOGRAPHY (1)

DENITRIFICATION (1) DENSITY (6) DESORPTION (1) DETENTIONRETENTION ( 1 ) DETRITUS (1) DEVELOPMENT (2) DIATOMS (1) DICHLOBENIL (2) DIPOTASSIUM ENDOTHAL ( 1 ) DIQUAT (89) DISCHARGE ( 1 ) DISPERS ION (1) DISSOLVED OXYGEN (14) DISSO LVED SOLIDS (2) DISTRIBUTION (16) DIURNAL (1) DRAINAGE (4) DREDGING (1) DYSTROPHIC (1) EARLY DEVELOPMENT (2) ECOLOGY (15) ECONOMIC ANALYSIS (1) ECONOMICS (1) ECOSYSTEM (1) EFFLUENT REDUCTION (1) EFFLUENT (1) EGERIA (6) EICHHORNIA (13) ELODEA (20) EMBRYO ( 1 ) ENDOTHAL-POTASSIUM ( 1 ) ENDOTHALL (20) ENTRAINMENT (2) EPIPHYTES (1) EUTROPHICATION (12) EVERGLADES ( 9 ) EVERGLADES COUNTY (1) EXOGENOUS FEEDING (2) EXPLORATION (2) FAUNA (2) FEEDING ( 9 ) FEEDING RELATIONSHIPS (2) FENAC (5) FIRST YEAR SURVIVAL ( 1 ) FISH (130) FLOOD CONTROL (1) FLOODING ( 1 ) FLORIDA (31) FLORIDA EVERGLADES (1) FLORIDA LAKES (4) FLORIDA DUCK (1) FLORIDAN AQUIFER (2)

2-24

F LOW RATES (1) F LURIDONE (9) FOOD CHA I NS (1) FOOD HABITS (2) FOOD (6) FORAGE ( 1 ) FORAGING ( 1 ) FREQUENCY ANALYSIS (1) FRESHWATER SPECIES (1) FRESHWATER DISCHARGE ( 1 ) FRESHWATER (27) FRESHWATER MARSH (1) GEOLOGY ( 9 ) GERMINATION (1) GIZZARD F I SH (1) GIZZARD SHAD (2) GLADES COUNTY (9) GLYPHOSATE ( 6 ) GRAPNEL SAMPLER (3) GRASS CARP (8 ) GREAT BRITAIN ( 6 ) GROUNDWATER (5) GROWTH (11) GROWTH INHIBITORS (1) HABITAT (2) HABITAT PARTITION ING (1) HARVESTING (7) HAUL SEINE ( 1 ) HENDRY COUNTY (9) HERBICIDES (47) HEXAZINONE ( 1 ) HIGHlANDS COUNTY (1) HISTORY (3) HOST SPECIFICITY (1) HYDRILLA (42) HYDROCARBONS (1) HYDROCOTYLE (1) HYDROGEOLOGY (2) HYDROLOGY (17) HYDROPERIOD CHANGES (1) HYGROPHILA (1) HYPERmiddotEUTROPHIC (1) ICHTHYOFAUNA (1) ICHTHYOPLANKTON (2) IDENTIFICATION KEY (1) IDENTIFICATION GUIDE (10) IMAZAPYR (1) IMPOUNDMENTS (3) IMPROVING CATCH (1) INDICATOR SPECIES (1) INORGANIC PHOSPHATE (1) INSECT CONTROL (1)

INSECTS (4) INVERTEBRATES (9) IRON (2) IRON CHELATE (1) IRR IGAT ION (2) ISOPODS (1) JASM INE (1) JUNCUS (2) JUVEN ILE F ISH (5) K ISS IMMEE R IVER (11) LABORATORY STUD IES (1) LAGAROS I PHON (3) LAKE LEVELS (2) LAKE WANAKA (1) LAKE CONWAY (1) LAKE OKEECHOBEE (89) LAKE DRAWDOWN (1) LAKES (75) LAND USE (6) LARGEMOUTH BASS (16) LARVAE (1) LARVAL F ISH (25) LEAF PRODUCTION (1) LEMNA (8 ) LEPOMIS (1) L IFE HISTORY ( 9 ) L IGHT INTENSITY (1) L IGHT TRAPS (1) L IMNOLOGY (2) LI MNO PH I LA (1) L ITERATURE SURVEY (5) L ITHOLOG IC ANALYSIS (3) L ITTORAL (12) L ITTORAL ZONE (9) LOTAC (3) MACRO INVERTEBRATES (12) MACROPHYTES (18) MANAGEMENT PLAN (3) MANGANESE (3) MARION COUNTY (3) MARSH PLANTS (3) MARTIN COUNTY (27) MASS BALANCE MODEL (3) MATERIAL BUDGET (3) MATHEMAT ICAL MODELLING (3) MATHEMATICAL MODELS (3) MECHAN ICAL CONTROL (15) MECHANICAL HARVEST ING (24) METHODS ( 9 ) M ICROBES (3) MICROPTERUS (6) MINERAL RETENTION (3)

2-25

MINERAL ADSORPTION (3) M INERAL NUTRITION (3) MINERALIZATION (3) M ISS ISSI PPI S ILVERSIDE (3) MODELING (6) MODELS (12) MOLLUSKS (3) MONITOR ING (15) MORPHOLOGY (3) MORTALITY (12) MOTHS (3) MOWING (3) MYOMERE NUMBERS (3) MYR IOPHYLLUM (84) MYSIDS (3) NAIDIDAE (3) NAJAS (18) NEKTON (3) NEMATODES (3) NEOCHETINA (6) NETS (6) N ICKEL (3) N ITRATES (3) N ITROGEN (81) NORTHERN P IKE (3) NUPHAR ( 9 ) NUTR IENTS (141) OCALA GROUP (3) OKEECHOBEE COUNTY (33) OKLAWAHA R IVER (3) OL IGOCHAETES (3) OLIGOTHROPHIC (6) ORANGE LAKE (3) ORGANIC MATTER (3) OSCEOLA COUNTY (3) OXYGEN (9) PALAEOLIMNOLOGY (3) PALM BEACH COUNTY (30) PAN ICUM (67) PARAQUAT (39) PARTICULATE MATTER (3) PASPALUM (3) PATHOGENS (3) PERI PHYTON (3) PERSISTENCE (9) PESTICIDES (27) PH ( 9 ) PHOSPHATE (15) PHOSPHORUS (135) PHOTOSYNTHES IS (12) PHYS IOLOGY (12) PHYTOPLANKTON (27)

PHYTOTOXICITY (3) PIKE (3) PISCIVOROUS FISH ( 6 ) PISTIA (15) PLANKTON (15) PLANNING (3) PLANT SUCCESSION (9) PLANT HARVESTING (9) PLANT ABUNDANCE ( 6 ) PLANT DENSITY (3) PLANT COMMUNITIES (9) PLANT SURVEY TECHNIQUES (9) PLANT COMPOSITION (9) PLANT NUTRITION (3) PLANT GROWTH ( 6 ) PLANT BIOMASS (3) POLLUTION (3) POLLUTION CONTROL (3) POLYCHAETES (3) POLYMER ( 6 ) POMACEA (3) POHOXIS ( 6 ) PONAR GRAB SAMPLER (9) PONDS ( 6 ) POPULATION DYNAMICS (9) POPULATION (21) POTAMOGETON (57) POTASSIUM (9) PREDATION (3) PREDATOR - PREY (15) PRIMARY PRODUCTION (36 ) PROPAGU1ES (3) PUMP STATIONS (3) PUMPING (3) RADAR (3) RADIOPHOSPHORUS (3) RAINFALL (18) RANUNCULUS ( 6 ) RATS (3) RECLAMATION ( 3 ) RECORDING FATHOMETER (3) RECRUITMENT (3) REDBREAST SUNFISH (3) REDEAR SUNFISH (3) REFERENCES (3) REGRESSION ANALYSIS (15) RELEASE RATES (3) REMOTE SENSING (3) REPRODUCTION (12) RESERVOIRS (51) RESIDUES (27) RESOURCE PARTITIONING (9)

2-26

RESPIRATION (3) REVIEW (3) RIVERS (42) RUNOFF (33) SAGITTARIA (3 ) SALVINIA (18) SAMPLING (15) SAMPLING METHODS ( 6 ) SAMPLING GEAR (3) SCIRPUS (3) SEA LEVEL RISE (3) SEASONAL EFFECTS (12) SEASONAL SUCCESSION (3 ) SEASONAL (9) SECCHI DISK (9) SEDIMENTARY ROCKS (3 ) SEDIMENTS (78) SEEPAGE (12) SEWAGE DISCHARGES (3) SHAD (15) SHINERS (3) SHOREFLIES (3) SHORELINE AREAS (3 ) SILICA (3) SILICON (3) SIZE CLASS ( 6 ) SNAILS (3) SODIUM ALGINATE ( 6 ) SODIUM (3) SOILS (9) SOUTH FLORIDA (24) SPARGANIUM (3 ) SPAWNING (21) SPECIES DIVERSITY (3 ) SPECIES COMPOSITION (3 ) SPECIFIC CONDUCTANCE (15) SPOTTED BASS (3 ) ST LUCIE ESTUARY (3 ) ST JOHNS RIVER (3 ) ST LUCIE COUNTY (3 ) STANDING CROP (15) STOCHASTIC LAKE MODELS (3 ) STORHWATER (3) STRATIGRAPHY ( 6 ) STREAMS (9) SUNFISH (18) SURFACE DISCHARGES (3) SURFACE WATER (21) SURFACTANTS ( 6 ) SURVIVAL ( 3 ) SUSPENDED SOLIDS (3 ) SWIM PROGRAM ( 3)

TAYLOR CREEK (6) TAYLOR CREEK WATERSHED (3) TEMPERATURE (9) TENNESSEE (6) TERRESTRIAL (6) THREADFIN SHAD (15) TILAPIA (3) TOXICITY (36) TRACE METALS (3) TRANSMISSIBILITY (3) TRANSPARENCY (6) TROPHIC STRUCTURE (30) TUBER PRODUCTION (3) TUBER DENSITY (3) TURBIDITY (12) TURION (9) TYPHA (9) UPPER TAYLOR CREEK (3) USGS (3) UTILIZATION (3) UTRICULARIA (3) VALLISNERIA (15) VAUCHERIA (3) VEGETATED HABITATS (3) VEGETATION (15) VEGETATIVE PROPAGULES (3) VEGETATIVE REPRODUCTION (6) VELOCITY (3) VERTEBRATES (3) WASTELOAD ALLOCATION (6) WASTEWATER TREATMENT (6) WASTEWATER (3) WATER SUPPLY (12) WATER RECYCLING (3) WATER LEVELS (6) WATER CONSERVATION AREA 2A (3) WATER CHEMISTRY (21) WATER QUALITY (Ill) WATER MANAGEMENT (6) WATER LEVEL (9) WATER CIRCULATION (3) WATER BUDGET (3) WATERSHED ANALYSIS (3) WEIGHT DISTRIBUTION (3) WEIR BOX (3) WET AND DRY SEASON (9) WETLANDS (9) WHITE CRAPPIE (6) WILDLIFE (3) WITHLACOOCHEE RIVER (6) WOLFFIA (3) XYLENE (6)

2-27

ZINC (3) ZOOLOGY (3) ZOOPLANKTON (21)

I I I BIOMASS - M ID-COURSE SUMMARY

I I I A INTRODUCT ION

The experimental removal of Hydr i l l a vert i c i 1 1 ata R i s bei ng

conducted to prov ide removal of nutr i ents phosphorus i n part icul ar from

Lake Okeechobee as wel l as the anc i l l ary benefi ts of i ncreased fi sh

hab i tat and nav igat i onal acces s To determi ne benefi ts and costs of

removal an i ndependent est i mate of both b i omass and nutri ent content of

vert i ci l l ata has been conducted

The bi omass sampl i ng effort was conducted i n August 1987 and was

compl eted pri or to the actual harvest i ng Stat i ons were concentrated i n

the area of the Hydri l l a mat but some non -Hydr i 1 1 a spec i es were al so

col l ected Sampl i ng l ocat i ons were sel ected on the bas i s of qual i tat i ve

cl ass i ficati ons of Hydri l l a growth character i s t ics

Based on fi e l d reconna i ssance i n Aprll and Ju l y 1987 a

s ubstant i al amount of spati al nonhomogene i ty i n both weed dens i ty and

spec i es compos i t i on was observed throughout the proposed s tudy s i te A

vari ety of env i ronmental factors such as substrate compos i t i on water

qual i ty and to a l es ser degree l i ght penetrat i on and water depth may

have been respons i bl e for these observed d i fferences Any past

appl icat i on and poss i bl e res i dual effects of weed control herb ic i des may

al so be contr i buti ng envi ronmental factors As growth character i st ics

w i th i n th i s area were not un i form i t was assumed un l i ke ly that nutri ent

content was evenly d i stri buted To quanti fy these area -wi de var i ati ons

a s ampl i ng scheme emphas iz i ng the range of Hydril l a growth cond i t i ons was

des i gned

III B MATER IALS AND METHODS

I I I B 1 Sampl e Col l ecti on

Prec i s i on measurement of Hydri l l a bi omass i s h igh l y dependent upon

the representat i veness of the sampl es as wel l as evenness of growth

character i st ics wi thi n the study s i te As di fferences i n dens i ty had

3 - 1

been observed duri ng reconnai ssance surveys fi ve Hydri l l a cond i t i on

factors were establ i shed ( see Tabl e 3 1 ) Stat i ons were apport i oned

among these fi ve categor i es rat i ng sel ected s i tes accord i ng to these

cond i t i on factors to i nsure that comparabl e representat i ve sampl es were

col l ected

As a resul t fi fteen ( 1 5 ) stat i ons were establ i shed wi th i n the

weed harvest i ng area ( Fi gure 3 1 ) Sampl i ng l ocat i ons were fi xed and

recorded i n the fi e l d us i ng Loran C (Apel co model DXL -6000 ) Sampl e

col l ect i on at each stat i on con s i sted of three repl i cated cl i pped - pl ots of

Hydri l l a removed from wi thi n a 202Sm2 sampl i ng dev i ce pl aced on the

substrate The sampl i ng box was constructed of steel pl ate 3 mm th ick

The overal l des i gn was s imi l ar to that descri bed by Mart i n and Sherman

( 1979 ) The top of the box however was covered by a d i amond pattern

screen wi th an attached hook to fac i l i tate l i ft i ng the sampl er wh i ch

contai ned the Hydr i l l a sampl e i nto the boat

The sampl er was l owered to the substrate and the Hydri l l a adjacent

to the edge of the box was cut by the d i ver wi th a kn i fe The bottom

sl i d i ng pl ate was then i nserted to conta i n the Hydri l l a sampl e and the

sampl er was then retri eved to the surface

Onl y the above- substrate port i ons of the pl ant were col l ected

s i nce thi s was cons i dered to be the port i on of the pl ant subject to

removal by the mechan i cal harvester Unconsol i d ated detri tal materi al

and roots were not col l ected Any non -Hydri J 1 a macrophytes col l ected

were separated from the Hydri l l a sampl es and treated as d i screte sampl es

Each l abel l ed repl i cate sampl e was we i ghed separatel y to the nearest gram

to determ i ne fresh wet we i ght s The i nd i v i dual repl i cates were then

i ced and shi pped to the l aboratory for dry we ight and nutr i ent content

analys i s

Add i t i onal fi el d procedures i ncl uded a near-fi el d and obl i que

photograph taken at each bi omass sampl i ng stat i on

3-2

I I I B 2 Anal yt i cal Methods

Percent mo i sture was determi ned on al l sampl es Sampl es were

dri ed at 103 - 1050C and the dri ed materi al was used i n n i trogen

phosphorus and potass i um anal yses A total of 52 sampl es were processed

(45 Hydri l l a and 7 non - Hydrjl l a fract i ons ) by MML Total Kjel dahl

n i t rogen and total phosphorus were analyzed from dri ed ground pl ant

materi al Methods ut i l i zed were from the AOAC Methods of Anal ysi s 13th

Ed i t i on 1980 Kjel dahl d i gesti on i n a bl ock d i gester of l ess than O lg

pl ant materi al was fol l owed by sampl e reconst i tut i on automated d i l ut i on

and col ori metri c determi nati on o f amon i a and phosphate by Techn i con

AutoAnal yzer II The resul tant n i trogen and phosphorus concentrat i ons

were converted to a dry we i ght basi s

Procedures for the potass i um anal ysi s are deri ved from the AOAC

Methods of Ana lys i s 13th Ed i t i on 1980 Less than 0 3g of dri ed ground

p l ant materi al was d i gested wi th n i tr ic and perchl ori c ac i ds d l l utjed

wi th 1+1 hydrochl ori c ac i d and anal yzed by atomi c adsorpt i on

1 1 1 B 3 Dat a Management

B i omass data col l ected duri ng thi s study was used to generate the

fol l ow i ng types of data

o Wet and dry wei ghts of Hydri l l a expressed as gm2

o Nutri ents [n i trogen ( N ) phosphorous ( P) potas s i um (K ) ]

per we i ght of Hydri l l a

I I I C I NTERMIM RESULTS - BIOMASS

I I I C l B IOMASS ANALYSIS

Monocul tures of Hydri l l a were present except at Stat i ons 1 2 5

9 and 13 At these fi ve l ocat i ons i nc i dental col l ect i ons of

Ceratoohyl l um sp were made I n i t i al process i ng of these sampl es

cons i sted of separat i ng Hydril l a and non -Hydri l l a spec i es and anal yzi ng

and eval uati ng each fract i on as a d i screte sampl e Once the eval uati on

3 -3

was compl eted b i omass val ues from both sets of sampl es were combi ned to

represent the overal l b i omass harvested from the study are a

B i omass val ues (dry we ights a l l spec i es combi ned ) ranged from

1 9 33 gm2 ( 02 kgm2 ) to 3 1 7 67 gmm2 (0 32 kgm2 ) (Tabl e 3 2 ) The

l ower b i omass val ues were found at stat i ons 1 and 2 wh i ch were nearshore

stat i ons The h i ghest b i omass general l y occurred at the stati ons l ocated

i n the central port i ons of the Hydri 1 1 a mat The range i n wet and dry

b i omass val ues wi th i n a confi dence i nterval of 1 plusmn standard dev i at i on

( SO ) are graph i cal l y presented i n F i gures 3 2 and 3 3 The cons iderabl e

var i at i on i n b i omass val ues among the stati ons i s rel ated to onshy

shoreoff-s hore d i fferences in stat i on l ocat i on and var i at i on in b i omass

maturi ty wh i ch i s descri bed by the prev i ous ly l i sted cond i t i on factors

rhe Hydri 1 1 a cond i t i on factors have been devel oped to prov ide an

i nd i cat i on of the vari abi l i ty of pl ant maturi ty and were used to prov ide

a prel i mi nary eval uati on of the rel ati onsh i p between pl ant maturi ty and

nutrient content The cond i t i on factors recorded at each stat i on dur i ng

b i omass sampl i ng are summari zed i n Tabl e 3 3

The Hydr i 1 1 a b i omass val ues for each sampl i ng stat i on were grouped

accord i ng to the i r respecti ve cond i t i on factor and pl otted ( F i gure 3 4 )

The resul ts of th i s group i ng dep i cts a cl ear pattern of the d i stri but i on

of b i omass versus p 1 ant maturi ty or cond i t i on factor The new growth

cond i t i ons (1 and 2) had the l owest mean bi omass val ues whi l e cond i t i on

4 (mature cond i t i on ) had the h i ghest val ue and cond i t i on 5 (senescence )

i nd i cated a decl i n i ng b i omass of the Hydri 1 1 a mat at the stati on

l ocat i ons The stat i ons sampl ed and the study area were pr i mari l y

con s idered to be represented by a mature growth cond i t i on duri ng the

August col l ecti on Cond i t i on factors ( pl ant maturi ty) are al so rel ated

to nutri ent content as i s subsequently d i scussed

A gross esti mate of b i omass i n terms of areal extent was projected

us i ng the wei ghtarea rat i o for each stat i on and then averag i ng the

rat i os It shoul d be noted however that stat i on sel ect i on for thi s

task was not random and stat i ons were del i beratel y chosen wh i ch

refl ected a range of growth cond i t i ons By the same l og i c l ocat i ons of

transects to be harvested were not random and were chosen i n an attempt

to sel ect maxi mum dens i t i es of Hydri l l a Wi th these qual i fi ers the

3 -4

average b i omass sampl ed ranged from l ess than 1 to over 14 tons per acre

and averaged 7 tonsacre Esti mates for tons of b i omass i n fres h both

wet and dry cond i ti ons al so appear i n Tabl e 3 2 The wet b i omass val ues

represent we ights of the pl ant materi al after surface water has been

removed from the pl ant by bl ott i ng wi th a dry med i um Because of t h i s

handl i ng procedure a d i rect compari son wi th the harvest contractor s

fi el d est i mates (of merely dra i ned materi al ) are not val i d s i nce the

water associ ated wi th the Hydri l 1 a cou l d add a con s i derabl e but unknown

amount to the esti mated total we ight

B iomass sampl i ng i n the study area has been l i mi ted to a s i ng l e

event and the resul t s of the samp l i ng effort do not refl ect seasonal

vari at i ons However Bowes et al ( 1 979) i nvest i g ated the seasonal

Hydri lJ a b i omass product i on of three Fl ori da l akes Lake Trafford

Orange and Jackson Thei r study i ndi cated that the t i me for seasonal

peaks i n bi omass vari ed wi th the southern most 1 ake Lake Trafford

produc i ng the max i mum Hydri l l a bi omass i n August wh i l e the more northern

l akes Orange and Jackson produced more Hydri l l a b i omass i n Novernber

I 1 I C 2 NUTRI ENT REMOVAL

Phosphorus content of Hydri 1 1 a and the potent i al for removi ng

phosphorus from the l ake system was the pri mary focus of the data

anal ys i s Secondary aspects were quant i fyi ng n i trogen and potass i um as

they rel ate to the overal l nutri ent content of the study area and

prov i d i ng i nformat i on for any poss i bl e uses for the harvested materi a l

Tabl e 3 4 summari zes the analyti cal data for bi omass sampl es

col l ected Hydri l l a and total b i omass are tabul ated separatel y s i nce

Hydri l J a i s the target spec i es of the harvest i ng program and i t compri ses

the majori ty of the pl ant materi al i n the study area Inter-spec i fi c

d i fferences i n pl ant chemi cal compos i t i on are al so reported by Boyd

( 1978) as the greatest source of vari at i on i n characteri zat i on stud i es of

aquat i c macrophytes

3 - 5

I I I C 2 1 Phosphorus

Total phosphorus ranged from 9 1 mgg to 2 68 mgg for al l spec i es

comb i ned and 91 mgg to 2 67 mgg for Hvdrill a only (Tabl e 3 4) The

comb i ned data wi th confidence i nterval s ( 1plusmn SO) are shown i n F i gure 3 5

The somewhat h i gher var i at i on i n phosphorus content at Stat i on s 2 5 9

and 13 i s est imated to occur as a resul t of the presence of non -Hvdri l l a

spec i e s at these l ocat i ons Therefore the presence of other spec i es i n

the sampl es ( i f not separated ) i s ant i c i pated to produce data that have a

greater vari abi l i ty and consequently are not as rel i abl e an est i mate of

nutri ent content as des i red for management dec i s i ons

Coeffi c i ents of var i at i on I n phosphorus content were cal cul ated

and pl otted by stat i on for comb i ned pl ants and for Hydr i l l a on l y ( F i gures

3 6 and 3 7) A compari son o f F i gures 3 6 and 3 7 however i ndi cates

that a rel at i vely smal l amount of the vari at i on observed can be

attri buted to the presence of two spec i es at a s i ngl e stat i on F i gure

3 7 demonstrates an i mportant con s iderat i on for any future sampl i ng and

asses sment effort s Sampl es o f Hydri l l a from the extremes of the

cond i t i on factors i e 1 and 5 produce data that may vary from 20 to

more than 30 i n est i mates of phosphorus content

The comb inat i on of cond i t i on factors and means for phos phorous

content at each stat i on i ndi cate a rel ati onsh i p between cond i t i on i e

re l at i ve maturi ty and phosphorus content ( F i gure 3 8) Stati ons wh i ch

cons i st pr imari ly of new pl ant growth (cond i t i on 1 ) contai n the l east

amount of phosphorus on a mgg (p l ant mater i al ) bas i s wh i l e stati on s

wi th pl ants that are descri bed as bei ng i n cond i t i on 4 (mature) have the

greatest amount of phosphorous A dec 1 i ne in phosphorus content al so

apparently accompan i es pl ant senescence

RegreSS i on anal ys i s was conducted to determ i ne the rel at i onsh i p

between b i omass and phosphorus content Because onl y one i ndependent

vari abl e (b i omas s ) was used i n the regress i on mode i t is necessary to

report only the resul ts of the two-tai l ed test u s i ng Student s t shy

stat i ons The nul l hypothes i s for the two -tai l ed test i s that there i s

no rel at i onsh i p between the dependent vari abl e and a spec i fi c i ndependent

vari abl e namel y bi omas s The t -stati st ic generated by the model

3-6

i nd i cated that b i omass s i gn i fi cantly effects phosphorus content at a 43

confidence l evel That i s there i s a 57 chance of i nd i cat i ng there i s

no rel ati onsh i p between b i omass and phosphorus i f the nul l hypothes i s i s

rejected

Add i t i onal stat i st i cal model i ng and an al ys i s i nd i cated that

b i omass at stati ons categori zed as Cond i t i on 4 were s i gn i fi cant ly rel ated

to phosphorous content at onl y a 75 confi dence l evel or a 25 chance

that a re 1 at i onshi p between b i omass and phosphorous content does not

exi st The h i gher confi dence l evel provi des some support for the use of

Hydrj 1 1 a cond i t i on factors part i cul arl y cond i t i on 4 for est i mat i ng the

nutri ent content of Hydri 1 1 a

To prov i de some prel i mi nary est i mates of potent i al phosphorous

removal rel ated to Hydri 1 1 a matur i ty each sampl i ng stat i on s phosphorous

we i ght to area rat i o was determi ned (Tabl e 3 5 ) These rat ios were then

averaged by cond i t i on factor The resu1 tant overal l phosphorus content

ranged from 16 1 bacre (cond i t i on 1 ) to 3 40 1 bacre (cond i t i on 4) and

dupl i cated the trend observed i n the b i omass data ( F i gure 3 4 )

The range of Hydri 1 1 a cond i t i ons factors and the presence o f other

macrophyte spec i es wi thi n the harvest area i nd i cates that further

defi n i t i on of the nutri ent removal est i mates are requ i red Th i s further

quant i fi cati on can be accompl i shed i n part through the use of aeri al

photographs The i nter im report by 15ampT ( 1 987 ) i nd i cates that sca1 ed

true col or and fa1 se col or i nfrared photographs of the study area have

been rout i ne1 y fl own Cop i es of these photographs and vegetat i on maps

wi 1 1 be requested from 15ampT The vegetati on maps produced from these

photographs by 15ampT wi l l be computer d i g i t i zed and acreage measurements

cal cul ated I t shoul d be noted that remote resource sens i ng techn i ques

part i cul arl y stud i es i nvol v i ng submerged pl ants have l i mi tati ons rel ated

primari l y to water depth and cl ari ty These 1 im i tati ons restri ct the

quant i ficat i on of i mmature Hydri 1 1 a represent i ng cond i t i on factors 1 and

2 because i t i s unl i ke1 y these p1 ants can be detected due to thei r

submerged cond i t i on Hydri ll a exh i bi t i ng cond i t i on factors 3 4 and 5

shoul d be v i s i bl e i n the l ate summer aeri al photographs as emergent mats

The fal se col or i nfrared aeri al photographs wi l l al so be anal yzed to

3 - 7

further separate the area i nto cond i t i on factors (3 4 and 5 ) These

refi ned est imates wi l l be i ncl uded in the fi nal report

An i ntegrated seasonal data base on nutri ent content of Hydri l l a

i n Lake Okeechobee i s l acki ng However recent data ( 1 5ampT 1988 )

i nd i cates there may be a pronounced seasonal d i fference i n t he chemi cal

compos i t i on of Hydrll l a from the l ake Hydri l l a sampl es col l ected by

15ampT duri ng January 1988 had phosphorus and n i trogen val ues that were

two to t hree t i mes h igher than the val ues reported for Aug ust 1987

(Tabl e 3 6 )

Spl i t sampl es anal yzed by the same l aboratory wh i ch prov i ded the

I SampT data provi ded veri fi cati on for the August phosphorus data reported

i n th i s study Therefore i t appears to be reasonabl e to assume that an

i ncrease i n Hydri l l a nutri ent content has occurred between August 1 987

and January 1988 The spec i fi c causes for th i s i ncrease are present ly

unknown but Federi co et al 1981 have suggested a nutri ent i nput

mechan i sm for the l ake based on l ake management W i th the fal lwi nter

i ncrease i n l ake surface area nutri ents conta i ned i n the l i ttoral zone

cou l d be transported l ake-ward by the fl ood i ng of the l i ttoral zone

Water qual i ty data from the present study does i n fact i nd i cate an

i ncrease i n i norgan i c phosphorus (P04- P ) from August 1 987 to January

1988 I t may be specul ated that i ncreased nutri ent avai l ab i l i ty may have

produced t h i s i ncrease i n Hydri l l a nutri ent content I t shoul d al so be

noted however that a seasonal i ncrease i n Hydri l l a phosphorus and

n i trogen content may occur i ndependent of any l ake management reg i me

Th i s seasonal vari at i on i n Hydri l l a nutri ent content has i mportant

rami fi cat i ons for any cont i nued or future harvest i ng programs I t al so

creates some add i t i onal quest i ons For exampl e i s th i s Hydri l l a

nutri ent i ncrease a l akewi de phenomenon or i s i t a near fi el d effect that

might be rel ated to the recent harvest i ng I f th i s i s a l akewide

i ncrease i n nutri ent content does it al so produce a correspond i ng

i ncrease i n bi omass so that phosphorus removal per acre cou l d be

max i mi zed I f th i s were true then the seasonal t i m i ng of any future

harvest i ng efforts need s to be careful l y cons i dered

Converse l y i f the wi nter i ncrease i n phosphorus content i s a near

fi el d effect rel ated to harvest i ng then perhaps harvest i ng des i gn i e

3 - 8

n umber and widths of harvested l anes needs to be re -exami ned and t i mi ng

of the harvest i ng may become l ess i mportant S i nce Hydri l l a i s a

n u i s ance spec i es al l prev i ous harvest i ng strateg i es have been a i med

toward weed el i mi nat i on for n av igat i onal purposes Because of th i s

nu i sance status management strateg i es have not been dev i sed or tested to

ut i l i ze Hydrj l l a as a nutri ent removal middotcrop middot For exampl e a seri es of

narrow but cl osely spaced cuts may be v i ewed as crop th i nn i ng wh i ch may

resul t i n greater nutri ent uptake by the adjacent unthi nned port i on of

the middotcrop middot Th i s act i on cou l d al so be coord i nated wi th n av i gat i onal

concerns and where appropri ate habi tat restorat i on or ma i ntenance

1 1 1 C 2 2 Ni trogen

As previ ous l y noted n i trogen has al so been eval uated as part of

the nutri ent analys i s N i trogen (TKN) ranged from 13 45 mgg to 26 34

mgg for al l spec i es combi ned and 13 45 mgg to 26 1 5 mgg for Hydri l l a

onl y (Tabl e 3 4) I ts d i stri but i on among stat i ons ( F i gure 3 9 ) fol l owed

the pattern prev i ousl y d i scussed for phosphorus Thi s pattern i ncl uded

the h i gh vari at i on attri buted to the presence of other spec i es ( F i gures

3 10 and 3 1 1 ) as wel l as the cond i t i on factornutri ent content

rel ati onsh i p of Hydri l l a ( F i gure 3 1 2 )

1 1 1 C 2 3 Potas s i um

The rema l n l ng nutri ent i ncl uded i n the anal ys i s was potass i um

wh i ch vari ed from 10 20 mgg to 26 28 mgg for al l spec i es combi ned and

10 20 mgg to 26 28 mgg for Hydri 1 1 a (Tabl e 3 4) Wi th several mi nor

except i ons potass i um content was a more vari abl e pl ant nutri ent than

e i ther phosphorus or n i trogen ( Fi gure 3 13 ) Thi s vari abi l i ty i n

potass i um content has al so been prev i ousl y reported by Sutton and Port i er

( 1983 )

A c o n s i d erabl e amou n t of the vari abi l i ty i n potas s i um

concentrat i ons was attri buted to the presence of other spec i es ( F i gures

3 1 4 and 3 1 5 ) but even when monocul tures of Hydri l l a are con s i dered a

h i gh amount of vari abi l i ty st i l l exi sts Kl opatek ( 1978) suggests that

3 - 9

vari at i on i n potass i um l evel s i n aquat i c macrophytes may refl ect h i gh

metabol i c demand duri ng the peri od of rap i d growth and that potass i um i s

not stored by pl ants s i nce th i s nutri ent i s read i l y avai l abl e from most

soi 1 s When grouped by cond i t i on factor the h i ghest potass i IJm contents

occurred i n the new or rapi d ly growi ng pl ants (cond i t i ons 1 2 and 3 )

( F i gure 2 - 1 6 ) Potass i um content decreases i n the l atter growth stages

assoc i ated wi th cond i t i on factors 4 and 5

I I I D CONCLUS IONS

The Hydri l l a b i omassnutri ent data anal yzed to date i nd i cates that

there are several important factors to be cons idered for future or

conti nued Hydri l l a harvest i ng programs

o Recogn i t i on and categori zati on of the rel ati ve maturi ty

state (cond i t i on factor) of the Hydri l l a mat i s i mportant

to sel ect sampl i ng l ocat i ons for nutri ent ana lys i s

o Anal ysi s of the nutri ent content of Hydri l l a i s most

preci se i e l owest sampl e vari at i on when col l ected from

areas of the mature mat The extremes of growth cond i t i on

new growth and senescence produced more vari abl e data

requ i ri ng l arger numbers of sampl es for rel i abl e mean

determi nat i ons

o Further testi ng of season a 1 d i fferences i n Hydri 1 1 a

nutri ent content and coup 1 i ng wi th harvest j ng-management

strateg i es cou l d s ign i ficantl y opt i m i ze the amount of

nutri ents removed through mechan i cal harvest i ng

I I I E RECOMMENDATIONS

Based on the data col l ected and anal yzed to date the fol l owi ng i s

the recommended course of act i on

Add i t i onal quant i tat i ve sampl i ng of Hydri l l a i n Lake Okeechobee i s

recommended Th i s add i t i onal sampl i ng effort shou l d be conducted at

3 - 10

1 ocat i ons both wi th i n the present study area as wel l as some 1 ocat i ons

out s i de of the study area Th i s general i zed pl an wi l l test for near

fi el d effects i e those effects that m ight be rel ated to harvest i ng

vs l akewi de effects Th i s sampl i ng effort shou l d be conducted quarterl y

to i nvest i gate the apparent seasonal changes i n Hydri l l a nutri ent

content Sampl i ng shou l d dupl i cate earl i er efforts and shou l d be

conducted at e i ght l ocat i on s four wi th i n and four outs i de of the present

study area

I I I F QUALITY ASSURANCE RESULTS

Tabl e 3 7 deta i l s the prec i s i on and accuracy of anal yt i cal resul ts

of dr i ed pl ant t i ssue Al l data were generated i n groups wi th

sat i sfactory qual i ty assurance cri teri a

3 - 1 1

LITERATURE CITED

Bowes G A S Hol aday W T Hal l er 1979 Seasonal vari ati on i n the b i omas s tuber dens i ty and photosynthet i c metabol i sm of Hydr i l l a i n three Fl ori d a l akes J Aquat i c Pl ant Mgt 17 61-65

Boyd C E 1978 Chemi cal Compos i t i on of Wetl and Pl ants IN Freshwater Ecol ogical Processes and Management Potenti al eds R E Good D F Wh i gham R L S i mpson C G Jackson J r Academi c Pres s N Y 378p

Freder i co A C K G D i c kson C R Kratzer F E Davi s 1981 Lake Okeechobee Water Qual i ty Stud i es and Eutroph i cat i on Assessment Techn i cal Publ i cati on 181-2 May 1981 Resource Pl ann i ng Department South Fl ori da Water Management D i stri c t West Pal m Beach FL 270pp + App

Kl opatek J M 1978 Nutri ent Dynami cs of Freshwater R i ver i ne Marshes and the Rol e of Emergent Macrophytes IN Freshwater Ecol og i cal Processes and Management Potent i al eds R E Good D F Wh i gham R L S i mpson C G Jackson Jr Academi c Press N Y 378p

ISampT 1987 Letter to Mr Ed Terczak dated Sep t 3 1987 Subj ect Chemi cal Anal yses resul ts of sampl es of Hydri l l a and mi crodeus

ISampT 1988 Letter to Mr Ed Terczak dated Jan 25 1988 Subj ect Compari son of nutri ent content i n Hydri l l a and water hyaci nth sampl es from the Demonstrat i on Project study area

Sutton D L and K H Port i e r 1983 Var i ati on of n i trogen phosphorus and potass i um contents of Hydri 1 l a i n South Fl orida J Aquat i c Pl ant Mgt 2 1 87 -92

3-12

Tabl e 3 1

Cond i t i on 1

Cond i t i on 2

Cond i t i on 3

Cond i t i on 4

Cond i t i on 5

Hvdrll l a Cond i t i on Factors to Descri be Pl ant Maturi ty i n the Lake Okeechobee Study Area

Areas of new pl ant growth rooted pl ants are l ess

than a foot h i g h

Pl ant growt h i s v igorou s but does not extend to the

surface P l ant s extend from 12 to 34 of the water

col umn i n height

Pl ant growth i s v igorous reaches the surface not

matted or at l east not brown and dyi ng on the

surface

Pl ant g rowth i s matted at the surfac e fl oat i ng

pl ants trapped s i gns of earl y decompos i t i on

P l ant mats are senescent and some open water i s

evident under mat

Source DSA Group I nc 1988

T-- 3 BiJS s_ bull aty 6 Sct irg 1tilt in _ Ia1 kee--gtee OJ --l l

my WEI lOOS lOOS

station GM2 so KGM2 so ArnE GM2 so KGM2 so ArnE

1 19 33 17 10 0 02 0 02 0 09 197 00 188 04 0 20 0 19 0 88

2 32 00 12 53 0 03 0 01 0 14 364 67 127 36 0 36 0 13 1 63

3 67 00 18 19 0 07 0 02 0 30 636 00 191 01 0 64 0 19 2 84

4 155 00 72 75 0 16 0 07 0 69 1660 33 733 09 1 66 0 73 7 41

5 195 33 85 82 0 20 0 09 0 86 1757 00 720 00 176 0 72 7 84

6 166 33 37 58 0 17 0 04 0 74 1695 33 335 67 1 70 0 34 7 56

7 263 33 56 70 0 26 0 06 1 18 2158 67 538 68 2 16 0 54 9 63

8 67 33 4067 0 07 0 04 0 30 676 33 302 63 0 68 0 30 3 02

9 184 67 94 85 0 18 0 09 0 77 1765 66 719 58 1 77 0 72 7 88

10 317 67 155 28 0 32 0 16 1 42 3165 33 1379 28 3 17 1 38 14 12

11 205 67 82 37 0 21 0 08 0 92 1716 00 500 11 1 72 0 50 7 66

12 200 67 47 60 0 20 0 05 0 90 2192 00 554 43 2 19 0 55 9 78

13 188 67 49 17 0 19 0 05 0 84 2326 00 492 11 2 33 0 49 10 38

14 116 00 29 82 0 12 0 03 0 52 1228 33 334 60 123 0 33 5 48

15 234 67 66 29 0 23 0 07 1 05 1997 33 527 08 2 00 0 53 8 91

Notes GM2= Grams Per Meter Square

SD= staOOald Deviation 1lGM2= Kilograms Per Meter Square

Dlta Ioolules Nan-Hydrilla Values for lhese stations

SOlllCe DSA Group Inc 1988

Tabl e 3 3

Cond i t i on

1

2

3

4

5

Sununary of Hydr i l l a Cond i t i on Factor by stat i on for the Lake Okeechobee study area August 18- 21 1987

Hydri 1 1 a Stat i ons

lt1 h i gh 1 2

12middot34 water col umn i n hei ght 2

at surface not matted 8 1 4 1 5

matted earl y decompos i t i on 4 6 7 1 0 1 1 1 2 1 3

senescent open water 5 9

Source DSA Group I nc 1987

Table 3 4 SUImlary ot Hyt1rllla Nl11rlent conumt nan Ole JaKe UKeeCnacee -oxty AJea 11

--- --------- - - ----- - -

Hydrilla Total Hydrilla Total Hydrilla Total p P TlltN TlltN K K

station I-CG so I-CG so I-CG so I-CG so I-CG so I-CG so

1 1 20 0 35 1 20 0 35 13 45 4 66 13 45 4 66 20 78 9 78 20 78 9 78

2 1 55 0 53 1 40 0 35 15 02 4 80 16 39 2 83 2156 12 06 16 45 6 23

3 1 43 0 06 1 43 0 06 15 78 1 37 15 78 1 37 19 66 6 19 19 66 6 19

4 2 36 0 27 2 36 0 27 20 67 2 76 20 67 2 76 20 57 4 81 20 57 4 81

5 1 28 0 14 1 47 0 30 16 49 0 88 16 93 1 10 19 09 2 11 18 99 1 98

6 1 60 0 02 1 60 0 02 17 16 028 17 16 0 28 23 56 5 57 23 56 5 57

7 0 91 0 07 0 91 0 07 15 58 0 38 15 58 0 38 10 20 0 53 10 20 0 53

8 1 37 0 15 1 37 0 15 13 60 2 50 13 60 2 50 26 28 8 25 26 28 8 25

9 1 45 0 36 1 48 0 39 17 60 2 38 17 73 2 56 18 34 5 30 18 59 5 35

10 1 96 0 14 1 96 0 14 21 35 1 69 21 35 1 69 18 71 2 73 18 71 2 73

11 1 63 0 13 1 63 0 13 16 71 0 37 16 71 0 37 16 60 5 06 16 60 5 06

12 1 81 0 12 1 81 0 12 21 97 1 04 21 97 1 04 14 43 1 37 14 43 1 37

13 2 67 0 27 2 68 25 26 15 2 29 26 34 1 97 15 89 4 52 15 89 4 52

14 2 14 0 09 2 14 0 09 20 68 1 12 20 68 1 12 23 68 1 72 23 68 1 72

15 1 33 0 11 1 33 0 11 14 01 0 47 14 01 0 47 15 82 1 99 15 82 1 99

Note All Values Expressed as Milligrams Per Gram of Dry Weight

50ur0e DSA Group Inc 1988

Tabl e 3 6

Sampl i ng Peri od Pl ant

August 1987

Tops

Steins

Whol e Pl ants

August 1987

Whol e P l ants

+January 1988

Who l e Pl ants

A Compari son of Hydri l l a Nutri ent Content for Samp l i ng Periods Conducted i n August 1987 and January 1987 i n t he Lake O keechobee Study Area

N i trogen Phosphorous (mgg-dry wei ght) (mgg-dry wei ght)

19 5 3 21

10 4 1 49

16 3 1 53

13 45 - 26 15 91 - 2 67

31 2 - 35 2 6 9 - 9 2

Source IST Augu s t 1987 Source DSA HHL August 1987

+Source IST January 1988

Tabl e 3 7 Bi omass anal ys i s qual i ty assurance resul ts

Prec i s i on Accuracy Parameter ( n X RSO SO) ( n X RSO SO)

Total phosphorus 6 3 8 1 4 4 1 0 1 7 6 5

Tota l Kje l dahl n i trogen 8 3 2 2 2 4 1 06 6 1 1 2

Potas s i um 6 3 1 1 8 5 12 1 2 43 5

zB

Figure middot3- 1 BIOMASS SAMPLING LOCATIONS

_c liOn Aalill LAaoaATOAV bullbull DA OAOb INC 18 bull

EVALUATION OF AQUATIC WEED HARVESTING DEMONSTRATION

IN LAKE OKEECHOBEE

Cl M EANS

B I O MAS S WET WE IG HT GRAS METER SQUARE

5--------------------------------------------------

45

4

3 5

3

25

1 5

1

05

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

+ UPPER CONFIDENCE STATION

o LOWER COIJADENCE

re 3 2

w a 4 J a tJ) lr w-ti

o M EANS

500

450-

40

350

300

2 50

20

1 50

1 00

50

0

1 2 3 4

+ UPPER CONfIDB-JCE

_ GPnl IP INC

81 0M-ASS D RY WEIGHT CRAMS METER SQUARE

-1-5 e 7 8 sa 1 0 1 1 1 2 1 3 1 4 1 5

STAriON o LOWER (ONlDENCE

ure 3 - 3

________________________________________________________ -____ G

c- -0 (I) (I) -laquo l 0 m J 0 I-

TOTAL BI O MASS VS HYDRI LLA C ONDITIO N DRY WEIGHT GlA2

3 00--------------------------------------------

2 80

1 80

1 60

1 40

1 20

1 00

80

6 0

40

20

middot0 1 2 3

CONDITION FACTOR IS I GM2 DRY NEIGHT

4 6

Figure 3-4

J laquo It w -It 0 L-a 0 -CL lt)

o M EAtJS

M I LLI G RAM S O F TOTA L P H O S PH O RUS

3--------------------------------------------

1

1 4

1 2

1

08 -1 2 3 4

+ UPPER CONFID ENCE

5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION gt LOWER CONFlDENCE

Figure 3-

z o tr 4 gt IL o

w o b IL W o o

C O EFFI C I ENT OF VARI ATION

TOTAL PHOSFHORUS 1 00-----------------------------------------------

90

80

70

60

50

40

30

2 0

1 0-

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION

i

z o ti gt b o

w o b h W o o

CO EFFIC I ENT OF VARIATION TOTAL PHOSA-lORUS (HtDRILLA ONLY)

I OO------------------------------------------------

90

80

70

60

50

40

30

20

1 0

1

IS I CONDlllON FACTORS STATION

9 1 0 1 1 1 2 1 3 1 4 1 5

Figure 3 -7

c - t) 2 0 -1 0 I-

TOTAL PH O S PH U RS VS H YDR I LLA C O N DITI ON

3--------------------------------------------

28

2

2

1 8

1 6 1 4

1

1 2 3

CONOrTJOt FACTOR -I I MGG my yenEIGHT

4 5

ure 3-8

J laquo cr

2 2 w l-e )- 20 (( 0 b 1 8 0 (-

z 1 6 t= 1 4

1 2

1 0

8

o M EANS

M ILLIGRAMS O F TOTAL KJELDAHL NITROGEN

1 2 3 4

+ UPPER CONFDE1CE

----r f 5 bull 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION ltgt LOWER COtADENCE

-ltlilirA 3-9

z 0

gt La 0

I-Z w

0 La La w

0 0

CO EFFIC I ENT OF VARI ATION

TOTAL l1ltJtJ

4

30

2

1 0

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

IS I CONDITlON FACTOR kZ 1 CV ()

Figure 3-1 0

z o t( tr laquo gt L o

tshyZ W o L L W o o

middot

CO EFFIC I ENT O F VARIATIO N 1lltN (HfDRlliA ONLY)

1 00-----------------------------------------------

90

80

70

80

50

40-

30

20

1 0

IS I CONDlllON FACTORS STATION WJ CV(7) 3- 1 1

0 -lt- z a

I--1 0 I-

30

28

28

24

22

2

1 8

1 8

1

1

2

0 1

TOTAL TKN VS HYDRI LLA CON DITION

2 3

CONDITION FACTOR r ] GG CRY WEIGHT

3- 1 2

-oJ ( tr W gt-cr n L 0 Cl - Cl E

o M EANS

M I LL IG RA M S O F TOTAL POTASSI U M

38---------------------------------------------

2

1

8--------------------- 1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

+ UPPER CONFDENCE STATION

ltgt LCJWER CONFIDENCE

z o n 4 gt LL o

I-shyZ bJ o LL LL W o o

1 00

90

80

70

80

50

40

30

20

1 0

0 -

CO EFFIC I ENT O F VARIATION POTASSIUU

-- _-_------ ------

1 2 3 4 5 8 7 8 1

IS I CONDITION FACTOR STATION ---

l2 J cv(-)

1 4 1 5

3- 1 4

z 0 t a oC gt Iamp-0

--

It

r z w 0 lamp-Iamp-w 0 0

C O EFFIC I ENT O F VARI ATION

POTASSlUA (HfffiILLA 011 Y) 1 00 - - - - - - -- - ---- - - - -- - -- - - - ---- --- - -- - - - - - - - - - - -- - - - - -

90

80

70

60

50

40

30 -

20

-

1 0

0 - 1 2 3 4

IS I CONDIllON FACTORS

l 7

J

r t

I 10 1 1 1 2 13

STATON LUd CV ( )

3- 1 5

TOTAL P OTASS I U M VS HYD RI L LA CON DITI ON

30------------------------------------------

28

28

1 2 3

CONDfTION FACTOR 1 I GG y WEIGHT

4 5

3- 1 8

IV WATER QUALITY SURVEYS

IV A INTRODUCTION

Concerns for water qual i ty i n Lake Okeechobee are pr i mar i l y

focused on nutri ent storage and cycl i ng between the water col umn

sedi ments and bi omass and the impl i cat i ons of these processes for the

current and future troph i c state of the l ake The harvest i ng

demonstrat i on project undertaken by the South Fl ori da Water Management

Di strict and conducted by I nternat i onal Sci ence and Technol ogy I nc

( ISampT) i s one of the remed i al measures proposed to arrest the apparently

i ncreas i ng troph i c state The harvest i ng and subsequent upl and d i sposal

of Hydrj l l a i s bei ng u sed to effect the removal of total nutri ents

( phos phorus in part i cul ar) from the aquat i c system The Di str i ct s

eval u at i on and research project ( EampR) conducted by Mote Mari ne Laboratory

(MML) was des i gned to del i neate other env i ronmental i mpacts and cost

benefi ts associ ated wi th mechan i cal weed removal

The goal of the water qual i ty task of the EampR s tudy was to

del i neate changes that cou l d be attri buted to the removal of dense stands

of Hydri l l a vert i c i l l ata ( Fi gure 4 1 ) Al though the i mmed i ate i mpacts of

weed harvest i ng on water qual i ty may be substant i al those wh i ch

perS i sted over a peri od of t i me were expected to be fai rl y smal l and

l ocal i zed due to the advect i ve barri er of the Hydri l l a mat Accord i ngl y

i n order t o resol ve these changes from background vari abi l i ty grad i ents

of water qual i ty were assumed to exi st across the s i te al though they may

be wea k

The sampl i ng program was desi gned t o al l ow the stat i st i c al

eval uat i on of water qual i ty d i fferences between stat i ons at any one poi nt

i n t i me prov id i ng enough anal yt i cal data to produce mean i ngful

compari sons As a resu l t a mi n i mum of tri pl i cate col l ect i on s per

stat i on were necessary Th i s approach was preferabl e to more frequent

sampl i ngs because i t centered on quant i fy i ng i mpacts at part i cul ar

i nstances rather than on a conti nu i ng bas i s when seasonal processes i n

the study area woul d compl i cate anal yses of data

4 - 1

Water qual i ty i nformati on i s al so necessary for the i nterpretat i on

and anal ys i s of many of the other tasks Phytopl ankton and pri mary

product i v i ty stud i es i n part i cul ar are heavi l y dependent on t h i s task and

wi l l exami ne ava i l abl e nutri ents tox i c compounds ( copper) as wel l as

phys i cal data produced by thi s tas k Accord i ng l y sampl i ngs for water

qual i ty were conducted on each of the days that Envi ronmenta 1 Qual i ty

Laboratory ( EQL) depl oyed primary producti v i ty equ i pment In add i t i on

certa i n parameters (d i ssol ved s i l i cates col or and i norgan i c carbon )

were added to the analyti c al su i te at stat i ons where product i v i ty was

be i ng determi ned Water qual i ty sampl i ngs were al so conducted wi th i n 24

hours of the communi ty metabol i sm task fi el d efforts and wi th i n two weeks

of l arval and juven i l e fi sh sampl i ngs

IV B METHODS

IV B l Water Qual i tv Stat i on locat i ons

The northern 1 200-m (4000 ft ) of Transect 3 was des i gnated as the

experimental transect where a majori ty of the tasks focused the i r

efforts Th i s harvested area was sel ected based upon central 1 ocat i on

wi th i n the study s i te representati veness of the study s i te as a whol e

wi th respect to depth fetch shore proxi mi ty and speci es compos i t i on

and the dens i ty of the Hydri l l a mat of the area

Stat i on l ocat i ons for most sampl i ng s of the water qual i ty task

were i l l ustrated i n F igure 4 2 a superi mposed on the Loran C l i nes mapped

for the study s i te dur i ng the August 1 987 reconnai ssance A tabul at i on

of Loran coordi nates of these stat i ons appears i n Tabl e 4 1 Stat i ons

were establ i shed to defi ne any ex i st i ng water qual i ty grad i ents across

the s i te as wel l as i mpacts due to harvest i ng and so extend beyond the

boundari es of the area schedul ed for harvest Stat i ons 1 2 3 13 1 5

and 1 6 represented the perimeter o f the study s i te Stat i ons 7 - 9 were

l ocated on the northern hal f of Transect 3 the experi mental transect

and represented the treatment stat i ons the treatment be i ng harvest i ng

Control ( unharvested ) stat i on 10- 1 2 were adj acent to the

experi mental transect i n the unharvested l ane between Transects 3 and 4

4 -2

( Stat i ons 4 -6 were al ternate control stati ons to be used onl y i f unusual

cond i t i ons at Stat i ons 10- 1 2 i nd i cated that they woul d not represent

und i sturbed cond i t i ons These stat ions have not been occup i ed to date )

Stat i ons 7 - 1 2 were al so the same areas sampl ed for phytopl ankto n benth i c

i nfauna and sed i ment chemi stry Stat i on 1 5 was or i g i nal l y establ i s hed

beyond the southern end of Transects 6 and 7 However dense growths of

Amer i can Lotus i n the area made i t l i kel y that water exchange was

mi n i mi zed wi th the rest of the study area Th i s stat i on was accord i ng l y

moved t o the north but kept between transects s o that i t represented

unharvested cond i t i ons

I V B 2 Parameters

In liY i nstrumentat i on (Hartek Hark V I I ) was used to determi ne

depth profi l es (at 0 2 and 0 5 meter i ncrements from the surface and at

bottom) of temperature conduct i v i ty pH and ox idat i on-reduct i on

potent i a l (ORP) bull Di ssol ved oxygen ( DO) meters ( YS I 57 pol arographi c

el ectrodes equ i pped wi th st i rrers ) were used to measure DO at the same

depths Heters ( and i nstruments ava i l abl e as backup equ i pment ) had been

bench cal i brated aga i nst known standards or phys i ca l constants pri or to

each sampl i ng Cal i brat i ons of the meters empl oyed were repeated

fol l owi ng each sampl i ng L i -Cor i ntegrat i ng photometers were ut i l i zed to

quant i fy i nc i dent and penetrant l i ght Care was taken i n performi ng

these measurements to mi n i mi ze weed d i sturbance i n l oweri ng the

i nstruments and ext i nct i on coeffic i ents were cal cul ated from both the

upper ( 0 5 m) and l ower ( bottom) read i ngs to provi de est i mates of both

weed mass and water col umn l i ght attenuati on Water sampl es were

col l ected for l aboratory analys i s outs ide of the i nfl uence of any meter

d i sturbances

Sampl es were secured us i ng a non -metal l i c i mpel l er-type pump wi th

a weed excl ud i ng cage mesh s i ze of 1 mm ( F i gure 9 3 ) The cage was

l owered wi th a mi n i mum of d i sturbance to the weed mat to prevent

resuspens i on and entrai nment of l oose ly attached al ga l materi al or other

pl ant debri s Th i s col l ecti on techn i que was empl oyed for al l sampl i ngs

Chemi cal parameters i ncl uded al l standard n i trogen and phosphorus

4-3

spec i es Inorgan i c forms - -orthophosphorus ammon i a- n i trate- and

n i tri te -n i trogen - - were determi ned on fi l tered sampl es ( 0 45 micon

effect i ve pore s i ze ) to ascerta i n the ava i l abl e amounts most mean i ngfu l

for b i ol og i cal assessments Potass i um and sodi um were quant i f i ed on a

fi l tered sampl e Trace metal concentrat i ons copper ( Cu ) and i ron ( Fe )

al so were determi ned o n fi l tered sampl es due t o the affi n i ty of these

e l ements for suspended part i cul ates

Total organ i c carbon total Kjel dahl n i trogen total phosphorus

and al kal i n i t i es were determi ned on unfi l tered s ampl es as was

bi ochem ica l oxygen demand Turb i d i ty and suspended l oads were quant i fi ed

and total col i form was analyzed by the membrane fi l ter techni que The

analys i s of sampl es for sod i um chl ori de and fl uori de concentrat i ons was

performed to permi t water mass cal cul at i ons and determi nat i on of water

qual i ty grad i ents across the s i te Anal yses necessary for the pri mary

product i v i ty task were col or d i ssol ved s i l i ca and i norgan i c carbon

Water qual i ty anal yt i ca 1 methods used were those approved by the

Envi ronmental Protect ion Agency ( EPA ) and the Fl orida Department of

Envi ronmental Regul ati on ( FDER) Method references anal yt i cal hol d i ng

t i mes and preservati ves are detai l ed i n Tabl e 4 2

Lake l evel s for spec i fi c dates were obtai ned from the Di stri ct and

represent 1 ake wide averages of stage recorders operated by both the

Di stri ct and the u s Army Corps of Eng i neers

IV B 3 Sampl i ng

There were four types of water qual i ty sampl i ngs each vary i ng i n

the numbers of stat i ons sampl ed t imi ng of col l ecti ons or parameters

anal yzed The s ampl i ngs were enti tl ed basel i ne short - term impacts

quarterl y and fi el d demonstrati on Col l ect i ons were focused around the

experimental transect Analyti cal sui tes i nc l uded both phys i cal and

chemi cal parameters Sampl i ngs performed to date appear i n Tabl e 4 3

4 -4

Basel i ne Sampl i ng

Basel i ne sampl i ng was conducted on August 18 1 987 pri or to any

harves t i ng act i v i ty wi t h i n the s i te The day was cl ear hot and cal m

Average l ake l evel for the day was 4 22 m ( 13 85 ft ) A total of n i ne

( 9 ) l ocati ons ( Figure 4 2 ) was sampl ed to establ i sh a grid of control

stat i ons ( Stat i ons sampl ed were 1 2 3 10 1 1 12 13 1 5 and 16 )

These stat i ons were al l i n areas where no harvest i ng act i v i t i es were

schedul ed Stat i ons 10 1 1 and 1 2 were l ocated i n a heavi l y weeded

area whi l e the rema i n i ng control stat i ons were outs i de the area to be

harvested and were i n comparati vely open water At each stati on a total

of three separate sampl es was col l ected from a depth of 0 2 m for

l aboratory analys i s

At Stati ons 1 3 13 and 16 sampl es were al so sec ured from 0 8

of the overal l depth Water depth ranged from 0 9 to 2 0 meters at al l

stat i on s These corners of the study si te represented the spat 1 a1

extremes and water qual i ty data from surface and at depth were used as

i nd i cat i ons of verti cal gradi ents over the s i te

One add i t i onal stat i on at the mouth of the K i s s i mmee R i ver

( Stati on 20) was sampl ed at the surface (0 2m ) The effect of thi s

tri butary on l ake nutri ent l oad i ng and resul tant spat i al grad i ents may

thus be cons i dered Th i s s i ng l e sampl e however was not i ncl uded i n

stat i st i cal anal yses

A total of fourteen ( 14) stati on-depths resul ted from thi s

sampl i ng for a total of forty ( 40 ) sampl es for anal ys i s In ll1Y and

l aboratory analyses i ncl uded al l wi th the except i on of col or s i l i cates

and org an i c carbon as no phytopl ankton sampl i ng was conducted duri ng

th i s epi sod e Sampl es for total col i form were col l ected from Stat i ons

10 1 1 and 1 2 onl y ( n i ne sampl es)

Short Term Impacts Sampl i ng

Two short term impacts water qual i ty sampl i ngs were conducted

i mmed i atel y after and approx i matel y one week fol l owi ng the compl et i on

of harvest on the exper imental transect These sampl i ngs were i n

4 - 5

conjunct i on wi th and on the same day as phytopl ankton and pr i mary

product i v i ty sampl i ngs Sampl es were col l ected from Stati ons 10 1 1 and

1 2 the control stat i ons and from Stat i ons 7 8 and 9 the experi mental

stat i ons ( F1 gure 4 5 ) Experimental stat i ons were l ocated approxi mately

150m 600m 1070m ( 500 ft 2000 ft and 3500 ft ) from the northern end of

the transect and were approximate ly 75 m ( 250 ft ) from e i ther edge of the

harvested area Contro 1 stat i ons were pa i red wi th each experi mental

stat i on and were adj acent approx1mate1y mi dway between Transect 3 and 4

1 n the center o f the unharvested are a Sampl es were col l ected from 0 2m

depth onl y

Aquat i c weed harvest1 ng on the experi mental transect began

September 3 1987 and the northern 1 220 m was compl eted on September 1 7

Dur1 ng th i s and the succeed 1 ng dayt 1 me sampl i ng events the ongo i ng

harvest of weeds cont i nued nearby An MHl fi el d crew conducted sampl i ng

on September 1 7 a hot cal m and cl ear day when l ake l evel s averaged 4 13

m ( 13 56 ft ) Th 1ck Hvdri 1 1 a growth was v 1 s i b1 e at depth w1 th i n the

tran sect Another sampl i ng occurred on September 22 1987 ( l ake l evel

4 1 2 m ( 1 3 51 ft raquo under s imi l ar cond i t i ons Regrowth of Hydri 1 1 a i n the

experiment al transect was extens ive by th i s date Sampl es were col l ected

near the mouth of the Ki s s immee Ri ver on both occas i ons Seven ( 7 )

stat i on depths resul ted 1 n the col l ect1 0n o f n i neteen ( 1 9 ) sampl es on

eah date Al l in si tu parameters and l aboratory anal yses were i nc l uded

Quarterl y Sampl i ng

As wi th the i mmed i ate i mpacts sampl i ng s quarterl y sampl i ngs were

conducted i n conjunct i on wi th phytopl ankton work Stat i ons sampl ed

i nc l uded 1 2 3 7 8 9 10 1 1 1 2 13 1 5 and 16 at 0 2m depth

( F i gure 4 2 ) and Stat i ons 1 3 1 3 and 16 at 0 8m overal l dept h

S i xteen ( 16 ) stat i on depth s pl us one ri ver sampl e resul ted i n at l east

49 sampl es duri ng each of the four efforts In s i tu and 1 aboratory

parameters i ncl uded al l those l i sted wi th the except i on that total

col i form d i s sol ved s i l i cates col or and i norgan i c carbon were anal yzed

on l y on sampl es from Stat i ons 7 8 9 1 0 1 1 and 12 onl y ( the

exper i mental stat i ons and the i r control pa i rs )

4 -6

Quarterly sampl i ngs took pl ace on September 30 1 987 and January

1 3 1 988 wi th the rema i n i ng sampl i ngs schedul ed for Apr i l and June 1988

Lake l evel s were 4 1 4 and 4 90m ( 1 3 60 and 16 07 ft ) i n September and

January respect i vel y The September event was conducted o n a bl ustery

day (wi nds from the west at 5- 10 kts ) wh i ch l ater produced a dr i v i ng

rai nstorm Vi s i b i l i ty both in and above the l ake was obscured currents

were al so noted Li ght and vari abl e w i nds from the NE to W were noted

duri ng the January sampl i ng Hydrilla had regrown to t he surface i n some

cases by th i s date but otherwi se was not often vi s I b1 e due to i ncreased

l ake l evel s

The northern 180m of the experi mental transect was reharvested

duri ng December 1987 Stati ons 7 and 10 were sampl ed i n January and thus

represented a t h i rd treatment ( 1 e harvested twi ce ) In order to

ma i nta i n a bal anced des i gn for stat i st i cal anal yses however two ( 2 )

stati ons were added t o the sampl i ng schedul e The pos i t i on of Stat i on

7 5 was just south of the mowed sect i on and another control ( 10 5 ) was

added i n a comparabl e l ocat i on south of Stat i on 1 0 Stat i ons 7 5 8 and

9 then became the experimental group to be consi dered i n data analyses

F i el d Demonstrat i on Sampl i ng

Water qua 1 i ty impacts duri ng the actual harvest i ng process were

expected to be pri mari l y a product of turbul ence generated by harvest i ng

These effects were al so expected to be fa i rl y l ocal i zed due to the

dens i ty of the weed mat Any temporary resuspen s i on of organ i c detr i tus

or el evat i on of sol i ds or nutri ent concentrati ons wou l d be establ i shed by

an i ntens i ve t i me seri es wh i ch woul d exami ne the degree and durat i on of

any d i sturbance

The fi el d demonstrat i on water qual i ty samp l l ng was conducted on

October 28-29 1 987 when l ake l evel s were at 14 26 ft Three pai rs of

stat i ons approxi matel y 100 ft apart were establ i shed at the northern edge

of the wi nd fence or harvested area l ocated between Tran sects 2 and 3

( Fi gure 4 6 ) Subsequent to preharvest sampl i ng a harvester made two

passe s each approx i mately 100m l ong A smal l barri er of Hydri l l a ( ca

3m w ide ) was l eft i ntact between the harvested area of Transect 2 and the

4 - 7

RharvestedR area for th i s study Stat i ons were i dent i fi ed as Rcut R (Cl

C2 C3 ) or R uncut R (UCl UC2 UC3 ) duri ng th i s effort

Fol l owi ng the two passes of the harvester over the experi mental

swath no more harvest i ng occurred in that area for at l east 24 hours A

t i me seri es of sampl es were col l ected from -each of the s i x ( 6 ) stat i ons

Data were to be compared from each of the two stat i on types for

quant i fyi ng i mpacts and traci ng the i r durat i o n

Sampl es were col l ected a t 0 2m and 0 8m o f the overal l depth us i ng

the pump and the weed excl ud i ng cage to el imi nate the l argest Hydri l l a

fragments from the sampl e Col l ect i ons took pl ace i mmedi atel y pri or to

the passage of the harvester immedi atel y subsequent to the harvest of

the experimental stat i ons (wi th i n approxi matel y 0 5 hr) and then aga i n

at roughl y 2 5 10 and 24 h r i nterval s after the harvest Sampl es were

not col l ected i n tri pl i cate i nstead the three stat i ons i n each

treatment type formed the basi s for stati sti cal compari son A total of

twel ve ( 1 2 ) stat i on depths and s i x (6) col l ect i ons resul ted i n seventyshy

two sampl es for ana lys i s The s i x col l ect i ons were i dent i fi ed as rounds

1 -6 i n data pri ntouts In 11Y parameters to be determi ned i ncl uded al l

l i sted with the except i on of l i ght penetrat i on and secchi depth

measurements Total col i form was not anal yzed due to the extremel y short

hol d i ng t i me of that parameter nor were repet i ti ve l i ght measurements

wh i ch have a h i gh potenti al for d i sturbance of the water mass due to the

actual sampl i ng process Suspended l oad and turbi d i ty anal yses were

ut i l i zed for est imates of l i ght attenuat i on S i l i cates col or and

i norgan i c carbon were not anal yzed as no phytopl ankton work was

conducted at th i s t i me

IV C INTER IM RESULTS

Al l water qual i ty data col l ected through the m idpo i nt of thi s

project appear i n Append i x 4 A and i ncl ude in s i tu and chemi cal anal yses

from the sampl i ngs performed on August 18 September 1 7 September 22

September 30 and October 28-29 1 987 and January 13 1 988 Means of

al l parameters measured i n the study s i te are presented i n Tabl es 4 4

and 4 5 by date but wi thout regard to treatment stat i on or depth

4 -8

The most notabl e of the in ll1Y parameters i s di ssol ved oxygen

More than 32 of al l observat i ons made were i n v i ol ati on of t he 5 0 mg1

i nstantaneous d i s so 1 ved oxygen cri teri on for C1 ass I waters and 20 of

a l l observat i ons were bel ow 4 0 mg1 (Tabl e 3 4 ) Samp1 i ng t i mes were

skewed toward the morn i ng hours and were thus abl e to record the effects

of pre-dawn resp i rati on of aquat i c vegetat i on at the s i t e

Surface sampl es were al so col l ected i n the Ki s s i mmee Ri ver

approximatel y midway between the S R 78 bri dge and Lake Okeechobee i n

add i t i on t o those sampl es spec i fi ed by the scope of work (Tabl e 4 6 )

Ion content ( sod i um potass i um chl ori de al kal i n i ty s i l i cates )

typi cal l y was l ower i n the ri ver than the s i te waters and i ncreased

sod i um and chl oride concentrat i ons were observed i n the southern port i on

of the study area The ri ver was general l y l ess turbi d ( turbid i ty total

suspended sol ids ) hi gher in col or and apparent ly represented a source

of d i ssol ved i ron to the area

Both throughout the s i te and i n the Ki ss immee Ri ver d i ssol ved

copper l evel s i f detected were only sl i ghtl y above the l i m its of

detect i on The same was true of n i trite-ni trogen wi th the excepti on of

the January sampl i ng On th i s date concentrati ons at the Ki ss inunee

stat i on were h i gher (0 027 mg1 ) than the rema i nder of the stat i on s and

concentrat i on grad i ents were apparent across the study s i te Data on

col or si l i cates and i norgan i c carbon al though presented i n the

append i x wi l l not be extens i vel y analyzed i n thi s sect i on as such data

were pri mari l y col l ected for use i n i nterpretat i on of phytopl ankton

anal yses

IV D DATA REDUCTIONS

Stati sti cal anal yses of i n s i ty and chemi cal data empl oyed one and

two-way analyses of vari ance where treatment effects ( harvested non shy

harvested stat i ons depths ) were consi dered as fi xed (Model I ANOVA)

Two-way anal yses were conducted empl oyi ng the same assumpt i ons when the

rel at i ve magni tude of effects was of i nterest S ign i fi cance l evel s were

set at 0 05 ( P 95) Except where noted anal yses ut i l i zed the

untransformed val ues of the vari ous parameters Log ( base e) data

4-9

trans format i ons were usual ly used to approxi mate normal d i stri but i ons

Parameters trans formed for analys i s i ncl uded orthophosphate ammoni a

n i trate -n i tri te-n i trogen potass i um i ron BOD turbi d i ty TSS and

sod i um

When vari ances among groups were s i gni fi cant i nd i v i dual means

were contrasted us i ng e i ther Student t-tests or Tukey s Student i zed Range

Test wh i ch computes the smal l est HSD ( honestly s ig n i fi cant d i fference )

for determi n i ng d i fferences Both were ap pl i ed at the P - 95 l evel

IV E DISCUSSION

IYr E I In 1i1Y Parameters

D i ssol ved oxygen l evel s and percent s aturat i on of d i ssol ved oxygen

were expected to show the most change from harvest i ng act i v i ti es W ide

d i urna 1 swi ngs shoul d be damped by the removal of 1 arge amounts of

Hydril l a D i urnal pH cycl es and to a l esser extent ORP woul d be

expected to fol l ow thi s pattern as l ess vegetat i on woul d be present to

con sume carbon d i ox ide Seasonal cycl es were expected i n temperature

data however d i urnal cycl es and verti cal thermal grad i ents were l ess

l i kely 1 n areas where dense stands of fl oat i ng Hydri l l a had been removed

For al l parameters wi nd generated m ix i ng i n harvested areas shou ld

1 es sen the degree of al l surface-to-bottom grad i ents Any changes i n

conduct i v i ty at a part i cul ar l ocat i on as a resul t of harvesti ng woul d be

i nd i rect and woul d l i kel y refl ect al terat i ons i n current structure by

removal of the Hvdri l1a mat and the i ncreased fl ush i ng i n harvested

areas

Due to the obv ious d i fferences between sampl i ngs anal yses of i n

tliY data empl oyed two -way ANOVAs usi ng date and treatment ( harvested

Stat i ons 7 8 and 9 and non-harvested Stati ons 10 1 1 and 1 2 ) as

factors Further as vert i cal grad i ents for some parameters appeared

substant i al data sets were al so subd i v i ded i nto surface and bottom

readi ngs and exami ned separately Data were anal yzed from the sampl i ngs

of September 1 7 22 and 30 and January 13 As ant ic i pated sampl i ng

date was a h i ghl y s i gn i fi cant factor for al l i n s i tu parameters

4 - 10

conduct i v i ty ORP pH temperature DO and percent saturat i on Those

parameters exh i bi t i ng d i fferences attri butabl e to harvest i ng impact were

DO and percent saturat i on at both surface and bottom and pH at bottom

No i nteract i ve terms were s i gn i fi cant i nd icat i ng a consi stent and

pred i ctabl e pattern of d i fferences

Di ssol ved oxygen l evel s averaged between 0 5 and 3 6 mgl h i g her

i n the experi mental ( harvested ) transect than i n the adj acent control

stat i ons Th i s pattern was general ly most ev i dent from read i ngs at the

bottom of the water col umn Overal l i ncreases i n percent saturat i on were

approxi mately 20

It shoul d be noted that the majori ty of these data were col l ected

before 1000 ( EST ) and that th i s t i mi ng affected both the magni tude and

the d i rect i on of d i fferences i n DO l evel s Had sampl i ng been conducted

predomi nantly dur i ng mid- to l ate afternoon i t i s most probabl e that the

unharvested and heav i l y weeded areas would have had s i gn i fi cant ly h i gher

DO val ues than the adj acent harvested areas The observed pattern i s

cons i stent wi th an enhanced pre-dawn DO middot sag middot i n areas wi th h i gher

dens i t i es of aquati c vegetat i on (control s ) To ensure that no bi as was

i ntroduced by sequence of sampl i ng on each date stat i ons were ranked by

t i me of sampl i ng the ranks summed by treatment and compared Duri ng that

sampl i ng with the most d i screpancy between treatment rank sums September

30 DO l evel s i ndi cated that thi s was not a seri ous factor

The overal l s i gni fi cance of date i n the previ ous anal yses was due

predomi nantl y to the i ncl us i on of the January data set as can be deduced

from the means presented i n Tabl e 4 4 W i th removal of th i s data set and

reanal ys i s of the three September sampl i ngs the onl y parameters where

date was a s i g n i fi cant factor were pH and ORP I n attempt i ng to quant i fy

the i mmed i ate i mpacts of harvest i ng the removal of the January data set

can be j ust i fi ed on the bas i s that the regrowth of Hydri l l a was

essent i al l y compl ete by th i s sampl i ng and that there were no obv i ous

d i fferences between experi mental and control stat i ons The s i gn i fi cant

d i fferences between experimental and control s for DO percent saturat i on

and bottom pH however were essent i al l y the same i n th i s reanal ysi s

i mpl y i ng that the i mpacts were most marked e i ther wi th i n the th i rty days

of harves t or duri ng that part i cul ar port i on of the growi ng season

4- 1 1

The i ntens i ve fi e l d demonstrat i on sampl i ng carr i ed out on October

28 and 29 1 987 to del 1 neate the invned i ate impacts of harvest i ng was

pr i mari ly desi gned to measure turbid i ty associ ated parameters or

nutri ents rel eased from the sed iments as a resul t of the passage of the

harvester The in 1iY data co 1 1 ected however were subjected to an

ana l ys i s s i mi l ar to the above (Tabl e 4 7 ) D i fferences between harvested

and unharve sted areas were s i gn i fi cant here for a l l parameters but

pri mar i l y for the val ues at depth D i ssol ved oxygen duri ng - th i s

samp 1 1 ng however was l ower overa 1 1 i n the harvested area As water

col umn oxygen demand (BOD ) was comparabl e between transects reference to

sampl i ng t imes the majori ty after 1000 EST cl ari fy thi s apparent

d i screpancy These d i urnal cycl es are apparent i n F i gure 3 7

Duri ng the i mmedi ate impacts sampl i ng conduct i v i t i es were

s i gn i fi cant ly h i gher i n the experimental area than at the control

stat i ons wi th i n one hour of the passage of the harvester ( F i gure 4 6)

Cond i t i ons i n both areas had been comparabl e just pri or to the harvest

Th i s may i l l ustrate the rap id i ty wi th wh i ch fl ush i ng rates are i ncreased

Al l other in 1i1Y parameters wi th the except i on of percent saturat i on

exh i b i ted s ign i f i cant changes over t ime part i cul arly a t the bottom of

the water col umn These are i l l u strated for the rema i n i ng parameters i n

F i gures 3 9 through 3 1 1 where subtl e di fferences produced by harvest i ng

are superi mposed upon d i urnal cycl es The magni tude and s i gn of

d i fferences for many parameters in add i t i on to DO between harvested and

control stat i ons were heav i l y dependent on the t i me of day

Vert i cal grad i ents i n vari ous parameters were expected to be

reduced as a resul t of the removal of the advect i ve barri er of the

Hydri l l a mat and the consequent i ncrease i n wi nd -generated mi x i ng

Anal yses of vari ance of surface mi nus bottom in s i tu val ues as a s i ng l e

vari abl e were performed wi th stati ons

( harvested ) and control ( unharvested

comparat i ve ly non -weeded stat i ons ) Of

categori zed i nto experi mental

i ncl ud i ng both weeded and

the s i x sampl i ngs anal yzed i n

th i s manner surface to bottom grad i ents were most often observed for pH

DO and percent satura t i on Surface DO val ues ranged between 0 3 and 3 8

mgl h i gher (4 -46 saturat i on ) and surface pH between 0 04 and 0 2 SU

h i gher

4 - 1 2

Surface to bottom grad i ents were a 1 so apparent i n both

experi mental and control areas duri ng the immed i ate i mpacts sampl i ng of

October 28 and 29 Except for conduct i v i ty vert i cal grad i ents for these

two treatments were not stat i st i cal l y d i fferent from one another when the

fi ve post -harvest sampl i ng rounds were consi dered as a un i t Thi s

s i mi l ari ty i n grad i ents however shoul d not be confused wi t h the

d i fferences previ ousl y demonstrated between treatment areas for th i s

sampl i ng as the grad i ent anal ys i s i s concerned onl y wi th the d i fference

between surface and bottom val ues and makes no statement concern i ng the

rel ati ve posi t i ons of i nd i v i dual val ues

The fact that gradi ents were present at al l i n the harvested area

duri ng October may impl y that the d i mensi ons of the pl ot from wh i ch

HydrjJ l a was removed ( approxi matel y 6 by 1 20 meters ) were i nsuffi c i ent

for exi st i ng wi nd d i rect i on and vel oc i ty to cause substanti al mix i ng

Water depths ranged between 1 2 and I Sm These grad i ents were present

for pH DO and percent saturat i on agai n for the January sampl i ng i n both

control and experi mental transects wh i ch i s not surpri s i ng i n l i ght of

the degree of regrowth over four months s i nce harvest and the phys i cal

s imi l ari ty of stat i ons at th i s t i me

E2 Chemical Parameters

The anal ys i s of chemi cal data was desi gned to answer the fol l owi ng

questi ons for the sampl i ngs to date

o Are there detectabl e water qual i ty d i fferences between the

experimental and control stat i ons

o If there are was thi s ei ther d i rect l y or i nd i rect ly a product of

harvest i ng act i v i ty or i s i t the byproduct of stat i on l ocat i on

and the resul t of natural d i l ut i on grad i ents ( i e l oad i ng from

the Ki s s immee Ri ver or other sources )

o I f there are no s ign i fi cant d i fferences between harvested and

unharvested areas were d i fferences to be expected on the bas i s of

water mass compos i t i on

4 - 13

Where chemi cal spec i es are not d i rect ly correl ated wi th a d i st i nct

water mass or where i nputs to the water col umn are d i ffuse enough to

prevent the ma i ntenance of a spat i a 1 grad i ent or the detect i on of a

s i ngl e sourc e data analysi s i s s i mpl i fi ed to a compari son of treatment s

experimenta1 s agai nst control s Seasonal trend s i f present can be

factored i nto the stat i st i cal ana lys i s A s i mpl e compari son of harvested

aga i nst unharvested area chemi stry can al so be performed shoul d i on

content and rat i os i ndi cate that these water masses were i denti cal duri ng

sampl e col l ect i on and that d i l ut i on grad i ents can be i gnored

However when nutri ents or other spec i es are i ntroduced i nto a

system a ssoc i ated wi th a di sti nct water mass and when d i l ut i on with

ex i st i ng waters produces detectabl e gradi ents the quest i on s become more

compl ex In add i t i o n b i ol og i cal uptake wi l l produce non - l i near

rel a t i on sh i ps and the separati on of harvesti ng impacts from expected

gradi ents becomes more d i ffi cul t

The compl ex i ty of these questi ons i n the presence of d i l ut i on

grad i ents can be i l l ustrated graph i cal l y by reference to Fi gure 4 1 2

where hypotheti cal data appear In the fi rst part parameter X i s a

l i near func t i on of sod i um or i n other word s X i s a l so a con servati ve

parameter so i ts absol ute l evel i s affected onl y by d i l uti on wh i ch

mai nta i n s a constant X Sod i um rat i o Th i s regress i on would be devel oped

u s i ng one day s data from the ent i re gri d of n i ne control stat i ons across

the study s i te The hypothet ical data from a harvested stat i on (Stat i on

7 ) and the control (Stat i on 10 ) are al so pl otted It i s apparent that

wh i l e the l evel s of parameter X at the harvested and control stat i on

shown are probabl y not stat i st i cal l y d i fferent from one another the

harvested stat i on c l earl y fal l s outside of the 95 confi dence i nterval of

the X Sod i um regress ion for thi s data set and d i fferences from the l evel s

expected may refl ect harvest i ng i mpacts

In the second port i on of Figure 4 1 2 an al ternate s i tuat i on i s

i l l ustrated where the 1 eve1 s of parameter X at h arvested and control

stat i ons are shown to be c l earl y d i fferent However it i s apparent that

the water mass at the harvested stat i on i s sl i ghtl y more d i l ute and that

the correspond i ngl y l ower l evel s of parameter X are to be expected I n

4 - 14

both s i tuat i ons any b i ol og i cal processes affect i ng parameter X wi l l

produce even more compl ex rel at i onsh i ps

Sod i um and chl ori de were fi rst exami ned for i ns i g ht i nto water

mass movement and d i l ut i on processes occurri ng across the study s i te

The sum of these two i ons ( i n mi l l i equ i va1ent s ) was empl oyed a s an

approxi mat i on of total i on content They were both assumed to be

conservat i ve i e not part i ci pat i ng to any substant i al degree i n

b i ol og i cal processes where they might be sequestered or added to t he

water col umn F i gure 4 13 i l l ustrates thi s d i l ut i on process as i t occurs

across the study s i te The rat i o of sod i um to chl oride was al so

cal cul ated as an i dent i fy i ng feature of a part i cul ar stat i on

The gri d of ni ne control stat i ons was sampl ed on three occas i ons

August 1 8 September 30 1987 and January 13 1988 These data were

exami ned as t hey represented the 1 argest spat i a 1 area Anal yses of

vari ance i nd i cated that both total i on content and sod i um ch1 0r ide rati os

vari ed s ign i fi cant ly wi th respect to sampl i ng date I n l i ght of the

seasonal pattern of preci p i tat i on and the i nfl uence of ri ver d i scharge on

the area th i s was not surpri s i ng I n add i t i on however stat i on was

h i gh l y s i gn i f icant as a factor In the case of sod i um pl us chl ori de

th i s represents a change i n total i on content or d i l ut i on occurri ng

across a spat i al grad i ent ( Fi gure 4 14 ) I n the case of sod i um ch 1 0r i de

rat i os the fact that rat i os are di fferent at d i fferent stat i ons impl i es

that two or more separate water bod ies are represented across the s i te

( F i gure 4 1 5) I nteract i ve terms were al so s i gn i fi cant for each

parameter i nd i cat i ng that d i fferences were not cons i stent across t i me or

space Th i s i s apparent i n compari ng Fi gure 4 13 wi th Fi gure 4 14

As the mi xi ng of more than two water masses together woul d make

ana l ys i s of the rema i n i ng parameters extreme ly mathemat i cal l y compl ex

regress i ons of sodi um aga i n st chl ori de were performed for al l control

stat i ons on the three sampl i ng dates On each date correl at i ons for

l i near rel at ionshi ps were s ign i fi cant at pgt99 9 Th i s resul t al l owed

the use of the assumpt i on that onl y two water masses were mi x i ng across

the s i te Parameters associ ated wi th one of the two water masses coul d

therefore be detected by regress i ons on sod i um or some other conservat i ve

parameter

4 - 1 5

Anal yses of water qual i ty impacts were i n i t i al l y restri cted to

four sampl i ngs September 1 7 22 and 30 1 987 and January 13 1 988

Stat i ons 7 - 9 for experimental and Stat i ons 10 - 1 2 for control s (Stat i on

7 5 and 10 5 were used for the J anuary data set as an area wh i ch

i nc l uded Stat i on 7 had been reharvested shortl y before the sampl i ng )

S i gn i fi cant amounts of vari ati on between experi mental (Stat i on s 7

8 9 ) and control s ( Stati ons 1 0 1 1 1 2 ) as groups were found us i ng

two-way ANOVAs wi th date and treatment as factors (Tabl e 4 8 ) Al l

n i trogen and phosphorus spec i es (wi th the except i on of orthophosphate )

conta i ned s i gn i fi cant amounts of vari at i on d i stri buted between the

harvested and unharvested control stat i ons In add i t i on for BOD

turb id i ty and total suspended sol i d s d i fferences were present as wel l

As expected potassi um fl uoride chl ori de and sod i um d i d not d i spl ay

s i gn i fi cant vari ati ons between data from harvested and unharvested

stat i ons I ron copper total organ i c carbon and al kal i n i ty were al so

not s i gn i fi cant ly d i fferent between treatments

As d i scussed above however d i fferences between harvested and

unharvested areas are strai ghtforward onl y i f I water masses i n each of

the two treatment areas were identi cal or 2 the anal yzed parameter has

no s i gn i fi c ant rel ati onsh i p to a part i cul ar water mas s or to sod i um

Al though n o s ign i fi cant d i fferences i n sod i um o r chl ori de

concentrat i ons were observed between harvested and unharvested stat i ons

as a group di 1 ut i on grad i ents of these parameters were present wh i ch

paral l el ed the axi s of the harvested transects ( Fi gure 4 1 4 ) As a

resul t the data envel ope for the stati ons of a s i ngl e treatment was

l arge i n compar i son to any subtl e d i fferences between transects (F i gure

4 16 ) The fact that any di fferences were detected between experi mental

and control transects (Tabl e 4 8) impl i ed that they were substanti al

enough to overr ide the wi th i n -treatment vari abi l i ty expected from the

sod i um grad i ent S i gn i fi cance of i nteract i ve tems i n these model s

i nd i cated that d i fferences were not cons i stent from sampl i ng to sampl i ng

To d i rect l y compare harvested and non-harvested water qual i ty the

water of the two treatments must represent i dent i cal d i l ut i ons of source

and rece i v i ng waters As d i l ut i on gradi ents were roughly paral l el to the

transect axes stat i ons were pa i red and the d i fferences of experimental s

4 - 1 6

l ess control s cal cul ated for each pa i r of sod i um and chl ori de data

( Stat i ons 7 - 1 0 8- 1 1 9 - 1 2 Tabl es 4 9 4 10 ) The mean d i fferences

computed for al l sampl i ngs or for each date were on no occas i on d i fferent

from zero ( t - tests ) I n add i t i on no cons i stent pattern of d i fferences

was observed The conc1 us i on was that wh l l e di fferences 1 n the water

mass were present between stat i ons w ith i n a s i ngl e treatment harvested

stat i ons and t he i r adjacent control pai rs represented i dent i cal waters on

each date w i th respect to d i l ut i on

As water masses were i dent i cal the d i fferences i n parameter

concentrat i ons were cal cul ated for each stat i on pa i r as for sod i um and

chl ori de above These d i fferences are summari zed i n Tabl e 4 1 1 for those

parameters for wh i ch treatment was a s i gn i f icant factor i n the two-way

ANOVAs descri bed above (Tabl e 4 8 ) The magn i tudes of the d i fferences on

i nd i v i dual dates when not stat i st i cal l y equ i val ent to zero are al so

presented

Us i ng the pai red compari sons of stat i ons al l n i trogen s peci es and

total phosphorus exh i bi ted s i gn i fi cant al though subtl e d i fferences

between harvested and unharvested areas for the sampl i ngs to date (The

only date where orthophosphorus showed treatment d i fferences was on

September 22 and on th i s occas i on the magni tude was onl y 0 002 11191

1 ess than the 1 im i t of detect i on ) These d i fferences are most notabl e

for n i trate and ammon i a n i trogen and are i n add i t i on to any d i l ut i on

grad i ents across the s i te They can be presumed to refl ect the i mpacts

e i ther d i rect or i nd i rect of harvest i ng

Concentrat i ons where d i fferent were typi cal l y l arger i n the

unharvested control transect Th i s may be attri buted to e i ther uptake by

regrowth at harvested stat i ons or to the rel ease of nutri ents by

senescent macrophytes or peri phyton at the unharvested l ocat i ons

Fl oat i ng mats of Hydrj 1 1 a i n vari ous cond i t i ons were present through the

September 30 sampl i ng

B i ochemi cal oxygen demand turbi d i ty and suspended sol i d s al so

showed d i fferences us i ng stat i on pa i rs al though i n the i n stance of

suspended sol i ds concentrat i ons were sl i ghtl y h i gher at the harvested

stat i ons Wi nd -generated sed i ment resuspensi on i n harvested areas and

suspended senescent pl ant materi al i n the unharvested areas (contri but i ng

4- 1 7

to turbi d i ty and oxygen demand but wi th rel at i vely l i ttl e dry we i ght ) are

postul ated to account for these d i fferences Th i s i s supported

c i rcumstant i al l y by the l argest d i fference i n suspended sol ids be i ng

observed on September 30 when w i nd cond i t i ons were the most extreme of

any of the days sampl ed

The l argest number of parameters d i fferent between harvested and

weeded areas was al so observed on September 30 wh i l e the fewest were

seen on January 1 3 1 988 Whether th i s d i stri but i on across t ime i s a

res ul t of 1 ) vary ing nutri ent uptake rates throughout the growi ng season

2 ) the essent i al l y compl eted regrowth observed by the January s ampl i ng

3 ) the h i gher l ake l evel s and l ack of a fl oati ng mat of Hydri l l a perhaps

reduc i ng res idence t i mes of water across the s i te duri ng January or

4) the h i gher January nutri ent l evel s maki ng d i fferences more d i ff icul t

to d i scern i s i mposs i bl e to resol ve

Another techn i que for data anal ys i s was empl oyed on the September

30 and January 13 data sets for those parameters wh i ch were associ ated

wi th d i l ut i on grad i ents across the s i te Bri efl y i f the grid of control

stat i on s d i spl ayed s i gn i fi cant regress i ons with sod i um theoret ical

parameter concentrat i ons were cal cul ated for al l control and experimental

stati ons based on the observed sod i um data and that funct i on wi th the

h i ghest regress i on coeffi ci ent Res i dual s (V i - V hat) were then

compared by t - tests between means of experimental and control groups to

determi ne i f popul ati ons were the s ame (no impacts F i gure 3 1 2B) or

d i fferent ( i mpacts Fi gure 4 1 2A)

L i sted i n Tabl e 4 1 2 by date are the regres s i on types and

coeffi c i ents of the vari ous parameter concentrat i ons wi th sod i um Onl y

surface data from control stat i ons were used The vari ed nature of i nputs

to the s i te i s exempl i fi ed by F igures 4 1 7 and 4 18 dep i cti ng the vast l y

d i fferent d i stri buti ons of orthophosphorus between September and January

Whi l e rel at i vel y few parameters were apparentl y associ ated wi th

d i l ut i on duri ng the August sampl i ng the h i gher l oads i n September and

January perhaps coupl ed with sl owed uptake and growth rates duri ng the

l atter part of the year may produce l onger water col umn res idence t i mes

for nutri ent spec i es and permi t the detect i on of d i l ut i on grad i ents i n

4 - 18

these parameters Chl ori de and potas s i um and any other parameter onl y

s l ightl y affected by bi ol og i cal act i v i ty shoul d certa i nl y produce

s i gn i fi cant rel ati onsh i ps (The l ack of s i gn i fi cance of fl uor i de wi th

res pect to sod i um i s attri buted to the extremel y l ow l evel s encountered

e g concentrat i ons at or bel ow the l i mi t of detect i on for th i s

parameter )

Overal l the res i dual s anal ys i s of sod i um dependency proved l es s

sens i t i ve than that o f the pai red stat i ons anal yses O f the twenty-two

parameter-date combi nati ons where a s i gn i fi cant regress i on wi th sod i um

was obtai ned res i dual s of experimental stat i ons were s i gn i fi cant ly

d i fferent from res i dual s from control stat i ons for onl y three parameters

- - orthophosphorus and al kal i n i ty duri ng September 30 1 987 and n i tri teshy

n i trogen dur i ng January 13 1 988 Figure 4 19 superimposes the

experi mental stat i on orthophosphorus concentrati ons upon the rel at i onsh i p

devel oped for control stati ons i n September I t can be seen here that

the experimental stat i ons (X) are not evenl y d i stri buted around the

regress i on l i ne

Orthophosphorus concentrat i ons on th i s occas i on were l ower i n

the experi mental transect but onl y by 0 002 mgl l ess than the l i mi t of

detect i on Al kal i n i t i es at these stat i on s were h i gher than sod i um

concentrat i on s mi ght pred i ct by about 9 mgl as CaC03 Duri ng January

n i tri te - n i trogen was al so l ower at the harvested stat i ons than woul d be

expected on the bas i s of d i l ut i on al one but aga i n by l ess than the l imi t

of detect i on

As troph i c states and nutri ent l i mi tati ons wi thi n Lake Okeechobee

area of concern rati os of d i ssol ved and i norgan i c n i trogen to phosphorus

spec i es were cal cul ated and summari zed i n Tabl e 4 1 3 On a we ight bas i s

systems wi th rat i os l ess than 1 0 are typ i cal l y cons i dered n i trogen

1 i mi ted wh i l e phosphorus 1 im i tat i ons occur at rat i os greater than 1 7

( Sakamoto 1 966) Wi th th i s cr i teri on the waters o f the study s i te are

cl earl y n i trogen l imi ted i n contrast to al gal assays performed i n the

v i c i n i ty duri ng 1 974 and 1 975 ( Dye et al 1975 ) These resul ts have the

most consequences for phytopl ankton popul ati ons rather than macrophytes

as the rooted pl ants are capabl e of extracti ng at l east some i f not the

majori ty of thei r requ i red nutri ents from the hydroso i l

4 - 19

The stati st i cal anal yses d i scussed earl i er for the i ndi vi dual

parameters determi ned i norgan i c ni trogen spec i es to be h i gher i n the

unharvested control stat i ons and orthophosphorus to be s l i ghtl y l ower

ANaYA s of N P rat i os al so found s i gni fi cant d i fferences The treatment

( harvested or unharvested ) or stat i on was more important than date i n

account i ng for vari ati on Al l September and January sampl i ngs combi ned

produced mean N P rat i os for the harvested stat i ons ( 7 - 9 ) of 3 0 and for

the unharvested d i fferences coul d be attri buted e i ther to uptake by

act i vel y growi ng p l ants or to rel ease of nutri ents by senescent p l ant

materi a 1 Oi fferences between harvested and nonharvested areas were

l east apparent duri ng the January sampl i ng when ri s i ng l ake l evel and

Hydri l l a regrowth combi ned to i ncrease stat i on to stat i on phys i cal

s i m i l ari t i es

E 2 Bacteri ol ogi cal Parameters

Resul ts of total col i form anal yses (membrane fi l ter techn i que) of

sampl es col l ected on August 18 September 1 7 22 30 1987 and January 13

1 988 appear in Tabl es 4 1 4 After the August fi e ld effort sampl es were

col l ected i n conjuncti on wi th the phytopl ankton work and al l sampl es were

anal yzed by EQL Overal l bacteri ol ogi cal qual i ty was qu i t e good wi th

on ly a s i ngl e sampl e exceed i ng the 1000 counts per 100 ml cri teri on for

Cl ass I waters Th i s s i ngl e val ue of 5000 (Stat i on 1 1 September 30

1 987 ) was cl as sed as a stat i st i cal outl i er for the study as a whol e The

other two val ues from sampl es col l ected s i mul taneously were 900 and

100100 ml Most stat i on means were bel ow 200 countslOa ml

Stat i st i cal anal yses of these data empl oyed natural l og

transformat i on s Two way ANaYA s (by date and treatment and by date and

s t at i o n ) prod uced s i gn i fi cant terms for date and i nteract i ve

rel at i onsh i ps however nei ther harvesti ng nor stat i on accounted for

s ign i fi cant amounts of vari at i on Further anal yses cons i sted of mul t i pl e

l i near regress i ons of l og transformed total col i form counts aga i nst BOD

turb i d i ty total suspended sol i d s sod i um and chl ori de content ( as water

mass i ndi cators ) col or and s i l i cates A s i gn i fi cant regress i on model

whi ch i ncl uded BOD col or and TSS was obtai ned (r2 = 0 255 n 72) A

4 -20

d i rect rel ati onsh i p wi th BOD was not surpri s i ng The vari at i on wi th

col or val ues may be support for runoff control l ed bacteri a l evel s in the

l ake i ncreas i ng duri ng peri ods of h i gh d i scharge or backpump i ng (wh ich

are themsel ves characteri zed by i ncreased col or l evel s from t he

accumul ated surface waters An i nverse rel at i onsh i p w i th TSS l evel s was

l ess amenabl e to i nterpretat i on and i s l i kely to have been an art i fact of

some other control l i ng i nfl uence

IV E WATER QUALITY IMPACTS - QUALITY ASSURANCE OBJECTIVES

Prec i s i on and accuracy targets and resul ts for in ll1Y water

qual i ty parameters are presented in Tabl e 4 1 5 Prec i s i on est i mates were

based on dupl i cate in 1iY determi nat i ons expressed as percent rel ati ve

standard devi at i on (S RSD) Measurements at one stat i on per day were

typ i cal l y repl i cated i n thi s fash i on Prec i s i on est i mates for fi el d

measurements necessari l y i nc l uded the representati veness of the sampl i ng

as any non - homogene i ty of the s i te bei ng sampl ed appeared i n these

resul t s

Accuracy was determi ned from both pre- and post - sampl i ng

cal i brat i on of i nstrumentati on and where appl i cabl e the s i mu l taneous

col l ect i on of sampl es for l aboratory analysi s wi th al ternate procedures

or equ i pment Thi s was expressed as percent recovery ( R) of

f i el dl aboratory val ues t i mes 1 0 Col l ect i on of sampl es for

veri f icat i on was typi cal l y conducted at a rate of 1 for every 1 0 stati ons

samp l ed For th i s project di ssol ved oxygen and conducti v i ty were so

veri fi ed

Comparabi l i ty o f data was veri fi ed duri ng the pre- and postshy

sampl i ng cal i brati ons of i nstrumentat i on aga i nst standard sol ut i ons or

phys i c al constants Compl eteness of in 1iY data was esti mated to be

greater than 88 throughout the sampl i ngs to date

The qual i ty assurance object i ves for l aboratory anal yses were

anal ogous to those d i scussed for the i n s i tu parameters and are l i sted i n

Tabl e 4 14 Prec i s i on esti mates were determi ned from the anal yt i cal

resul ts and SRSD between the concentrati ons of two al i quots of a s i ng l e

conta i ner Dupl i cate analyses were performed at a rate of at l east one

4 - 2 1

for every ten sampl es The RSD between sampl es only sl i ghtly above the

l i mi t of detect i on i s often qu i te h i gh al though the analys i s i s

extremel y prec i se ( L e 0 001 and 0 002 11191 47 1 RSD ) Some mean

tRSD val ues and SD val ues are skewed by these seemi ngl y i mprec i se

dupl i cates that are actual l y wi th i n QA l i mi ts Accuracy of analyses was

assessed by the analys i s of sampl es to wh i ch known amounts of standard

materi al s had been added

IVG I NTERIM SUMMARY AND CONCLUSIONS

The study area i mmedi ately south of the entrance of the Ki s s 1mee

R i ver i nto Lake Okeechobee represents a compl ex combi nat i on of factors

wi t h regard to water qual i ty Vari at i ons with t i me were observed for

almost al l parameters measured D i ssol ved oxygen v i ol at i ons of the 5 0

11191 i nstantaneous cri teri on were common and d i urnal cycl es of DO and

rel ated parameters were apparent The skew i n sampl i ng t i mes toward the

morn i ng hours undoubtedly i ncreased the number of observed v i ol at i ons

a l though sampl i ng l ater i n the afternoon woul d i ncrease the percent

saturat i on of d i ssol ved gases and val ues i n excess of the 1 10 cri terion

wou l d have resul ted

In li1Y parameters were i n i t i al l y eval uated for stat i st i cal

d i fferences between harvested and unharvested stat i ons as a grou p

Di fferences i n DO percent saturat i on and p H were observed and were most

marked at the bottom of the water col umn and duri ng the September

sampl i ngs Pred i ct abl y harvesti ng reduced the ampl i tude of the d i urnal

DO cycl e such that DO concentrat i ons were h i gher i n the harvested

transect i n the morn i ng hours and l ower duri ng the afternoon Both the

magn i tude and the d i rect i on of the observed d i fferences were therefore a

funct i on of the t i me of sampl i ng

A rap i d change i n water masses was al so observed at harvested

stat i ons and th i s was attri buted to the i ncreased fl ush i ng potent i al

produced by Hydri l l a removal Inten s i ve surveys detected vert i cal

grad i ents of s i mi l ar magn i tudes for i n s i tu parameters at both harvested

and control stati ons The s i ze of the harvested transect may have been

too smal l to al l ow wi nd-generated vert i cal mi xi ng to be effect i ve

4-22

Bacteri ol og i cal water qual i ty at the s i te was good overal l wel l

wi th i n the 1000 1100 ml cri teri on and correl at i ons w ith col or BOD and

TSS were present Col or rel at i onshi ps i ndi cate a functi onal rel at i onsh i p

of total col i form wi th d i scharge i nto the l ake whi l e the rel at i onsh i p

wi th TSS was i nverse

Chemi cal water qual i ty d i stri but i ons at the s i te were a l so qu i te

compl ex Spat i al and d i l uti on grad i ents produced by the i nfl uence of the

K i s s i mmee Ri ver were qu i t e apparent as determi ned by conservat i ve

parameters such as sod i um and chl ori de The d i l ut i on grad i ents were

roughl y paral l el wi th the l ong axi s of the harvested transects such that

a progress i on of i ncreas i ng strengths of Lake Ri ver d i l ut i ons were

observed al ong both the experimental harvested transect and the adjacent

unharvested control transect Thi s transl ated to a h i gh wi th i n -treatment

va ri a b n i ty of water masses compared to the between- treatment

vari abi l i ty wh i ch i n turn may obscure d i fferences between harvested and

unharvested areas i n stra ightforward stat i st i cal compari sons

Overal l stat i sti cal techni ques were sat i sfactory because the

number of sampl es adequate for determi ni ng di fferences i n concentrat i ons

was at or near the analyt i cal l imi ts of detect i on The three stat i st i cal

anal yses were 1 ) d i rect compari sons (means test i ng and ANOVA s ) of

harvested to unharvested data sets 2) ana lys i s by d i fference of stat i on

pa i rs ( harvested l ess the adjacent control stati on) and whether

d i fferences were stat i sti cal l y d i fferent from zero and 3) res i dual s

anal ysi s of those parameters wi th a s ign i fi cant rel at i onsh i p w i th sod i um

and whether the popul ati on of res i dual s from control stati ons was

equ i val ent to those from the harvested stati ons

Ana lys i s of harvested versus unharvested data groups by parameter

reveal ed s i gn i fi cant d i fferences between treatments for al l n i trogen

spec i es total phosphorus BOD turb id i ty and total suspended sol i ds

These d i fferences are i n sp i te of the broad envel ope i n water qual i ty

conta i ned wi th i n each treatment type However d i rect compari sons and

correct est i mati on of the magni tude of harvest i ng impacts are poss i bl e

onl y where the water masses of the two treatments can be assumed to

represent equ i val ent po i nts on the d i l ut i on grad i ent

The d i fference i n sod i um and chl ori de concentrat i ons between each

harvested stat i on and i ts adjacent unharvested stat i on was cal cul ated

For al l dates these d i fferences were equ i val ent to zero mean i ng that

the water mass was i dent i cal at Stati ons 7 and 10 at Stat i ons 8 and 1 1

and at Stat i ons 9 and 1 2 The d i fferences i n concentrat i ons between the

stat i on pai rs cou l d then be calcul ated Al l n i trogen spec i es and total

phosphorus concentrat i ons were typ i cal l y h i gher i n the unharvested

transect On the one occas i on where orthophosphorus d i ffered between

treatments i t was s l i ghtl y h i gher i n the harvested transect Turbid i ty

and BOD were al so h i gher at the control stat i ons wh i l e total suspended

sol i ds were sl ightly l ess Uptake by macrophytes i n act i ve regrowth

rel ease o f nutri ents by senescent and matted pl ant mater i al and wi nd shy

generated resuspens i on may account for thi s pattern

Ana lys i s of those parameters associ ated wi th d i l u t i on and of those

wi th s i gn i fi cant correl at i ons wi th sod i um proved l ess sens i t i ve for

detect i ng d i fferences Al though many parameters d i spl ayed s i gn i f icant

rel at i onsh i ps the i r d i stri but i on around the regress i on l i ne was

cons i derabl e and res i dual popul at i ons were s i gn i fi cantly d i fferent

between treatments for only three parameters

The s i te as a whol e appeared to be n i t rogen 1 i mi ted based on

we i g ht r at i os of i norgan i c n i trogen forms to orthophosphorus

O i fferences between harvested and unharvested areas were apparent here

al so w i th average rat i o s of 3 0 and 9 4 respect i vely

IVG RECOMMENDATIONS - FINAL REPORT

For the rema i n i ng two quarterly sampl i ngs i n th i s task a

real l ocat i on of effort i s proposed wh i ch woul d del ete copper and fl uori de

from the anal yt i cal su i tes These two parameters were e i ther at or near

the 1 im i ts of analyt i cal detect i on for al most al l s ampl es and

stat i sti cal analyses were not effect i ve i n determi n i ng any d i fferences

attri butabl e to harvest i ng at these l ow concentrat i ons N i tri teshy

n i trogen however shoul d be reta i ned Al though l evel s were l ow they

are i mportant i n th i s n i trogen 1 i mi ted system and d i fferences between

treatments were apparent The Ki ss i mmee R i ver stat i on shou l d cont i nue to

4-24

be sampl ed and another stat i on shou l d be added to the west of Stat i on 1

toward Buckhead Ridge as an i ntermi ttent nutri ent i nput may be present

there Mon i tori ng of these two add i t i onal stat i ons shou l d cont i nue for

al l parameters In pl ace of copper and fl uor ide anal yses d i ssol ved

cal c i um i s suggested as a repl acement to prov ide a bas i s of compari son

wi th other work done prev i ously i n the l ake and to exam i ne i ts behav i or

across the s i te The poss i b i l i ty of mov i ng the exper imental and control

stat i on pai rs ( Stat i ons 7 - 1 2 ) to the most recently harvested area for the

subsequent sampl i ng i s currentl y be i ng d i scussed wi th the task l eaders of

the i nter-rel ated tasks

Future data exami nat i ons wh i ch wi 1 1 be conducted for the fi nal

report of th i s project i ncl ude the deta i l ed assessment of l i ght

penetrat i on profi l es and the effect of the weed mat upon these The data

from the 24 hour fi el d demonstrat i on sampl i ng wi l l be eval uated w ith

regard to chemi cal parameters and the i mmedi ate effects produced by

harvest i ng S i l i cates col or and i norgan i c carbon data wi l l be

processed as wi l l the rema i n i ng parameters for d i fferences between

experi mental and control stat i on s and a further anal ys i s of d i ssol ved

oxygen wi th cons i derat i ons for t i me of day vegetat i on and even sed i ment

type wi l l be conducted

4-25

LITERATURE CITED

Dye C W D A Jones L T Ros s R L Wi l l more 1 975 L imi t i ng nutri ents i n the Ki ss i llll1ee Ri ver - Lake Okeechobee Bas i n based on al gal assay techni ques Fl a Dept Envi ronmental Regul at i on Sakamoto H 1 966 Pri mary product i on by phytopl ankton conununi ty i n some Japanese l akes and i ts dependence on l ake depth Arch Hydrobi ol 62 1 - 28

4-26

Table 4 1 Mean IDran coordinates of water quality staticns

STATIOO NO

1 2 3 7 7 5 8 9 10 10 5 11 12 13 15 16

Ipound)RAN 1 JPRAN 2

14313 2 45453 2 14312 6 43449 1 14312 4 43445 9 14313 6 43449 1 14313 4 43448 2 14313 2 43447 7 14312 9 43446 1 14313 7 43448 5 14313 5 43447 7 14313 4 43447 3 14312 9 43445 7 14315 1 43444 6 14313 9 43443 2 143109 43437 8

Table 4 2 water Quality parameters methods ard holdirq times

Parameter

TeJlFerature Corrluctivity pi ORP Dissolved Oxygen Light Penetratim Secxhl laboratory 0rthqil0spl0rus (D) Total AlosJtIorus (D) AImalia-Nitrogen (D) Nitrite-Nitrogen (D) Nitrate-Nitrogen (D) Total Kjeldahl Nitrogen ium (D) Ccgler (D) Iran (D) Total OJgan1c carbon Alkalinity Biochemical Oxygen DeuanI lu1)idity SUspenled Solids Ibtal Ollifonn auoride Scdium Fluoride Color silicates (D) Inorganic Cartlon

MetbodlInstrument

Martek Mark VII Martek Mark VII Martek Mark VII Martek Mark VII YSI 57 LiOlr Secxhl Disk (LiDngtlogical)

EPA 365 1 365 3 EPA 365 3 365 4 SM 417F EPA 350 3 EPA 353 3 353 3 EPA 353 2 353 3 EPA 351 2 SM 30lA SM 303A B SM 303A B EPA 415 1 8M 403 4C EPA 3102 EPA 405 1 EPA 180 1 SM 2090 8M 908A 909A SM 4070 EPA 325 3 SM 303A EPA 3402 SM 204A B EPA 370 1 SM 425C EPA 415 1

Holdirg TimePreservative Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable

Filter iDmSdiately 48 hrs4Oc 28 daYSH2S04 to pllt2 40c Filter bImadiately 28 daYSH2S04 to pllt2 40c Filter bImadiately 48 hrsH4 to pllt2 40c Filter iDmSdiately 28 daYSH4 to pHlt2 40c 28 daYSH2S04 to pllt2 40c Filter iDmSdlately 6 1IDSIftll) to pllt2 40c Filter iDmSdiately 6 1IDSIftll) to pllt2 40c Filter inmediately 6 1IDSIftll) to pHlt2 40c 28 daYSH2S04 to pIlt2 40c 14 days4oC 48 hrs4Oc 48 hrs4Oc 7 days4Oc 6 hrs4Oc 28 days4Oc Filter inmdiately 6 lOOIlthslftll) to pIlt2 40c 28 days4Oc 48 hrs4Oc 28 days4Oc 28 days4Oc

EPA = EPA 6004-7920 Methods for OJemical Analysis of water ard wastes SM = stanIard Methods for the Examination of water ard wastewater 15th Fdition 1980 (D) = Dissolved

Tabl e 4 3

Date

Aug 18 1987

Sept 17 1987

Sept 22 1987

Sept 30 1987

Oct 28-29 1987

Jan 13 1988

Sampl i ng efforts and dates Water Qual i ty Tas k

Sampl i ng Type

Basel i ne

Short Term Impacts

Short Term Impacts

Quarterly

F i el d Demonstrat i on

Quart erly

No of Stat i ons

9

6

6

12

6

12

No of V i al s

1

1

1

1

6

1

Table 4 4 site averages of in situ parameters by sanplirg date all stations all depths

1987 1988

AU 18 SEP 17 SEP 22 SEP 30 ocr 28-29 JAN 13

n 28 18 18 36 144 68

2 SD 2 S D 2 S D S( S D S( S D 2 SD

onluctivity 0 5350 0661 0 5397 0351 0 5074 0550 0 4985 0517 0 3921 0731 0 3017 0895

ORP 493 109 441 42 298 77 293 47 295 31 247 55

Pi 8 02 0 55 8 27 0 34 7 56 027 7 47 043 7 72 0 51 7 59 0 30

lenperature 28 95 144 27 34 0 50 27 23 054 26 67 041 23 11 099 16 67 078

Dissolved Oxygen (00) 5 02 3 20 3 51 2 20 2 87 1 32 5 11 2 28 664 2 25 8 16 1 58

PeJta1t SaturatiCBl 66 1 42 9 44 4 27 9 36 3 16 7 64 0 28 6 77 8 269 84 0 16 7

00 cbs lt1 0 nql 128 318 218 336 0144 168

00 cbs lt4 0 nql 1428 U18 1318 936 14144 168

00 cbs lt5 0 ugII 1428 1218 1618 1536 41144 268

Table 4 5 Site averages of water quality parameters by sanplirg date all stations all depths

1987 l2sectsect AU 18 SEP 17 SEP 22 SEP 30 ocr 28-29 JAN 13

n 39 18 18 48 7 3 54 K SD K SD I SD K S D K SD K SD

0rthqil0sJil0 0 019 0 007 0 017 0 005 OOll 0 003 O OlS 0 014 0 033 0 011 0 082 0 045 Total rus 0 07 0 11 0 10 0 01 0 08 0 01 0 09 0 03 0 12 0 06 0 15 0 05

Anrncnia-nitrogen 0 039 0 018 0 04 5 0 042 0 017 0 012 0 012 0 017 0 040 0 029 0 04 6 0 036 Nitrite-nitrogen 0 004 0 001 0 005 0 004 0 004 0 001 0 003 0 003 0 004 0 001 0 008 0 004 Nitrate-nitrite-nitrogen 0 009 0 003 0 034 0 036 0 039 0 021 0 048 0 046 0 038 Q 019 0 190 0 039 Total Kjeldahl nitrogen 1 52 0 26 1 75 0 15 1 55 0 28 1 47 0 18 1 29 0 20 1 20 0 17 Potassium 4 4 0 9 4 7 0 3 4 5 0 3 4 2 1 0 2 9 0 5 3 9 1 0

Cqpar 0 003 0 002 0 003 0 002 0 003 0 001 0 002 0 001 0 001 0 001 0 002 0 002 Iron 0 002 0 002 0 014 0 007 0 014 0 007 0 015 0 019 0 048 0 018 0 090 0 031 ampxlium 4 8 9 7 6 47 3 4 6 46 9 4 7 49 0 9 4 31 0 8 9 28 2 8 1 Olloride 8 5 8 13 1 79 6 6 4 76 5 8 6 76 2 10 0 55 9 14 9 48 2 16 7 Fluoride 0 3 0 03 0 3 0 05 0 3 0 03 0 3 0 04 0 1 0 03 0 2 0 03 lbtal organic carlxln 2 1 7 1 6 17 9 0 9 18 1 0 8 18 4 1 0 19 7 2 5 18 4 3 0 Alkalinity 105 14 117 5 113 8 1U 10 7 3 15 68 lS Biochemical oxygen deHard 1 9 1 0 2 7 1 3 2 2 0 6 2 3 1 2 1 5 0 7 1 1 0 6 lubidi ty 2 4 1 9 4 2 0 9 4 1 1 5 4 0 2 9 3 1 2 5 3 7 2 1 Total susperded solids 3 3 3 3 6 0 2 3 5 7 2 4 6 3 4 7 4 5 3 9 3 1 4 1 Oller 61 5 66 9 81 9 113 10 silicates 12 8 2 2 13 1 2 2 12 0 3 0 5 4 0 5 Inorganic carlon 17 4 4 3 19 9 2 8 20 4 4 4 11 9 5 2

11=18

Table 4 6 site averages of water quality parameters for the KissiJulse River by sanpling date

1987 1988

AU 18 SEP 17 SEP 22 SEP 30 JAN 13

0 032 0 096 0 12 7 0 116 0 063 Total (ilcsphorus 0 09 0 18 0 20 0 20 0 12 Almalia-nitrcgen 0 021 0 036 lt0 005 0 017 0 069 Nitrite-nitrcgen lt0 005 lt0 005 lt0 005 lt0 005 0 027 Nitrate-nitrite-nitrogen 0 012 0 009 0 072 0 188 0 151 Total Kje1dahl nitrogen 0 51 1 39 1 40 1 12 1 08 Ibtassium 3 7 3 6 3 5 2 9 3 2

((gler 0 003 0 003 0 004 0 001 lt0 001 Iron 0 008 0 085 0 095 0 172 0 225 Sodium 3 3 4 2 6 5 24 2 2 1 0 15 0 Olloride 60 6 47 8 4 1 9 38 7 23 7 Fluoride 0 3 0 3 0 3 0 2 0 2 Total organic cartxn 19 6 19 5 19 9 18 8 17 4 Alkalinity 89 7 3 66 57 34 Biochemical oxygen daDaM 2 4 3 0 1 5 1 3 0 5 lJnbidity 3 0 3 9 2 7 2 3 2 3 Total suspenied solids J 9 4 8 4 0 2 5 2 0 Color 110 130 130 125 Silicates 6 58 6 42 5 67 3 17 Iooxganic carbon 4 4 9 6 7 2 1 1

Tabl e 4 7 S i g n i f icant F middot test rat i os for two-way ANOVA s by treatment and samp 1 1 ng round for in illY data co 1 1 ected duri ng fi el d demonstrat i on samp l i ng October 28-29 1987

FmiddotTET RAT IOS

TREATMENI ROUND INTERACTION (Exp vs control ) (1-5 only ) (Treatment x Round )

CONDUCTI V lTV Surface 25 99 1 14 56 Bottom 28 3 5 4 26 1 6 73

ORP Surface 2 1 10 Bottom 5 35

pH Surface 32 67 33 10 Bottom 1 1 1 5 4 5 1 4 48

Temperature Surface 104 64 Bottom 21 95 1 1 73 8 17

D i s sol ved Surface Oxygen Bottom 14 1 5 7 98 5 20

Saturat i on Surface Bottom 7 66 3 87

df df error bull 20 F 0 05 [df 20 ] bull

1

4 35

4

2 87

4

2 87

Table 4 8 Significant F-test ratios fnD two way analysis of variane by date ani treatment statiCllS 7-12 only Septedler 17 22 30 1987 ani JanJaIY 13 1988 data

rus dissolved Total pnsphorus Anroonia-nitrogen di ssolved Nitrite-nitrogen dissolved Nitrate-nitrite-nitrogen dissolved Total Kjeldahl nitrogen RltassilDU di ssel ved Cqpr di ssolved Iron dissolved Total organic car1xXl Alkalinity Biochemical oxygen demard TUlbidi ty Total suspenied solids Chloride SOdilDU Fluoride

Degrees of freedaD

Degrees freedan of error = 64

F 0 05 [df 60]

595 12 31 05

4 09 96 71 51 06 31 28

225 02 6 34

424 47 23 36 18 32 28 69

171 46 145 71

49 55

3

2 76

lREMMENl ( vs cxmR)L)

10 24 4 81

17 59 12 57

6 75

6 31 24 03 22 36

1

4 00

3 89

4 64 4 94 5 08

3

2 76

EVALUATION AND RESEARCH OF IMPACTS

OF MECHAN I CAL WEED HARVEST I NG I N LAKE OKEECHOBEE

I EXECUT IVE SUMMARY - MID-COLIRSE REPORT

Mote Mari ne Laboratory assi sted by DSA

Envi ronmental Qual i ty Laboratory i s mi dway through

research project conducted for the South Fl ori da

Grou p I nc and

an eval uat i on and

Water Management

D i str i ct to assess the envi ronmental i mpacts of mechani cal harvest i ng of

Hydri l l a The harvest i ng and subsequent upl and d i sposal of materi al are

be i ng performed as a demonstrat i on project to eval uate the nutri ent

( part i cul arl y phosphorus ) removal potent i al and operati onal costs of th i s

techn i que The study s i te ( F i gure 1 1) i s on the northwestern shore of

Lake Okeechobee where approxi mate ly 1000 acres of Hydri 1 1 a are to be

harvested by I nternat i onal Sc i ence and Technol ogy I nc together wi th

L a ke Weed Cutt i ng Serv i ce I nc Spec i f i c i mpacts and s i te

characteri stics to be eval uated incl ude s i te b i omass water qual i ty

phytopl ankton and pri mary product i v i ty cOlMlun i ty metabol i sm sed i ment

chemi stry benth i c i nfauna and ep i phyte commun i t i es and l arval and

juven i l e f i sh popu l at i on s In add i tion a cost benefi t anal ysi s i s to be

performed address i ng the harvest i ng vari abl es and poss i bl e products to

opt i m i ze the cost effect i veness of harvesti ng A l i terature survey of

pert i nent top i cs i s al so i ncl uded as a separate tas k and the enti re

project i s conducted under the auspi ces of a Qual i ty Assurance program

des i gned to ensure the prec i s i on accuracy representat i veness and

compl eteness of al l data

The l i terature survey i s compl ete and over 400 annotated documents

have been comp i l ed i nto a cOlMlercial l y avai l abl e b i bl i ograph i c retri eval

system by key words Task members are abl e to request searches of th i s

database for i nformati on on top i cs spec i f i c to the i r tas k I n add i t i on

summari es o f i nformat i on on sel ected keywords such as Hydri l l a

phosphorous and others have been prepared a s Lake Fact Sheetsmiddot

The bi omass sampl i ng (August 19B7) was del i beratel y conducted i n

a wide range of growth cond i t i ons for eval uat i on of Hvdri l l a dens i t i es

and nutri ent content A cond i t i on i ndex was devel oped to eval uate pl ant

1-1

maturi ty Hvdri l l a senescence and peri phyton i nfestat i on was accompan i ed

by an areal decl i ne i n both bi omass and nutri ent content Max i mum

n i trogen and phosphorus t i ssue concentrat i ons were associ ated with ful l y

mature pl ants pri or t o senescence The presence o f other macrophytes was

respons i bl e for most wi thi n- stati on vari ati on Th i s task i nc i dental l y

d i scovered l arge seasonal d i fferences i n Hydr i l l a phosphorus and n i trogen

content Sampl es col l ected at the study s i te by ISampT duri ng J anuary

1988 were roughly f i ve t i mes h i gher i n phosphorus content than the

materi al col l ected by thi s project duri ng August 1987

Water qual i ty wi thi n the s i te represented an extremel y dynami c

system The i n fl uence of the Ki s s immee Ri ver and any other l ocal

d i sch arges produced d i l ut i on grad i ents across the s i te Vari at i ons i n

qual i ty were apparent between sampl i ng dates Numerous v i ol at i ons of the

i nstantaneous d i ssol ved oxygen cri ter ion (5 0 mgl ) were recorded

part i cu l arl y near the lake bottom Damp i ng of d i urnal oxygen extremes

was observed i n the harvested transects Al l n i trogen spec i es and total

phosphorous were h igher i n the unharvested transect waters than i n the

harvested transect The d i fference may be due e i ther to nutri ent

ut i l i zat i on i n the regrowth areas or to the rel ease of nutri ents from the

senescent Hydr i l l a mat present i n harvested areas The ent i re study s i te

was n i trogen l i mi ted wi th N P rat i os ( by we i ght ) of 3 0 i n the harvested

areas and 9 4 i n the unharvested control s

li ght penetrati on of the water at al l harvested stat i ons was

demonstrated to be s i gn i fi cantl y h i gher than at the unharvested control s

duri ng September onl y By January regrowth of Hvdri l l a produced

s l i ghtl y smal l er compensat i on depths on the harvested transect

Grad i ents i n l i ght penetrat i on were al so apparent wi th i n the experi mental

transect and may be rel ated to t ime s i nce harvest Vert i cal grad i ents

for in 1i1Y data were part i cul arly apparent at the weeded stat i ons

Bl ue-green al gae were the domi nant phytopl an kton taxa at al l

stat i ons d uri ng the September sampl i ngs Thi s domi nance was much reduced

duri ng J anuary when more green al gae were present Di vers i ty and number

of tax a i ncreased at four of the s i x stat i ons i n January but no

cons i stent pattern was apparent for e i ther harvested or control stat i ons

I n add i t i on there were no systemat ic d i fferences between harvested and

1 - 2

unharvested areas on the bas i s of spec i es compos i t i on Vari at i ons i n

chl orophyl l content al so were affected more by seasonal cond i t i ons than

by harvest i ng

The conunun i ty metabol i sm measurements conducted durlng September

1 987 i nd i cate probabl e d i fferences i n oxygen budgets for control and

harvested areas al though i n i t i al stat i st i cal methods d i d not establ i sh

the s i gni f i cance of such d i fferences Th i s was attri buted to anomal ous

data col l ected at a stat i on with unusual sed iment character i s t i cs ( h i ghly

organ i c unconsol idated f i ne grai ned mater i al in contrast to f i ne

grai ned sand ) Add i t i onal data analyses wi l l excl ude thi s stat i on from

cons i derat i on and future sampl i ngs wi l l be conducted at al ternate

l ocat i ons Di fferences by treatment duri ng the January sampl i ng were not

as pronounced as i n September and i nd i cate that regrowth of Hvdri 1 1 a with i n t hat peri od had offset harvest i ng e ffects

Sed i ment heterogenei ty was marked wi th i n the s i te with organ i c

w ith nutri ent content were fa i rl y l ow Organ i c content averaged 0 7

n i trogen 0 27 mgg total phosphorous 0 08 mgg and potass i um 0 49 mgg

on a dry we ight basi s Ni trate-n i tri te -n i trogen concentrati ons were l ess

than 1 of the total present Total n i trogen tota1 phosphorous rat i os

averaged 3 1 and were markedl y l ower than comparabl e rat i os i n e i ther t he

water col umn or the bi omass sampl es refl ect i ng a preferenti al

mobi l i zati on of n i trogen from s i te sed iments Few stat i st i cal l y

s i gn i f i cant d i fferences were detected a s a resul t o f w ith i n - stat i on

vari ati ons and the col l ect i on of more total phosphorus and total n i trogen

val ues are proposed for the second effort of th i s tas k

Data anal yses t o date for benth i c i nfauna i ncl ude preharvest and

postharvest cond i t i ons duri ng August and October respect i vel y The

August fauna was notabl y depauperate both i n taxa and numbers of

i nd i v i dual s wh i l e pronounced i ncreases in both were observed for

October D i urnal l y oxygen - poor cond i t i ons part i cul arl y duri ng August

may l i mi t benth i c fauna Spati al grad i ents were al so noted w ith

decreas i ng s pec i es ri chness and faunal dens i ti es at the southern end of

the study area Experimental and control stat i ons exh i bi ted s i mi l ar

faunal densi t i es and spec i es richness pri or to harvest wh i l e both

1 -3

parameters were substant i al ly greater at the harvested stat i ons duri ng

the October sampl i ng

Based on sampl i ngs i n September and J anuary the l arval and

juven i l e f i sh task col l ected 44 ( 2 1 ) of al l spec i es prev i ously reported

for Lake Okeechobee F i ve habi tats represent i ng both natural and

harvested edges and open water as wel l as heav i ly vegetated areas

were sampl ed Heterandria formosa LeDomi s sp and Gambus i a aff i nis

were the most abundant spec i es Centrarch i ds were the most abundant eggs

recovered The col l ect i on methods were f a i rly specif i c for part i cul ar

l i fe stage juven i l es were taken primari ly i n l i g ht trap sampl es whereas

postl arvae and eggs were taken i n pl ankton tows and Hvdri l l a sampl es

col l ected by the harvester LeDomi s s p appears to ut i l i ze al l fi ve

hab i tats dependent on l i festage No vert i cal strat i fi cat i on of organ i sms

was detected i n the weeded hab i tat and spec i es d i vers i t i es were

equ i val ent at both natural and harvested RedgesR of the Hydri l l a mat No

stat i s t i ca l ly s i gn i f i cant short term i mpacts of harvesti ng on spec i es

abundance or d i str i buti on are apparent

The cost-benefi t analys i s i s restri cted to eval uati ng mechan i cal

harvest i ng al one Benefi ts of thi s techni que wi th the except i on of

sal eabl e byproducts or costs assoc i ated wi th harvested mater i al are

pr i mari l y non -quanti fi abl e ( i mproved habi tat and water qual i ty boater

access nutri ent removal ) Therefore ranges of econom i c parameters wi l l

be ut i 1 i zed together wi th operat i ona 1 data from harvest i ng and

env i ronmental vari abl es from th i s project to present an economi cal l y

opt im i zed harvest i ng pl an to the Di stri ct

I n sunvnary no catastroph i c impacts due to mechan ical harvest i ng

have been detected i n the foregoi ng categori es al though subtl e

d i fferences have been determi ned by the study des ign Harvest i ng reduces

the amount of oxygen stress i n the study area and the nutri ent content of

the water col umn i s l ower i n the harvested than the unharvested areas

The s i te i s n i trogen l i mi ted based on water col umn sed i ment and pl ant

t i ssue anal yses Seasonal vari at i ons are l arge wi th respect to

d i fferences between harvested and unharvested areas for a l gal and l arval

fi sh popUl at i ons Spati al grad i ents were apparent i n many parameters

1 -4

The qual i ty assurance program associ ated wi th thi s project has

thus far conducted a systems aud i t for the pl an of study and at l east one

performance aud i t on f i e l dwork A Qual i ty Assurance Project Pl an has

been prepared and i s i n use as a project control document Aud i ts of

data management and anal ysi s are pl anned for the fi nal report i ng phase

At mi d -course sampl i ng anal yses and del i verabl es are on

schedul e and the project is operati ng wi th i n the budget No probl ems are

foreseen to prevent t imely compl eti on of the remai nder of the schedul ed

work Where al terati ons to speci f ic tasks have been recommended the

support for these efforts wi l l be obtai ned by real l ocati on of funds

wi th i n the project rather than by add i t i onal fund i ng

1-5

o 18 bullbull UNnar tllllllllI UINL UNnan

_ bull 0111 II wilD LlMi

lAKE (J(EECH08EE

Figure 11 Stu dy site l ocation Evaluation and research of impacts o f mechanical harves ting in Lake Okeechobee

I

I I LAKE OKEECHOBEE LITERATURE REV I EW

I I A INTRODUCTION

A 1 i terature rev i ew was conducted as a d i screte task of the

research project The Eval uat i on and Research of Impacts of Aquat i c Weed

Harvest i ng Demonstrat i on i n Lake Okeechobee cond ucted by Mote Mari ne

Laboratory The purpose of the l i terature rev i ew was to provide project

team members wi th economi c geol og i c hydrol og i c chemi cal and

b i ol og i cal i nformat i on on Lake Okeechobee wi th part i cu l ar emphas i s on

water qual i ty probl ems concern i ng phosphorus storage and cycl i ng between

the water col umn sed i ments and aquat i c weeds

I I B METHODS

Three techn i cal el ements were undertaken i n compl et i ng the

l i terature rev i ew 1) ident i fy i ng and search i ng i nformat i on 2) creat i ng

f i l es and 3 ) devel opi ng outputs

I nformati on was obtai ned by rev i ewi ng journal s for art i cl es

search i ng card catal ogs of area l i brar ies contact i ng major authors

conduct i ng research and request i ng key word searches of avai l abl e

computer l i brari es Journal s searched i ncl uded The Journal of Aquat i c

Pl ant Management Quarterly Journal o f the Fl ori da Academy o f Sci ences

( and Fl ori da Sc i ent i st ) L i mnol ogy and Oceanography Hydrobi ol og i a and

North Amer i can Journal of F i sher i es Management L i brari es vi s i ted

i ncl uded Un i vers i ty of South Fl or ida Uni vers i ty of Fl orid a Mote Mari ne

Laboratory Southwest Fl or ida Reg i onal Pl ann i ng Counci l South Fl ori da

Water Management D i str i c t and the Okeechobee off i ce of the Fl ori da Game

and Freshwater Fi sh Commi ss i on Key word l i terature searches were

c o n d u c t e d on d i qu at Lake O keechobee Hyd r i l l a and

nutr i entsaquat i c pl ants u s i ng searches avai l abl e from the Fl ori da

Department of Env i ronmental Regul at i on the Un i vers i ty of Fl ori da Aquati c

Weed Program and the U S Fi sh and Wi l d l i fe Servi ce

2-1

I I C PRODUCT

After rev i ew each publ icat i on was cited keyworded and annotated

u s i ng ARTF I LE vers i on 3 02 software for l i brar i es and b i bl i ographic

storage

Two outputs were devel oped from the comp i l ed i nformat i on 1 )

annotated c i tation s of each i nd i v i dual report and 2 ) Lake Fact Sheets

wh ich summari ze ava i l abl e i nformat i on on a spec i fic top ic requested by

members of t he study team Lake Fact Sheets and keyword b i bl i ographies

were d i stri buted t hroughout the course of the study as requested by

i nd i vi dual project members Lake Fact Sheets and a key word l i st

fol l ow Annotated c i tat i ons appear i n Append i x 2 A

2-2

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on AQUATIC PLANTS

Entri es i n Bi bl i ography 69

( For more deta i l s on spec i fic top ics pl ease see other fact sheets i e

hydri l l a b i omass harvest i ng etc )

Types of stud i es noted

- -Aquat ic pl ant ecol ogy (Moss 1980 23 Lugo and Snedaker 1971 113

Bl ackburn n 11 1968 128 Canfi el d et J 1983 260 Cassan i and

Caton 1985 352 Marshal l 1984 386)

- -Informat i on on aquat i c pl ant communi t i e s as habi tat (Wi l ey etI 1984

34 Durocher niI 1984 38 Mi l l eson nI 1980 40 Watki ns et I

1983 45 Ager and Kerce 1974 190 Sav i no et il 1985 196 Richard

n iI 1985 262)

- -Aquatic pl ant and sed i ment rel ati onsh i ps (Engel and N ichol s 1984 44

Barko and Smart 1986 106 Barko et 11 1983 147 L i et I 1974

108)

- -Aquat i c p l ant management ( Fl or ida DER nI 1986 415)

- - Nutrjent removal by aquat i c pl ants ( Reddy and DeBusk 1985 132)

- -Stud i es on harvest i ng aquat i c pl ants and the effects of harvest i ng

( Carpenter and Adams 1978 17 Sabol 1987 37 Mi ko l 1985 41

Wi l e 1978 57 Neel n 11 1973 114 N ichol s 1974 115

Smal l et

I 1985 130 Wi l e 1975 135)

- -Stud i es on chemical and other control s of aquat i c pl ants ( H i l t i bran n

J 1972 105 Ganstad 1978 110 deNoyel l es and Kett l e 1980 118

M i l on n 11 1986 119 Smal l et I 1985 130 Sutton and Vand i ver

1986 139 Lesl i e and Kobyl i nsk i 1985 255 Langel and and DeMont

1986 227 Barrett 1981 342 Barrett and Murphy 1982 344 Cl ayton

and Tanner 1982 355 Frank and Comes 1967 364 Graham 1976 369

Hughes and McCol l 1980 377 Richard et I 1984 426)

- -Aquat i c pl ant chem i s try and phys i ol ogy ( LaLonde 1970 107 Gerl off

1978 111 Gerl off 1973 112 Bri stow and Wh i tcombe 1971 136)

- - Chl orophyl l a concentrat i ons and aquat i c macrophytes ( Canfi e l d et I

1984 263)

2-3

Produced by Mote Marine Laboratory for South Florida Water Management District

- -B i omass stud i es and methods ( Schl oesser and Manny 1984 14 Mace i n a

J il 1984 33)

- -Uses for aquat i c weed s such as cattl e s i l age ( Bagnal l n l 1978

18) and compost (Wi l e g1 Jl 1978 19)

--Stud i es concern i ng Hydrilla vertic1llata ( Bagnal l 1980 18 Bol e and

Al l an 1978 15 P i erterse J il 1984 42 Bruner and Batterson 1984

43 Bowes 11 il 1979 47 Sutton 1982 52 Sutton and Port i er 1985

53 Sutton and Port i er 1983 57 McGhehee 1979 57 Bal c i unas 1985

116 Mart i n 1983 146 Johnston n Jl 1983 36 Canfi el d et l

1983 265 Mace i n a and Shi reman 1982 281 Hodgson and Carter 1982 423)

2-4

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fa c t She e t on BIOMASS

Entri es i n B i bl i ography 14

Types of stud i es noted

- -A troph i c state i ndex for l akes based on al gal bi omass (Carl son 1977

2)

- -Chl orophyl l -b i omas s - nutri ent rel ati onsh i ps for phytopl ankton (Canfi el d

et gl 1985 4)

--An assessment of bi omass control for water qual i ty management (Wong et

li 1979 9) --Methodol og ies for est imat i ng or measuri ng bi omass (Schl oesser and

Manny 1984 14 Mace i na g1 li 1984 33)

--Effects of harvest i ng or other weed control methods on aquat i c

vegetat i on b i omass (Mi kol 1985 41 Wi l e 1978 57 Cassani and Caton

1985 352 Hughes 1974 378 Sch i l l er 1983 398)

--B i omass measurements rel ati ng seasonal and b i otype vari at i ons i n

Hydr i l l a (Bowes et 11 1979 47 Steward 1987 408)

--Seasonal b i omas s of sel ected spec i es (Bowes et li 1979 47 Dewey et

l 19a1 266)

SUMMARY

Several stud i es use b iomass as a measure of aquat i c pl ant control

and as part of overal l assessments of water qual i ty management Mi ko 1

(1985) uses total pl ant bi omass measurements to asses s the effects of

mechan i cal harvesti ng on aquat i c vegetati on Wi l e (1978) al so presents

bi omass data as part of an assessment of envi ronmental effects of

mechan i cal harvesting Cassine and Caton (1985) asses s the same for

chem i cal and b i ol og i cal weed control Mace i na et li (1984) present a

method for est i mat i ng submersed pl ant bi omass by us i ng a record i ng

fathometer The i r data showed that the tech n i que i s not equal l y rel i abl e

for al l water bod i es However accurate b iomass determi nat i ons cou l d be

obt ai ned i f fathometer traci ngs are cal i brated w i th actual b i omas s data

Add i t i onal b iomass data for aquat i c p l ants are presented by Hughes

2-5

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

( 1974) Sch i l l er ( 1983 ) and Steward ( 1987 ) Bowes n il ( 1979) and

Steward ( 1987 ) present bi omass data for Hydri l l a i n Fl ori da

Canfi e l d et il ( 1985 ) address chl orophyl l - bi omass - nutri ent

rel at i onsh i ps for n atural assembl ages of Fl ori da phytopl ankton Carl son

( 1977 ) presents a troph i c state i ndex for l akes and uses al gal b i omass as

a parameter for the i ndex

2-6

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STU DY

Fact Sheet on D IQUAT

Entr i es i n B i bl i ography 84

Types of stud i es noted

- -Taxi c i ty data ( Mayer and El l ers i eck 1986 270 Berry and Schreck

1976 346 Funderburk and Lawrence 1967 366 Howe and Wri gt 1965

376 Kam W i ng and Furtado 1977 381 Naqui et Ai 1980 390)

- - Effects of d i quat on aquat i c commun i t i es ( H i l t i bran I 1972 105

Berry sl 1964 347 Cas san i and Caton 1985 352 Cal derban k 1972

351 C l ayton 1986 356 Dan i el 1972 358 G i l derhus 1967 368

Haag 1986 370 H i l senhoff 1966 372 Hughes and McCol l 1980 377

Joyce and Thayer 1986 379 Marshal l 1984 386 M i chaud 1979 387)

- -General chem i cal control gu i des and control of spec i fi c aquat i c

pl ants (Abery 1986 339 Barrett 1981 342 Barrett and Murphy 1982

344 Barrett and Logan 1982 345 Chevron Chemi cal Corp 1978 354

Hi l t i bran 1971 373 H i mel n li 1981 375 Ki l l gore 1984 383

Mac kenz i e 1966 385 Mobl ey n il 1971 388)

- -Di quat accumul ati on i n pl ants and sed i ments ( B i rmi ngham and Colman

1983 348 Dav i s and Seaman 1968 359 Frank and Comes 1967 364

Langeland and Warner 1986 384)

- - Experi mental data on herb i c i de treatments (Bri t i sh Col umbi a 1975

350 Clayton and Tanner 1982 355 Dunn et I 1983 362 Hal l er

1982 371 K i l l gore 1981 382 Newroth and L i m 1980 392)

- -Di quat u se wi th other types of control s (Charudattan 1986 353 Frank

AI 1979 365 Ganstad 1986 367 Graham 1976 369 Newroth

1974 391)

SUMMARY

I n add i t i on to the above noted stud i es three l i terature summari es and

rev i ews prov ide good i nformat i on on d i quat stud i es

Joyce and Ramey (1986) prov ide a good annotated rev i ew of 1 i terature

concern i ng research on the fate of aquat i c herb i c i de s i n water w i th

emphas i s on Fl ori d a s freshwater ecosystems Tucker (1980) rev i ews 50

c i tat i ons on d i quat c i tat i ons and prov ides a deta i l ed summary on the

2-7

Produced by Mote Marine Laboratory for South Florida Water Management District

foll ow i ng aspects of d i quat env i ronmental chemi stry adsorpt i on by so il

and cl ay mi neral s aerob i c and anaerob i c soi l stud i es soi l stud i es under

fi el d cond i t i ons aquat i c studi es soi l l eaching stud i es rotat i onal crop

stud i es photochem i cal degradat i on stud i es and mi croorgan i sm stud i es

Langel and and DeMont ( 1986 ) prov i de a thorough rev i ew of the l i terature

on the detect i on tox i c i ty and pers i stence of d i quat endotha1 1 and

f1 uri done They al so present speci fi c data on stud i es of the pers i stence

of d i quat endothal l and f1 uridone i n North Carol i na ponds and water

movement patterns i n Lake Wheel er North Carol i na

2-8

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fact Sheet on EUTROPHICATION

Entr i es i n Bi bl i ography 12

Types of stud i es noted

- -Eval uati ons of nutri ents i n eutroph i c l akes (Canfi el d 1983 5

Schi ndl er 1971 131 Michaud n ll 1979 387 Lee and Jones 1980

175)

- -Aquati c pl ant probl ems i n eutroph i c l akes (Graham 1976 369 Hughes

and McCol l 1980 377)

--Assess i ng eutroph i cati on based on water qual i ty stud i es ( Federi co et

Al 1981 67)

--Troph i c structure assessments and changes i n eutroph i c l akes ( Gayl e

1975 181 US Envi ronmental Protect i on Agency 1975 161)

SUMMARY

A number of stud i es address eutroph i cati on i n Lake Okeechobee

US Env i ronmental Protect i on Agency (1975 161) reports on Lake

Okeechobee as part of the Nat i onal Eutroph i cat i on Survey and a number of

state gency commi ttee stud i es and eng i neeri ng reports provi de anal yses

of Lake Okeechobee eutroph i cati on (MacGl l n AI 1976 174 Bl ack Crow

Ei dsness Inc 1976 185 Lee and Jone s 1980 175)

Us i g seven years of water qual i ty data Federi co et it 1 (1981

67) i dent i fy annual and seasonal l mnet i c water qual i ty trends exami ne

the re l at i o n s hi p to t r i but ary i n fl ow s i d en tify trends and

quali tyd i scharge rel ati onsh i p s cal cul ate annual l ake materi al budgets

for each year and assess the trophi c status of the 1 ake Gayl e (1975

181) presents a systems model for understanding eutrophicat i on i n Lake

Okeechobee

2-9

Produced by Mote Marine Laboratory for South Flori da Water Management District

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on HARVESTING

Entr i es i n B i bl i ography 15

Types of stud i es noted

--Effects of harvesti ng aquat i c pl ants on nutr i ent removal ( Bol e and

Al l an 1978 15 Wi l e 1978 57 Neel et AI 1973 114)

--Compari sons of mechan ical and b i ol og i cal harvest i ng wi th herbi c i de

control ( Carpenter and Adams 1978 17 Smal l et AI 1985 130

Sch i l l er 1983 398)

--Di sposal of and uses for harvested hydri l l a ( Bagnal l et AI 1978 18

Sabol 1987 37)

--Harvest i ng effects on aquat i c fl ora and fauna (Mi kol 1985 41 Wi l e

1978 57 N i chol s 1974 115 Wi l e 1975 135 Schramm et AI 1985

212 Lesl i e and Kobyl i nsk i 1985 255)

- - Economi c s of mechani cal harvest i ng (McGhehee 1979 57)

- - Phys i cal propert i es of hydri l l a for harvesti ng ( Bagnal l 1980 59)

SUMMARY

Most of the stud i es address the effects of mechan i cal ly harvest i ng

aquat i c pl ants Bol e and Al l an (1978) report that the harvest i ng of

Hydr i l la vert i c illata woul d result i n the d i rect transfer of onl y a smal l

amount of phosphorus i n the soi l i nto the water and the organ i cal l y-bound

phosphorus removed i n harvested pl ants woul d be deri ved l argely from the

sed i ment and not the water body W i l e (1978) and Neel n AI (1973)

present data and anal yses on l ake nutri ent dynam i cs resul t i ng from

harvest i ng aquat i c pl ants W i l e (1978) al so presents data on al gae

phytopl an kton fi sh and water qual i ty changes

A number of other stud i es address harvest i ng affects on fl ora and

fauna Mi kol (1985) reports that harvest i ng pl ants al so removed from 2-

8 of the total stand i ng crop of juven i l e fi sh Lesl i e and Kobyl i ns ki

(1985) address benth i c macro i nvertebrate response to aquat i c vegetat i on

removal wh il e Sabol (1087) addresses the env i ronmental effects of aquat i c

d i sposal o f chopped hydr i l l a

2-10

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

Compar i sons of mechan i cal harvest i ng and herbi c i des address

phosphorus cycl i ng (Carpenter and Adams 1 978) and Smal l et Jl ( 1 985)

report that herbi c i des reduced aquat i c vegetat i on but d i d not el i mi nate

i t Us i ng grass carp as bi ol og i cal control s el im i nated or red uced the

vegetat i on depend i ng on the stocki ng rat i o ( Smal l et AI 1985 )

2-11

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fact Sheet on Hydrjlla vertic11l ata

Entri es i n B i bl i ography 37

Spec i fi c stud i es on hydri l l a i n Lake Okeechobee i ncl ude a

compari son of dens i ty data for Lake Okeechobee and three other areas of

Fl ori da wi th stud i es spec i fi c to the speci a l i zed reproducti ve structures

of hydri l l a (Sutton and Port i er 1985 53) and an ana lys i s of potass i um

n i trogen and phosphorus content i n hydri 11 a from Lake Okeechobee and

three other areas of Sout h Fl ori da ( Sutton and Porti er 1983 56)

Pl ants from Lake Okeechobee had the h i ghest concentrat i on s of each

Other types of stud i e s on hydri l l anoted

--Phys i cal and mechani cal propert i es of hydri l l a (Bagnal l 1980

59)

--Nutri ent uptake stud i es of hydri l l a (Bol e and Al l an 1978 15)

--Us i ng hydri l l a for s i l age ( Bagnal l et Al 1978 18)

--Methods for determi n i ng or est i mat i ng pl ant biomass (Maceina et

li 1984 33)

--Growth reproduct i on and l i fe hi story of hydril l a ( Langel and and

Sutto 1980 35 Bruner and Batterson 1984 43 Spencer et li 1987

48 Sutton 1982 52)

--Habi tat i mportance and ecol ogy of hydril l a communit i es and

al terations to hydril l a communities (Watkins et li 1983 45middot

Bowes et

li 1979 47 Bl ackburn et li 1968 128 Sutton and Vandiver 1986

139 Can f i el d n Al 1983 265 Mace i na and Sh i reman 1982 281

R i chard i1 Al 1985 396)

--Biol ogical control s of hyd ri l l a (Bal ciunas and Minno 1985 46

Bal ciunas 1985 116 Johnston et li 1983 36 Cas sani and Caton

1985 352)

--Mechanical control s of hydril l a (McGhehee 1979 57)

--Chemical control of hydri l l a (Martin 1983 146 Cassani and

Caton 1985 352 Frank et li 1979 365 Hughes 1974 378 Small et

Al 1985 404 Steward 1972 405 Steward 1982 406 Steward 1976

407 Steward 1987 408 Van 1985 419 Van et Al 1987 420)

2-12

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

SUMMARY

Most of the stud i es deal w ith ways to control Hydr i l l a

verticilJata as a nui sance weed The effects of harvest i ng Hydri l l a i s

frequent l y addressed wi th mi xed resul ts Bol e and Al l an ( 1978) report

that the harvest i ng of Hydri 1 1 a woul d resul t i n the d i rect transfer of

onl y a smal l amount of phosphorus in the so i l i nto the water and the

organ i cal ly-bound phosphorus removed i n the harvested pl ants woul d be

deri ved l argel y from the sed i ment and not the water body

Johnston g1 il ( 1 983 ) report on the recol oni zat i on of a smal l pond

wi th aquat i c vegetat i on where grass carp have been used to control

Hydrill a They demonstrate the feas i b i l i ty o f reduc i ng the compet i t i ve

advantage of Hydri l l a i n order to l l ow other spec i es to become

establ i shed but al so note that care must be exerc i sed i n sel ect i ng

repl acement spec i es Other aquat i c pl ants may grow as prol i fi cal l y as

the Hydri 1 1 a bei ng repl aced

Sabol ( 1 987) and Langel and and Sutton ( 1 980 ) report on the

regrowth of fragmented Hydri l 1 a w i th confl i ct i ng resul t s In f iel d

stud i es Sabol ( 1 987) tested the re -growth potent i al of chopped Hydri 1 1 a

and found that a very smal l port i on of fragments cou1 d produce new

g rowth Conversely Langel and and Sutton ( 1980 ) under control l ed

l aboratory and f i e l d cond i t i ons demonstrated that 40 of the pl ant

fragments wi th one or two nodes were capabl e of vegetat i ve reproduct i o n

Bagnal l 11 il ( 1984 ) eval uated the feas i b i l i ty o f us i ng Hydri l 1 a

for cattl e feed and Macei na 1 il ( 1 984 ) present a method for pred i cti ng

pl ant b i omass us i ng a record i ng fathometer

2-13

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on N ITROGEN

Entri es i n B i bl i ography 27

Types of stud i es noted

- - Land userunoff rel at i onsh i ps w i th nutri ents i ncl ud i ng n i trogen

( Feder i c o 1 977 3 )

- - Nutri ent i n fluences on aquat i c pl ants and phytopl ankton (Canfi el d et

li 1985 4 Can fi el d 1 983 5 Davi s 1980 20 Dav i s 1 982 27

P i eterse 1 984 42 Sutton and Port i er 1 983 56 Bl ac kburn et il

1 968 1 28 Reddy and DeBus k 1 985 13 2 Jones and Federi co 1 984 1 )

- - Water qual i ty stud i es that i ncl ude nitrogen parameters ( Lutz 1 977a

7 Lutz 1 977b 16 M i l ler 1 980 20 Mi l l er et li 1982 26 Dav i s

and Marshal l 1 975 65 Peverl y and Johnson 1 979 394 Jones 1 983

9 )

- - Nutri ent rel at i onsh i ps w i th the troph i c structure of l akes (Henri kson

11 il 1 980 32 Dye 11 il 1975 138)

- - N i trogen and other water qual i ty data for Lake Okeechobee ( Di c kson et

li 1978 66 Davi s and Marshal l 1975 65 Federi co g1 li 1981 67

Fre i betger 1972 69 Mi l l er 1975 70 Jones and Federi co 1984 1

Jones 1 983 9)

- -N i t rogen i nputs and l ake eutroph i cat i on ( Sch i ndl er 197 1 13 1

Feder i co et il 1981 67 Canfi el d 1 983 5 )

- -Den i tri ficat i on i n Lake Okeechobee (Messer et li 1979 1 43 Messer

and Brezon i c 1 984 1 58)

- -Geochemi cal exchanges across the sed i ment -water i nterface ( Burton et

il 1975 1 45 Messer and Brezon i c 1984 158 )

- -Model s pred i ct i ng n i t rogen concentrat i ons (Jones 1983 9 )

SUMMARY

Several stud i es prov i de data on n i trogen for Lake Okeechobee

(M i l l er 1 980 20 Di c kson et li 1978 66 ) Many of these prov ide

n i trogen data as part of l arger studies for i nstance Federi co et li

( 1981 67 ) summari ze seven years of water qual i ty data i n order to

ident i fy annual and seasonal trends cal cu l ate annual budgets and assess

2-14

Produced by Mote Marine Laboratory for South Florida Water Management District

the troph i c state of the l ake Two stud ies ( Fre i berger 1 972 69

Mi l l er 1 97 5 70) i ncl ude lake Okeechobee as part of l arger wet and dry

season nutri ent surveys of South Fl ori d a

Jones ( 1 983 9 ) eval uates the qual i ty o f d i scharges t o Lake

Okeechobee nutr i ent concentrat i ons affects of var i ous changes i n l ake

l evel s and the abi l i ty of var i ous model s to accuratel y pred i ct n i trogen

and phosphorus concentrat i ons Jones and Federi co ( 1984 I) al so apply

nutr i ent model smiddot to Lake Okeechobee Dav i s and Marshal l ( 1 975 65)

present i nformat i on on areal and seasonal vari at i on s of n i trogen l evel s

nutri ent l oad i ngs and budgets for Lake Okeechobee and other chemi stry

d ata

Sutton and Port i er ( 1 983 56) eval uate the potass i um n i trogen

and phosphorus content of Hydri l l a from fi ve l ocat i on s i n South F l ori da

Sampl es were eval uated for wi th i n 1 ocat i on vari abi l i ty and for between

l ocat i on vari abi l i ty and resul ts showed that pl ants from lake Okeechobee

had h i gher concentrat i ons of nutri ents than pl ants from other areas

2-15

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on PHOSPHORUS

Entr ies i n Bi bl i ography 135

Phosphorus stud i es speci fi c to Lake Okeechobee i ncl ude

- -An anal ys i s o f the effect o f reduced nutri ent l oad i ngs on Lake

Okeechobe chl orophyl l (Jones and Feder i co 1984 )

- -An eval u at i on of the qual i ty of d i scharges to l ake nutri ent

concentrat i on s (Jones 1983 )

- -An analys i s of the abi l i ty of vari ous model s to accurately pred i ct

phosphorus concentrat i on s (Jones 1983 )

- -A comp ari son of phosphorus content i n hydri l l a from Lake Okeechobee and

four other l ocat i ons (Sutton and Porter 1 983 )

- -Aer i a 1 and seasonal vari at i ons of phosphoru s 1 eve 1 s i n Lake Okeechobee

(Davi s and Marshal l 1975 )

-A survey of total ortho p l us aci d - hydrol yzabl e phosphorus ( P- P04)

dur i ng a peri od of h igh water and a peri od of l ow water at 1 1 stat i on s i n

Lake Okeechobee and several stat i ons el sewhere i n South Fl or1 da

(Fre i berger 1972 )

- -An anal ys i s of l i mi t i ng factors based on al gal assays on water sampl es

from 30 s i tes i n the Ki s s i mmee R i ver- Lake Okeechobee Bas i n (Dye tl AI

1 975 )

- - Stud i es on nutri ent exchange across the sed i ment-water i nterface

(Burton et il 1975 )

Add i t i onal l y spec i fi c phosphorus d ata for Lake Okeechobee and i t s

watershed are presented i n a number o f reports (Jones and Feder i co 1984

Jones 1983 Mil l er 1980 Davi s and Marshal l 1975 Fre i berger 1 972

Messer et il 1 979 Dye et il 1975 Burton et Al 1975 Lee and Jones

1975 Lutz 1 977 Mi l l er et il 1982 Di ckson et Al 1978 M i l l er 1975)

Regard i ng management pl an s for phosphorus l evel s t he Lake

Okeechobee Techni cal Commi ttee ( 1 986 ) recommended to reduce phosphorus

l oads by at l east 40 (based on the mod i fi ed Vol l enwe i der nutri ent

l oad i ng model s ) through a program of d i vers i ons and treatment

2-16

Produced by Mote Marine Laboratory for South Florida Water Management District

Stud i es out s i de the lake Okeechobee area wh i ch prov i de i nformat i on

val uabl e to the study of phosphorus i ncl ude

- - Uptake of phosphorus from sed i ment and the water col umn by pl ants ( Bol e

and Al l an 1978 Dav i s 1984 Dav i s 1982 Reddy and DeBus k 1985 Dav i s

and Harri s n d li i1 Al 1974)

- -The i nfl uence of 1 and use patterns and other control s on phosphorus

l evel s ( Federi co 1977 Mi chal ski i1 Al 1975)

- -The correl at ion of nutri ent l evel s w i th chl orophyl l and phytopl ankton

l evel s ( Canfi el d i1 Al 1985 )

- - I ndexi ng and model l i ng techn i ques for l akes us i ng phosphorus and

rel ated data ( Carl son 1977 Canfi el d 1983 Meri cas and Mal one 1984)

- - Data on removal of phosphorus by mechan i ca l l y harvest i ng pl ants

( Carpenter and Adams 1978 Wi l e 1978 )

- -Rel ati on sh i p between nutri ents and b i ol og i cal parameters ( Henri kson g1

Al 1980 Pi eterse 1984 Enn i s 197 5 Re i nertsen 1 986 )

- - Phosphorussed i ment i nteract i ons (Twi nch and Peters 1984 li et li

1 97 1

- -laboratory and other control l ed stud i es on the propert i es of phosphorus

( Shannon and lee 1966 li et li 197 1 )

--Other l i terature stud i es ( Sch i ndl er et Al 197 1 )

2-17

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on PHYTOPLANKTON

Entr i es i n B i bl i ography 8

Types of stud i es noted

- - Phytopl ankton stud i es for Lake Okeechobee (Marshal l 1977 1 2 Dav i s

and Marshal l 1975 65 Marshal l 1977 424 Jones and Federi co 1 984

1 )

- - Phytopl anktonnutri entl ake eutroph i cat i on rel at i onsh i ps (Canfi el d et

AI 1985 4 Sch i ndl er 1971 13 1 Hughes and McCol l 1 980 377 Jones

and Federi co 1 984 1 )

- - Phytopl ankton pri mary producti on methodol ogy ( Schearer et AI 1985

278)

--Phytopl ankton responses to aquat i c pl ant removal (R i chard et AI 1985

426)

SUMMARY

Dav i s and Marshal l ( 1975 65) present 2 - 12 years of

phytopl an kton dens i ty data for Lake Okeechobee as wel l as i nformat i on on

n i trogn and phosphorus l evel s ( areal and season al vari at i on s ) pri mary

product i v i ty changes in al gal popul at i on s nutr i ent l oad ings and

budgets ra i n fal l chemi stry dat a regress i on anal yses on bi ol og i cal

act i v i ty and chemi cal or phys i cal propert i e s and trophic state

Marshal l s ( 1 977 1 2 ) phytopl ankton dens i ty data for 1974 show peaks i n

May and September i n Lake Okeechobee Marshal l concl udes that Lake

Okeechobee exh i b i t s seasonal patterns and peri od i c i ty typ i cal of

temperate l akes al though the seasonal vari at i on i n den s i t i es i s typi cal

of a trop i cal l ake

Jones and Federi co ( 1984 1 ) present over four years of d ata on

chl orophyl l a pri mary product i v i ty phytopl ankton dens i t i es and domi nant

species They al so an al yze the effect of reduced nutri ent l oad i ng s on

L a ke Okeechobee chl orophyl l and concl ude that chl orophyl l and

product i v i ty l evel s have not changed substanti al l y dur i ng the study

peri od except that peak val ues were h i gher i n 1981

2-18

Produced by Mote Marine Laboratory for South Florida Water Management District

Canfi el d n li ( 1985 4) col l ected data from 165 Fl ori da l akes

and reported a s i gn i fi cant correl at i on between chl orophyl l a

concentrat i ons and phytopl ankton bi omass Mul t i pl e repress i on anal yses

i nd i cated that phytopl ankton bi omass was dependent on both the total

phosphorus and total n i trogen concentrati on Nutri ent-phytopl ankton and

Secch i - phytopl ankton rel ati onsh i ps for the Fl orida l akes had h i gher

coeffi c i ents of determi nat i on i f chl orophyl l a concentrat i ons rather than

bi omass data were used

2-19

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fa ct Sheet on PRIMARY PRODUCTIVITY

Entries in Bibl iography 11

Types of studies noted

- -General ecol ogy studies incl uding primary productivity (Fontaine and

Ewe l 1981 31)

- -Trophic studies of l akes (Henrikson it 11 1980 32)

--Nutrient infl uences on primary productivity (Davis and Harris no date

141)

- -Primary production methodol ogy (Shearer l1 11 1985 278)

--Primary production data in Fl orida (Odum 1974 169 Brezonic et 11

1979 155 Jones and Federico 1984 1 Davis and Marshal 1975 65

Marshal l 1974 424)

- -Seasonal primary productivi ty cycl es (Comita 1985 1195 Marshal l

1974 424)

SUMMARY

Severa 1 stud i es concern primary production in Lake Okeechobee

Brezonjc l1 11 (1979 155) report to the Fl orida Sugar Cane League on

factors affect i ng primary product ion n Lake Okeechobee Jones and

Federico (1984 1) present primary productivity data on Lake Okeechobee

for 1974-76 and 1979-82 as wel l as information on chl orophyl l a

phytop 1 ankton dens i ties and domi nant spec 1 es and an anal ys s of the

effect of reduced nutrient l oadings Their report concl udes that

ch l orophyl l and productivity l evel s have not c hanged substantial l y during

the study period except for peak val ues that were higher in 1981 and

overal l val ues were higher In the Lake s north end Marshal l (1974

424) add resses seasonal changes for primary productivity and

phytopl ankton He concl udes that considering primary productivity and

other factors Lake Okeechobee phytopl ankton dynamics resembl e temperate

l akes Davis and Marshal l (1975 65) present over two years of data on

chemical and biol ogical investigations of Lake Okeechobee incl uding

primary productivity

2-20

Produced by Mote Marine Laboratory for South Florida Water ManaQement District

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet o n SED IMENTS

E ntr i es i n B i bl i ography 21

Types of stud i es noted

Most of the stud i es i nvol ve sedi ment nutr i ent ava i l abi l i ty fl uxes

and uptake by pl ants These i ncl ude reports on

-- Laboratory experiments to determi ne phosphorus uptake from the

sed i ments by Myri ophyl l ym and Hydri l l a ( Bol e and Al l an 1978 1 5 )

- - Phosphate exchange i n l ake sed i ments (Twi nch and Peters 1984 295 L i

et l 197 1 1 49 li Al 1973 )

- -Ava i l ab i l i ty of sedi ment phosphorus for macrophytes ( L i et l 1974

108)

- - Phosphorus fl uxes i n south Fl ori da marshes (Dav i s and Harri s no date

143 )

- -The i mportance of den i tr i fi cati on i n lake Okeechobee (Messer et l

1979 1 43 )

- -Geochemi cal exchanges across the sed i ment -water i nterface i n the

Ki s s i mmee Ri ver- Lake Okeechobee watershed ( Burton g1 l 1975 145)

- - lak sed i ment den i tri f i cat ion model s (Messer and Brezon i c 1 984 1 58)

There are al so a number of stud i es concern i ng the rel at i onsh i p of

sedi ment type and other factors to pl ant growth ( Bruner and Batterson

1984 43 Mart i n 1983 146 Barko et il 1983 147 Engel and

N i chol s 1 984 44 Barko and Smart 1986 106) pest i c i de and other

chemi cal res i dues i n sedi ments ( Pfeuffer 1985 298 Hughes and McCol l

1980 377 S i ms i man and Chesters 1976 402 )

SUMMARY

BUrton et l ( l979) documents the rol e of sed i ments i n determi n i ng

water qual i ty i n the Ki s s immee Ri ver-lake Okeechobee watershed wi th an

emphas i s on nutri ent exchange across the sed i ment -water i nterface They

a l so prov ide survey i nformat i on on sediment d i str i but i on and transport

Mes ser et l ( 1979) summari zes the i mportance of den i tr if i cat i on i n lake

Okeechobee i ncl ud i ng a d i scuss i on on the rol e of sedi ments i n the

2-21

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

den i tr i fi cat i on process

eval uat i on o f l ake sed i ment

Lake Okeechobee

Messer and Brezon i c ( 1 984 ) present an

den i tri fi cat i on model s and i ncl ude data from

Dav i s and Harri s ( n d ) provi de est i mates of phosphorus fl uxes

wh i ch d i rectly contri bute to uptake through pl ant growth and to retent i on

through pl ant detri tus sed i mentat i on for the Evergl ades Conservat i on Area

2

2-22

LAKE OKEECHOBEE LITERATURE REVIEW

LIST OF KEY WORDS

ABUNDANCE ( 2 ) ADSORPTION ( 2 ) AGE (1) AGRICULTURE (1) ALGAE (14) ALGAL BIOASSAY (1) ALGICIDES ( 2 ) ALKALI N I TY (1) ALKALOIDS (1) ALTERNANTHERA ( 2 ) ALTERNATHERA (1) AMMONIA (1) AMPH I PODS (1) ANALYSIS OF COVARIANCE (1) ANIMAL BEHAVIOR (1) ANIMALS ( 2 ) AQUATHOL (1) AQUATIC PLANT CHEMISTRY (1) AQUATIC PLANTS (76) AQUATIC ORGANISMS ( 2 ) AQUATIC ( 1 ) AQUIFER ( 2 ) ARGULUS ( 1 ) ARTHROPODS ( 1 ) ATHERINE FISH (1) BACKPUMPING ( 2 ) BACTERIA ( 3 ) BASS (18) BEACH HAB ITATS ( 2 ) BEHAVIOR ( 2 ) BENTHOS (9 ) BEST MANAGEMENT PRACTICES (1) B IOACCUMULATION (1) BIOASSAY (1) BIOLOGICAL CONTROL (8) BIOLOGY ( 6 ) BIOMASS (15) BIOTIC ASSESSMENT (1) BIOTYPES (1) BIRDS ( 2 ) BLACK CRAPPIE (19) BLACK BULLHEADS (1) BLUEGILL ( 1 2 ) BODY FORM ( 2 ) BREEDING (1) BROMAC I L (1) BROOK SILVERSIDE (1) CABOMBA (1)

2-23

CADDISFLIES (1) CADMIUM (1) CALLITRICHE (1) CALOOSAHATCHEE RIVER (5) CANALS ( 2 ) CARBON (1) CARBONATE ROCKS (1) CARBOXYLASE (1) CAREX (1) CATTAI LS (1) CATTLE FEED (1) CENTRARCHIDS (5) CERATOPHYLLUM (5) CHAIN PICKEREL ( 1 ) CHANN ELS ( 1 ) CHAOBORUS (1) CHARA ( 6 ) CHEMICAL CONTROL ( 66 ) CHEMISTRY (10) CHIRONOMID LARVAE (1) CHIRONOMIDS (1) CHLORIDE (4) CHLORINATED HYDROCARBONS (1) CHLOROPHYLL (11) CLADIUM ( 2 ) CLASSIFICATION (1) COEFFICIENT OF DETERMINATION (1) COMMERCIAL FISHERY (2 ) COMMUNI TIES (1) COMMUNITY STRUCTURE ( 7 ) COMPETITION ( 3 ) COMPOST (1) COMPUTER MODELS (1) CONFINING BEDS (1) CONTOUR MAPPING (1) CONTROLLED RELEASE (1) COPEPODS (1) COPPER ( 9 ) COPPER SULFATE (1) CORE SAMPLER (1) COST BENEFIT ANALYSIS (1) CRUSTACEANS ( 2 ) CTENOPHARYNGODON IDE (2 ) CULTURAL CONTROL ( 2 ) CYANATRYN (1) DALAPON (4) DEGRADATION ( 3 ) DEMOGRAPHY (1)

DENITRIFICATION (1) DENSITY (6) DESORPTION (1) DETENTIONRETENTION ( 1 ) DETRITUS (1) DEVELOPMENT (2) DIATOMS (1) DICHLOBENIL (2) DIPOTASSIUM ENDOTHAL ( 1 ) DIQUAT (89) DISCHARGE ( 1 ) DISPERS ION (1) DISSOLVED OXYGEN (14) DISSO LVED SOLIDS (2) DISTRIBUTION (16) DIURNAL (1) DRAINAGE (4) DREDGING (1) DYSTROPHIC (1) EARLY DEVELOPMENT (2) ECOLOGY (15) ECONOMIC ANALYSIS (1) ECONOMICS (1) ECOSYSTEM (1) EFFLUENT REDUCTION (1) EFFLUENT (1) EGERIA (6) EICHHORNIA (13) ELODEA (20) EMBRYO ( 1 ) ENDOTHAL-POTASSIUM ( 1 ) ENDOTHALL (20) ENTRAINMENT (2) EPIPHYTES (1) EUTROPHICATION (12) EVERGLADES ( 9 ) EVERGLADES COUNTY (1) EXOGENOUS FEEDING (2) EXPLORATION (2) FAUNA (2) FEEDING ( 9 ) FEEDING RELATIONSHIPS (2) FENAC (5) FIRST YEAR SURVIVAL ( 1 ) FISH (130) FLOOD CONTROL (1) FLOODING ( 1 ) FLORIDA (31) FLORIDA EVERGLADES (1) FLORIDA LAKES (4) FLORIDA DUCK (1) FLORIDAN AQUIFER (2)

2-24

F LOW RATES (1) F LURIDONE (9) FOOD CHA I NS (1) FOOD HABITS (2) FOOD (6) FORAGE ( 1 ) FORAGING ( 1 ) FREQUENCY ANALYSIS (1) FRESHWATER SPECIES (1) FRESHWATER DISCHARGE ( 1 ) FRESHWATER (27) FRESHWATER MARSH (1) GEOLOGY ( 9 ) GERMINATION (1) GIZZARD F I SH (1) GIZZARD SHAD (2) GLADES COUNTY (9) GLYPHOSATE ( 6 ) GRAPNEL SAMPLER (3) GRASS CARP (8 ) GREAT BRITAIN ( 6 ) GROUNDWATER (5) GROWTH (11) GROWTH INHIBITORS (1) HABITAT (2) HABITAT PARTITION ING (1) HARVESTING (7) HAUL SEINE ( 1 ) HENDRY COUNTY (9) HERBICIDES (47) HEXAZINONE ( 1 ) HIGHlANDS COUNTY (1) HISTORY (3) HOST SPECIFICITY (1) HYDRILLA (42) HYDROCARBONS (1) HYDROCOTYLE (1) HYDROGEOLOGY (2) HYDROLOGY (17) HYDROPERIOD CHANGES (1) HYGROPHILA (1) HYPERmiddotEUTROPHIC (1) ICHTHYOFAUNA (1) ICHTHYOPLANKTON (2) IDENTIFICATION KEY (1) IDENTIFICATION GUIDE (10) IMAZAPYR (1) IMPOUNDMENTS (3) IMPROVING CATCH (1) INDICATOR SPECIES (1) INORGANIC PHOSPHATE (1) INSECT CONTROL (1)

INSECTS (4) INVERTEBRATES (9) IRON (2) IRON CHELATE (1) IRR IGAT ION (2) ISOPODS (1) JASM INE (1) JUNCUS (2) JUVEN ILE F ISH (5) K ISS IMMEE R IVER (11) LABORATORY STUD IES (1) LAGAROS I PHON (3) LAKE LEVELS (2) LAKE WANAKA (1) LAKE CONWAY (1) LAKE OKEECHOBEE (89) LAKE DRAWDOWN (1) LAKES (75) LAND USE (6) LARGEMOUTH BASS (16) LARVAE (1) LARVAL F ISH (25) LEAF PRODUCTION (1) LEMNA (8 ) LEPOMIS (1) L IFE HISTORY ( 9 ) L IGHT INTENSITY (1) L IGHT TRAPS (1) L IMNOLOGY (2) LI MNO PH I LA (1) L ITERATURE SURVEY (5) L ITHOLOG IC ANALYSIS (3) L ITTORAL (12) L ITTORAL ZONE (9) LOTAC (3) MACRO INVERTEBRATES (12) MACROPHYTES (18) MANAGEMENT PLAN (3) MANGANESE (3) MARION COUNTY (3) MARSH PLANTS (3) MARTIN COUNTY (27) MASS BALANCE MODEL (3) MATERIAL BUDGET (3) MATHEMAT ICAL MODELLING (3) MATHEMATICAL MODELS (3) MECHAN ICAL CONTROL (15) MECHANICAL HARVEST ING (24) METHODS ( 9 ) M ICROBES (3) MICROPTERUS (6) MINERAL RETENTION (3)

2-25

MINERAL ADSORPTION (3) M INERAL NUTRITION (3) MINERALIZATION (3) M ISS ISSI PPI S ILVERSIDE (3) MODELING (6) MODELS (12) MOLLUSKS (3) MONITOR ING (15) MORPHOLOGY (3) MORTALITY (12) MOTHS (3) MOWING (3) MYOMERE NUMBERS (3) MYR IOPHYLLUM (84) MYSIDS (3) NAIDIDAE (3) NAJAS (18) NEKTON (3) NEMATODES (3) NEOCHETINA (6) NETS (6) N ICKEL (3) N ITRATES (3) N ITROGEN (81) NORTHERN P IKE (3) NUPHAR ( 9 ) NUTR IENTS (141) OCALA GROUP (3) OKEECHOBEE COUNTY (33) OKLAWAHA R IVER (3) OL IGOCHAETES (3) OLIGOTHROPHIC (6) ORANGE LAKE (3) ORGANIC MATTER (3) OSCEOLA COUNTY (3) OXYGEN (9) PALAEOLIMNOLOGY (3) PALM BEACH COUNTY (30) PAN ICUM (67) PARAQUAT (39) PARTICULATE MATTER (3) PASPALUM (3) PATHOGENS (3) PERI PHYTON (3) PERSISTENCE (9) PESTICIDES (27) PH ( 9 ) PHOSPHATE (15) PHOSPHORUS (135) PHOTOSYNTHES IS (12) PHYS IOLOGY (12) PHYTOPLANKTON (27)

PHYTOTOXICITY (3) PIKE (3) PISCIVOROUS FISH ( 6 ) PISTIA (15) PLANKTON (15) PLANNING (3) PLANT SUCCESSION (9) PLANT HARVESTING (9) PLANT ABUNDANCE ( 6 ) PLANT DENSITY (3) PLANT COMMUNITIES (9) PLANT SURVEY TECHNIQUES (9) PLANT COMPOSITION (9) PLANT NUTRITION (3) PLANT GROWTH ( 6 ) PLANT BIOMASS (3) POLLUTION (3) POLLUTION CONTROL (3) POLYCHAETES (3) POLYMER ( 6 ) POMACEA (3) POHOXIS ( 6 ) PONAR GRAB SAMPLER (9) PONDS ( 6 ) POPULATION DYNAMICS (9) POPULATION (21) POTAMOGETON (57) POTASSIUM (9) PREDATION (3) PREDATOR - PREY (15) PRIMARY PRODUCTION (36 ) PROPAGU1ES (3) PUMP STATIONS (3) PUMPING (3) RADAR (3) RADIOPHOSPHORUS (3) RAINFALL (18) RANUNCULUS ( 6 ) RATS (3) RECLAMATION ( 3 ) RECORDING FATHOMETER (3) RECRUITMENT (3) REDBREAST SUNFISH (3) REDEAR SUNFISH (3) REFERENCES (3) REGRESSION ANALYSIS (15) RELEASE RATES (3) REMOTE SENSING (3) REPRODUCTION (12) RESERVOIRS (51) RESIDUES (27) RESOURCE PARTITIONING (9)

2-26

RESPIRATION (3) REVIEW (3) RIVERS (42) RUNOFF (33) SAGITTARIA (3 ) SALVINIA (18) SAMPLING (15) SAMPLING METHODS ( 6 ) SAMPLING GEAR (3) SCIRPUS (3) SEA LEVEL RISE (3) SEASONAL EFFECTS (12) SEASONAL SUCCESSION (3 ) SEASONAL (9) SECCHI DISK (9) SEDIMENTARY ROCKS (3 ) SEDIMENTS (78) SEEPAGE (12) SEWAGE DISCHARGES (3) SHAD (15) SHINERS (3) SHOREFLIES (3) SHORELINE AREAS (3 ) SILICA (3) SILICON (3) SIZE CLASS ( 6 ) SNAILS (3) SODIUM ALGINATE ( 6 ) SODIUM (3) SOILS (9) SOUTH FLORIDA (24) SPARGANIUM (3 ) SPAWNING (21) SPECIES DIVERSITY (3 ) SPECIES COMPOSITION (3 ) SPECIFIC CONDUCTANCE (15) SPOTTED BASS (3 ) ST LUCIE ESTUARY (3 ) ST JOHNS RIVER (3 ) ST LUCIE COUNTY (3 ) STANDING CROP (15) STOCHASTIC LAKE MODELS (3 ) STORHWATER (3) STRATIGRAPHY ( 6 ) STREAMS (9) SUNFISH (18) SURFACE DISCHARGES (3) SURFACE WATER (21) SURFACTANTS ( 6 ) SURVIVAL ( 3 ) SUSPENDED SOLIDS (3 ) SWIM PROGRAM ( 3)

TAYLOR CREEK (6) TAYLOR CREEK WATERSHED (3) TEMPERATURE (9) TENNESSEE (6) TERRESTRIAL (6) THREADFIN SHAD (15) TILAPIA (3) TOXICITY (36) TRACE METALS (3) TRANSMISSIBILITY (3) TRANSPARENCY (6) TROPHIC STRUCTURE (30) TUBER PRODUCTION (3) TUBER DENSITY (3) TURBIDITY (12) TURION (9) TYPHA (9) UPPER TAYLOR CREEK (3) USGS (3) UTILIZATION (3) UTRICULARIA (3) VALLISNERIA (15) VAUCHERIA (3) VEGETATED HABITATS (3) VEGETATION (15) VEGETATIVE PROPAGULES (3) VEGETATIVE REPRODUCTION (6) VELOCITY (3) VERTEBRATES (3) WASTELOAD ALLOCATION (6) WASTEWATER TREATMENT (6) WASTEWATER (3) WATER SUPPLY (12) WATER RECYCLING (3) WATER LEVELS (6) WATER CONSERVATION AREA 2A (3) WATER CHEMISTRY (21) WATER QUALITY (Ill) WATER MANAGEMENT (6) WATER LEVEL (9) WATER CIRCULATION (3) WATER BUDGET (3) WATERSHED ANALYSIS (3) WEIGHT DISTRIBUTION (3) WEIR BOX (3) WET AND DRY SEASON (9) WETLANDS (9) WHITE CRAPPIE (6) WILDLIFE (3) WITHLACOOCHEE RIVER (6) WOLFFIA (3) XYLENE (6)

2-27

ZINC (3) ZOOLOGY (3) ZOOPLANKTON (21)

I I I BIOMASS - M ID-COURSE SUMMARY

I I I A INTRODUCT ION

The experimental removal of Hydr i l l a vert i c i 1 1 ata R i s bei ng

conducted to prov ide removal of nutr i ents phosphorus i n part icul ar from

Lake Okeechobee as wel l as the anc i l l ary benefi ts of i ncreased fi sh

hab i tat and nav igat i onal acces s To determi ne benefi ts and costs of

removal an i ndependent est i mate of both b i omass and nutri ent content of

vert i ci l l ata has been conducted

The bi omass sampl i ng effort was conducted i n August 1987 and was

compl eted pri or to the actual harvest i ng Stat i ons were concentrated i n

the area of the Hydri l l a mat but some non -Hydr i 1 1 a spec i es were al so

col l ected Sampl i ng l ocat i ons were sel ected on the bas i s of qual i tat i ve

cl ass i ficati ons of Hydri l l a growth character i s t ics

Based on fi e l d reconna i ssance i n Aprll and Ju l y 1987 a

s ubstant i al amount of spati al nonhomogene i ty i n both weed dens i ty and

spec i es compos i t i on was observed throughout the proposed s tudy s i te A

vari ety of env i ronmental factors such as substrate compos i t i on water

qual i ty and to a l es ser degree l i ght penetrat i on and water depth may

have been respons i bl e for these observed d i fferences Any past

appl icat i on and poss i bl e res i dual effects of weed control herb ic i des may

al so be contr i buti ng envi ronmental factors As growth character i st ics

w i th i n th i s area were not un i form i t was assumed un l i ke ly that nutri ent

content was evenly d i stri buted To quanti fy these area -wi de var i ati ons

a s ampl i ng scheme emphas iz i ng the range of Hydril l a growth cond i t i ons was

des i gned

III B MATER IALS AND METHODS

I I I B 1 Sampl e Col l ecti on

Prec i s i on measurement of Hydri l l a bi omass i s h igh l y dependent upon

the representat i veness of the sampl es as wel l as evenness of growth

character i st ics wi thi n the study s i te As di fferences i n dens i ty had

3 - 1

been observed duri ng reconnai ssance surveys fi ve Hydri l l a cond i t i on

factors were establ i shed ( see Tabl e 3 1 ) Stat i ons were apport i oned

among these fi ve categor i es rat i ng sel ected s i tes accord i ng to these

cond i t i on factors to i nsure that comparabl e representat i ve sampl es were

col l ected

As a resul t fi fteen ( 1 5 ) stat i ons were establ i shed wi th i n the

weed harvest i ng area ( Fi gure 3 1 ) Sampl i ng l ocat i ons were fi xed and

recorded i n the fi e l d us i ng Loran C (Apel co model DXL -6000 ) Sampl e

col l ect i on at each stat i on con s i sted of three repl i cated cl i pped - pl ots of

Hydri l l a removed from wi thi n a 202Sm2 sampl i ng dev i ce pl aced on the

substrate The sampl i ng box was constructed of steel pl ate 3 mm th ick

The overal l des i gn was s imi l ar to that descri bed by Mart i n and Sherman

( 1979 ) The top of the box however was covered by a d i amond pattern

screen wi th an attached hook to fac i l i tate l i ft i ng the sampl er wh i ch

contai ned the Hydr i l l a sampl e i nto the boat

The sampl er was l owered to the substrate and the Hydri l l a adjacent

to the edge of the box was cut by the d i ver wi th a kn i fe The bottom

sl i d i ng pl ate was then i nserted to conta i n the Hydri l l a sampl e and the

sampl er was then retri eved to the surface

Onl y the above- substrate port i ons of the pl ant were col l ected

s i nce thi s was cons i dered to be the port i on of the pl ant subject to

removal by the mechan i cal harvester Unconsol i d ated detri tal materi al

and roots were not col l ected Any non -Hydri J 1 a macrophytes col l ected

were separated from the Hydri l l a sampl es and treated as d i screte sampl es

Each l abel l ed repl i cate sampl e was we i ghed separatel y to the nearest gram

to determ i ne fresh wet we i ght s The i nd i v i dual repl i cates were then

i ced and shi pped to the l aboratory for dry we ight and nutr i ent content

analys i s

Add i t i onal fi el d procedures i ncl uded a near-fi el d and obl i que

photograph taken at each bi omass sampl i ng stat i on

3-2

I I I B 2 Anal yt i cal Methods

Percent mo i sture was determi ned on al l sampl es Sampl es were

dri ed at 103 - 1050C and the dri ed materi al was used i n n i trogen

phosphorus and potass i um anal yses A total of 52 sampl es were processed

(45 Hydri l l a and 7 non - Hydrjl l a fract i ons ) by MML Total Kjel dahl

n i t rogen and total phosphorus were analyzed from dri ed ground pl ant

materi al Methods ut i l i zed were from the AOAC Methods of Anal ysi s 13th

Ed i t i on 1980 Kjel dahl d i gesti on i n a bl ock d i gester of l ess than O lg

pl ant materi al was fol l owed by sampl e reconst i tut i on automated d i l ut i on

and col ori metri c determi nati on o f amon i a and phosphate by Techn i con

AutoAnal yzer II The resul tant n i trogen and phosphorus concentrat i ons

were converted to a dry we i ght basi s

Procedures for the potass i um anal ysi s are deri ved from the AOAC

Methods of Ana lys i s 13th Ed i t i on 1980 Less than 0 3g of dri ed ground

p l ant materi al was d i gested wi th n i tr ic and perchl ori c ac i ds d l l utjed

wi th 1+1 hydrochl ori c ac i d and anal yzed by atomi c adsorpt i on

1 1 1 B 3 Dat a Management

B i omass data col l ected duri ng thi s study was used to generate the

fol l ow i ng types of data

o Wet and dry wei ghts of Hydri l l a expressed as gm2

o Nutri ents [n i trogen ( N ) phosphorous ( P) potas s i um (K ) ]

per we i ght of Hydri l l a

I I I C I NTERMIM RESULTS - BIOMASS

I I I C l B IOMASS ANALYSIS

Monocul tures of Hydri l l a were present except at Stat i ons 1 2 5

9 and 13 At these fi ve l ocat i ons i nc i dental col l ect i ons of

Ceratoohyl l um sp were made I n i t i al process i ng of these sampl es

cons i sted of separat i ng Hydril l a and non -Hydri l l a spec i es and anal yzi ng

and eval uati ng each fract i on as a d i screte sampl e Once the eval uati on

3 -3

was compl eted b i omass val ues from both sets of sampl es were combi ned to

represent the overal l b i omass harvested from the study are a

B i omass val ues (dry we ights a l l spec i es combi ned ) ranged from

1 9 33 gm2 ( 02 kgm2 ) to 3 1 7 67 gmm2 (0 32 kgm2 ) (Tabl e 3 2 ) The

l ower b i omass val ues were found at stat i ons 1 and 2 wh i ch were nearshore

stat i ons The h i ghest b i omass general l y occurred at the stati ons l ocated

i n the central port i ons of the Hydri 1 1 a mat The range i n wet and dry

b i omass val ues wi th i n a confi dence i nterval of 1 plusmn standard dev i at i on

( SO ) are graph i cal l y presented i n F i gures 3 2 and 3 3 The cons iderabl e

var i at i on i n b i omass val ues among the stati ons i s rel ated to onshy

shoreoff-s hore d i fferences in stat i on l ocat i on and var i at i on in b i omass

maturi ty wh i ch i s descri bed by the prev i ous ly l i sted cond i t i on factors

rhe Hydri 1 1 a cond i t i on factors have been devel oped to prov ide an

i nd i cat i on of the vari abi l i ty of pl ant maturi ty and were used to prov ide

a prel i mi nary eval uati on of the rel ati onsh i p between pl ant maturi ty and

nutrient content The cond i t i on factors recorded at each stat i on dur i ng

b i omass sampl i ng are summari zed i n Tabl e 3 3

The Hydr i 1 1 a b i omass val ues for each sampl i ng stat i on were grouped

accord i ng to the i r respecti ve cond i t i on factor and pl otted ( F i gure 3 4 )

The resul ts of th i s group i ng dep i cts a cl ear pattern of the d i stri but i on

of b i omass versus p 1 ant maturi ty or cond i t i on factor The new growth

cond i t i ons (1 and 2) had the l owest mean bi omass val ues whi l e cond i t i on

4 (mature cond i t i on ) had the h i ghest val ue and cond i t i on 5 (senescence )

i nd i cated a decl i n i ng b i omass of the Hydri 1 1 a mat at the stati on

l ocat i ons The stat i ons sampl ed and the study area were pr i mari l y

con s idered to be represented by a mature growth cond i t i on duri ng the

August col l ecti on Cond i t i on factors ( pl ant maturi ty) are al so rel ated

to nutri ent content as i s subsequently d i scussed

A gross esti mate of b i omass i n terms of areal extent was projected

us i ng the wei ghtarea rat i o for each stat i on and then averag i ng the

rat i os It shoul d be noted however that stat i on sel ect i on for thi s

task was not random and stat i ons were del i beratel y chosen wh i ch

refl ected a range of growth cond i t i ons By the same l og i c l ocat i ons of

transects to be harvested were not random and were chosen i n an attempt

to sel ect maxi mum dens i t i es of Hydri l l a Wi th these qual i fi ers the

3 -4

average b i omass sampl ed ranged from l ess than 1 to over 14 tons per acre

and averaged 7 tonsacre Esti mates for tons of b i omass i n fres h both

wet and dry cond i ti ons al so appear i n Tabl e 3 2 The wet b i omass val ues

represent we ights of the pl ant materi al after surface water has been

removed from the pl ant by bl ott i ng wi th a dry med i um Because of t h i s

handl i ng procedure a d i rect compari son wi th the harvest contractor s

fi el d est i mates (of merely dra i ned materi al ) are not val i d s i nce the

water associ ated wi th the Hydri l 1 a cou l d add a con s i derabl e but unknown

amount to the esti mated total we ight

B iomass sampl i ng i n the study area has been l i mi ted to a s i ng l e

event and the resul t s of the samp l i ng effort do not refl ect seasonal

vari at i ons However Bowes et al ( 1 979) i nvest i g ated the seasonal

Hydri lJ a b i omass product i on of three Fl ori da l akes Lake Trafford

Orange and Jackson Thei r study i ndi cated that the t i me for seasonal

peaks i n bi omass vari ed wi th the southern most 1 ake Lake Trafford

produc i ng the max i mum Hydri l l a bi omass i n August wh i l e the more northern

l akes Orange and Jackson produced more Hydri l l a b i omass i n Novernber

I 1 I C 2 NUTRI ENT REMOVAL

Phosphorus content of Hydri 1 1 a and the potent i al for removi ng

phosphorus from the l ake system was the pri mary focus of the data

anal ys i s Secondary aspects were quant i fyi ng n i trogen and potass i um as

they rel ate to the overal l nutri ent content of the study area and

prov i d i ng i nformat i on for any poss i bl e uses for the harvested materi a l

Tabl e 3 4 summari zes the analyti cal data for bi omass sampl es

col l ected Hydri l l a and total b i omass are tabul ated separatel y s i nce

Hydri l J a i s the target spec i es of the harvest i ng program and i t compri ses

the majori ty of the pl ant materi al i n the study area Inter-spec i fi c

d i fferences i n pl ant chemi cal compos i t i on are al so reported by Boyd

( 1978) as the greatest source of vari at i on i n characteri zat i on stud i es of

aquat i c macrophytes

3 - 5

I I I C 2 1 Phosphorus

Total phosphorus ranged from 9 1 mgg to 2 68 mgg for al l spec i es

comb i ned and 91 mgg to 2 67 mgg for Hvdrill a only (Tabl e 3 4) The

comb i ned data wi th confidence i nterval s ( 1plusmn SO) are shown i n F i gure 3 5

The somewhat h i gher var i at i on i n phosphorus content at Stat i on s 2 5 9

and 13 i s est imated to occur as a resul t of the presence of non -Hvdri l l a

spec i e s at these l ocat i ons Therefore the presence of other spec i es i n

the sampl es ( i f not separated ) i s ant i c i pated to produce data that have a

greater vari abi l i ty and consequently are not as rel i abl e an est i mate of

nutri ent content as des i red for management dec i s i ons

Coeffi c i ents of var i at i on I n phosphorus content were cal cul ated

and pl otted by stat i on for comb i ned pl ants and for Hydr i l l a on l y ( F i gures

3 6 and 3 7) A compari son o f F i gures 3 6 and 3 7 however i ndi cates

that a rel at i vely smal l amount of the vari at i on observed can be

attri buted to the presence of two spec i es at a s i ngl e stat i on F i gure

3 7 demonstrates an i mportant con s iderat i on for any future sampl i ng and

asses sment effort s Sampl es o f Hydri l l a from the extremes of the

cond i t i on factors i e 1 and 5 produce data that may vary from 20 to

more than 30 i n est i mates of phosphorus content

The comb inat i on of cond i t i on factors and means for phos phorous

content at each stat i on i ndi cate a rel ati onsh i p between cond i t i on i e

re l at i ve maturi ty and phosphorus content ( F i gure 3 8) Stati ons wh i ch

cons i st pr imari ly of new pl ant growth (cond i t i on 1 ) contai n the l east

amount of phosphorus on a mgg (p l ant mater i al ) bas i s wh i l e stati on s

wi th pl ants that are descri bed as bei ng i n cond i t i on 4 (mature) have the

greatest amount of phosphorous A dec 1 i ne in phosphorus content al so

apparently accompan i es pl ant senescence

RegreSS i on anal ys i s was conducted to determ i ne the rel at i onsh i p

between b i omass and phosphorus content Because onl y one i ndependent

vari abl e (b i omas s ) was used i n the regress i on mode i t is necessary to

report only the resul ts of the two-tai l ed test u s i ng Student s t shy

stat i ons The nul l hypothes i s for the two -tai l ed test i s that there i s

no rel at i onsh i p between the dependent vari abl e and a spec i fi c i ndependent

vari abl e namel y bi omas s The t -stati st ic generated by the model

3-6

i nd i cated that b i omass s i gn i fi cantly effects phosphorus content at a 43

confidence l evel That i s there i s a 57 chance of i nd i cat i ng there i s

no rel ati onsh i p between b i omass and phosphorus i f the nul l hypothes i s i s

rejected

Add i t i onal stat i st i cal model i ng and an al ys i s i nd i cated that

b i omass at stati ons categori zed as Cond i t i on 4 were s i gn i fi cant ly rel ated

to phosphorous content at onl y a 75 confi dence l evel or a 25 chance

that a re 1 at i onshi p between b i omass and phosphorous content does not

exi st The h i gher confi dence l evel provi des some support for the use of

Hydrj 1 1 a cond i t i on factors part i cul arl y cond i t i on 4 for est i mat i ng the

nutri ent content of Hydri 1 1 a

To prov i de some prel i mi nary est i mates of potent i al phosphorous

removal rel ated to Hydri 1 1 a matur i ty each sampl i ng stat i on s phosphorous

we i ght to area rat i o was determi ned (Tabl e 3 5 ) These rat ios were then

averaged by cond i t i on factor The resu1 tant overal l phosphorus content

ranged from 16 1 bacre (cond i t i on 1 ) to 3 40 1 bacre (cond i t i on 4) and

dupl i cated the trend observed i n the b i omass data ( F i gure 3 4 )

The range of Hydri 1 1 a cond i t i ons factors and the presence o f other

macrophyte spec i es wi thi n the harvest area i nd i cates that further

defi n i t i on of the nutri ent removal est i mates are requ i red Th i s further

quant i fi cati on can be accompl i shed i n part through the use of aeri al

photographs The i nter im report by 15ampT ( 1 987 ) i nd i cates that sca1 ed

true col or and fa1 se col or i nfrared photographs of the study area have

been rout i ne1 y fl own Cop i es of these photographs and vegetat i on maps

wi 1 1 be requested from 15ampT The vegetati on maps produced from these

photographs by 15ampT wi l l be computer d i g i t i zed and acreage measurements

cal cul ated I t shoul d be noted that remote resource sens i ng techn i ques

part i cul arl y stud i es i nvol v i ng submerged pl ants have l i mi tati ons rel ated

primari l y to water depth and cl ari ty These 1 im i tati ons restri ct the

quant i ficat i on of i mmature Hydri 1 1 a represent i ng cond i t i on factors 1 and

2 because i t i s unl i ke1 y these p1 ants can be detected due to thei r

submerged cond i t i on Hydri ll a exh i bi t i ng cond i t i on factors 3 4 and 5

shoul d be v i s i bl e i n the l ate summer aeri al photographs as emergent mats

The fal se col or i nfrared aeri al photographs wi l l al so be anal yzed to

3 - 7

further separate the area i nto cond i t i on factors (3 4 and 5 ) These

refi ned est imates wi l l be i ncl uded in the fi nal report

An i ntegrated seasonal data base on nutri ent content of Hydri l l a

i n Lake Okeechobee i s l acki ng However recent data ( 1 5ampT 1988 )

i nd i cates there may be a pronounced seasonal d i fference i n t he chemi cal

compos i t i on of Hydrll l a from the l ake Hydri l l a sampl es col l ected by

15ampT duri ng January 1988 had phosphorus and n i trogen val ues that were

two to t hree t i mes h igher than the val ues reported for Aug ust 1987

(Tabl e 3 6 )

Spl i t sampl es anal yzed by the same l aboratory wh i ch prov i ded the

I SampT data provi ded veri fi cati on for the August phosphorus data reported

i n th i s study Therefore i t appears to be reasonabl e to assume that an

i ncrease i n Hydri l l a nutri ent content has occurred between August 1 987

and January 1988 The spec i fi c causes for th i s i ncrease are present ly

unknown but Federi co et al 1981 have suggested a nutri ent i nput

mechan i sm for the l ake based on l ake management W i th the fal lwi nter

i ncrease i n l ake surface area nutri ents conta i ned i n the l i ttoral zone

cou l d be transported l ake-ward by the fl ood i ng of the l i ttoral zone

Water qual i ty data from the present study does i n fact i nd i cate an

i ncrease i n i norgan i c phosphorus (P04- P ) from August 1 987 to January

1988 I t may be specul ated that i ncreased nutri ent avai l ab i l i ty may have

produced t h i s i ncrease i n Hydri l l a nutri ent content I t shoul d al so be

noted however that a seasonal i ncrease i n Hydri l l a phosphorus and

n i trogen content may occur i ndependent of any l ake management reg i me

Th i s seasonal vari at i on i n Hydri l l a nutri ent content has i mportant

rami fi cat i ons for any cont i nued or future harvest i ng programs I t al so

creates some add i t i onal quest i ons For exampl e i s th i s Hydri l l a

nutri ent i ncrease a l akewi de phenomenon or i s i t a near fi el d effect that

might be rel ated to the recent harvest i ng I f th i s i s a l akewide

i ncrease i n nutri ent content does it al so produce a correspond i ng

i ncrease i n bi omass so that phosphorus removal per acre cou l d be

max i mi zed I f th i s were true then the seasonal t i m i ng of any future

harvest i ng efforts need s to be careful l y cons i dered

Converse l y i f the wi nter i ncrease i n phosphorus content i s a near

fi el d effect rel ated to harvest i ng then perhaps harvest i ng des i gn i e

3 - 8

n umber and widths of harvested l anes needs to be re -exami ned and t i mi ng

of the harvest i ng may become l ess i mportant S i nce Hydri l l a i s a

n u i s ance spec i es al l prev i ous harvest i ng strateg i es have been a i med

toward weed el i mi nat i on for n av igat i onal purposes Because of th i s

nu i sance status management strateg i es have not been dev i sed or tested to

ut i l i ze Hydrj l l a as a nutri ent removal middotcrop middot For exampl e a seri es of

narrow but cl osely spaced cuts may be v i ewed as crop th i nn i ng wh i ch may

resul t i n greater nutri ent uptake by the adjacent unthi nned port i on of

the middotcrop middot Th i s act i on cou l d al so be coord i nated wi th n av i gat i onal

concerns and where appropri ate habi tat restorat i on or ma i ntenance

1 1 1 C 2 2 Ni trogen

As previ ous l y noted n i trogen has al so been eval uated as part of

the nutri ent analys i s N i trogen (TKN) ranged from 13 45 mgg to 26 34

mgg for al l spec i es combi ned and 13 45 mgg to 26 1 5 mgg for Hydri l l a

onl y (Tabl e 3 4) I ts d i stri but i on among stat i ons ( F i gure 3 9 ) fol l owed

the pattern prev i ousl y d i scussed for phosphorus Thi s pattern i ncl uded

the h i gh vari at i on attri buted to the presence of other spec i es ( F i gures

3 10 and 3 1 1 ) as wel l as the cond i t i on factornutri ent content

rel ati onsh i p of Hydri l l a ( F i gure 3 1 2 )

1 1 1 C 2 3 Potas s i um

The rema l n l ng nutri ent i ncl uded i n the anal ys i s was potass i um

wh i ch vari ed from 10 20 mgg to 26 28 mgg for al l spec i es combi ned and

10 20 mgg to 26 28 mgg for Hydri 1 1 a (Tabl e 3 4) Wi th several mi nor

except i ons potass i um content was a more vari abl e pl ant nutri ent than

e i ther phosphorus or n i trogen ( Fi gure 3 13 ) Thi s vari abi l i ty i n

potass i um content has al so been prev i ousl y reported by Sutton and Port i er

( 1983 )

A c o n s i d erabl e amou n t of the vari abi l i ty i n potas s i um

concentrat i ons was attri buted to the presence of other spec i es ( F i gures

3 1 4 and 3 1 5 ) but even when monocul tures of Hydri l l a are con s i dered a

h i gh amount of vari abi l i ty st i l l exi sts Kl opatek ( 1978) suggests that

3 - 9

vari at i on i n potass i um l evel s i n aquat i c macrophytes may refl ect h i gh

metabol i c demand duri ng the peri od of rap i d growth and that potass i um i s

not stored by pl ants s i nce th i s nutri ent i s read i l y avai l abl e from most

soi 1 s When grouped by cond i t i on factor the h i ghest potass i IJm contents

occurred i n the new or rapi d ly growi ng pl ants (cond i t i ons 1 2 and 3 )

( F i gure 2 - 1 6 ) Potass i um content decreases i n the l atter growth stages

assoc i ated wi th cond i t i on factors 4 and 5

I I I D CONCLUS IONS

The Hydri l l a b i omassnutri ent data anal yzed to date i nd i cates that

there are several important factors to be cons idered for future or

conti nued Hydri l l a harvest i ng programs

o Recogn i t i on and categori zati on of the rel ati ve maturi ty

state (cond i t i on factor) of the Hydri l l a mat i s i mportant

to sel ect sampl i ng l ocat i ons for nutri ent ana lys i s

o Anal ysi s of the nutri ent content of Hydri l l a i s most

preci se i e l owest sampl e vari at i on when col l ected from

areas of the mature mat The extremes of growth cond i t i on

new growth and senescence produced more vari abl e data

requ i ri ng l arger numbers of sampl es for rel i abl e mean

determi nat i ons

o Further testi ng of season a 1 d i fferences i n Hydri 1 1 a

nutri ent content and coup 1 i ng wi th harvest j ng-management

strateg i es cou l d s ign i ficantl y opt i m i ze the amount of

nutri ents removed through mechan i cal harvest i ng

I I I E RECOMMENDATIONS

Based on the data col l ected and anal yzed to date the fol l owi ng i s

the recommended course of act i on

Add i t i onal quant i tat i ve sampl i ng of Hydri l l a i n Lake Okeechobee i s

recommended Th i s add i t i onal sampl i ng effort shou l d be conducted at

3 - 10

1 ocat i ons both wi th i n the present study area as wel l as some 1 ocat i ons

out s i de of the study area Th i s general i zed pl an wi l l test for near

fi el d effects i e those effects that m ight be rel ated to harvest i ng

vs l akewi de effects Th i s sampl i ng effort shou l d be conducted quarterl y

to i nvest i gate the apparent seasonal changes i n Hydri l l a nutri ent

content Sampl i ng shou l d dupl i cate earl i er efforts and shou l d be

conducted at e i ght l ocat i on s four wi th i n and four outs i de of the present

study area

I I I F QUALITY ASSURANCE RESULTS

Tabl e 3 7 deta i l s the prec i s i on and accuracy of anal yt i cal resul ts

of dr i ed pl ant t i ssue Al l data were generated i n groups wi th

sat i sfactory qual i ty assurance cri teri a

3 - 1 1

LITERATURE CITED

Bowes G A S Hol aday W T Hal l er 1979 Seasonal vari ati on i n the b i omas s tuber dens i ty and photosynthet i c metabol i sm of Hydr i l l a i n three Fl ori d a l akes J Aquat i c Pl ant Mgt 17 61-65

Boyd C E 1978 Chemi cal Compos i t i on of Wetl and Pl ants IN Freshwater Ecol ogical Processes and Management Potenti al eds R E Good D F Wh i gham R L S i mpson C G Jackson J r Academi c Pres s N Y 378p

Freder i co A C K G D i c kson C R Kratzer F E Davi s 1981 Lake Okeechobee Water Qual i ty Stud i es and Eutroph i cat i on Assessment Techn i cal Publ i cati on 181-2 May 1981 Resource Pl ann i ng Department South Fl ori da Water Management D i stri c t West Pal m Beach FL 270pp + App

Kl opatek J M 1978 Nutri ent Dynami cs of Freshwater R i ver i ne Marshes and the Rol e of Emergent Macrophytes IN Freshwater Ecol og i cal Processes and Management Potent i al eds R E Good D F Wh i gham R L S i mpson C G Jackson Jr Academi c Press N Y 378p

ISampT 1987 Letter to Mr Ed Terczak dated Sep t 3 1987 Subj ect Chemi cal Anal yses resul ts of sampl es of Hydri l l a and mi crodeus

ISampT 1988 Letter to Mr Ed Terczak dated Jan 25 1988 Subj ect Compari son of nutri ent content i n Hydri l l a and water hyaci nth sampl es from the Demonstrat i on Project study area

Sutton D L and K H Port i e r 1983 Var i ati on of n i trogen phosphorus and potass i um contents of Hydri 1 l a i n South Fl orida J Aquat i c Pl ant Mgt 2 1 87 -92

3-12

Tabl e 3 1

Cond i t i on 1

Cond i t i on 2

Cond i t i on 3

Cond i t i on 4

Cond i t i on 5

Hvdrll l a Cond i t i on Factors to Descri be Pl ant Maturi ty i n the Lake Okeechobee Study Area

Areas of new pl ant growth rooted pl ants are l ess

than a foot h i g h

Pl ant growt h i s v igorou s but does not extend to the

surface P l ant s extend from 12 to 34 of the water

col umn i n height

Pl ant growth i s v igorous reaches the surface not

matted or at l east not brown and dyi ng on the

surface

Pl ant g rowth i s matted at the surfac e fl oat i ng

pl ants trapped s i gns of earl y decompos i t i on

P l ant mats are senescent and some open water i s

evident under mat

Source DSA Group I nc 1988

T-- 3 BiJS s_ bull aty 6 Sct irg 1tilt in _ Ia1 kee--gtee OJ --l l

my WEI lOOS lOOS

station GM2 so KGM2 so ArnE GM2 so KGM2 so ArnE

1 19 33 17 10 0 02 0 02 0 09 197 00 188 04 0 20 0 19 0 88

2 32 00 12 53 0 03 0 01 0 14 364 67 127 36 0 36 0 13 1 63

3 67 00 18 19 0 07 0 02 0 30 636 00 191 01 0 64 0 19 2 84

4 155 00 72 75 0 16 0 07 0 69 1660 33 733 09 1 66 0 73 7 41

5 195 33 85 82 0 20 0 09 0 86 1757 00 720 00 176 0 72 7 84

6 166 33 37 58 0 17 0 04 0 74 1695 33 335 67 1 70 0 34 7 56

7 263 33 56 70 0 26 0 06 1 18 2158 67 538 68 2 16 0 54 9 63

8 67 33 4067 0 07 0 04 0 30 676 33 302 63 0 68 0 30 3 02

9 184 67 94 85 0 18 0 09 0 77 1765 66 719 58 1 77 0 72 7 88

10 317 67 155 28 0 32 0 16 1 42 3165 33 1379 28 3 17 1 38 14 12

11 205 67 82 37 0 21 0 08 0 92 1716 00 500 11 1 72 0 50 7 66

12 200 67 47 60 0 20 0 05 0 90 2192 00 554 43 2 19 0 55 9 78

13 188 67 49 17 0 19 0 05 0 84 2326 00 492 11 2 33 0 49 10 38

14 116 00 29 82 0 12 0 03 0 52 1228 33 334 60 123 0 33 5 48

15 234 67 66 29 0 23 0 07 1 05 1997 33 527 08 2 00 0 53 8 91

Notes GM2= Grams Per Meter Square

SD= staOOald Deviation 1lGM2= Kilograms Per Meter Square

Dlta Ioolules Nan-Hydrilla Values for lhese stations

SOlllCe DSA Group Inc 1988

Tabl e 3 3

Cond i t i on

1

2

3

4

5

Sununary of Hydr i l l a Cond i t i on Factor by stat i on for the Lake Okeechobee study area August 18- 21 1987

Hydri 1 1 a Stat i ons

lt1 h i gh 1 2

12middot34 water col umn i n hei ght 2

at surface not matted 8 1 4 1 5

matted earl y decompos i t i on 4 6 7 1 0 1 1 1 2 1 3

senescent open water 5 9

Source DSA Group I nc 1987

Table 3 4 SUImlary ot Hyt1rllla Nl11rlent conumt nan Ole JaKe UKeeCnacee -oxty AJea 11

--- --------- - - ----- - -

Hydrilla Total Hydrilla Total Hydrilla Total p P TlltN TlltN K K

station I-CG so I-CG so I-CG so I-CG so I-CG so I-CG so

1 1 20 0 35 1 20 0 35 13 45 4 66 13 45 4 66 20 78 9 78 20 78 9 78

2 1 55 0 53 1 40 0 35 15 02 4 80 16 39 2 83 2156 12 06 16 45 6 23

3 1 43 0 06 1 43 0 06 15 78 1 37 15 78 1 37 19 66 6 19 19 66 6 19

4 2 36 0 27 2 36 0 27 20 67 2 76 20 67 2 76 20 57 4 81 20 57 4 81

5 1 28 0 14 1 47 0 30 16 49 0 88 16 93 1 10 19 09 2 11 18 99 1 98

6 1 60 0 02 1 60 0 02 17 16 028 17 16 0 28 23 56 5 57 23 56 5 57

7 0 91 0 07 0 91 0 07 15 58 0 38 15 58 0 38 10 20 0 53 10 20 0 53

8 1 37 0 15 1 37 0 15 13 60 2 50 13 60 2 50 26 28 8 25 26 28 8 25

9 1 45 0 36 1 48 0 39 17 60 2 38 17 73 2 56 18 34 5 30 18 59 5 35

10 1 96 0 14 1 96 0 14 21 35 1 69 21 35 1 69 18 71 2 73 18 71 2 73

11 1 63 0 13 1 63 0 13 16 71 0 37 16 71 0 37 16 60 5 06 16 60 5 06

12 1 81 0 12 1 81 0 12 21 97 1 04 21 97 1 04 14 43 1 37 14 43 1 37

13 2 67 0 27 2 68 25 26 15 2 29 26 34 1 97 15 89 4 52 15 89 4 52

14 2 14 0 09 2 14 0 09 20 68 1 12 20 68 1 12 23 68 1 72 23 68 1 72

15 1 33 0 11 1 33 0 11 14 01 0 47 14 01 0 47 15 82 1 99 15 82 1 99

Note All Values Expressed as Milligrams Per Gram of Dry Weight

50ur0e DSA Group Inc 1988

Tabl e 3 6

Sampl i ng Peri od Pl ant

August 1987

Tops

Steins

Whol e Pl ants

August 1987

Whol e P l ants

+January 1988

Who l e Pl ants

A Compari son of Hydri l l a Nutri ent Content for Samp l i ng Periods Conducted i n August 1987 and January 1987 i n t he Lake O keechobee Study Area

N i trogen Phosphorous (mgg-dry wei ght) (mgg-dry wei ght)

19 5 3 21

10 4 1 49

16 3 1 53

13 45 - 26 15 91 - 2 67

31 2 - 35 2 6 9 - 9 2

Source IST Augu s t 1987 Source DSA HHL August 1987

+Source IST January 1988

Tabl e 3 7 Bi omass anal ys i s qual i ty assurance resul ts

Prec i s i on Accuracy Parameter ( n X RSO SO) ( n X RSO SO)

Total phosphorus 6 3 8 1 4 4 1 0 1 7 6 5

Tota l Kje l dahl n i trogen 8 3 2 2 2 4 1 06 6 1 1 2

Potas s i um 6 3 1 1 8 5 12 1 2 43 5

zB

Figure middot3- 1 BIOMASS SAMPLING LOCATIONS

_c liOn Aalill LAaoaATOAV bullbull DA OAOb INC 18 bull

EVALUATION OF AQUATIC WEED HARVESTING DEMONSTRATION

IN LAKE OKEECHOBEE

Cl M EANS

B I O MAS S WET WE IG HT GRAS METER SQUARE

5--------------------------------------------------

45

4

3 5

3

25

1 5

1

05

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

+ UPPER CONFIDENCE STATION

o LOWER COIJADENCE

re 3 2

w a 4 J a tJ) lr w-ti

o M EANS

500

450-

40

350

300

2 50

20

1 50

1 00

50

0

1 2 3 4

+ UPPER CONfIDB-JCE

_ GPnl IP INC

81 0M-ASS D RY WEIGHT CRAMS METER SQUARE

-1-5 e 7 8 sa 1 0 1 1 1 2 1 3 1 4 1 5

STAriON o LOWER (ONlDENCE

ure 3 - 3

________________________________________________________ -____ G

c- -0 (I) (I) -laquo l 0 m J 0 I-

TOTAL BI O MASS VS HYDRI LLA C ONDITIO N DRY WEIGHT GlA2

3 00--------------------------------------------

2 80

1 80

1 60

1 40

1 20

1 00

80

6 0

40

20

middot0 1 2 3

CONDITION FACTOR IS I GM2 DRY NEIGHT

4 6

Figure 3-4

J laquo It w -It 0 L-a 0 -CL lt)

o M EAtJS

M I LLI G RAM S O F TOTA L P H O S PH O RUS

3--------------------------------------------

1

1 4

1 2

1

08 -1 2 3 4

+ UPPER CONFID ENCE

5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION gt LOWER CONFlDENCE

Figure 3-

z o tr 4 gt IL o

w o b IL W o o

C O EFFI C I ENT OF VARI ATION

TOTAL PHOSFHORUS 1 00-----------------------------------------------

90

80

70

60

50

40

30

2 0

1 0-

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION

i

z o ti gt b o

w o b h W o o

CO EFFIC I ENT OF VARIATION TOTAL PHOSA-lORUS (HtDRILLA ONLY)

I OO------------------------------------------------

90

80

70

60

50

40

30

20

1 0

1

IS I CONDlllON FACTORS STATION

9 1 0 1 1 1 2 1 3 1 4 1 5

Figure 3 -7

c - t) 2 0 -1 0 I-

TOTAL PH O S PH U RS VS H YDR I LLA C O N DITI ON

3--------------------------------------------

28

2

2

1 8

1 6 1 4

1

1 2 3

CONOrTJOt FACTOR -I I MGG my yenEIGHT

4 5

ure 3-8

J laquo cr

2 2 w l-e )- 20 (( 0 b 1 8 0 (-

z 1 6 t= 1 4

1 2

1 0

8

o M EANS

M ILLIGRAMS O F TOTAL KJELDAHL NITROGEN

1 2 3 4

+ UPPER CONFDE1CE

----r f 5 bull 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION ltgt LOWER COtADENCE

-ltlilirA 3-9

z 0

gt La 0

I-Z w

0 La La w

0 0

CO EFFIC I ENT OF VARI ATION

TOTAL l1ltJtJ

4

30

2

1 0

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

IS I CONDITlON FACTOR kZ 1 CV ()

Figure 3-1 0

z o t( tr laquo gt L o

tshyZ W o L L W o o

middot

CO EFFIC I ENT O F VARIATIO N 1lltN (HfDRlliA ONLY)

1 00-----------------------------------------------

90

80

70

80

50

40-

30

20

1 0

IS I CONDlllON FACTORS STATION WJ CV(7) 3- 1 1

0 -lt- z a

I--1 0 I-

30

28

28

24

22

2

1 8

1 8

1

1

2

0 1

TOTAL TKN VS HYDRI LLA CON DITION

2 3

CONDITION FACTOR r ] GG CRY WEIGHT

3- 1 2

-oJ ( tr W gt-cr n L 0 Cl - Cl E

o M EANS

M I LL IG RA M S O F TOTAL POTASSI U M

38---------------------------------------------

2

1

8--------------------- 1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

+ UPPER CONFDENCE STATION

ltgt LCJWER CONFIDENCE

z o n 4 gt LL o

I-shyZ bJ o LL LL W o o

1 00

90

80

70

80

50

40

30

20

1 0

0 -

CO EFFIC I ENT O F VARIATION POTASSIUU

-- _-_------ ------

1 2 3 4 5 8 7 8 1

IS I CONDITION FACTOR STATION ---

l2 J cv(-)

1 4 1 5

3- 1 4

z 0 t a oC gt Iamp-0

--

It

r z w 0 lamp-Iamp-w 0 0

C O EFFIC I ENT O F VARI ATION

POTASSlUA (HfffiILLA 011 Y) 1 00 - - - - - - -- - ---- - - - -- - -- - - - ---- --- - -- - - - - - - - - - - -- - - - - -

90

80

70

60

50

40

30 -

20

-

1 0

0 - 1 2 3 4

IS I CONDIllON FACTORS

l 7

J

r t

I 10 1 1 1 2 13

STATON LUd CV ( )

3- 1 5

TOTAL P OTASS I U M VS HYD RI L LA CON DITI ON

30------------------------------------------

28

28

1 2 3

CONDfTION FACTOR 1 I GG y WEIGHT

4 5

3- 1 8

IV WATER QUALITY SURVEYS

IV A INTRODUCTION

Concerns for water qual i ty i n Lake Okeechobee are pr i mar i l y

focused on nutri ent storage and cycl i ng between the water col umn

sedi ments and bi omass and the impl i cat i ons of these processes for the

current and future troph i c state of the l ake The harvest i ng

demonstrat i on project undertaken by the South Fl ori da Water Management

Di strict and conducted by I nternat i onal Sci ence and Technol ogy I nc

( ISampT) i s one of the remed i al measures proposed to arrest the apparently

i ncreas i ng troph i c state The harvest i ng and subsequent upl and d i sposal

of Hydrj l l a i s bei ng u sed to effect the removal of total nutri ents

( phos phorus in part i cul ar) from the aquat i c system The Di str i ct s

eval u at i on and research project ( EampR) conducted by Mote Mari ne Laboratory

(MML) was des i gned to del i neate other env i ronmental i mpacts and cost

benefi ts associ ated wi th mechan i cal weed removal

The goal of the water qual i ty task of the EampR s tudy was to

del i neate changes that cou l d be attri buted to the removal of dense stands

of Hydri l l a vert i c i l l ata ( Fi gure 4 1 ) Al though the i mmed i ate i mpacts of

weed harvest i ng on water qual i ty may be substant i al those wh i ch

perS i sted over a peri od of t i me were expected to be fai rl y smal l and

l ocal i zed due to the advect i ve barri er of the Hydri l l a mat Accord i ngl y

i n order t o resol ve these changes from background vari abi l i ty grad i ents

of water qual i ty were assumed to exi st across the s i te al though they may

be wea k

The sampl i ng program was desi gned t o al l ow the stat i st i c al

eval uat i on of water qual i ty d i fferences between stat i ons at any one poi nt

i n t i me prov id i ng enough anal yt i cal data to produce mean i ngful

compari sons As a resu l t a mi n i mum of tri pl i cate col l ect i on s per

stat i on were necessary Th i s approach was preferabl e to more frequent

sampl i ngs because i t centered on quant i fy i ng i mpacts at part i cul ar

i nstances rather than on a conti nu i ng bas i s when seasonal processes i n

the study area woul d compl i cate anal yses of data

4 - 1

Water qual i ty i nformati on i s al so necessary for the i nterpretat i on

and anal ys i s of many of the other tasks Phytopl ankton and pri mary

product i v i ty stud i es i n part i cul ar are heavi l y dependent on t h i s task and

wi l l exami ne ava i l abl e nutri ents tox i c compounds ( copper) as wel l as

phys i cal data produced by thi s tas k Accord i ng l y sampl i ngs for water

qual i ty were conducted on each of the days that Envi ronmenta 1 Qual i ty

Laboratory ( EQL) depl oyed primary producti v i ty equ i pment In add i t i on

certa i n parameters (d i ssol ved s i l i cates col or and i norgan i c carbon )

were added to the analyti c al su i te at stat i ons where product i v i ty was

be i ng determi ned Water qual i ty sampl i ngs were al so conducted wi th i n 24

hours of the communi ty metabol i sm task fi el d efforts and wi th i n two weeks

of l arval and juven i l e fi sh sampl i ngs

IV B METHODS

IV B l Water Qual i tv Stat i on locat i ons

The northern 1 200-m (4000 ft ) of Transect 3 was des i gnated as the

experimental transect where a majori ty of the tasks focused the i r

efforts Th i s harvested area was sel ected based upon central 1 ocat i on

wi th i n the study s i te representati veness of the study s i te as a whol e

wi th respect to depth fetch shore proxi mi ty and speci es compos i t i on

and the dens i ty of the Hydri l l a mat of the area

Stat i on l ocat i ons for most sampl i ng s of the water qual i ty task

were i l l ustrated i n F igure 4 2 a superi mposed on the Loran C l i nes mapped

for the study s i te dur i ng the August 1 987 reconnai ssance A tabul at i on

of Loran coordi nates of these stat i ons appears i n Tabl e 4 1 Stat i ons

were establ i shed to defi ne any ex i st i ng water qual i ty grad i ents across

the s i te as wel l as i mpacts due to harvest i ng and so extend beyond the

boundari es of the area schedul ed for harvest Stat i ons 1 2 3 13 1 5

and 1 6 represented the perimeter o f the study s i te Stat i ons 7 - 9 were

l ocated on the northern hal f of Transect 3 the experi mental transect

and represented the treatment stat i ons the treatment be i ng harvest i ng

Control ( unharvested ) stat i on 10- 1 2 were adj acent to the

experi mental transect i n the unharvested l ane between Transects 3 and 4

4 -2

( Stat i ons 4 -6 were al ternate control stati ons to be used onl y i f unusual

cond i t i ons at Stat i ons 10- 1 2 i nd i cated that they woul d not represent

und i sturbed cond i t i ons These stat ions have not been occup i ed to date )

Stat i ons 7 - 1 2 were al so the same areas sampl ed for phytopl ankto n benth i c

i nfauna and sed i ment chemi stry Stat i on 1 5 was or i g i nal l y establ i s hed

beyond the southern end of Transects 6 and 7 However dense growths of

Amer i can Lotus i n the area made i t l i kel y that water exchange was

mi n i mi zed wi th the rest of the study area Th i s stat i on was accord i ng l y

moved t o the north but kept between transects s o that i t represented

unharvested cond i t i ons

I V B 2 Parameters

In liY i nstrumentat i on (Hartek Hark V I I ) was used to determi ne

depth profi l es (at 0 2 and 0 5 meter i ncrements from the surface and at

bottom) of temperature conduct i v i ty pH and ox idat i on-reduct i on

potent i a l (ORP) bull Di ssol ved oxygen ( DO) meters ( YS I 57 pol arographi c

el ectrodes equ i pped wi th st i rrers ) were used to measure DO at the same

depths Heters ( and i nstruments ava i l abl e as backup equ i pment ) had been

bench cal i brated aga i nst known standards or phys i ca l constants pri or to

each sampl i ng Cal i brat i ons of the meters empl oyed were repeated

fol l owi ng each sampl i ng L i -Cor i ntegrat i ng photometers were ut i l i zed to

quant i fy i nc i dent and penetrant l i ght Care was taken i n performi ng

these measurements to mi n i mi ze weed d i sturbance i n l oweri ng the

i nstruments and ext i nct i on coeffic i ents were cal cul ated from both the

upper ( 0 5 m) and l ower ( bottom) read i ngs to provi de est i mates of both

weed mass and water col umn l i ght attenuati on Water sampl es were

col l ected for l aboratory analys i s outs ide of the i nfl uence of any meter

d i sturbances

Sampl es were secured us i ng a non -metal l i c i mpel l er-type pump wi th

a weed excl ud i ng cage mesh s i ze of 1 mm ( F i gure 9 3 ) The cage was

l owered wi th a mi n i mum of d i sturbance to the weed mat to prevent

resuspens i on and entrai nment of l oose ly attached al ga l materi al or other

pl ant debri s Th i s col l ecti on techn i que was empl oyed for al l sampl i ngs

Chemi cal parameters i ncl uded al l standard n i trogen and phosphorus

4-3

spec i es Inorgan i c forms - -orthophosphorus ammon i a- n i trate- and

n i tri te -n i trogen - - were determi ned on fi l tered sampl es ( 0 45 micon

effect i ve pore s i ze ) to ascerta i n the ava i l abl e amounts most mean i ngfu l

for b i ol og i cal assessments Potass i um and sodi um were quant i f i ed on a

fi l tered sampl e Trace metal concentrat i ons copper ( Cu ) and i ron ( Fe )

al so were determi ned o n fi l tered sampl es due t o the affi n i ty of these

e l ements for suspended part i cul ates

Total organ i c carbon total Kjel dahl n i trogen total phosphorus

and al kal i n i t i es were determi ned on unfi l tered s ampl es as was

bi ochem ica l oxygen demand Turb i d i ty and suspended l oads were quant i fi ed

and total col i form was analyzed by the membrane fi l ter techni que The

analys i s of sampl es for sod i um chl ori de and fl uori de concentrat i ons was

performed to permi t water mass cal cul at i ons and determi nat i on of water

qual i ty grad i ents across the s i te Anal yses necessary for the pri mary

product i v i ty task were col or d i ssol ved s i l i ca and i norgan i c carbon

Water qual i ty anal yt i ca 1 methods used were those approved by the

Envi ronmental Protect ion Agency ( EPA ) and the Fl orida Department of

Envi ronmental Regul ati on ( FDER) Method references anal yt i cal hol d i ng

t i mes and preservati ves are detai l ed i n Tabl e 4 2

Lake l evel s for spec i fi c dates were obtai ned from the Di stri ct and

represent 1 ake wide averages of stage recorders operated by both the

Di stri ct and the u s Army Corps of Eng i neers

IV B 3 Sampl i ng

There were four types of water qual i ty sampl i ngs each vary i ng i n

the numbers of stat i ons sampl ed t imi ng of col l ecti ons or parameters

anal yzed The s ampl i ngs were enti tl ed basel i ne short - term impacts

quarterl y and fi el d demonstrati on Col l ect i ons were focused around the

experimental transect Analyti cal sui tes i nc l uded both phys i cal and

chemi cal parameters Sampl i ngs performed to date appear i n Tabl e 4 3

4 -4

Basel i ne Sampl i ng

Basel i ne sampl i ng was conducted on August 18 1 987 pri or to any

harves t i ng act i v i ty wi t h i n the s i te The day was cl ear hot and cal m

Average l ake l evel for the day was 4 22 m ( 13 85 ft ) A total of n i ne

( 9 ) l ocati ons ( Figure 4 2 ) was sampl ed to establ i sh a grid of control

stat i ons ( Stat i ons sampl ed were 1 2 3 10 1 1 12 13 1 5 and 16 )

These stat i ons were al l i n areas where no harvest i ng act i v i t i es were

schedul ed Stat i ons 10 1 1 and 1 2 were l ocated i n a heavi l y weeded

area whi l e the rema i n i ng control stat i ons were outs i de the area to be

harvested and were i n comparati vely open water At each stati on a total

of three separate sampl es was col l ected from a depth of 0 2 m for

l aboratory analys i s

At Stati ons 1 3 13 and 16 sampl es were al so sec ured from 0 8

of the overal l depth Water depth ranged from 0 9 to 2 0 meters at al l

stat i on s These corners of the study si te represented the spat 1 a1

extremes and water qual i ty data from surface and at depth were used as

i nd i cat i ons of verti cal gradi ents over the s i te

One add i t i onal stat i on at the mouth of the K i s s i mmee R i ver

( Stati on 20) was sampl ed at the surface (0 2m ) The effect of thi s

tri butary on l ake nutri ent l oad i ng and resul tant spat i al grad i ents may

thus be cons i dered Th i s s i ng l e sampl e however was not i ncl uded i n

stat i st i cal anal yses

A total of fourteen ( 14) stati on-depths resul ted from thi s

sampl i ng for a total of forty ( 40 ) sampl es for anal ys i s In ll1Y and

l aboratory analyses i ncl uded al l wi th the except i on of col or s i l i cates

and org an i c carbon as no phytopl ankton sampl i ng was conducted duri ng

th i s epi sod e Sampl es for total col i form were col l ected from Stat i ons

10 1 1 and 1 2 onl y ( n i ne sampl es)

Short Term Impacts Sampl i ng

Two short term impacts water qual i ty sampl i ngs were conducted

i mmed i atel y after and approx i matel y one week fol l owi ng the compl et i on

of harvest on the exper imental transect These sampl i ngs were i n

4 - 5

conjunct i on wi th and on the same day as phytopl ankton and pr i mary

product i v i ty sampl i ngs Sampl es were col l ected from Stati ons 10 1 1 and

1 2 the control stat i ons and from Stat i ons 7 8 and 9 the experi mental

stat i ons ( F1 gure 4 5 ) Experimental stat i ons were l ocated approxi mately

150m 600m 1070m ( 500 ft 2000 ft and 3500 ft ) from the northern end of

the transect and were approximate ly 75 m ( 250 ft ) from e i ther edge of the

harvested area Contro 1 stat i ons were pa i red wi th each experi mental

stat i on and were adj acent approx1mate1y mi dway between Transect 3 and 4

1 n the center o f the unharvested are a Sampl es were col l ected from 0 2m

depth onl y

Aquat i c weed harvest1 ng on the experi mental transect began

September 3 1987 and the northern 1 220 m was compl eted on September 1 7

Dur1 ng th i s and the succeed 1 ng dayt 1 me sampl i ng events the ongo i ng

harvest of weeds cont i nued nearby An MHl fi el d crew conducted sampl i ng

on September 1 7 a hot cal m and cl ear day when l ake l evel s averaged 4 13

m ( 13 56 ft ) Th 1ck Hvdri 1 1 a growth was v 1 s i b1 e at depth w1 th i n the

tran sect Another sampl i ng occurred on September 22 1987 ( l ake l evel

4 1 2 m ( 1 3 51 ft raquo under s imi l ar cond i t i ons Regrowth of Hydri 1 1 a i n the

experiment al transect was extens ive by th i s date Sampl es were col l ected

near the mouth of the Ki s s immee Ri ver on both occas i ons Seven ( 7 )

stat i on depths resul ted 1 n the col l ect1 0n o f n i neteen ( 1 9 ) sampl es on

eah date Al l in si tu parameters and l aboratory anal yses were i nc l uded

Quarterl y Sampl i ng

As wi th the i mmed i ate i mpacts sampl i ng s quarterl y sampl i ngs were

conducted i n conjunct i on wi th phytopl ankton work Stat i ons sampl ed

i nc l uded 1 2 3 7 8 9 10 1 1 1 2 13 1 5 and 16 at 0 2m depth

( F i gure 4 2 ) and Stat i ons 1 3 1 3 and 16 at 0 8m overal l dept h

S i xteen ( 16 ) stat i on depth s pl us one ri ver sampl e resul ted i n at l east

49 sampl es duri ng each of the four efforts In s i tu and 1 aboratory

parameters i ncl uded al l those l i sted wi th the except i on that total

col i form d i s sol ved s i l i cates col or and i norgan i c carbon were anal yzed

on l y on sampl es from Stat i ons 7 8 9 1 0 1 1 and 12 onl y ( the

exper i mental stat i ons and the i r control pa i rs )

4 -6

Quarterly sampl i ngs took pl ace on September 30 1 987 and January

1 3 1 988 wi th the rema i n i ng sampl i ngs schedul ed for Apr i l and June 1988

Lake l evel s were 4 1 4 and 4 90m ( 1 3 60 and 16 07 ft ) i n September and

January respect i vel y The September event was conducted o n a bl ustery

day (wi nds from the west at 5- 10 kts ) wh i ch l ater produced a dr i v i ng

rai nstorm Vi s i b i l i ty both in and above the l ake was obscured currents

were al so noted Li ght and vari abl e w i nds from the NE to W were noted

duri ng the January sampl i ng Hydrilla had regrown to t he surface i n some

cases by th i s date but otherwi se was not often vi s I b1 e due to i ncreased

l ake l evel s

The northern 180m of the experi mental transect was reharvested

duri ng December 1987 Stati ons 7 and 10 were sampl ed i n January and thus

represented a t h i rd treatment ( 1 e harvested twi ce ) In order to

ma i nta i n a bal anced des i gn for stat i st i cal anal yses however two ( 2 )

stati ons were added t o the sampl i ng schedul e The pos i t i on of Stat i on

7 5 was just south of the mowed sect i on and another control ( 10 5 ) was

added i n a comparabl e l ocat i on south of Stat i on 1 0 Stat i ons 7 5 8 and

9 then became the experimental group to be consi dered i n data analyses

F i el d Demonstrat i on Sampl i ng

Water qua 1 i ty impacts duri ng the actual harvest i ng process were

expected to be pri mari l y a product of turbul ence generated by harvest i ng

These effects were al so expected to be fa i rl y l ocal i zed due to the

dens i ty of the weed mat Any temporary resuspen s i on of organ i c detr i tus

or el evat i on of sol i ds or nutri ent concentrati ons wou l d be establ i shed by

an i ntens i ve t i me seri es wh i ch woul d exami ne the degree and durat i on of

any d i sturbance

The fi el d demonstrat i on water qual i ty samp l l ng was conducted on

October 28-29 1 987 when l ake l evel s were at 14 26 ft Three pai rs of

stat i ons approxi matel y 100 ft apart were establ i shed at the northern edge

of the wi nd fence or harvested area l ocated between Tran sects 2 and 3

( Fi gure 4 6 ) Subsequent to preharvest sampl i ng a harvester made two

passe s each approx i mately 100m l ong A smal l barri er of Hydri l l a ( ca

3m w ide ) was l eft i ntact between the harvested area of Transect 2 and the

4 - 7

RharvestedR area for th i s study Stat i ons were i dent i fi ed as Rcut R (Cl

C2 C3 ) or R uncut R (UCl UC2 UC3 ) duri ng th i s effort

Fol l owi ng the two passes of the harvester over the experi mental

swath no more harvest i ng occurred in that area for at l east 24 hours A

t i me seri es of sampl es were col l ected from -each of the s i x ( 6 ) stat i ons

Data were to be compared from each of the two stat i on types for

quant i fyi ng i mpacts and traci ng the i r durat i o n

Sampl es were col l ected a t 0 2m and 0 8m o f the overal l depth us i ng

the pump and the weed excl ud i ng cage to el imi nate the l argest Hydri l l a

fragments from the sampl e Col l ect i ons took pl ace i mmedi atel y pri or to

the passage of the harvester immedi atel y subsequent to the harvest of

the experimental stat i ons (wi th i n approxi matel y 0 5 hr) and then aga i n

at roughl y 2 5 10 and 24 h r i nterval s after the harvest Sampl es were

not col l ected i n tri pl i cate i nstead the three stat i ons i n each

treatment type formed the basi s for stati sti cal compari son A total of

twel ve ( 1 2 ) stat i on depths and s i x (6) col l ect i ons resul ted i n seventyshy

two sampl es for ana lys i s The s i x col l ect i ons were i dent i fi ed as rounds

1 -6 i n data pri ntouts In 11Y parameters to be determi ned i ncl uded al l

l i sted with the except i on of l i ght penetrat i on and secchi depth

measurements Total col i form was not anal yzed due to the extremel y short

hol d i ng t i me of that parameter nor were repet i ti ve l i ght measurements

wh i ch have a h i gh potenti al for d i sturbance of the water mass due to the

actual sampl i ng process Suspended l oad and turbi d i ty anal yses were

ut i l i zed for est imates of l i ght attenuat i on S i l i cates col or and

i norgan i c carbon were not anal yzed as no phytopl ankton work was

conducted at th i s t i me

IV C INTER IM RESULTS

Al l water qual i ty data col l ected through the m idpo i nt of thi s

project appear i n Append i x 4 A and i ncl ude in s i tu and chemi cal anal yses

from the sampl i ngs performed on August 18 September 1 7 September 22

September 30 and October 28-29 1 987 and January 13 1 988 Means of

al l parameters measured i n the study s i te are presented i n Tabl es 4 4

and 4 5 by date but wi thout regard to treatment stat i on or depth

4 -8

The most notabl e of the in ll1Y parameters i s di ssol ved oxygen

More than 32 of al l observat i ons made were i n v i ol ati on of t he 5 0 mg1

i nstantaneous d i s so 1 ved oxygen cri teri on for C1 ass I waters and 20 of

a l l observat i ons were bel ow 4 0 mg1 (Tabl e 3 4 ) Samp1 i ng t i mes were

skewed toward the morn i ng hours and were thus abl e to record the effects

of pre-dawn resp i rati on of aquat i c vegetat i on at the s i t e

Surface sampl es were al so col l ected i n the Ki s s i mmee Ri ver

approximatel y midway between the S R 78 bri dge and Lake Okeechobee i n

add i t i on t o those sampl es spec i fi ed by the scope of work (Tabl e 4 6 )

Ion content ( sod i um potass i um chl ori de al kal i n i ty s i l i cates )

typi cal l y was l ower i n the ri ver than the s i te waters and i ncreased

sod i um and chl oride concentrat i ons were observed i n the southern port i on

of the study area The ri ver was general l y l ess turbi d ( turbid i ty total

suspended sol ids ) hi gher in col or and apparent ly represented a source

of d i ssol ved i ron to the area

Both throughout the s i te and i n the Ki ss immee Ri ver d i ssol ved

copper l evel s i f detected were only sl i ghtl y above the l i m its of

detect i on The same was true of n i trite-ni trogen wi th the excepti on of

the January sampl i ng On th i s date concentrati ons at the Ki ss inunee

stat i on were h i gher (0 027 mg1 ) than the rema i nder of the stat i on s and

concentrat i on grad i ents were apparent across the study s i te Data on

col or si l i cates and i norgan i c carbon al though presented i n the

append i x wi l l not be extens i vel y analyzed i n thi s sect i on as such data

were pri mari l y col l ected for use i n i nterpretat i on of phytopl ankton

anal yses

IV D DATA REDUCTIONS

Stati sti cal anal yses of i n s i ty and chemi cal data empl oyed one and

two-way analyses of vari ance where treatment effects ( harvested non shy

harvested stat i ons depths ) were consi dered as fi xed (Model I ANOVA)

Two-way anal yses were conducted empl oyi ng the same assumpt i ons when the

rel at i ve magni tude of effects was of i nterest S ign i fi cance l evel s were

set at 0 05 ( P 95) Except where noted anal yses ut i l i zed the

untransformed val ues of the vari ous parameters Log ( base e) data

4-9

trans format i ons were usual ly used to approxi mate normal d i stri but i ons

Parameters trans formed for analys i s i ncl uded orthophosphate ammoni a

n i trate -n i tri te-n i trogen potass i um i ron BOD turbi d i ty TSS and

sod i um

When vari ances among groups were s i gni fi cant i nd i v i dual means

were contrasted us i ng e i ther Student t-tests or Tukey s Student i zed Range

Test wh i ch computes the smal l est HSD ( honestly s ig n i fi cant d i fference )

for determi n i ng d i fferences Both were ap pl i ed at the P - 95 l evel

IV E DISCUSSION

IYr E I In 1i1Y Parameters

D i ssol ved oxygen l evel s and percent s aturat i on of d i ssol ved oxygen

were expected to show the most change from harvest i ng act i v i ti es W ide

d i urna 1 swi ngs shoul d be damped by the removal of 1 arge amounts of

Hydril l a D i urnal pH cycl es and to a l esser extent ORP woul d be

expected to fol l ow thi s pattern as l ess vegetat i on woul d be present to

con sume carbon d i ox ide Seasonal cycl es were expected i n temperature

data however d i urnal cycl es and verti cal thermal grad i ents were l ess

l i kely 1 n areas where dense stands of fl oat i ng Hydri l l a had been removed

For al l parameters wi nd generated m ix i ng i n harvested areas shou ld

1 es sen the degree of al l surface-to-bottom grad i ents Any changes i n

conduct i v i ty at a part i cul ar l ocat i on as a resul t of harvesti ng woul d be

i nd i rect and woul d l i kel y refl ect al terat i ons i n current structure by

removal of the Hvdri l1a mat and the i ncreased fl ush i ng i n harvested

areas

Due to the obv ious d i fferences between sampl i ngs anal yses of i n

tliY data empl oyed two -way ANOVAs usi ng date and treatment ( harvested

Stat i ons 7 8 and 9 and non-harvested Stati ons 10 1 1 and 1 2 ) as

factors Further as vert i cal grad i ents for some parameters appeared

substant i al data sets were al so subd i v i ded i nto surface and bottom

readi ngs and exami ned separately Data were anal yzed from the sampl i ngs

of September 1 7 22 and 30 and January 13 As ant ic i pated sampl i ng

date was a h i ghl y s i gn i fi cant factor for al l i n s i tu parameters

4 - 10

conduct i v i ty ORP pH temperature DO and percent saturat i on Those

parameters exh i bi t i ng d i fferences attri butabl e to harvest i ng impact were

DO and percent saturat i on at both surface and bottom and pH at bottom

No i nteract i ve terms were s i gn i fi cant i nd icat i ng a consi stent and

pred i ctabl e pattern of d i fferences

Di ssol ved oxygen l evel s averaged between 0 5 and 3 6 mgl h i g her

i n the experi mental ( harvested ) transect than i n the adj acent control

stat i ons Th i s pattern was general ly most ev i dent from read i ngs at the

bottom of the water col umn Overal l i ncreases i n percent saturat i on were

approxi mately 20

It shoul d be noted that the majori ty of these data were col l ected

before 1000 ( EST ) and that th i s t i mi ng affected both the magni tude and

the d i rect i on of d i fferences i n DO l evel s Had sampl i ng been conducted

predomi nantly dur i ng mid- to l ate afternoon i t i s most probabl e that the

unharvested and heav i l y weeded areas would have had s i gn i fi cant ly h i gher

DO val ues than the adj acent harvested areas The observed pattern i s

cons i stent wi th an enhanced pre-dawn DO middot sag middot i n areas wi th h i gher

dens i t i es of aquati c vegetat i on (control s ) To ensure that no bi as was

i ntroduced by sequence of sampl i ng on each date stat i ons were ranked by

t i me of sampl i ng the ranks summed by treatment and compared Duri ng that

sampl i ng with the most d i screpancy between treatment rank sums September

30 DO l evel s i ndi cated that thi s was not a seri ous factor

The overal l s i gni fi cance of date i n the previ ous anal yses was due

predomi nantl y to the i ncl us i on of the January data set as can be deduced

from the means presented i n Tabl e 4 4 W i th removal of th i s data set and

reanal ys i s of the three September sampl i ngs the onl y parameters where

date was a s i g n i fi cant factor were pH and ORP I n attempt i ng to quant i fy

the i mmed i ate i mpacts of harvest i ng the removal of the January data set

can be j ust i fi ed on the bas i s that the regrowth of Hydri l l a was

essent i al l y compl ete by th i s sampl i ng and that there were no obv i ous

d i fferences between experi mental and control stat i ons The s i gn i fi cant

d i fferences between experimental and control s for DO percent saturat i on

and bottom pH however were essent i al l y the same i n th i s reanal ysi s

i mpl y i ng that the i mpacts were most marked e i ther wi th i n the th i rty days

of harves t or duri ng that part i cul ar port i on of the growi ng season

4- 1 1

The i ntens i ve fi e l d demonstrat i on sampl i ng carr i ed out on October

28 and 29 1 987 to del 1 neate the invned i ate impacts of harvest i ng was

pr i mari ly desi gned to measure turbid i ty associ ated parameters or

nutri ents rel eased from the sed iments as a resul t of the passage of the

harvester The in 1iY data co 1 1 ected however were subjected to an

ana l ys i s s i mi l ar to the above (Tabl e 4 7 ) D i fferences between harvested

and unharve sted areas were s i gn i fi cant here for a l l parameters but

pri mar i l y for the val ues at depth D i ssol ved oxygen duri ng - th i s

samp 1 1 ng however was l ower overa 1 1 i n the harvested area As water

col umn oxygen demand (BOD ) was comparabl e between transects reference to

sampl i ng t imes the majori ty after 1000 EST cl ari fy thi s apparent

d i screpancy These d i urnal cycl es are apparent i n F i gure 3 7

Duri ng the i mmedi ate impacts sampl i ng conduct i v i t i es were

s i gn i fi cant ly h i gher i n the experimental area than at the control

stat i ons wi th i n one hour of the passage of the harvester ( F i gure 4 6)

Cond i t i ons i n both areas had been comparabl e just pri or to the harvest

Th i s may i l l ustrate the rap id i ty wi th wh i ch fl ush i ng rates are i ncreased

Al l other in 1i1Y parameters wi th the except i on of percent saturat i on

exh i b i ted s ign i f i cant changes over t ime part i cul arly a t the bottom of

the water col umn These are i l l u strated for the rema i n i ng parameters i n

F i gures 3 9 through 3 1 1 where subtl e di fferences produced by harvest i ng

are superi mposed upon d i urnal cycl es The magni tude and s i gn of

d i fferences for many parameters in add i t i on to DO between harvested and

control stat i ons were heav i l y dependent on the t i me of day

Vert i cal grad i ents i n vari ous parameters were expected to be

reduced as a resul t of the removal of the advect i ve barri er of the

Hydri l l a mat and the consequent i ncrease i n wi nd -generated mi x i ng

Anal yses of vari ance of surface mi nus bottom in s i tu val ues as a s i ng l e

vari abl e were performed wi th stati ons

( harvested ) and control ( unharvested

comparat i ve ly non -weeded stat i ons ) Of

categori zed i nto experi mental

i ncl ud i ng both weeded and

the s i x sampl i ngs anal yzed i n

th i s manner surface to bottom grad i ents were most often observed for pH

DO and percent satura t i on Surface DO val ues ranged between 0 3 and 3 8

mgl h i gher (4 -46 saturat i on ) and surface pH between 0 04 and 0 2 SU

h i gher

4 - 1 2

Surface to bottom grad i ents were a 1 so apparent i n both

experi mental and control areas duri ng the immed i ate i mpacts sampl i ng of

October 28 and 29 Except for conduct i v i ty vert i cal grad i ents for these

two treatments were not stat i st i cal l y d i fferent from one another when the

fi ve post -harvest sampl i ng rounds were consi dered as a un i t Thi s

s i mi l ari ty i n grad i ents however shoul d not be confused wi t h the

d i fferences previ ousl y demonstrated between treatment areas for th i s

sampl i ng as the grad i ent anal ys i s i s concerned onl y wi th the d i fference

between surface and bottom val ues and makes no statement concern i ng the

rel ati ve posi t i ons of i nd i v i dual val ues

The fact that gradi ents were present at al l i n the harvested area

duri ng October may impl y that the d i mensi ons of the pl ot from wh i ch

HydrjJ l a was removed ( approxi matel y 6 by 1 20 meters ) were i nsuffi c i ent

for exi st i ng wi nd d i rect i on and vel oc i ty to cause substanti al mix i ng

Water depths ranged between 1 2 and I Sm These grad i ents were present

for pH DO and percent saturat i on agai n for the January sampl i ng i n both

control and experi mental transects wh i ch i s not surpri s i ng i n l i ght of

the degree of regrowth over four months s i nce harvest and the phys i cal

s imi l ari ty of stat i ons at th i s t i me

E2 Chemical Parameters

The anal ys i s of chemi cal data was desi gned to answer the fol l owi ng

questi ons for the sampl i ngs to date

o Are there detectabl e water qual i ty d i fferences between the

experimental and control stat i ons

o If there are was thi s ei ther d i rect l y or i nd i rect ly a product of

harvest i ng act i v i ty or i s i t the byproduct of stat i on l ocat i on

and the resul t of natural d i l ut i on grad i ents ( i e l oad i ng from

the Ki s s immee Ri ver or other sources )

o I f there are no s ign i fi cant d i fferences between harvested and

unharvested areas were d i fferences to be expected on the bas i s of

water mass compos i t i on

4 - 13

Where chemi cal spec i es are not d i rect ly correl ated wi th a d i st i nct

water mass or where i nputs to the water col umn are d i ffuse enough to

prevent the ma i ntenance of a spat i a 1 grad i ent or the detect i on of a

s i ngl e sourc e data analysi s i s s i mpl i fi ed to a compari son of treatment s

experimenta1 s agai nst control s Seasonal trend s i f present can be

factored i nto the stat i st i cal ana lys i s A s i mpl e compari son of harvested

aga i nst unharvested area chemi stry can al so be performed shoul d i on

content and rat i os i ndi cate that these water masses were i denti cal duri ng

sampl e col l ect i on and that d i l ut i on grad i ents can be i gnored

However when nutri ents or other spec i es are i ntroduced i nto a

system a ssoc i ated wi th a di sti nct water mass and when d i l ut i on with

ex i st i ng waters produces detectabl e gradi ents the quest i on s become more

compl ex In add i t i o n b i ol og i cal uptake wi l l produce non - l i near

rel a t i on sh i ps and the separati on of harvesti ng impacts from expected

gradi ents becomes more d i ffi cul t

The compl ex i ty of these questi ons i n the presence of d i l ut i on

grad i ents can be i l l ustrated graph i cal l y by reference to Fi gure 4 1 2

where hypotheti cal data appear In the fi rst part parameter X i s a

l i near func t i on of sod i um or i n other word s X i s a l so a con servati ve

parameter so i ts absol ute l evel i s affected onl y by d i l uti on wh i ch

mai nta i n s a constant X Sod i um rat i o Th i s regress i on would be devel oped

u s i ng one day s data from the ent i re gri d of n i ne control stat i ons across

the study s i te The hypothet ical data from a harvested stat i on (Stat i on

7 ) and the control (Stat i on 10 ) are al so pl otted It i s apparent that

wh i l e the l evel s of parameter X at the harvested and control stat i on

shown are probabl y not stat i st i cal l y d i fferent from one another the

harvested stat i on c l earl y fal l s outside of the 95 confi dence i nterval of

the X Sod i um regress ion for thi s data set and d i fferences from the l evel s

expected may refl ect harvest i ng i mpacts

In the second port i on of Figure 4 1 2 an al ternate s i tuat i on i s

i l l ustrated where the 1 eve1 s of parameter X at h arvested and control

stat i ons are shown to be c l earl y d i fferent However it i s apparent that

the water mass at the harvested stat i on i s sl i ghtl y more d i l ute and that

the correspond i ngl y l ower l evel s of parameter X are to be expected I n

4 - 14

both s i tuat i ons any b i ol og i cal processes affect i ng parameter X wi l l

produce even more compl ex rel at i onsh i ps

Sod i um and chl ori de were fi rst exami ned for i ns i g ht i nto water

mass movement and d i l ut i on processes occurri ng across the study s i te

The sum of these two i ons ( i n mi l l i equ i va1ent s ) was empl oyed a s an

approxi mat i on of total i on content They were both assumed to be

conservat i ve i e not part i ci pat i ng to any substant i al degree i n

b i ol og i cal processes where they might be sequestered or added to t he

water col umn F i gure 4 13 i l l ustrates thi s d i l ut i on process as i t occurs

across the study s i te The rat i o of sod i um to chl oride was al so

cal cul ated as an i dent i fy i ng feature of a part i cul ar stat i on

The gri d of ni ne control stat i ons was sampl ed on three occas i ons

August 1 8 September 30 1987 and January 13 1988 These data were

exami ned as t hey represented the 1 argest spat i a 1 area Anal yses of

vari ance i nd i cated that both total i on content and sod i um ch1 0r ide rati os

vari ed s ign i fi cant ly wi th respect to sampl i ng date I n l i ght of the

seasonal pattern of preci p i tat i on and the i nfl uence of ri ver d i scharge on

the area th i s was not surpri s i ng I n add i t i on however stat i on was

h i gh l y s i gn i f icant as a factor In the case of sod i um pl us chl ori de

th i s represents a change i n total i on content or d i l ut i on occurri ng

across a spat i al grad i ent ( Fi gure 4 14 ) I n the case of sod i um ch 1 0r i de

rat i os the fact that rat i os are di fferent at d i fferent stat i ons impl i es

that two or more separate water bod ies are represented across the s i te

( F i gure 4 1 5) I nteract i ve terms were al so s i gn i fi cant for each

parameter i nd i cat i ng that d i fferences were not cons i stent across t i me or

space Th i s i s apparent i n compari ng Fi gure 4 13 wi th Fi gure 4 14

As the mi xi ng of more than two water masses together woul d make

ana l ys i s of the rema i n i ng parameters extreme ly mathemat i cal l y compl ex

regress i ons of sodi um aga i n st chl ori de were performed for al l control

stat i ons on the three sampl i ng dates On each date correl at i ons for

l i near rel at ionshi ps were s ign i fi cant at pgt99 9 Th i s resul t al l owed

the use of the assumpt i on that onl y two water masses were mi x i ng across

the s i te Parameters associ ated wi th one of the two water masses coul d

therefore be detected by regress i ons on sod i um or some other conservat i ve

parameter

4 - 1 5

Anal yses of water qual i ty impacts were i n i t i al l y restri cted to

four sampl i ngs September 1 7 22 and 30 1 987 and January 13 1 988

Stat i ons 7 - 9 for experimental and Stat i ons 10 - 1 2 for control s (Stat i on

7 5 and 10 5 were used for the J anuary data set as an area wh i ch

i nc l uded Stat i on 7 had been reharvested shortl y before the sampl i ng )

S i gn i fi cant amounts of vari ati on between experi mental (Stat i on s 7

8 9 ) and control s ( Stati ons 1 0 1 1 1 2 ) as groups were found us i ng

two-way ANOVAs wi th date and treatment as factors (Tabl e 4 8 ) Al l

n i trogen and phosphorus spec i es (wi th the except i on of orthophosphate )

conta i ned s i gn i fi cant amounts of vari at i on d i stri buted between the

harvested and unharvested control stat i ons In add i t i on for BOD

turb id i ty and total suspended sol i d s d i fferences were present as wel l

As expected potassi um fl uoride chl ori de and sod i um d i d not d i spl ay

s i gn i fi cant vari ati ons between data from harvested and unharvested

stat i ons I ron copper total organ i c carbon and al kal i n i ty were al so

not s i gn i fi cant ly d i fferent between treatments

As d i scussed above however d i fferences between harvested and

unharvested areas are strai ghtforward onl y i f I water masses i n each of

the two treatment areas were identi cal or 2 the anal yzed parameter has

no s i gn i fi c ant rel ati onsh i p to a part i cul ar water mas s or to sod i um

Al though n o s ign i fi cant d i fferences i n sod i um o r chl ori de

concentrat i ons were observed between harvested and unharvested stat i ons

as a group di 1 ut i on grad i ents of these parameters were present wh i ch

paral l el ed the axi s of the harvested transects ( Fi gure 4 1 4 ) As a

resul t the data envel ope for the stati ons of a s i ngl e treatment was

l arge i n compar i son to any subtl e d i fferences between transects (F i gure

4 16 ) The fact that any di fferences were detected between experi mental

and control transects (Tabl e 4 8) impl i ed that they were substanti al

enough to overr ide the wi th i n -treatment vari abi l i ty expected from the

sod i um grad i ent S i gn i fi cance of i nteract i ve tems i n these model s

i nd i cated that d i fferences were not cons i stent from sampl i ng to sampl i ng

To d i rect l y compare harvested and non-harvested water qual i ty the

water of the two treatments must represent i dent i cal d i l ut i ons of source

and rece i v i ng waters As d i l ut i on gradi ents were roughly paral l el to the

transect axes stat i ons were pa i red and the d i fferences of experimental s

4 - 1 6

l ess control s cal cul ated for each pa i r of sod i um and chl ori de data

( Stat i ons 7 - 1 0 8- 1 1 9 - 1 2 Tabl es 4 9 4 10 ) The mean d i fferences

computed for al l sampl i ngs or for each date were on no occas i on d i fferent

from zero ( t - tests ) I n add i t i on no cons i stent pattern of d i fferences

was observed The conc1 us i on was that wh l l e di fferences 1 n the water

mass were present between stat i ons w ith i n a s i ngl e treatment harvested

stat i ons and t he i r adjacent control pai rs represented i dent i cal waters on

each date w i th respect to d i l ut i on

As water masses were i dent i cal the d i fferences i n parameter

concentrat i ons were cal cul ated for each stat i on pa i r as for sod i um and

chl ori de above These d i fferences are summari zed i n Tabl e 4 1 1 for those

parameters for wh i ch treatment was a s i gn i f icant factor i n the two-way

ANOVAs descri bed above (Tabl e 4 8 ) The magn i tudes of the d i fferences on

i nd i v i dual dates when not stat i st i cal l y equ i val ent to zero are al so

presented

Us i ng the pai red compari sons of stat i ons al l n i trogen s peci es and

total phosphorus exh i bi ted s i gn i fi cant al though subtl e d i fferences

between harvested and unharvested areas for the sampl i ngs to date (The

only date where orthophosphorus showed treatment d i fferences was on

September 22 and on th i s occas i on the magni tude was onl y 0 002 11191

1 ess than the 1 im i t of detect i on ) These d i fferences are most notabl e

for n i trate and ammon i a n i trogen and are i n add i t i on to any d i l ut i on

grad i ents across the s i te They can be presumed to refl ect the i mpacts

e i ther d i rect or i nd i rect of harvest i ng

Concentrat i ons where d i fferent were typi cal l y l arger i n the

unharvested control transect Th i s may be attri buted to e i ther uptake by

regrowth at harvested stat i ons or to the rel ease of nutri ents by

senescent macrophytes or peri phyton at the unharvested l ocat i ons

Fl oat i ng mats of Hydrj 1 1 a i n vari ous cond i t i ons were present through the

September 30 sampl i ng

B i ochemi cal oxygen demand turbi d i ty and suspended sol i d s al so

showed d i fferences us i ng stat i on pa i rs al though i n the i n stance of

suspended sol i ds concentrat i ons were sl i ghtl y h i gher at the harvested

stat i ons Wi nd -generated sed i ment resuspensi on i n harvested areas and

suspended senescent pl ant materi al i n the unharvested areas (contri but i ng

4- 1 7

to turbi d i ty and oxygen demand but wi th rel at i vely l i ttl e dry we i ght ) are

postul ated to account for these d i fferences Th i s i s supported

c i rcumstant i al l y by the l argest d i fference i n suspended sol ids be i ng

observed on September 30 when w i nd cond i t i ons were the most extreme of

any of the days sampl ed

The l argest number of parameters d i fferent between harvested and

weeded areas was al so observed on September 30 wh i l e the fewest were

seen on January 1 3 1 988 Whether th i s d i stri but i on across t ime i s a

res ul t of 1 ) vary ing nutri ent uptake rates throughout the growi ng season

2 ) the essent i al l y compl eted regrowth observed by the January s ampl i ng

3 ) the h i gher l ake l evel s and l ack of a fl oati ng mat of Hydri l l a perhaps

reduc i ng res idence t i mes of water across the s i te duri ng January or

4) the h i gher January nutri ent l evel s maki ng d i fferences more d i ff icul t

to d i scern i s i mposs i bl e to resol ve

Another techn i que for data anal ys i s was empl oyed on the September

30 and January 13 data sets for those parameters wh i ch were associ ated

wi th d i l ut i on grad i ents across the s i te Bri efl y i f the grid of control

stat i on s d i spl ayed s i gn i fi cant regress i ons with sod i um theoret ical

parameter concentrat i ons were cal cul ated for al l control and experimental

stati ons based on the observed sod i um data and that funct i on wi th the

h i ghest regress i on coeffi ci ent Res i dual s (V i - V hat) were then

compared by t - tests between means of experimental and control groups to

determi ne i f popul ati ons were the s ame (no impacts F i gure 3 1 2B) or

d i fferent ( i mpacts Fi gure 4 1 2A)

L i sted i n Tabl e 4 1 2 by date are the regres s i on types and

coeffi c i ents of the vari ous parameter concentrat i ons wi th sod i um Onl y

surface data from control stat i ons were used The vari ed nature of i nputs

to the s i te i s exempl i fi ed by F igures 4 1 7 and 4 18 dep i cti ng the vast l y

d i fferent d i stri buti ons of orthophosphorus between September and January

Whi l e rel at i vel y few parameters were apparentl y associ ated wi th

d i l ut i on duri ng the August sampl i ng the h i gher l oads i n September and

January perhaps coupl ed with sl owed uptake and growth rates duri ng the

l atter part of the year may produce l onger water col umn res idence t i mes

for nutri ent spec i es and permi t the detect i on of d i l ut i on grad i ents i n

4 - 18

these parameters Chl ori de and potas s i um and any other parameter onl y

s l ightl y affected by bi ol og i cal act i v i ty shoul d certa i nl y produce

s i gn i fi cant rel ati onsh i ps (The l ack of s i gn i fi cance of fl uor i de wi th

res pect to sod i um i s attri buted to the extremel y l ow l evel s encountered

e g concentrat i ons at or bel ow the l i mi t of detect i on for th i s

parameter )

Overal l the res i dual s anal ys i s of sod i um dependency proved l es s

sens i t i ve than that o f the pai red stat i ons anal yses O f the twenty-two

parameter-date combi nati ons where a s i gn i fi cant regress i on wi th sod i um

was obtai ned res i dual s of experimental stat i ons were s i gn i fi cant ly

d i fferent from res i dual s from control stat i ons for onl y three parameters

- - orthophosphorus and al kal i n i ty duri ng September 30 1 987 and n i tri teshy

n i trogen dur i ng January 13 1 988 Figure 4 19 superimposes the

experi mental stat i on orthophosphorus concentrati ons upon the rel at i onsh i p

devel oped for control stati ons i n September I t can be seen here that

the experimental stat i ons (X) are not evenl y d i stri buted around the

regress i on l i ne

Orthophosphorus concentrat i ons on th i s occas i on were l ower i n

the experi mental transect but onl y by 0 002 mgl l ess than the l i mi t of

detect i on Al kal i n i t i es at these stat i on s were h i gher than sod i um

concentrat i on s mi ght pred i ct by about 9 mgl as CaC03 Duri ng January

n i tri te - n i trogen was al so l ower at the harvested stat i ons than woul d be

expected on the bas i s of d i l ut i on al one but aga i n by l ess than the l imi t

of detect i on

As troph i c states and nutri ent l i mi tati ons wi thi n Lake Okeechobee

area of concern rati os of d i ssol ved and i norgan i c n i trogen to phosphorus

spec i es were cal cul ated and summari zed i n Tabl e 4 1 3 On a we ight bas i s

systems wi th rat i os l ess than 1 0 are typ i cal l y cons i dered n i trogen

1 i mi ted wh i l e phosphorus 1 im i tat i ons occur at rat i os greater than 1 7

( Sakamoto 1 966) Wi th th i s cr i teri on the waters o f the study s i te are

cl earl y n i trogen l imi ted i n contrast to al gal assays performed i n the

v i c i n i ty duri ng 1 974 and 1 975 ( Dye et al 1975 ) These resul ts have the

most consequences for phytopl ankton popul ati ons rather than macrophytes

as the rooted pl ants are capabl e of extracti ng at l east some i f not the

majori ty of thei r requ i red nutri ents from the hydroso i l

4 - 19

The stati st i cal anal yses d i scussed earl i er for the i ndi vi dual

parameters determi ned i norgan i c ni trogen spec i es to be h i gher i n the

unharvested control stat i ons and orthophosphorus to be s l i ghtl y l ower

ANaYA s of N P rat i os al so found s i gni fi cant d i fferences The treatment

( harvested or unharvested ) or stat i on was more important than date i n

account i ng for vari ati on Al l September and January sampl i ngs combi ned

produced mean N P rat i os for the harvested stat i ons ( 7 - 9 ) of 3 0 and for

the unharvested d i fferences coul d be attri buted e i ther to uptake by

act i vel y growi ng p l ants or to rel ease of nutri ents by senescent p l ant

materi a 1 Oi fferences between harvested and nonharvested areas were

l east apparent duri ng the January sampl i ng when ri s i ng l ake l evel and

Hydri l l a regrowth combi ned to i ncrease stat i on to stat i on phys i cal

s i m i l ari t i es

E 2 Bacteri ol ogi cal Parameters

Resul ts of total col i form anal yses (membrane fi l ter techn i que) of

sampl es col l ected on August 18 September 1 7 22 30 1987 and January 13

1 988 appear in Tabl es 4 1 4 After the August fi e ld effort sampl es were

col l ected i n conjuncti on wi th the phytopl ankton work and al l sampl es were

anal yzed by EQL Overal l bacteri ol ogi cal qual i ty was qu i t e good wi th

on ly a s i ngl e sampl e exceed i ng the 1000 counts per 100 ml cri teri on for

Cl ass I waters Th i s s i ngl e val ue of 5000 (Stat i on 1 1 September 30

1 987 ) was cl as sed as a stat i st i cal outl i er for the study as a whol e The

other two val ues from sampl es col l ected s i mul taneously were 900 and

100100 ml Most stat i on means were bel ow 200 countslOa ml

Stat i st i cal anal yses of these data empl oyed natural l og

transformat i on s Two way ANaYA s (by date and treatment and by date and

s t at i o n ) prod uced s i gn i fi cant terms for date and i nteract i ve

rel at i onsh i ps however nei ther harvesti ng nor stat i on accounted for

s ign i fi cant amounts of vari at i on Further anal yses cons i sted of mul t i pl e

l i near regress i ons of l og transformed total col i form counts aga i nst BOD

turb i d i ty total suspended sol i d s sod i um and chl ori de content ( as water

mass i ndi cators ) col or and s i l i cates A s i gn i fi cant regress i on model

whi ch i ncl uded BOD col or and TSS was obtai ned (r2 = 0 255 n 72) A

4 -20

d i rect rel ati onsh i p wi th BOD was not surpri s i ng The vari at i on wi th

col or val ues may be support for runoff control l ed bacteri a l evel s in the

l ake i ncreas i ng duri ng peri ods of h i gh d i scharge or backpump i ng (wh ich

are themsel ves characteri zed by i ncreased col or l evel s from t he

accumul ated surface waters An i nverse rel at i onsh i p w i th TSS l evel s was

l ess amenabl e to i nterpretat i on and i s l i kely to have been an art i fact of

some other control l i ng i nfl uence

IV E WATER QUALITY IMPACTS - QUALITY ASSURANCE OBJECTIVES

Prec i s i on and accuracy targets and resul ts for in ll1Y water

qual i ty parameters are presented in Tabl e 4 1 5 Prec i s i on est i mates were

based on dupl i cate in 1iY determi nat i ons expressed as percent rel ati ve

standard devi at i on (S RSD) Measurements at one stat i on per day were

typ i cal l y repl i cated i n thi s fash i on Prec i s i on est i mates for fi el d

measurements necessari l y i nc l uded the representati veness of the sampl i ng

as any non - homogene i ty of the s i te bei ng sampl ed appeared i n these

resul t s

Accuracy was determi ned from both pre- and post - sampl i ng

cal i brat i on of i nstrumentati on and where appl i cabl e the s i mu l taneous

col l ect i on of sampl es for l aboratory analysi s wi th al ternate procedures

or equ i pment Thi s was expressed as percent recovery ( R) of

f i el dl aboratory val ues t i mes 1 0 Col l ect i on of sampl es for

veri f icat i on was typi cal l y conducted at a rate of 1 for every 1 0 stati ons

samp l ed For th i s project di ssol ved oxygen and conducti v i ty were so

veri fi ed

Comparabi l i ty o f data was veri fi ed duri ng the pre- and postshy

sampl i ng cal i brati ons of i nstrumentat i on aga i nst standard sol ut i ons or

phys i c al constants Compl eteness of in 1iY data was esti mated to be

greater than 88 throughout the sampl i ngs to date

The qual i ty assurance object i ves for l aboratory anal yses were

anal ogous to those d i scussed for the i n s i tu parameters and are l i sted i n

Tabl e 4 14 Prec i s i on esti mates were determi ned from the anal yt i cal

resul ts and SRSD between the concentrati ons of two al i quots of a s i ng l e

conta i ner Dupl i cate analyses were performed at a rate of at l east one

4 - 2 1

for every ten sampl es The RSD between sampl es only sl i ghtly above the

l i mi t of detect i on i s often qu i te h i gh al though the analys i s i s

extremel y prec i se ( L e 0 001 and 0 002 11191 47 1 RSD ) Some mean

tRSD val ues and SD val ues are skewed by these seemi ngl y i mprec i se

dupl i cates that are actual l y wi th i n QA l i mi ts Accuracy of analyses was

assessed by the analys i s of sampl es to wh i ch known amounts of standard

materi al s had been added

IVG I NTERIM SUMMARY AND CONCLUSIONS

The study area i mmedi ately south of the entrance of the Ki s s 1mee

R i ver i nto Lake Okeechobee represents a compl ex combi nat i on of factors

wi t h regard to water qual i ty Vari at i ons with t i me were observed for

almost al l parameters measured D i ssol ved oxygen v i ol at i ons of the 5 0

11191 i nstantaneous cri teri on were common and d i urnal cycl es of DO and

rel ated parameters were apparent The skew i n sampl i ng t i mes toward the

morn i ng hours undoubtedly i ncreased the number of observed v i ol at i ons

a l though sampl i ng l ater i n the afternoon woul d i ncrease the percent

saturat i on of d i ssol ved gases and val ues i n excess of the 1 10 cri terion

wou l d have resul ted

In li1Y parameters were i n i t i al l y eval uated for stat i st i cal

d i fferences between harvested and unharvested stat i ons as a grou p

Di fferences i n DO percent saturat i on and p H were observed and were most

marked at the bottom of the water col umn and duri ng the September

sampl i ngs Pred i ct abl y harvesti ng reduced the ampl i tude of the d i urnal

DO cycl e such that DO concentrat i ons were h i gher i n the harvested

transect i n the morn i ng hours and l ower duri ng the afternoon Both the

magn i tude and the d i rect i on of the observed d i fferences were therefore a

funct i on of the t i me of sampl i ng

A rap i d change i n water masses was al so observed at harvested

stat i ons and th i s was attri buted to the i ncreased fl ush i ng potent i al

produced by Hydri l l a removal Inten s i ve surveys detected vert i cal

grad i ents of s i mi l ar magn i tudes for i n s i tu parameters at both harvested

and control stati ons The s i ze of the harvested transect may have been

too smal l to al l ow wi nd-generated vert i cal mi xi ng to be effect i ve

4-22

Bacteri ol og i cal water qual i ty at the s i te was good overal l wel l

wi th i n the 1000 1100 ml cri teri on and correl at i ons w ith col or BOD and

TSS were present Col or rel at i onshi ps i ndi cate a functi onal rel at i onsh i p

of total col i form wi th d i scharge i nto the l ake whi l e the rel at i onsh i p

wi th TSS was i nverse

Chemi cal water qual i ty d i stri but i ons at the s i te were a l so qu i te

compl ex Spat i al and d i l uti on grad i ents produced by the i nfl uence of the

K i s s i mmee Ri ver were qu i t e apparent as determi ned by conservat i ve

parameters such as sod i um and chl ori de The d i l ut i on grad i ents were

roughl y paral l el wi th the l ong axi s of the harvested transects such that

a progress i on of i ncreas i ng strengths of Lake Ri ver d i l ut i ons were

observed al ong both the experimental harvested transect and the adjacent

unharvested control transect Thi s transl ated to a h i gh wi th i n -treatment

va ri a b n i ty of water masses compared to the between- treatment

vari abi l i ty wh i ch i n turn may obscure d i fferences between harvested and

unharvested areas i n stra ightforward stat i st i cal compari sons

Overal l stat i sti cal techni ques were sat i sfactory because the

number of sampl es adequate for determi ni ng di fferences i n concentrat i ons

was at or near the analyt i cal l imi ts of detect i on The three stat i st i cal

anal yses were 1 ) d i rect compari sons (means test i ng and ANOVA s ) of

harvested to unharvested data sets 2) ana lys i s by d i fference of stat i on

pa i rs ( harvested l ess the adjacent control stati on) and whether

d i fferences were stat i sti cal l y d i fferent from zero and 3) res i dual s

anal ysi s of those parameters wi th a s ign i fi cant rel at i onsh i p w i th sod i um

and whether the popul ati on of res i dual s from control stati ons was

equ i val ent to those from the harvested stati ons

Ana lys i s of harvested versus unharvested data groups by parameter

reveal ed s i gn i fi cant d i fferences between treatments for al l n i trogen

spec i es total phosphorus BOD turb id i ty and total suspended sol i ds

These d i fferences are i n sp i te of the broad envel ope i n water qual i ty

conta i ned wi th i n each treatment type However d i rect compari sons and

correct est i mati on of the magni tude of harvest i ng impacts are poss i bl e

onl y where the water masses of the two treatments can be assumed to

represent equ i val ent po i nts on the d i l ut i on grad i ent

The d i fference i n sod i um and chl ori de concentrat i ons between each

harvested stat i on and i ts adjacent unharvested stat i on was cal cul ated

For al l dates these d i fferences were equ i val ent to zero mean i ng that

the water mass was i dent i cal at Stati ons 7 and 10 at Stat i ons 8 and 1 1

and at Stat i ons 9 and 1 2 The d i fferences i n concentrat i ons between the

stat i on pai rs cou l d then be calcul ated Al l n i trogen spec i es and total

phosphorus concentrat i ons were typ i cal l y h i gher i n the unharvested

transect On the one occas i on where orthophosphorus d i ffered between

treatments i t was s l i ghtl y h i gher i n the harvested transect Turbid i ty

and BOD were al so h i gher at the control stat i ons wh i l e total suspended

sol i ds were sl ightly l ess Uptake by macrophytes i n act i ve regrowth

rel ease o f nutri ents by senescent and matted pl ant mater i al and wi nd shy

generated resuspens i on may account for thi s pattern

Ana lys i s of those parameters associ ated wi th d i l u t i on and of those

wi th s i gn i fi cant correl at i ons wi th sod i um proved l ess sens i t i ve for

detect i ng d i fferences Al though many parameters d i spl ayed s i gn i f icant

rel at i onsh i ps the i r d i stri but i on around the regress i on l i ne was

cons i derabl e and res i dual popul at i ons were s i gn i fi cantly d i fferent

between treatments for only three parameters

The s i te as a whol e appeared to be n i t rogen 1 i mi ted based on

we i g ht r at i os of i norgan i c n i trogen forms to orthophosphorus

O i fferences between harvested and unharvested areas were apparent here

al so w i th average rat i o s of 3 0 and 9 4 respect i vely

IVG RECOMMENDATIONS - FINAL REPORT

For the rema i n i ng two quarterly sampl i ngs i n th i s task a

real l ocat i on of effort i s proposed wh i ch woul d del ete copper and fl uori de

from the anal yt i cal su i tes These two parameters were e i ther at or near

the 1 im i ts of analyt i cal detect i on for al most al l s ampl es and

stat i sti cal analyses were not effect i ve i n determi n i ng any d i fferences

attri butabl e to harvest i ng at these l ow concentrat i ons N i tri teshy

n i trogen however shoul d be reta i ned Al though l evel s were l ow they

are i mportant i n th i s n i trogen 1 i mi ted system and d i fferences between

treatments were apparent The Ki ss i mmee R i ver stat i on shou l d cont i nue to

4-24

be sampl ed and another stat i on shou l d be added to the west of Stat i on 1

toward Buckhead Ridge as an i ntermi ttent nutri ent i nput may be present

there Mon i tori ng of these two add i t i onal stat i ons shou l d cont i nue for

al l parameters In pl ace of copper and fl uor ide anal yses d i ssol ved

cal c i um i s suggested as a repl acement to prov ide a bas i s of compari son

wi th other work done prev i ously i n the l ake and to exam i ne i ts behav i or

across the s i te The poss i b i l i ty of mov i ng the exper imental and control

stat i on pai rs ( Stat i ons 7 - 1 2 ) to the most recently harvested area for the

subsequent sampl i ng i s currentl y be i ng d i scussed wi th the task l eaders of

the i nter-rel ated tasks

Future data exami nat i ons wh i ch wi 1 1 be conducted for the fi nal

report of th i s project i ncl ude the deta i l ed assessment of l i ght

penetrat i on profi l es and the effect of the weed mat upon these The data

from the 24 hour fi el d demonstrat i on sampl i ng wi l l be eval uated w ith

regard to chemi cal parameters and the i mmedi ate effects produced by

harvest i ng S i l i cates col or and i norgan i c carbon data wi l l be

processed as wi l l the rema i n i ng parameters for d i fferences between

experi mental and control stat i on s and a further anal ys i s of d i ssol ved

oxygen wi th cons i derat i ons for t i me of day vegetat i on and even sed i ment

type wi l l be conducted

4-25

LITERATURE CITED

Dye C W D A Jones L T Ros s R L Wi l l more 1 975 L imi t i ng nutri ents i n the Ki ss i llll1ee Ri ver - Lake Okeechobee Bas i n based on al gal assay techni ques Fl a Dept Envi ronmental Regul at i on Sakamoto H 1 966 Pri mary product i on by phytopl ankton conununi ty i n some Japanese l akes and i ts dependence on l ake depth Arch Hydrobi ol 62 1 - 28

4-26

Table 4 1 Mean IDran coordinates of water quality staticns

STATIOO NO

1 2 3 7 7 5 8 9 10 10 5 11 12 13 15 16

Ipound)RAN 1 JPRAN 2

14313 2 45453 2 14312 6 43449 1 14312 4 43445 9 14313 6 43449 1 14313 4 43448 2 14313 2 43447 7 14312 9 43446 1 14313 7 43448 5 14313 5 43447 7 14313 4 43447 3 14312 9 43445 7 14315 1 43444 6 14313 9 43443 2 143109 43437 8

Table 4 2 water Quality parameters methods ard holdirq times

Parameter

TeJlFerature Corrluctivity pi ORP Dissolved Oxygen Light Penetratim Secxhl laboratory 0rthqil0spl0rus (D) Total AlosJtIorus (D) AImalia-Nitrogen (D) Nitrite-Nitrogen (D) Nitrate-Nitrogen (D) Total Kjeldahl Nitrogen ium (D) Ccgler (D) Iran (D) Total OJgan1c carbon Alkalinity Biochemical Oxygen DeuanI lu1)idity SUspenled Solids Ibtal Ollifonn auoride Scdium Fluoride Color silicates (D) Inorganic Cartlon

MetbodlInstrument

Martek Mark VII Martek Mark VII Martek Mark VII Martek Mark VII YSI 57 LiOlr Secxhl Disk (LiDngtlogical)

EPA 365 1 365 3 EPA 365 3 365 4 SM 417F EPA 350 3 EPA 353 3 353 3 EPA 353 2 353 3 EPA 351 2 SM 30lA SM 303A B SM 303A B EPA 415 1 8M 403 4C EPA 3102 EPA 405 1 EPA 180 1 SM 2090 8M 908A 909A SM 4070 EPA 325 3 SM 303A EPA 3402 SM 204A B EPA 370 1 SM 425C EPA 415 1

Holdirg TimePreservative Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable

Filter iDmSdiately 48 hrs4Oc 28 daYSH2S04 to pllt2 40c Filter bImadiately 28 daYSH2S04 to pllt2 40c Filter bImadiately 48 hrsH4 to pllt2 40c Filter iDmSdiately 28 daYSH4 to pHlt2 40c 28 daYSH2S04 to pllt2 40c Filter iDmSdlately 6 1IDSIftll) to pllt2 40c Filter iDmSdiately 6 1IDSIftll) to pllt2 40c Filter inmediately 6 1IDSIftll) to pHlt2 40c 28 daYSH2S04 to pIlt2 40c 14 days4oC 48 hrs4Oc 48 hrs4Oc 7 days4Oc 6 hrs4Oc 28 days4Oc Filter inmdiately 6 lOOIlthslftll) to pIlt2 40c 28 days4Oc 48 hrs4Oc 28 days4Oc 28 days4Oc

EPA = EPA 6004-7920 Methods for OJemical Analysis of water ard wastes SM = stanIard Methods for the Examination of water ard wastewater 15th Fdition 1980 (D) = Dissolved

Tabl e 4 3

Date

Aug 18 1987

Sept 17 1987

Sept 22 1987

Sept 30 1987

Oct 28-29 1987

Jan 13 1988

Sampl i ng efforts and dates Water Qual i ty Tas k

Sampl i ng Type

Basel i ne

Short Term Impacts

Short Term Impacts

Quarterly

F i el d Demonstrat i on

Quart erly

No of Stat i ons

9

6

6

12

6

12

No of V i al s

1

1

1

1

6

1

Table 4 4 site averages of in situ parameters by sanplirg date all stations all depths

1987 1988

AU 18 SEP 17 SEP 22 SEP 30 ocr 28-29 JAN 13

n 28 18 18 36 144 68

2 SD 2 S D 2 S D S( S D S( S D 2 SD

onluctivity 0 5350 0661 0 5397 0351 0 5074 0550 0 4985 0517 0 3921 0731 0 3017 0895

ORP 493 109 441 42 298 77 293 47 295 31 247 55

Pi 8 02 0 55 8 27 0 34 7 56 027 7 47 043 7 72 0 51 7 59 0 30

lenperature 28 95 144 27 34 0 50 27 23 054 26 67 041 23 11 099 16 67 078

Dissolved Oxygen (00) 5 02 3 20 3 51 2 20 2 87 1 32 5 11 2 28 664 2 25 8 16 1 58

PeJta1t SaturatiCBl 66 1 42 9 44 4 27 9 36 3 16 7 64 0 28 6 77 8 269 84 0 16 7

00 cbs lt1 0 nql 128 318 218 336 0144 168

00 cbs lt4 0 nql 1428 U18 1318 936 14144 168

00 cbs lt5 0 ugII 1428 1218 1618 1536 41144 268

Table 4 5 Site averages of water quality parameters by sanplirg date all stations all depths

1987 l2sectsect AU 18 SEP 17 SEP 22 SEP 30 ocr 28-29 JAN 13

n 39 18 18 48 7 3 54 K SD K SD I SD K S D K SD K SD

0rthqil0sJil0 0 019 0 007 0 017 0 005 OOll 0 003 O OlS 0 014 0 033 0 011 0 082 0 045 Total rus 0 07 0 11 0 10 0 01 0 08 0 01 0 09 0 03 0 12 0 06 0 15 0 05

Anrncnia-nitrogen 0 039 0 018 0 04 5 0 042 0 017 0 012 0 012 0 017 0 040 0 029 0 04 6 0 036 Nitrite-nitrogen 0 004 0 001 0 005 0 004 0 004 0 001 0 003 0 003 0 004 0 001 0 008 0 004 Nitrate-nitrite-nitrogen 0 009 0 003 0 034 0 036 0 039 0 021 0 048 0 046 0 038 Q 019 0 190 0 039 Total Kjeldahl nitrogen 1 52 0 26 1 75 0 15 1 55 0 28 1 47 0 18 1 29 0 20 1 20 0 17 Potassium 4 4 0 9 4 7 0 3 4 5 0 3 4 2 1 0 2 9 0 5 3 9 1 0

Cqpar 0 003 0 002 0 003 0 002 0 003 0 001 0 002 0 001 0 001 0 001 0 002 0 002 Iron 0 002 0 002 0 014 0 007 0 014 0 007 0 015 0 019 0 048 0 018 0 090 0 031 ampxlium 4 8 9 7 6 47 3 4 6 46 9 4 7 49 0 9 4 31 0 8 9 28 2 8 1 Olloride 8 5 8 13 1 79 6 6 4 76 5 8 6 76 2 10 0 55 9 14 9 48 2 16 7 Fluoride 0 3 0 03 0 3 0 05 0 3 0 03 0 3 0 04 0 1 0 03 0 2 0 03 lbtal organic carlxln 2 1 7 1 6 17 9 0 9 18 1 0 8 18 4 1 0 19 7 2 5 18 4 3 0 Alkalinity 105 14 117 5 113 8 1U 10 7 3 15 68 lS Biochemical oxygen deHard 1 9 1 0 2 7 1 3 2 2 0 6 2 3 1 2 1 5 0 7 1 1 0 6 lubidi ty 2 4 1 9 4 2 0 9 4 1 1 5 4 0 2 9 3 1 2 5 3 7 2 1 Total susperded solids 3 3 3 3 6 0 2 3 5 7 2 4 6 3 4 7 4 5 3 9 3 1 4 1 Oller 61 5 66 9 81 9 113 10 silicates 12 8 2 2 13 1 2 2 12 0 3 0 5 4 0 5 Inorganic carlon 17 4 4 3 19 9 2 8 20 4 4 4 11 9 5 2

11=18

Table 4 6 site averages of water quality parameters for the KissiJulse River by sanpling date

1987 1988

AU 18 SEP 17 SEP 22 SEP 30 JAN 13

0 032 0 096 0 12 7 0 116 0 063 Total (ilcsphorus 0 09 0 18 0 20 0 20 0 12 Almalia-nitrcgen 0 021 0 036 lt0 005 0 017 0 069 Nitrite-nitrcgen lt0 005 lt0 005 lt0 005 lt0 005 0 027 Nitrate-nitrite-nitrogen 0 012 0 009 0 072 0 188 0 151 Total Kje1dahl nitrogen 0 51 1 39 1 40 1 12 1 08 Ibtassium 3 7 3 6 3 5 2 9 3 2

((gler 0 003 0 003 0 004 0 001 lt0 001 Iron 0 008 0 085 0 095 0 172 0 225 Sodium 3 3 4 2 6 5 24 2 2 1 0 15 0 Olloride 60 6 47 8 4 1 9 38 7 23 7 Fluoride 0 3 0 3 0 3 0 2 0 2 Total organic cartxn 19 6 19 5 19 9 18 8 17 4 Alkalinity 89 7 3 66 57 34 Biochemical oxygen daDaM 2 4 3 0 1 5 1 3 0 5 lJnbidity 3 0 3 9 2 7 2 3 2 3 Total suspenied solids J 9 4 8 4 0 2 5 2 0 Color 110 130 130 125 Silicates 6 58 6 42 5 67 3 17 Iooxganic carbon 4 4 9 6 7 2 1 1

Tabl e 4 7 S i g n i f icant F middot test rat i os for two-way ANOVA s by treatment and samp 1 1 ng round for in illY data co 1 1 ected duri ng fi el d demonstrat i on samp l i ng October 28-29 1987

FmiddotTET RAT IOS

TREATMENI ROUND INTERACTION (Exp vs control ) (1-5 only ) (Treatment x Round )

CONDUCTI V lTV Surface 25 99 1 14 56 Bottom 28 3 5 4 26 1 6 73

ORP Surface 2 1 10 Bottom 5 35

pH Surface 32 67 33 10 Bottom 1 1 1 5 4 5 1 4 48

Temperature Surface 104 64 Bottom 21 95 1 1 73 8 17

D i s sol ved Surface Oxygen Bottom 14 1 5 7 98 5 20

Saturat i on Surface Bottom 7 66 3 87

df df error bull 20 F 0 05 [df 20 ] bull

1

4 35

4

2 87

4

2 87

Table 4 8 Significant F-test ratios fnD two way analysis of variane by date ani treatment statiCllS 7-12 only Septedler 17 22 30 1987 ani JanJaIY 13 1988 data

rus dissolved Total pnsphorus Anroonia-nitrogen di ssolved Nitrite-nitrogen dissolved Nitrate-nitrite-nitrogen dissolved Total Kjeldahl nitrogen RltassilDU di ssel ved Cqpr di ssolved Iron dissolved Total organic car1xXl Alkalinity Biochemical oxygen demard TUlbidi ty Total suspenied solids Chloride SOdilDU Fluoride

Degrees of freedaD

Degrees freedan of error = 64

F 0 05 [df 60]

595 12 31 05

4 09 96 71 51 06 31 28

225 02 6 34

424 47 23 36 18 32 28 69

171 46 145 71

49 55

3

2 76

lREMMENl ( vs cxmR)L)

10 24 4 81

17 59 12 57

6 75

6 31 24 03 22 36

1

4 00

3 89

4 64 4 94 5 08

3

2 76

maturi ty Hvdri l l a senescence and peri phyton i nfestat i on was accompan i ed

by an areal decl i ne i n both bi omass and nutri ent content Max i mum

n i trogen and phosphorus t i ssue concentrat i ons were associ ated with ful l y

mature pl ants pri or t o senescence The presence o f other macrophytes was

respons i bl e for most wi thi n- stati on vari ati on Th i s task i nc i dental l y

d i scovered l arge seasonal d i fferences i n Hydr i l l a phosphorus and n i trogen

content Sampl es col l ected at the study s i te by ISampT duri ng J anuary

1988 were roughly f i ve t i mes h i gher i n phosphorus content than the

materi al col l ected by thi s project duri ng August 1987

Water qual i ty wi thi n the s i te represented an extremel y dynami c

system The i n fl uence of the Ki s s immee Ri ver and any other l ocal

d i sch arges produced d i l ut i on grad i ents across the s i te Vari at i ons i n

qual i ty were apparent between sampl i ng dates Numerous v i ol at i ons of the

i nstantaneous d i ssol ved oxygen cri ter ion (5 0 mgl ) were recorded

part i cu l arl y near the lake bottom Damp i ng of d i urnal oxygen extremes

was observed i n the harvested transects Al l n i trogen spec i es and total

phosphorous were h igher i n the unharvested transect waters than i n the

harvested transect The d i fference may be due e i ther to nutri ent

ut i l i zat i on i n the regrowth areas or to the rel ease of nutri ents from the

senescent Hydr i l l a mat present i n harvested areas The ent i re study s i te

was n i trogen l i mi ted wi th N P rat i os ( by we i ght ) of 3 0 i n the harvested

areas and 9 4 i n the unharvested control s

li ght penetrati on of the water at al l harvested stat i ons was

demonstrated to be s i gn i fi cantl y h i gher than at the unharvested control s

duri ng September onl y By January regrowth of Hvdri l l a produced

s l i ghtl y smal l er compensat i on depths on the harvested transect

Grad i ents i n l i ght penetrat i on were al so apparent wi th i n the experi mental

transect and may be rel ated to t ime s i nce harvest Vert i cal grad i ents

for in 1i1Y data were part i cul arly apparent at the weeded stat i ons

Bl ue-green al gae were the domi nant phytopl an kton taxa at al l

stat i ons d uri ng the September sampl i ngs Thi s domi nance was much reduced

duri ng J anuary when more green al gae were present Di vers i ty and number

of tax a i ncreased at four of the s i x stat i ons i n January but no

cons i stent pattern was apparent for e i ther harvested or control stat i ons

I n add i t i on there were no systemat ic d i fferences between harvested and

1 - 2

unharvested areas on the bas i s of spec i es compos i t i on Vari at i ons i n

chl orophyl l content al so were affected more by seasonal cond i t i ons than

by harvest i ng

The conunun i ty metabol i sm measurements conducted durlng September

1 987 i nd i cate probabl e d i fferences i n oxygen budgets for control and

harvested areas al though i n i t i al stat i st i cal methods d i d not establ i sh

the s i gni f i cance of such d i fferences Th i s was attri buted to anomal ous

data col l ected at a stat i on with unusual sed iment character i s t i cs ( h i ghly

organ i c unconsol idated f i ne grai ned mater i al in contrast to f i ne

grai ned sand ) Add i t i onal data analyses wi l l excl ude thi s stat i on from

cons i derat i on and future sampl i ngs wi l l be conducted at al ternate

l ocat i ons Di fferences by treatment duri ng the January sampl i ng were not

as pronounced as i n September and i nd i cate that regrowth of Hvdri 1 1 a with i n t hat peri od had offset harvest i ng e ffects

Sed i ment heterogenei ty was marked wi th i n the s i te with organ i c

w ith nutri ent content were fa i rl y l ow Organ i c content averaged 0 7

n i trogen 0 27 mgg total phosphorous 0 08 mgg and potass i um 0 49 mgg

on a dry we ight basi s Ni trate-n i tri te -n i trogen concentrati ons were l ess

than 1 of the total present Total n i trogen tota1 phosphorous rat i os

averaged 3 1 and were markedl y l ower than comparabl e rat i os i n e i ther t he

water col umn or the bi omass sampl es refl ect i ng a preferenti al

mobi l i zati on of n i trogen from s i te sed iments Few stat i st i cal l y

s i gn i f i cant d i fferences were detected a s a resul t o f w ith i n - stat i on

vari ati ons and the col l ect i on of more total phosphorus and total n i trogen

val ues are proposed for the second effort of th i s tas k

Data anal yses t o date for benth i c i nfauna i ncl ude preharvest and

postharvest cond i t i ons duri ng August and October respect i vel y The

August fauna was notabl y depauperate both i n taxa and numbers of

i nd i v i dual s wh i l e pronounced i ncreases in both were observed for

October D i urnal l y oxygen - poor cond i t i ons part i cul arl y duri ng August

may l i mi t benth i c fauna Spati al grad i ents were al so noted w ith

decreas i ng s pec i es ri chness and faunal dens i ti es at the southern end of

the study area Experimental and control stat i ons exh i bi ted s i mi l ar

faunal densi t i es and spec i es richness pri or to harvest wh i l e both

1 -3

parameters were substant i al ly greater at the harvested stat i ons duri ng

the October sampl i ng

Based on sampl i ngs i n September and J anuary the l arval and

juven i l e f i sh task col l ected 44 ( 2 1 ) of al l spec i es prev i ously reported

for Lake Okeechobee F i ve habi tats represent i ng both natural and

harvested edges and open water as wel l as heav i ly vegetated areas

were sampl ed Heterandria formosa LeDomi s sp and Gambus i a aff i nis

were the most abundant spec i es Centrarch i ds were the most abundant eggs

recovered The col l ect i on methods were f a i rly specif i c for part i cul ar

l i fe stage juven i l es were taken primari ly i n l i g ht trap sampl es whereas

postl arvae and eggs were taken i n pl ankton tows and Hvdri l l a sampl es

col l ected by the harvester LeDomi s s p appears to ut i l i ze al l fi ve

hab i tats dependent on l i festage No vert i cal strat i fi cat i on of organ i sms

was detected i n the weeded hab i tat and spec i es d i vers i t i es were

equ i val ent at both natural and harvested RedgesR of the Hydri l l a mat No

stat i s t i ca l ly s i gn i f i cant short term i mpacts of harvesti ng on spec i es

abundance or d i str i buti on are apparent

The cost-benefi t analys i s i s restri cted to eval uati ng mechan i cal

harvest i ng al one Benefi ts of thi s techni que wi th the except i on of

sal eabl e byproducts or costs assoc i ated wi th harvested mater i al are

pr i mari l y non -quanti fi abl e ( i mproved habi tat and water qual i ty boater

access nutri ent removal ) Therefore ranges of econom i c parameters wi l l

be ut i 1 i zed together wi th operat i ona 1 data from harvest i ng and

env i ronmental vari abl es from th i s project to present an economi cal l y

opt im i zed harvest i ng pl an to the Di stri ct

I n sunvnary no catastroph i c impacts due to mechan ical harvest i ng

have been detected i n the foregoi ng categori es al though subtl e

d i fferences have been determi ned by the study des ign Harvest i ng reduces

the amount of oxygen stress i n the study area and the nutri ent content of

the water col umn i s l ower i n the harvested than the unharvested areas

The s i te i s n i trogen l i mi ted based on water col umn sed i ment and pl ant

t i ssue anal yses Seasonal vari at i ons are l arge wi th respect to

d i fferences between harvested and unharvested areas for a l gal and l arval

fi sh popUl at i ons Spati al grad i ents were apparent i n many parameters

1 -4

The qual i ty assurance program associ ated wi th thi s project has

thus far conducted a systems aud i t for the pl an of study and at l east one

performance aud i t on f i e l dwork A Qual i ty Assurance Project Pl an has

been prepared and i s i n use as a project control document Aud i ts of

data management and anal ysi s are pl anned for the fi nal report i ng phase

At mi d -course sampl i ng anal yses and del i verabl es are on

schedul e and the project is operati ng wi th i n the budget No probl ems are

foreseen to prevent t imely compl eti on of the remai nder of the schedul ed

work Where al terati ons to speci f ic tasks have been recommended the

support for these efforts wi l l be obtai ned by real l ocati on of funds

wi th i n the project rather than by add i t i onal fund i ng

1-5

o 18 bullbull UNnar tllllllllI UINL UNnan

_ bull 0111 II wilD LlMi

lAKE (J(EECH08EE

Figure 11 Stu dy site l ocation Evaluation and research of impacts o f mechanical harves ting in Lake Okeechobee

I

I I LAKE OKEECHOBEE LITERATURE REV I EW

I I A INTRODUCTION

A 1 i terature rev i ew was conducted as a d i screte task of the

research project The Eval uat i on and Research of Impacts of Aquat i c Weed

Harvest i ng Demonstrat i on i n Lake Okeechobee cond ucted by Mote Mari ne

Laboratory The purpose of the l i terature rev i ew was to provide project

team members wi th economi c geol og i c hydrol og i c chemi cal and

b i ol og i cal i nformat i on on Lake Okeechobee wi th part i cu l ar emphas i s on

water qual i ty probl ems concern i ng phosphorus storage and cycl i ng between

the water col umn sed i ments and aquat i c weeds

I I B METHODS

Three techn i cal el ements were undertaken i n compl et i ng the

l i terature rev i ew 1) ident i fy i ng and search i ng i nformat i on 2) creat i ng

f i l es and 3 ) devel opi ng outputs

I nformati on was obtai ned by rev i ewi ng journal s for art i cl es

search i ng card catal ogs of area l i brar ies contact i ng major authors

conduct i ng research and request i ng key word searches of avai l abl e

computer l i brari es Journal s searched i ncl uded The Journal of Aquat i c

Pl ant Management Quarterly Journal o f the Fl ori da Academy o f Sci ences

( and Fl ori da Sc i ent i st ) L i mnol ogy and Oceanography Hydrobi ol og i a and

North Amer i can Journal of F i sher i es Management L i brari es vi s i ted

i ncl uded Un i vers i ty of South Fl or ida Uni vers i ty of Fl orid a Mote Mari ne

Laboratory Southwest Fl or ida Reg i onal Pl ann i ng Counci l South Fl ori da

Water Management D i str i c t and the Okeechobee off i ce of the Fl ori da Game

and Freshwater Fi sh Commi ss i on Key word l i terature searches were

c o n d u c t e d on d i qu at Lake O keechobee Hyd r i l l a and

nutr i entsaquat i c pl ants u s i ng searches avai l abl e from the Fl ori da

Department of Env i ronmental Regul at i on the Un i vers i ty of Fl ori da Aquati c

Weed Program and the U S Fi sh and Wi l d l i fe Servi ce

2-1

I I C PRODUCT

After rev i ew each publ icat i on was cited keyworded and annotated

u s i ng ARTF I LE vers i on 3 02 software for l i brar i es and b i bl i ographic

storage

Two outputs were devel oped from the comp i l ed i nformat i on 1 )

annotated c i tation s of each i nd i v i dual report and 2 ) Lake Fact Sheets

wh ich summari ze ava i l abl e i nformat i on on a spec i fic top ic requested by

members of t he study team Lake Fact Sheets and keyword b i bl i ographies

were d i stri buted t hroughout the course of the study as requested by

i nd i vi dual project members Lake Fact Sheets and a key word l i st

fol l ow Annotated c i tat i ons appear i n Append i x 2 A

2-2

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on AQUATIC PLANTS

Entri es i n Bi bl i ography 69

( For more deta i l s on spec i fic top ics pl ease see other fact sheets i e

hydri l l a b i omass harvest i ng etc )

Types of stud i es noted

- -Aquat ic pl ant ecol ogy (Moss 1980 23 Lugo and Snedaker 1971 113

Bl ackburn n 11 1968 128 Canfi el d et J 1983 260 Cassan i and

Caton 1985 352 Marshal l 1984 386)

- -Informat i on on aquat i c pl ant communi t i e s as habi tat (Wi l ey etI 1984

34 Durocher niI 1984 38 Mi l l eson nI 1980 40 Watki ns et I

1983 45 Ager and Kerce 1974 190 Sav i no et il 1985 196 Richard

n iI 1985 262)

- -Aquatic pl ant and sed i ment rel ati onsh i ps (Engel and N ichol s 1984 44

Barko and Smart 1986 106 Barko et 11 1983 147 L i et I 1974

108)

- -Aquat i c p l ant management ( Fl or ida DER nI 1986 415)

- - Nutrjent removal by aquat i c pl ants ( Reddy and DeBusk 1985 132)

- -Stud i es on harvest i ng aquat i c pl ants and the effects of harvest i ng

( Carpenter and Adams 1978 17 Sabol 1987 37 Mi ko l 1985 41

Wi l e 1978 57 Neel n 11 1973 114 N ichol s 1974 115

Smal l et

I 1985 130 Wi l e 1975 135)

- -Stud i es on chemical and other control s of aquat i c pl ants ( H i l t i bran n

J 1972 105 Ganstad 1978 110 deNoyel l es and Kett l e 1980 118

M i l on n 11 1986 119 Smal l et I 1985 130 Sutton and Vand i ver

1986 139 Lesl i e and Kobyl i nsk i 1985 255 Langel and and DeMont

1986 227 Barrett 1981 342 Barrett and Murphy 1982 344 Cl ayton

and Tanner 1982 355 Frank and Comes 1967 364 Graham 1976 369

Hughes and McCol l 1980 377 Richard et I 1984 426)

- -Aquat i c pl ant chem i s try and phys i ol ogy ( LaLonde 1970 107 Gerl off

1978 111 Gerl off 1973 112 Bri stow and Wh i tcombe 1971 136)

- - Chl orophyl l a concentrat i ons and aquat i c macrophytes ( Canfi e l d et I

1984 263)

2-3

Produced by Mote Marine Laboratory for South Florida Water Management District

- -B i omass stud i es and methods ( Schl oesser and Manny 1984 14 Mace i n a

J il 1984 33)

- -Uses for aquat i c weed s such as cattl e s i l age ( Bagnal l n l 1978

18) and compost (Wi l e g1 Jl 1978 19)

--Stud i es concern i ng Hydrilla vertic1llata ( Bagnal l 1980 18 Bol e and

Al l an 1978 15 P i erterse J il 1984 42 Bruner and Batterson 1984

43 Bowes 11 il 1979 47 Sutton 1982 52 Sutton and Port i er 1985

53 Sutton and Port i er 1983 57 McGhehee 1979 57 Bal c i unas 1985

116 Mart i n 1983 146 Johnston n Jl 1983 36 Canfi el d et l

1983 265 Mace i n a and Shi reman 1982 281 Hodgson and Carter 1982 423)

2-4

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fa c t She e t on BIOMASS

Entri es i n B i bl i ography 14

Types of stud i es noted

- -A troph i c state i ndex for l akes based on al gal bi omass (Carl son 1977

2)

- -Chl orophyl l -b i omas s - nutri ent rel ati onsh i ps for phytopl ankton (Canfi el d

et gl 1985 4)

--An assessment of bi omass control for water qual i ty management (Wong et

li 1979 9) --Methodol og ies for est imat i ng or measuri ng bi omass (Schl oesser and

Manny 1984 14 Mace i na g1 li 1984 33)

--Effects of harvest i ng or other weed control methods on aquat i c

vegetat i on b i omass (Mi kol 1985 41 Wi l e 1978 57 Cassani and Caton

1985 352 Hughes 1974 378 Sch i l l er 1983 398)

--B i omass measurements rel ati ng seasonal and b i otype vari at i ons i n

Hydr i l l a (Bowes et 11 1979 47 Steward 1987 408)

--Seasonal b i omas s of sel ected spec i es (Bowes et li 1979 47 Dewey et

l 19a1 266)

SUMMARY

Several stud i es use b iomass as a measure of aquat i c pl ant control

and as part of overal l assessments of water qual i ty management Mi ko 1

(1985) uses total pl ant bi omass measurements to asses s the effects of

mechan i cal harvesti ng on aquat i c vegetati on Wi l e (1978) al so presents

bi omass data as part of an assessment of envi ronmental effects of

mechan i cal harvesting Cassine and Caton (1985) asses s the same for

chem i cal and b i ol og i cal weed control Mace i na et li (1984) present a

method for est i mat i ng submersed pl ant bi omass by us i ng a record i ng

fathometer The i r data showed that the tech n i que i s not equal l y rel i abl e

for al l water bod i es However accurate b iomass determi nat i ons cou l d be

obt ai ned i f fathometer traci ngs are cal i brated w i th actual b i omas s data

Add i t i onal b iomass data for aquat i c p l ants are presented by Hughes

2-5

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

( 1974) Sch i l l er ( 1983 ) and Steward ( 1987 ) Bowes n il ( 1979) and

Steward ( 1987 ) present bi omass data for Hydri l l a i n Fl ori da

Canfi e l d et il ( 1985 ) address chl orophyl l - bi omass - nutri ent

rel at i onsh i ps for n atural assembl ages of Fl ori da phytopl ankton Carl son

( 1977 ) presents a troph i c state i ndex for l akes and uses al gal b i omass as

a parameter for the i ndex

2-6

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STU DY

Fact Sheet on D IQUAT

Entr i es i n B i bl i ography 84

Types of stud i es noted

- -Taxi c i ty data ( Mayer and El l ers i eck 1986 270 Berry and Schreck

1976 346 Funderburk and Lawrence 1967 366 Howe and Wri gt 1965

376 Kam W i ng and Furtado 1977 381 Naqui et Ai 1980 390)

- - Effects of d i quat on aquat i c commun i t i es ( H i l t i bran I 1972 105

Berry sl 1964 347 Cas san i and Caton 1985 352 Cal derban k 1972

351 C l ayton 1986 356 Dan i el 1972 358 G i l derhus 1967 368

Haag 1986 370 H i l senhoff 1966 372 Hughes and McCol l 1980 377

Joyce and Thayer 1986 379 Marshal l 1984 386 M i chaud 1979 387)

- -General chem i cal control gu i des and control of spec i fi c aquat i c

pl ants (Abery 1986 339 Barrett 1981 342 Barrett and Murphy 1982

344 Barrett and Logan 1982 345 Chevron Chemi cal Corp 1978 354

Hi l t i bran 1971 373 H i mel n li 1981 375 Ki l l gore 1984 383

Mac kenz i e 1966 385 Mobl ey n il 1971 388)

- -Di quat accumul ati on i n pl ants and sed i ments ( B i rmi ngham and Colman

1983 348 Dav i s and Seaman 1968 359 Frank and Comes 1967 364

Langeland and Warner 1986 384)

- - Experi mental data on herb i c i de treatments (Bri t i sh Col umbi a 1975

350 Clayton and Tanner 1982 355 Dunn et I 1983 362 Hal l er

1982 371 K i l l gore 1981 382 Newroth and L i m 1980 392)

- -Di quat u se wi th other types of control s (Charudattan 1986 353 Frank

AI 1979 365 Ganstad 1986 367 Graham 1976 369 Newroth

1974 391)

SUMMARY

I n add i t i on to the above noted stud i es three l i terature summari es and

rev i ews prov ide good i nformat i on on d i quat stud i es

Joyce and Ramey (1986) prov ide a good annotated rev i ew of 1 i terature

concern i ng research on the fate of aquat i c herb i c i de s i n water w i th

emphas i s on Fl ori d a s freshwater ecosystems Tucker (1980) rev i ews 50

c i tat i ons on d i quat c i tat i ons and prov ides a deta i l ed summary on the

2-7

Produced by Mote Marine Laboratory for South Florida Water Management District

foll ow i ng aspects of d i quat env i ronmental chemi stry adsorpt i on by so il

and cl ay mi neral s aerob i c and anaerob i c soi l stud i es soi l stud i es under

fi el d cond i t i ons aquat i c studi es soi l l eaching stud i es rotat i onal crop

stud i es photochem i cal degradat i on stud i es and mi croorgan i sm stud i es

Langel and and DeMont ( 1986 ) prov i de a thorough rev i ew of the l i terature

on the detect i on tox i c i ty and pers i stence of d i quat endotha1 1 and

f1 uri done They al so present speci fi c data on stud i es of the pers i stence

of d i quat endothal l and f1 uridone i n North Carol i na ponds and water

movement patterns i n Lake Wheel er North Carol i na

2-8

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fact Sheet on EUTROPHICATION

Entr i es i n Bi bl i ography 12

Types of stud i es noted

- -Eval uati ons of nutri ents i n eutroph i c l akes (Canfi el d 1983 5

Schi ndl er 1971 131 Michaud n ll 1979 387 Lee and Jones 1980

175)

- -Aquati c pl ant probl ems i n eutroph i c l akes (Graham 1976 369 Hughes

and McCol l 1980 377)

--Assess i ng eutroph i cati on based on water qual i ty stud i es ( Federi co et

Al 1981 67)

--Troph i c structure assessments and changes i n eutroph i c l akes ( Gayl e

1975 181 US Envi ronmental Protect i on Agency 1975 161)

SUMMARY

A number of stud i es address eutroph i cati on i n Lake Okeechobee

US Env i ronmental Protect i on Agency (1975 161) reports on Lake

Okeechobee as part of the Nat i onal Eutroph i cat i on Survey and a number of

state gency commi ttee stud i es and eng i neeri ng reports provi de anal yses

of Lake Okeechobee eutroph i cati on (MacGl l n AI 1976 174 Bl ack Crow

Ei dsness Inc 1976 185 Lee and Jone s 1980 175)

Us i g seven years of water qual i ty data Federi co et it 1 (1981

67) i dent i fy annual and seasonal l mnet i c water qual i ty trends exami ne

the re l at i o n s hi p to t r i but ary i n fl ow s i d en tify trends and

quali tyd i scharge rel ati onsh i p s cal cul ate annual l ake materi al budgets

for each year and assess the trophi c status of the 1 ake Gayl e (1975

181) presents a systems model for understanding eutrophicat i on i n Lake

Okeechobee

2-9

Produced by Mote Marine Laboratory for South Flori da Water Management District

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on HARVESTING

Entr i es i n B i bl i ography 15

Types of stud i es noted

--Effects of harvesti ng aquat i c pl ants on nutr i ent removal ( Bol e and

Al l an 1978 15 Wi l e 1978 57 Neel et AI 1973 114)

--Compari sons of mechan ical and b i ol og i cal harvest i ng wi th herbi c i de

control ( Carpenter and Adams 1978 17 Smal l et AI 1985 130

Sch i l l er 1983 398)

--Di sposal of and uses for harvested hydri l l a ( Bagnal l et AI 1978 18

Sabol 1987 37)

--Harvest i ng effects on aquat i c fl ora and fauna (Mi kol 1985 41 Wi l e

1978 57 N i chol s 1974 115 Wi l e 1975 135 Schramm et AI 1985

212 Lesl i e and Kobyl i nsk i 1985 255)

- - Economi c s of mechani cal harvest i ng (McGhehee 1979 57)

- - Phys i cal propert i es of hydri l l a for harvesti ng ( Bagnal l 1980 59)

SUMMARY

Most of the stud i es address the effects of mechan i cal ly harvest i ng

aquat i c pl ants Bol e and Al l an (1978) report that the harvest i ng of

Hydr i l la vert i c illata woul d result i n the d i rect transfer of onl y a smal l

amount of phosphorus i n the soi l i nto the water and the organ i cal l y-bound

phosphorus removed i n harvested pl ants woul d be deri ved l argely from the

sed i ment and not the water body W i l e (1978) and Neel n AI (1973)

present data and anal yses on l ake nutri ent dynam i cs resul t i ng from

harvest i ng aquat i c pl ants W i l e (1978) al so presents data on al gae

phytopl an kton fi sh and water qual i ty changes

A number of other stud i es address harvest i ng affects on fl ora and

fauna Mi kol (1985) reports that harvest i ng pl ants al so removed from 2-

8 of the total stand i ng crop of juven i l e fi sh Lesl i e and Kobyl i ns ki

(1985) address benth i c macro i nvertebrate response to aquat i c vegetat i on

removal wh il e Sabol (1087) addresses the env i ronmental effects of aquat i c

d i sposal o f chopped hydr i l l a

2-10

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

Compar i sons of mechan i cal harvest i ng and herbi c i des address

phosphorus cycl i ng (Carpenter and Adams 1 978) and Smal l et Jl ( 1 985)

report that herbi c i des reduced aquat i c vegetat i on but d i d not el i mi nate

i t Us i ng grass carp as bi ol og i cal control s el im i nated or red uced the

vegetat i on depend i ng on the stocki ng rat i o ( Smal l et AI 1985 )

2-11

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fact Sheet on Hydrjlla vertic11l ata

Entri es i n B i bl i ography 37

Spec i fi c stud i es on hydri l l a i n Lake Okeechobee i ncl ude a

compari son of dens i ty data for Lake Okeechobee and three other areas of

Fl ori da wi th stud i es spec i fi c to the speci a l i zed reproducti ve structures

of hydri l l a (Sutton and Port i er 1985 53) and an ana lys i s of potass i um

n i trogen and phosphorus content i n hydri 11 a from Lake Okeechobee and

three other areas of Sout h Fl ori da ( Sutton and Porti er 1983 56)

Pl ants from Lake Okeechobee had the h i ghest concentrat i on s of each

Other types of stud i e s on hydri l l anoted

--Phys i cal and mechani cal propert i es of hydri l l a (Bagnal l 1980

59)

--Nutri ent uptake stud i es of hydri l l a (Bol e and Al l an 1978 15)

--Us i ng hydri l l a for s i l age ( Bagnal l et Al 1978 18)

--Methods for determi n i ng or est i mat i ng pl ant biomass (Maceina et

li 1984 33)

--Growth reproduct i on and l i fe hi story of hydril l a ( Langel and and

Sutto 1980 35 Bruner and Batterson 1984 43 Spencer et li 1987

48 Sutton 1982 52)

--Habi tat i mportance and ecol ogy of hydril l a communit i es and

al terations to hydril l a communities (Watkins et li 1983 45middot

Bowes et

li 1979 47 Bl ackburn et li 1968 128 Sutton and Vandiver 1986

139 Can f i el d n Al 1983 265 Mace i na and Sh i reman 1982 281

R i chard i1 Al 1985 396)

--Biol ogical control s of hyd ri l l a (Bal ciunas and Minno 1985 46

Bal ciunas 1985 116 Johnston et li 1983 36 Cas sani and Caton

1985 352)

--Mechanical control s of hydril l a (McGhehee 1979 57)

--Chemical control of hydri l l a (Martin 1983 146 Cassani and

Caton 1985 352 Frank et li 1979 365 Hughes 1974 378 Small et

Al 1985 404 Steward 1972 405 Steward 1982 406 Steward 1976

407 Steward 1987 408 Van 1985 419 Van et Al 1987 420)

2-12

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

SUMMARY

Most of the stud i es deal w ith ways to control Hydr i l l a

verticilJata as a nui sance weed The effects of harvest i ng Hydri l l a i s

frequent l y addressed wi th mi xed resul ts Bol e and Al l an ( 1978) report

that the harvest i ng of Hydri 1 1 a woul d resul t i n the d i rect transfer of

onl y a smal l amount of phosphorus in the so i l i nto the water and the

organ i cal ly-bound phosphorus removed i n the harvested pl ants woul d be

deri ved l argel y from the sed i ment and not the water body

Johnston g1 il ( 1 983 ) report on the recol oni zat i on of a smal l pond

wi th aquat i c vegetat i on where grass carp have been used to control

Hydrill a They demonstrate the feas i b i l i ty o f reduc i ng the compet i t i ve

advantage of Hydri l l a i n order to l l ow other spec i es to become

establ i shed but al so note that care must be exerc i sed i n sel ect i ng

repl acement spec i es Other aquat i c pl ants may grow as prol i fi cal l y as

the Hydri 1 1 a bei ng repl aced

Sabol ( 1 987) and Langel and and Sutton ( 1 980 ) report on the

regrowth of fragmented Hydri l 1 a w i th confl i ct i ng resul t s In f iel d

stud i es Sabol ( 1 987) tested the re -growth potent i al of chopped Hydri 1 1 a

and found that a very smal l port i on of fragments cou1 d produce new

g rowth Conversely Langel and and Sutton ( 1980 ) under control l ed

l aboratory and f i e l d cond i t i ons demonstrated that 40 of the pl ant

fragments wi th one or two nodes were capabl e of vegetat i ve reproduct i o n

Bagnal l 11 il ( 1984 ) eval uated the feas i b i l i ty o f us i ng Hydri l 1 a

for cattl e feed and Macei na 1 il ( 1 984 ) present a method for pred i cti ng

pl ant b i omass us i ng a record i ng fathometer

2-13

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on N ITROGEN

Entri es i n B i bl i ography 27

Types of stud i es noted

- - Land userunoff rel at i onsh i ps w i th nutri ents i ncl ud i ng n i trogen

( Feder i c o 1 977 3 )

- - Nutri ent i n fluences on aquat i c pl ants and phytopl ankton (Canfi el d et

li 1985 4 Can fi el d 1 983 5 Davi s 1980 20 Dav i s 1 982 27

P i eterse 1 984 42 Sutton and Port i er 1 983 56 Bl ac kburn et il

1 968 1 28 Reddy and DeBus k 1 985 13 2 Jones and Federi co 1 984 1 )

- - Water qual i ty stud i es that i ncl ude nitrogen parameters ( Lutz 1 977a

7 Lutz 1 977b 16 M i l ler 1 980 20 Mi l l er et li 1982 26 Dav i s

and Marshal l 1 975 65 Peverl y and Johnson 1 979 394 Jones 1 983

9 )

- - Nutri ent rel at i onsh i ps w i th the troph i c structure of l akes (Henri kson

11 il 1 980 32 Dye 11 il 1975 138)

- - N i trogen and other water qual i ty data for Lake Okeechobee ( Di c kson et

li 1978 66 Davi s and Marshal l 1975 65 Federi co g1 li 1981 67

Fre i betger 1972 69 Mi l l er 1975 70 Jones and Federi co 1984 1

Jones 1 983 9)

- -N i t rogen i nputs and l ake eutroph i cat i on ( Sch i ndl er 197 1 13 1

Feder i co et il 1981 67 Canfi el d 1 983 5 )

- -Den i tri ficat i on i n Lake Okeechobee (Messer et li 1979 1 43 Messer

and Brezon i c 1 984 1 58)

- -Geochemi cal exchanges across the sed i ment -water i nterface ( Burton et

il 1975 1 45 Messer and Brezon i c 1984 158 )

- -Model s pred i ct i ng n i t rogen concentrat i ons (Jones 1983 9 )

SUMMARY

Several stud i es prov i de data on n i trogen for Lake Okeechobee

(M i l l er 1 980 20 Di c kson et li 1978 66 ) Many of these prov ide

n i trogen data as part of l arger studies for i nstance Federi co et li

( 1981 67 ) summari ze seven years of water qual i ty data i n order to

ident i fy annual and seasonal trends cal cu l ate annual budgets and assess

2-14

Produced by Mote Marine Laboratory for South Florida Water Management District

the troph i c state of the l ake Two stud ies ( Fre i berger 1 972 69

Mi l l er 1 97 5 70) i ncl ude lake Okeechobee as part of l arger wet and dry

season nutri ent surveys of South Fl ori d a

Jones ( 1 983 9 ) eval uates the qual i ty o f d i scharges t o Lake

Okeechobee nutr i ent concentrat i ons affects of var i ous changes i n l ake

l evel s and the abi l i ty of var i ous model s to accuratel y pred i ct n i trogen

and phosphorus concentrat i ons Jones and Federi co ( 1984 I) al so apply

nutr i ent model smiddot to Lake Okeechobee Dav i s and Marshal l ( 1 975 65)

present i nformat i on on areal and seasonal vari at i on s of n i trogen l evel s

nutri ent l oad i ngs and budgets for Lake Okeechobee and other chemi stry

d ata

Sutton and Port i er ( 1 983 56) eval uate the potass i um n i trogen

and phosphorus content of Hydri l l a from fi ve l ocat i on s i n South F l ori da

Sampl es were eval uated for wi th i n 1 ocat i on vari abi l i ty and for between

l ocat i on vari abi l i ty and resul ts showed that pl ants from lake Okeechobee

had h i gher concentrat i ons of nutri ents than pl ants from other areas

2-15

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on PHOSPHORUS

Entr ies i n Bi bl i ography 135

Phosphorus stud i es speci fi c to Lake Okeechobee i ncl ude

- -An anal ys i s o f the effect o f reduced nutri ent l oad i ngs on Lake

Okeechobe chl orophyl l (Jones and Feder i co 1984 )

- -An eval u at i on of the qual i ty of d i scharges to l ake nutri ent

concentrat i on s (Jones 1983 )

- -An analys i s of the abi l i ty of vari ous model s to accurately pred i ct

phosphorus concentrat i on s (Jones 1983 )

- -A comp ari son of phosphorus content i n hydri l l a from Lake Okeechobee and

four other l ocat i ons (Sutton and Porter 1 983 )

- -Aer i a 1 and seasonal vari at i ons of phosphoru s 1 eve 1 s i n Lake Okeechobee

(Davi s and Marshal l 1975 )

-A survey of total ortho p l us aci d - hydrol yzabl e phosphorus ( P- P04)

dur i ng a peri od of h igh water and a peri od of l ow water at 1 1 stat i on s i n

Lake Okeechobee and several stat i ons el sewhere i n South Fl or1 da

(Fre i berger 1972 )

- -An anal ys i s of l i mi t i ng factors based on al gal assays on water sampl es

from 30 s i tes i n the Ki s s i mmee R i ver- Lake Okeechobee Bas i n (Dye tl AI

1 975 )

- - Stud i es on nutri ent exchange across the sed i ment-water i nterface

(Burton et il 1975 )

Add i t i onal l y spec i fi c phosphorus d ata for Lake Okeechobee and i t s

watershed are presented i n a number o f reports (Jones and Feder i co 1984

Jones 1983 Mil l er 1980 Davi s and Marshal l 1975 Fre i berger 1 972

Messer et il 1 979 Dye et il 1975 Burton et Al 1975 Lee and Jones

1975 Lutz 1 977 Mi l l er et il 1982 Di ckson et Al 1978 M i l l er 1975)

Regard i ng management pl an s for phosphorus l evel s t he Lake

Okeechobee Techni cal Commi ttee ( 1 986 ) recommended to reduce phosphorus

l oads by at l east 40 (based on the mod i fi ed Vol l enwe i der nutri ent

l oad i ng model s ) through a program of d i vers i ons and treatment

2-16

Produced by Mote Marine Laboratory for South Florida Water Management District

Stud i es out s i de the lake Okeechobee area wh i ch prov i de i nformat i on

val uabl e to the study of phosphorus i ncl ude

- - Uptake of phosphorus from sed i ment and the water col umn by pl ants ( Bol e

and Al l an 1978 Dav i s 1984 Dav i s 1982 Reddy and DeBus k 1985 Dav i s

and Harri s n d li i1 Al 1974)

- -The i nfl uence of 1 and use patterns and other control s on phosphorus

l evel s ( Federi co 1977 Mi chal ski i1 Al 1975)

- -The correl at ion of nutri ent l evel s w i th chl orophyl l and phytopl ankton

l evel s ( Canfi el d i1 Al 1985 )

- - I ndexi ng and model l i ng techn i ques for l akes us i ng phosphorus and

rel ated data ( Carl son 1977 Canfi el d 1983 Meri cas and Mal one 1984)

- - Data on removal of phosphorus by mechan i ca l l y harvest i ng pl ants

( Carpenter and Adams 1978 Wi l e 1978 )

- -Rel ati on sh i p between nutri ents and b i ol og i cal parameters ( Henri kson g1

Al 1980 Pi eterse 1984 Enn i s 197 5 Re i nertsen 1 986 )

- - Phosphorussed i ment i nteract i ons (Twi nch and Peters 1984 li et li

1 97 1

- -laboratory and other control l ed stud i es on the propert i es of phosphorus

( Shannon and lee 1966 li et li 197 1 )

--Other l i terature stud i es ( Sch i ndl er et Al 197 1 )

2-17

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on PHYTOPLANKTON

Entr i es i n B i bl i ography 8

Types of stud i es noted

- - Phytopl ankton stud i es for Lake Okeechobee (Marshal l 1977 1 2 Dav i s

and Marshal l 1975 65 Marshal l 1977 424 Jones and Federi co 1 984

1 )

- - Phytopl anktonnutri entl ake eutroph i cat i on rel at i onsh i ps (Canfi el d et

AI 1985 4 Sch i ndl er 1971 13 1 Hughes and McCol l 1 980 377 Jones

and Federi co 1 984 1 )

- - Phytopl ankton pri mary producti on methodol ogy ( Schearer et AI 1985

278)

--Phytopl ankton responses to aquat i c pl ant removal (R i chard et AI 1985

426)

SUMMARY

Dav i s and Marshal l ( 1975 65) present 2 - 12 years of

phytopl an kton dens i ty data for Lake Okeechobee as wel l as i nformat i on on

n i trogn and phosphorus l evel s ( areal and season al vari at i on s ) pri mary

product i v i ty changes in al gal popul at i on s nutr i ent l oad ings and

budgets ra i n fal l chemi stry dat a regress i on anal yses on bi ol og i cal

act i v i ty and chemi cal or phys i cal propert i e s and trophic state

Marshal l s ( 1 977 1 2 ) phytopl ankton dens i ty data for 1974 show peaks i n

May and September i n Lake Okeechobee Marshal l concl udes that Lake

Okeechobee exh i b i t s seasonal patterns and peri od i c i ty typ i cal of

temperate l akes al though the seasonal vari at i on i n den s i t i es i s typi cal

of a trop i cal l ake

Jones and Federi co ( 1984 1 ) present over four years of d ata on

chl orophyl l a pri mary product i v i ty phytopl ankton dens i t i es and domi nant

species They al so an al yze the effect of reduced nutri ent l oad i ng s on

L a ke Okeechobee chl orophyl l and concl ude that chl orophyl l and

product i v i ty l evel s have not changed substanti al l y dur i ng the study

peri od except that peak val ues were h i gher i n 1981

2-18

Produced by Mote Marine Laboratory for South Florida Water Management District

Canfi el d n li ( 1985 4) col l ected data from 165 Fl ori da l akes

and reported a s i gn i fi cant correl at i on between chl orophyl l a

concentrat i ons and phytopl ankton bi omass Mul t i pl e repress i on anal yses

i nd i cated that phytopl ankton bi omass was dependent on both the total

phosphorus and total n i trogen concentrati on Nutri ent-phytopl ankton and

Secch i - phytopl ankton rel ati onsh i ps for the Fl orida l akes had h i gher

coeffi c i ents of determi nat i on i f chl orophyl l a concentrat i ons rather than

bi omass data were used

2-19

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fa ct Sheet on PRIMARY PRODUCTIVITY

Entries in Bibl iography 11

Types of studies noted

- -General ecol ogy studies incl uding primary productivity (Fontaine and

Ewe l 1981 31)

- -Trophic studies of l akes (Henrikson it 11 1980 32)

--Nutrient infl uences on primary productivity (Davis and Harris no date

141)

- -Primary production methodol ogy (Shearer l1 11 1985 278)

--Primary production data in Fl orida (Odum 1974 169 Brezonic et 11

1979 155 Jones and Federico 1984 1 Davis and Marshal 1975 65

Marshal l 1974 424)

- -Seasonal primary productivi ty cycl es (Comita 1985 1195 Marshal l

1974 424)

SUMMARY

Severa 1 stud i es concern primary production in Lake Okeechobee

Brezonjc l1 11 (1979 155) report to the Fl orida Sugar Cane League on

factors affect i ng primary product ion n Lake Okeechobee Jones and

Federico (1984 1) present primary productivity data on Lake Okeechobee

for 1974-76 and 1979-82 as wel l as information on chl orophyl l a

phytop 1 ankton dens i ties and domi nant spec 1 es and an anal ys s of the

effect of reduced nutrient l oadings Their report concl udes that

ch l orophyl l and productivity l evel s have not c hanged substantial l y during

the study period except for peak val ues that were higher in 1981 and

overal l val ues were higher In the Lake s north end Marshal l (1974

424) add resses seasonal changes for primary productivity and

phytopl ankton He concl udes that considering primary productivity and

other factors Lake Okeechobee phytopl ankton dynamics resembl e temperate

l akes Davis and Marshal l (1975 65) present over two years of data on

chemical and biol ogical investigations of Lake Okeechobee incl uding

primary productivity

2-20

Produced by Mote Marine Laboratory for South Florida Water ManaQement District

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet o n SED IMENTS

E ntr i es i n B i bl i ography 21

Types of stud i es noted

Most of the stud i es i nvol ve sedi ment nutr i ent ava i l abi l i ty fl uxes

and uptake by pl ants These i ncl ude reports on

-- Laboratory experiments to determi ne phosphorus uptake from the

sed i ments by Myri ophyl l ym and Hydri l l a ( Bol e and Al l an 1978 1 5 )

- - Phosphate exchange i n l ake sed i ments (Twi nch and Peters 1984 295 L i

et l 197 1 1 49 li Al 1973 )

- -Ava i l ab i l i ty of sedi ment phosphorus for macrophytes ( L i et l 1974

108)

- - Phosphorus fl uxes i n south Fl ori da marshes (Dav i s and Harri s no date

143 )

- -The i mportance of den i tr i fi cati on i n lake Okeechobee (Messer et l

1979 1 43 )

- -Geochemi cal exchanges across the sed i ment -water i nterface i n the

Ki s s i mmee Ri ver- Lake Okeechobee watershed ( Burton g1 l 1975 145)

- - lak sed i ment den i tri f i cat ion model s (Messer and Brezon i c 1 984 1 58)

There are al so a number of stud i es concern i ng the rel at i onsh i p of

sedi ment type and other factors to pl ant growth ( Bruner and Batterson

1984 43 Mart i n 1983 146 Barko et il 1983 147 Engel and

N i chol s 1 984 44 Barko and Smart 1986 106) pest i c i de and other

chemi cal res i dues i n sedi ments ( Pfeuffer 1985 298 Hughes and McCol l

1980 377 S i ms i man and Chesters 1976 402 )

SUMMARY

BUrton et l ( l979) documents the rol e of sed i ments i n determi n i ng

water qual i ty i n the Ki s s immee Ri ver-lake Okeechobee watershed wi th an

emphas i s on nutri ent exchange across the sed i ment -water i nterface They

a l so prov ide survey i nformat i on on sediment d i str i but i on and transport

Mes ser et l ( 1979) summari zes the i mportance of den i tr if i cat i on i n lake

Okeechobee i ncl ud i ng a d i scuss i on on the rol e of sedi ments i n the

2-21

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

den i tr i fi cat i on process

eval uat i on o f l ake sed i ment

Lake Okeechobee

Messer and Brezon i c ( 1 984 ) present an

den i tri fi cat i on model s and i ncl ude data from

Dav i s and Harri s ( n d ) provi de est i mates of phosphorus fl uxes

wh i ch d i rectly contri bute to uptake through pl ant growth and to retent i on

through pl ant detri tus sed i mentat i on for the Evergl ades Conservat i on Area

2

2-22

LAKE OKEECHOBEE LITERATURE REVIEW

LIST OF KEY WORDS

ABUNDANCE ( 2 ) ADSORPTION ( 2 ) AGE (1) AGRICULTURE (1) ALGAE (14) ALGAL BIOASSAY (1) ALGICIDES ( 2 ) ALKALI N I TY (1) ALKALOIDS (1) ALTERNANTHERA ( 2 ) ALTERNATHERA (1) AMMONIA (1) AMPH I PODS (1) ANALYSIS OF COVARIANCE (1) ANIMAL BEHAVIOR (1) ANIMALS ( 2 ) AQUATHOL (1) AQUATIC PLANT CHEMISTRY (1) AQUATIC PLANTS (76) AQUATIC ORGANISMS ( 2 ) AQUATIC ( 1 ) AQUIFER ( 2 ) ARGULUS ( 1 ) ARTHROPODS ( 1 ) ATHERINE FISH (1) BACKPUMPING ( 2 ) BACTERIA ( 3 ) BASS (18) BEACH HAB ITATS ( 2 ) BEHAVIOR ( 2 ) BENTHOS (9 ) BEST MANAGEMENT PRACTICES (1) B IOACCUMULATION (1) BIOASSAY (1) BIOLOGICAL CONTROL (8) BIOLOGY ( 6 ) BIOMASS (15) BIOTIC ASSESSMENT (1) BIOTYPES (1) BIRDS ( 2 ) BLACK CRAPPIE (19) BLACK BULLHEADS (1) BLUEGILL ( 1 2 ) BODY FORM ( 2 ) BREEDING (1) BROMAC I L (1) BROOK SILVERSIDE (1) CABOMBA (1)

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CADDISFLIES (1) CADMIUM (1) CALLITRICHE (1) CALOOSAHATCHEE RIVER (5) CANALS ( 2 ) CARBON (1) CARBONATE ROCKS (1) CARBOXYLASE (1) CAREX (1) CATTAI LS (1) CATTLE FEED (1) CENTRARCHIDS (5) CERATOPHYLLUM (5) CHAIN PICKEREL ( 1 ) CHANN ELS ( 1 ) CHAOBORUS (1) CHARA ( 6 ) CHEMICAL CONTROL ( 66 ) CHEMISTRY (10) CHIRONOMID LARVAE (1) CHIRONOMIDS (1) CHLORIDE (4) CHLORINATED HYDROCARBONS (1) CHLOROPHYLL (11) CLADIUM ( 2 ) CLASSIFICATION (1) COEFFICIENT OF DETERMINATION (1) COMMERCIAL FISHERY (2 ) COMMUNI TIES (1) COMMUNITY STRUCTURE ( 7 ) COMPETITION ( 3 ) COMPOST (1) COMPUTER MODELS (1) CONFINING BEDS (1) CONTOUR MAPPING (1) CONTROLLED RELEASE (1) COPEPODS (1) COPPER ( 9 ) COPPER SULFATE (1) CORE SAMPLER (1) COST BENEFIT ANALYSIS (1) CRUSTACEANS ( 2 ) CTENOPHARYNGODON IDE (2 ) CULTURAL CONTROL ( 2 ) CYANATRYN (1) DALAPON (4) DEGRADATION ( 3 ) DEMOGRAPHY (1)

DENITRIFICATION (1) DENSITY (6) DESORPTION (1) DETENTIONRETENTION ( 1 ) DETRITUS (1) DEVELOPMENT (2) DIATOMS (1) DICHLOBENIL (2) DIPOTASSIUM ENDOTHAL ( 1 ) DIQUAT (89) DISCHARGE ( 1 ) DISPERS ION (1) DISSOLVED OXYGEN (14) DISSO LVED SOLIDS (2) DISTRIBUTION (16) DIURNAL (1) DRAINAGE (4) DREDGING (1) DYSTROPHIC (1) EARLY DEVELOPMENT (2) ECOLOGY (15) ECONOMIC ANALYSIS (1) ECONOMICS (1) ECOSYSTEM (1) EFFLUENT REDUCTION (1) EFFLUENT (1) EGERIA (6) EICHHORNIA (13) ELODEA (20) EMBRYO ( 1 ) ENDOTHAL-POTASSIUM ( 1 ) ENDOTHALL (20) ENTRAINMENT (2) EPIPHYTES (1) EUTROPHICATION (12) EVERGLADES ( 9 ) EVERGLADES COUNTY (1) EXOGENOUS FEEDING (2) EXPLORATION (2) FAUNA (2) FEEDING ( 9 ) FEEDING RELATIONSHIPS (2) FENAC (5) FIRST YEAR SURVIVAL ( 1 ) FISH (130) FLOOD CONTROL (1) FLOODING ( 1 ) FLORIDA (31) FLORIDA EVERGLADES (1) FLORIDA LAKES (4) FLORIDA DUCK (1) FLORIDAN AQUIFER (2)

2-24

F LOW RATES (1) F LURIDONE (9) FOOD CHA I NS (1) FOOD HABITS (2) FOOD (6) FORAGE ( 1 ) FORAGING ( 1 ) FREQUENCY ANALYSIS (1) FRESHWATER SPECIES (1) FRESHWATER DISCHARGE ( 1 ) FRESHWATER (27) FRESHWATER MARSH (1) GEOLOGY ( 9 ) GERMINATION (1) GIZZARD F I SH (1) GIZZARD SHAD (2) GLADES COUNTY (9) GLYPHOSATE ( 6 ) GRAPNEL SAMPLER (3) GRASS CARP (8 ) GREAT BRITAIN ( 6 ) GROUNDWATER (5) GROWTH (11) GROWTH INHIBITORS (1) HABITAT (2) HABITAT PARTITION ING (1) HARVESTING (7) HAUL SEINE ( 1 ) HENDRY COUNTY (9) HERBICIDES (47) HEXAZINONE ( 1 ) HIGHlANDS COUNTY (1) HISTORY (3) HOST SPECIFICITY (1) HYDRILLA (42) HYDROCARBONS (1) HYDROCOTYLE (1) HYDROGEOLOGY (2) HYDROLOGY (17) HYDROPERIOD CHANGES (1) HYGROPHILA (1) HYPERmiddotEUTROPHIC (1) ICHTHYOFAUNA (1) ICHTHYOPLANKTON (2) IDENTIFICATION KEY (1) IDENTIFICATION GUIDE (10) IMAZAPYR (1) IMPOUNDMENTS (3) IMPROVING CATCH (1) INDICATOR SPECIES (1) INORGANIC PHOSPHATE (1) INSECT CONTROL (1)

INSECTS (4) INVERTEBRATES (9) IRON (2) IRON CHELATE (1) IRR IGAT ION (2) ISOPODS (1) JASM INE (1) JUNCUS (2) JUVEN ILE F ISH (5) K ISS IMMEE R IVER (11) LABORATORY STUD IES (1) LAGAROS I PHON (3) LAKE LEVELS (2) LAKE WANAKA (1) LAKE CONWAY (1) LAKE OKEECHOBEE (89) LAKE DRAWDOWN (1) LAKES (75) LAND USE (6) LARGEMOUTH BASS (16) LARVAE (1) LARVAL F ISH (25) LEAF PRODUCTION (1) LEMNA (8 ) LEPOMIS (1) L IFE HISTORY ( 9 ) L IGHT INTENSITY (1) L IGHT TRAPS (1) L IMNOLOGY (2) LI MNO PH I LA (1) L ITERATURE SURVEY (5) L ITHOLOG IC ANALYSIS (3) L ITTORAL (12) L ITTORAL ZONE (9) LOTAC (3) MACRO INVERTEBRATES (12) MACROPHYTES (18) MANAGEMENT PLAN (3) MANGANESE (3) MARION COUNTY (3) MARSH PLANTS (3) MARTIN COUNTY (27) MASS BALANCE MODEL (3) MATERIAL BUDGET (3) MATHEMAT ICAL MODELLING (3) MATHEMATICAL MODELS (3) MECHAN ICAL CONTROL (15) MECHANICAL HARVEST ING (24) METHODS ( 9 ) M ICROBES (3) MICROPTERUS (6) MINERAL RETENTION (3)

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MINERAL ADSORPTION (3) M INERAL NUTRITION (3) MINERALIZATION (3) M ISS ISSI PPI S ILVERSIDE (3) MODELING (6) MODELS (12) MOLLUSKS (3) MONITOR ING (15) MORPHOLOGY (3) MORTALITY (12) MOTHS (3) MOWING (3) MYOMERE NUMBERS (3) MYR IOPHYLLUM (84) MYSIDS (3) NAIDIDAE (3) NAJAS (18) NEKTON (3) NEMATODES (3) NEOCHETINA (6) NETS (6) N ICKEL (3) N ITRATES (3) N ITROGEN (81) NORTHERN P IKE (3) NUPHAR ( 9 ) NUTR IENTS (141) OCALA GROUP (3) OKEECHOBEE COUNTY (33) OKLAWAHA R IVER (3) OL IGOCHAETES (3) OLIGOTHROPHIC (6) ORANGE LAKE (3) ORGANIC MATTER (3) OSCEOLA COUNTY (3) OXYGEN (9) PALAEOLIMNOLOGY (3) PALM BEACH COUNTY (30) PAN ICUM (67) PARAQUAT (39) PARTICULATE MATTER (3) PASPALUM (3) PATHOGENS (3) PERI PHYTON (3) PERSISTENCE (9) PESTICIDES (27) PH ( 9 ) PHOSPHATE (15) PHOSPHORUS (135) PHOTOSYNTHES IS (12) PHYS IOLOGY (12) PHYTOPLANKTON (27)

PHYTOTOXICITY (3) PIKE (3) PISCIVOROUS FISH ( 6 ) PISTIA (15) PLANKTON (15) PLANNING (3) PLANT SUCCESSION (9) PLANT HARVESTING (9) PLANT ABUNDANCE ( 6 ) PLANT DENSITY (3) PLANT COMMUNITIES (9) PLANT SURVEY TECHNIQUES (9) PLANT COMPOSITION (9) PLANT NUTRITION (3) PLANT GROWTH ( 6 ) PLANT BIOMASS (3) POLLUTION (3) POLLUTION CONTROL (3) POLYCHAETES (3) POLYMER ( 6 ) POMACEA (3) POHOXIS ( 6 ) PONAR GRAB SAMPLER (9) PONDS ( 6 ) POPULATION DYNAMICS (9) POPULATION (21) POTAMOGETON (57) POTASSIUM (9) PREDATION (3) PREDATOR - PREY (15) PRIMARY PRODUCTION (36 ) PROPAGU1ES (3) PUMP STATIONS (3) PUMPING (3) RADAR (3) RADIOPHOSPHORUS (3) RAINFALL (18) RANUNCULUS ( 6 ) RATS (3) RECLAMATION ( 3 ) RECORDING FATHOMETER (3) RECRUITMENT (3) REDBREAST SUNFISH (3) REDEAR SUNFISH (3) REFERENCES (3) REGRESSION ANALYSIS (15) RELEASE RATES (3) REMOTE SENSING (3) REPRODUCTION (12) RESERVOIRS (51) RESIDUES (27) RESOURCE PARTITIONING (9)

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RESPIRATION (3) REVIEW (3) RIVERS (42) RUNOFF (33) SAGITTARIA (3 ) SALVINIA (18) SAMPLING (15) SAMPLING METHODS ( 6 ) SAMPLING GEAR (3) SCIRPUS (3) SEA LEVEL RISE (3) SEASONAL EFFECTS (12) SEASONAL SUCCESSION (3 ) SEASONAL (9) SECCHI DISK (9) SEDIMENTARY ROCKS (3 ) SEDIMENTS (78) SEEPAGE (12) SEWAGE DISCHARGES (3) SHAD (15) SHINERS (3) SHOREFLIES (3) SHORELINE AREAS (3 ) SILICA (3) SILICON (3) SIZE CLASS ( 6 ) SNAILS (3) SODIUM ALGINATE ( 6 ) SODIUM (3) SOILS (9) SOUTH FLORIDA (24) SPARGANIUM (3 ) SPAWNING (21) SPECIES DIVERSITY (3 ) SPECIES COMPOSITION (3 ) SPECIFIC CONDUCTANCE (15) SPOTTED BASS (3 ) ST LUCIE ESTUARY (3 ) ST JOHNS RIVER (3 ) ST LUCIE COUNTY (3 ) STANDING CROP (15) STOCHASTIC LAKE MODELS (3 ) STORHWATER (3) STRATIGRAPHY ( 6 ) STREAMS (9) SUNFISH (18) SURFACE DISCHARGES (3) SURFACE WATER (21) SURFACTANTS ( 6 ) SURVIVAL ( 3 ) SUSPENDED SOLIDS (3 ) SWIM PROGRAM ( 3)

TAYLOR CREEK (6) TAYLOR CREEK WATERSHED (3) TEMPERATURE (9) TENNESSEE (6) TERRESTRIAL (6) THREADFIN SHAD (15) TILAPIA (3) TOXICITY (36) TRACE METALS (3) TRANSMISSIBILITY (3) TRANSPARENCY (6) TROPHIC STRUCTURE (30) TUBER PRODUCTION (3) TUBER DENSITY (3) TURBIDITY (12) TURION (9) TYPHA (9) UPPER TAYLOR CREEK (3) USGS (3) UTILIZATION (3) UTRICULARIA (3) VALLISNERIA (15) VAUCHERIA (3) VEGETATED HABITATS (3) VEGETATION (15) VEGETATIVE PROPAGULES (3) VEGETATIVE REPRODUCTION (6) VELOCITY (3) VERTEBRATES (3) WASTELOAD ALLOCATION (6) WASTEWATER TREATMENT (6) WASTEWATER (3) WATER SUPPLY (12) WATER RECYCLING (3) WATER LEVELS (6) WATER CONSERVATION AREA 2A (3) WATER CHEMISTRY (21) WATER QUALITY (Ill) WATER MANAGEMENT (6) WATER LEVEL (9) WATER CIRCULATION (3) WATER BUDGET (3) WATERSHED ANALYSIS (3) WEIGHT DISTRIBUTION (3) WEIR BOX (3) WET AND DRY SEASON (9) WETLANDS (9) WHITE CRAPPIE (6) WILDLIFE (3) WITHLACOOCHEE RIVER (6) WOLFFIA (3) XYLENE (6)

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ZINC (3) ZOOLOGY (3) ZOOPLANKTON (21)

I I I BIOMASS - M ID-COURSE SUMMARY

I I I A INTRODUCT ION

The experimental removal of Hydr i l l a vert i c i 1 1 ata R i s bei ng

conducted to prov ide removal of nutr i ents phosphorus i n part icul ar from

Lake Okeechobee as wel l as the anc i l l ary benefi ts of i ncreased fi sh

hab i tat and nav igat i onal acces s To determi ne benefi ts and costs of

removal an i ndependent est i mate of both b i omass and nutri ent content of

vert i ci l l ata has been conducted

The bi omass sampl i ng effort was conducted i n August 1987 and was

compl eted pri or to the actual harvest i ng Stat i ons were concentrated i n

the area of the Hydri l l a mat but some non -Hydr i 1 1 a spec i es were al so

col l ected Sampl i ng l ocat i ons were sel ected on the bas i s of qual i tat i ve

cl ass i ficati ons of Hydri l l a growth character i s t ics

Based on fi e l d reconna i ssance i n Aprll and Ju l y 1987 a

s ubstant i al amount of spati al nonhomogene i ty i n both weed dens i ty and

spec i es compos i t i on was observed throughout the proposed s tudy s i te A

vari ety of env i ronmental factors such as substrate compos i t i on water

qual i ty and to a l es ser degree l i ght penetrat i on and water depth may

have been respons i bl e for these observed d i fferences Any past

appl icat i on and poss i bl e res i dual effects of weed control herb ic i des may

al so be contr i buti ng envi ronmental factors As growth character i st ics

w i th i n th i s area were not un i form i t was assumed un l i ke ly that nutri ent

content was evenly d i stri buted To quanti fy these area -wi de var i ati ons

a s ampl i ng scheme emphas iz i ng the range of Hydril l a growth cond i t i ons was

des i gned

III B MATER IALS AND METHODS

I I I B 1 Sampl e Col l ecti on

Prec i s i on measurement of Hydri l l a bi omass i s h igh l y dependent upon

the representat i veness of the sampl es as wel l as evenness of growth

character i st ics wi thi n the study s i te As di fferences i n dens i ty had

3 - 1

been observed duri ng reconnai ssance surveys fi ve Hydri l l a cond i t i on

factors were establ i shed ( see Tabl e 3 1 ) Stat i ons were apport i oned

among these fi ve categor i es rat i ng sel ected s i tes accord i ng to these

cond i t i on factors to i nsure that comparabl e representat i ve sampl es were

col l ected

As a resul t fi fteen ( 1 5 ) stat i ons were establ i shed wi th i n the

weed harvest i ng area ( Fi gure 3 1 ) Sampl i ng l ocat i ons were fi xed and

recorded i n the fi e l d us i ng Loran C (Apel co model DXL -6000 ) Sampl e

col l ect i on at each stat i on con s i sted of three repl i cated cl i pped - pl ots of

Hydri l l a removed from wi thi n a 202Sm2 sampl i ng dev i ce pl aced on the

substrate The sampl i ng box was constructed of steel pl ate 3 mm th ick

The overal l des i gn was s imi l ar to that descri bed by Mart i n and Sherman

( 1979 ) The top of the box however was covered by a d i amond pattern

screen wi th an attached hook to fac i l i tate l i ft i ng the sampl er wh i ch

contai ned the Hydr i l l a sampl e i nto the boat

The sampl er was l owered to the substrate and the Hydri l l a adjacent

to the edge of the box was cut by the d i ver wi th a kn i fe The bottom

sl i d i ng pl ate was then i nserted to conta i n the Hydri l l a sampl e and the

sampl er was then retri eved to the surface

Onl y the above- substrate port i ons of the pl ant were col l ected

s i nce thi s was cons i dered to be the port i on of the pl ant subject to

removal by the mechan i cal harvester Unconsol i d ated detri tal materi al

and roots were not col l ected Any non -Hydri J 1 a macrophytes col l ected

were separated from the Hydri l l a sampl es and treated as d i screte sampl es

Each l abel l ed repl i cate sampl e was we i ghed separatel y to the nearest gram

to determ i ne fresh wet we i ght s The i nd i v i dual repl i cates were then

i ced and shi pped to the l aboratory for dry we ight and nutr i ent content

analys i s

Add i t i onal fi el d procedures i ncl uded a near-fi el d and obl i que

photograph taken at each bi omass sampl i ng stat i on

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I I I B 2 Anal yt i cal Methods

Percent mo i sture was determi ned on al l sampl es Sampl es were

dri ed at 103 - 1050C and the dri ed materi al was used i n n i trogen

phosphorus and potass i um anal yses A total of 52 sampl es were processed

(45 Hydri l l a and 7 non - Hydrjl l a fract i ons ) by MML Total Kjel dahl

n i t rogen and total phosphorus were analyzed from dri ed ground pl ant

materi al Methods ut i l i zed were from the AOAC Methods of Anal ysi s 13th

Ed i t i on 1980 Kjel dahl d i gesti on i n a bl ock d i gester of l ess than O lg

pl ant materi al was fol l owed by sampl e reconst i tut i on automated d i l ut i on

and col ori metri c determi nati on o f amon i a and phosphate by Techn i con

AutoAnal yzer II The resul tant n i trogen and phosphorus concentrat i ons

were converted to a dry we i ght basi s

Procedures for the potass i um anal ysi s are deri ved from the AOAC

Methods of Ana lys i s 13th Ed i t i on 1980 Less than 0 3g of dri ed ground

p l ant materi al was d i gested wi th n i tr ic and perchl ori c ac i ds d l l utjed

wi th 1+1 hydrochl ori c ac i d and anal yzed by atomi c adsorpt i on

1 1 1 B 3 Dat a Management

B i omass data col l ected duri ng thi s study was used to generate the

fol l ow i ng types of data

o Wet and dry wei ghts of Hydri l l a expressed as gm2

o Nutri ents [n i trogen ( N ) phosphorous ( P) potas s i um (K ) ]

per we i ght of Hydri l l a

I I I C I NTERMIM RESULTS - BIOMASS

I I I C l B IOMASS ANALYSIS

Monocul tures of Hydri l l a were present except at Stat i ons 1 2 5

9 and 13 At these fi ve l ocat i ons i nc i dental col l ect i ons of

Ceratoohyl l um sp were made I n i t i al process i ng of these sampl es

cons i sted of separat i ng Hydril l a and non -Hydri l l a spec i es and anal yzi ng

and eval uati ng each fract i on as a d i screte sampl e Once the eval uati on

3 -3

was compl eted b i omass val ues from both sets of sampl es were combi ned to

represent the overal l b i omass harvested from the study are a

B i omass val ues (dry we ights a l l spec i es combi ned ) ranged from

1 9 33 gm2 ( 02 kgm2 ) to 3 1 7 67 gmm2 (0 32 kgm2 ) (Tabl e 3 2 ) The

l ower b i omass val ues were found at stat i ons 1 and 2 wh i ch were nearshore

stat i ons The h i ghest b i omass general l y occurred at the stati ons l ocated

i n the central port i ons of the Hydri 1 1 a mat The range i n wet and dry

b i omass val ues wi th i n a confi dence i nterval of 1 plusmn standard dev i at i on

( SO ) are graph i cal l y presented i n F i gures 3 2 and 3 3 The cons iderabl e

var i at i on i n b i omass val ues among the stati ons i s rel ated to onshy

shoreoff-s hore d i fferences in stat i on l ocat i on and var i at i on in b i omass

maturi ty wh i ch i s descri bed by the prev i ous ly l i sted cond i t i on factors

rhe Hydri 1 1 a cond i t i on factors have been devel oped to prov ide an

i nd i cat i on of the vari abi l i ty of pl ant maturi ty and were used to prov ide

a prel i mi nary eval uati on of the rel ati onsh i p between pl ant maturi ty and

nutrient content The cond i t i on factors recorded at each stat i on dur i ng

b i omass sampl i ng are summari zed i n Tabl e 3 3

The Hydr i 1 1 a b i omass val ues for each sampl i ng stat i on were grouped

accord i ng to the i r respecti ve cond i t i on factor and pl otted ( F i gure 3 4 )

The resul ts of th i s group i ng dep i cts a cl ear pattern of the d i stri but i on

of b i omass versus p 1 ant maturi ty or cond i t i on factor The new growth

cond i t i ons (1 and 2) had the l owest mean bi omass val ues whi l e cond i t i on

4 (mature cond i t i on ) had the h i ghest val ue and cond i t i on 5 (senescence )

i nd i cated a decl i n i ng b i omass of the Hydri 1 1 a mat at the stati on

l ocat i ons The stat i ons sampl ed and the study area were pr i mari l y

con s idered to be represented by a mature growth cond i t i on duri ng the

August col l ecti on Cond i t i on factors ( pl ant maturi ty) are al so rel ated

to nutri ent content as i s subsequently d i scussed

A gross esti mate of b i omass i n terms of areal extent was projected

us i ng the wei ghtarea rat i o for each stat i on and then averag i ng the

rat i os It shoul d be noted however that stat i on sel ect i on for thi s

task was not random and stat i ons were del i beratel y chosen wh i ch

refl ected a range of growth cond i t i ons By the same l og i c l ocat i ons of

transects to be harvested were not random and were chosen i n an attempt

to sel ect maxi mum dens i t i es of Hydri l l a Wi th these qual i fi ers the

3 -4

average b i omass sampl ed ranged from l ess than 1 to over 14 tons per acre

and averaged 7 tonsacre Esti mates for tons of b i omass i n fres h both

wet and dry cond i ti ons al so appear i n Tabl e 3 2 The wet b i omass val ues

represent we ights of the pl ant materi al after surface water has been

removed from the pl ant by bl ott i ng wi th a dry med i um Because of t h i s

handl i ng procedure a d i rect compari son wi th the harvest contractor s

fi el d est i mates (of merely dra i ned materi al ) are not val i d s i nce the

water associ ated wi th the Hydri l 1 a cou l d add a con s i derabl e but unknown

amount to the esti mated total we ight

B iomass sampl i ng i n the study area has been l i mi ted to a s i ng l e

event and the resul t s of the samp l i ng effort do not refl ect seasonal

vari at i ons However Bowes et al ( 1 979) i nvest i g ated the seasonal

Hydri lJ a b i omass product i on of three Fl ori da l akes Lake Trafford

Orange and Jackson Thei r study i ndi cated that the t i me for seasonal

peaks i n bi omass vari ed wi th the southern most 1 ake Lake Trafford

produc i ng the max i mum Hydri l l a bi omass i n August wh i l e the more northern

l akes Orange and Jackson produced more Hydri l l a b i omass i n Novernber

I 1 I C 2 NUTRI ENT REMOVAL

Phosphorus content of Hydri 1 1 a and the potent i al for removi ng

phosphorus from the l ake system was the pri mary focus of the data

anal ys i s Secondary aspects were quant i fyi ng n i trogen and potass i um as

they rel ate to the overal l nutri ent content of the study area and

prov i d i ng i nformat i on for any poss i bl e uses for the harvested materi a l

Tabl e 3 4 summari zes the analyti cal data for bi omass sampl es

col l ected Hydri l l a and total b i omass are tabul ated separatel y s i nce

Hydri l J a i s the target spec i es of the harvest i ng program and i t compri ses

the majori ty of the pl ant materi al i n the study area Inter-spec i fi c

d i fferences i n pl ant chemi cal compos i t i on are al so reported by Boyd

( 1978) as the greatest source of vari at i on i n characteri zat i on stud i es of

aquat i c macrophytes

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I I I C 2 1 Phosphorus

Total phosphorus ranged from 9 1 mgg to 2 68 mgg for al l spec i es

comb i ned and 91 mgg to 2 67 mgg for Hvdrill a only (Tabl e 3 4) The

comb i ned data wi th confidence i nterval s ( 1plusmn SO) are shown i n F i gure 3 5

The somewhat h i gher var i at i on i n phosphorus content at Stat i on s 2 5 9

and 13 i s est imated to occur as a resul t of the presence of non -Hvdri l l a

spec i e s at these l ocat i ons Therefore the presence of other spec i es i n

the sampl es ( i f not separated ) i s ant i c i pated to produce data that have a

greater vari abi l i ty and consequently are not as rel i abl e an est i mate of

nutri ent content as des i red for management dec i s i ons

Coeffi c i ents of var i at i on I n phosphorus content were cal cul ated

and pl otted by stat i on for comb i ned pl ants and for Hydr i l l a on l y ( F i gures

3 6 and 3 7) A compari son o f F i gures 3 6 and 3 7 however i ndi cates

that a rel at i vely smal l amount of the vari at i on observed can be

attri buted to the presence of two spec i es at a s i ngl e stat i on F i gure

3 7 demonstrates an i mportant con s iderat i on for any future sampl i ng and

asses sment effort s Sampl es o f Hydri l l a from the extremes of the

cond i t i on factors i e 1 and 5 produce data that may vary from 20 to

more than 30 i n est i mates of phosphorus content

The comb inat i on of cond i t i on factors and means for phos phorous

content at each stat i on i ndi cate a rel ati onsh i p between cond i t i on i e

re l at i ve maturi ty and phosphorus content ( F i gure 3 8) Stati ons wh i ch

cons i st pr imari ly of new pl ant growth (cond i t i on 1 ) contai n the l east

amount of phosphorus on a mgg (p l ant mater i al ) bas i s wh i l e stati on s

wi th pl ants that are descri bed as bei ng i n cond i t i on 4 (mature) have the

greatest amount of phosphorous A dec 1 i ne in phosphorus content al so

apparently accompan i es pl ant senescence

RegreSS i on anal ys i s was conducted to determ i ne the rel at i onsh i p

between b i omass and phosphorus content Because onl y one i ndependent

vari abl e (b i omas s ) was used i n the regress i on mode i t is necessary to

report only the resul ts of the two-tai l ed test u s i ng Student s t shy

stat i ons The nul l hypothes i s for the two -tai l ed test i s that there i s

no rel at i onsh i p between the dependent vari abl e and a spec i fi c i ndependent

vari abl e namel y bi omas s The t -stati st ic generated by the model

3-6

i nd i cated that b i omass s i gn i fi cantly effects phosphorus content at a 43

confidence l evel That i s there i s a 57 chance of i nd i cat i ng there i s

no rel ati onsh i p between b i omass and phosphorus i f the nul l hypothes i s i s

rejected

Add i t i onal stat i st i cal model i ng and an al ys i s i nd i cated that

b i omass at stati ons categori zed as Cond i t i on 4 were s i gn i fi cant ly rel ated

to phosphorous content at onl y a 75 confi dence l evel or a 25 chance

that a re 1 at i onshi p between b i omass and phosphorous content does not

exi st The h i gher confi dence l evel provi des some support for the use of

Hydrj 1 1 a cond i t i on factors part i cul arl y cond i t i on 4 for est i mat i ng the

nutri ent content of Hydri 1 1 a

To prov i de some prel i mi nary est i mates of potent i al phosphorous

removal rel ated to Hydri 1 1 a matur i ty each sampl i ng stat i on s phosphorous

we i ght to area rat i o was determi ned (Tabl e 3 5 ) These rat ios were then

averaged by cond i t i on factor The resu1 tant overal l phosphorus content

ranged from 16 1 bacre (cond i t i on 1 ) to 3 40 1 bacre (cond i t i on 4) and

dupl i cated the trend observed i n the b i omass data ( F i gure 3 4 )

The range of Hydri 1 1 a cond i t i ons factors and the presence o f other

macrophyte spec i es wi thi n the harvest area i nd i cates that further

defi n i t i on of the nutri ent removal est i mates are requ i red Th i s further

quant i fi cati on can be accompl i shed i n part through the use of aeri al

photographs The i nter im report by 15ampT ( 1 987 ) i nd i cates that sca1 ed

true col or and fa1 se col or i nfrared photographs of the study area have

been rout i ne1 y fl own Cop i es of these photographs and vegetat i on maps

wi 1 1 be requested from 15ampT The vegetati on maps produced from these

photographs by 15ampT wi l l be computer d i g i t i zed and acreage measurements

cal cul ated I t shoul d be noted that remote resource sens i ng techn i ques

part i cul arl y stud i es i nvol v i ng submerged pl ants have l i mi tati ons rel ated

primari l y to water depth and cl ari ty These 1 im i tati ons restri ct the

quant i ficat i on of i mmature Hydri 1 1 a represent i ng cond i t i on factors 1 and

2 because i t i s unl i ke1 y these p1 ants can be detected due to thei r

submerged cond i t i on Hydri ll a exh i bi t i ng cond i t i on factors 3 4 and 5

shoul d be v i s i bl e i n the l ate summer aeri al photographs as emergent mats

The fal se col or i nfrared aeri al photographs wi l l al so be anal yzed to

3 - 7

further separate the area i nto cond i t i on factors (3 4 and 5 ) These

refi ned est imates wi l l be i ncl uded in the fi nal report

An i ntegrated seasonal data base on nutri ent content of Hydri l l a

i n Lake Okeechobee i s l acki ng However recent data ( 1 5ampT 1988 )

i nd i cates there may be a pronounced seasonal d i fference i n t he chemi cal

compos i t i on of Hydrll l a from the l ake Hydri l l a sampl es col l ected by

15ampT duri ng January 1988 had phosphorus and n i trogen val ues that were

two to t hree t i mes h igher than the val ues reported for Aug ust 1987

(Tabl e 3 6 )

Spl i t sampl es anal yzed by the same l aboratory wh i ch prov i ded the

I SampT data provi ded veri fi cati on for the August phosphorus data reported

i n th i s study Therefore i t appears to be reasonabl e to assume that an

i ncrease i n Hydri l l a nutri ent content has occurred between August 1 987

and January 1988 The spec i fi c causes for th i s i ncrease are present ly

unknown but Federi co et al 1981 have suggested a nutri ent i nput

mechan i sm for the l ake based on l ake management W i th the fal lwi nter

i ncrease i n l ake surface area nutri ents conta i ned i n the l i ttoral zone

cou l d be transported l ake-ward by the fl ood i ng of the l i ttoral zone

Water qual i ty data from the present study does i n fact i nd i cate an

i ncrease i n i norgan i c phosphorus (P04- P ) from August 1 987 to January

1988 I t may be specul ated that i ncreased nutri ent avai l ab i l i ty may have

produced t h i s i ncrease i n Hydri l l a nutri ent content I t shoul d al so be

noted however that a seasonal i ncrease i n Hydri l l a phosphorus and

n i trogen content may occur i ndependent of any l ake management reg i me

Th i s seasonal vari at i on i n Hydri l l a nutri ent content has i mportant

rami fi cat i ons for any cont i nued or future harvest i ng programs I t al so

creates some add i t i onal quest i ons For exampl e i s th i s Hydri l l a

nutri ent i ncrease a l akewi de phenomenon or i s i t a near fi el d effect that

might be rel ated to the recent harvest i ng I f th i s i s a l akewide

i ncrease i n nutri ent content does it al so produce a correspond i ng

i ncrease i n bi omass so that phosphorus removal per acre cou l d be

max i mi zed I f th i s were true then the seasonal t i m i ng of any future

harvest i ng efforts need s to be careful l y cons i dered

Converse l y i f the wi nter i ncrease i n phosphorus content i s a near

fi el d effect rel ated to harvest i ng then perhaps harvest i ng des i gn i e

3 - 8

n umber and widths of harvested l anes needs to be re -exami ned and t i mi ng

of the harvest i ng may become l ess i mportant S i nce Hydri l l a i s a

n u i s ance spec i es al l prev i ous harvest i ng strateg i es have been a i med

toward weed el i mi nat i on for n av igat i onal purposes Because of th i s

nu i sance status management strateg i es have not been dev i sed or tested to

ut i l i ze Hydrj l l a as a nutri ent removal middotcrop middot For exampl e a seri es of

narrow but cl osely spaced cuts may be v i ewed as crop th i nn i ng wh i ch may

resul t i n greater nutri ent uptake by the adjacent unthi nned port i on of

the middotcrop middot Th i s act i on cou l d al so be coord i nated wi th n av i gat i onal

concerns and where appropri ate habi tat restorat i on or ma i ntenance

1 1 1 C 2 2 Ni trogen

As previ ous l y noted n i trogen has al so been eval uated as part of

the nutri ent analys i s N i trogen (TKN) ranged from 13 45 mgg to 26 34

mgg for al l spec i es combi ned and 13 45 mgg to 26 1 5 mgg for Hydri l l a

onl y (Tabl e 3 4) I ts d i stri but i on among stat i ons ( F i gure 3 9 ) fol l owed

the pattern prev i ousl y d i scussed for phosphorus Thi s pattern i ncl uded

the h i gh vari at i on attri buted to the presence of other spec i es ( F i gures

3 10 and 3 1 1 ) as wel l as the cond i t i on factornutri ent content

rel ati onsh i p of Hydri l l a ( F i gure 3 1 2 )

1 1 1 C 2 3 Potas s i um

The rema l n l ng nutri ent i ncl uded i n the anal ys i s was potass i um

wh i ch vari ed from 10 20 mgg to 26 28 mgg for al l spec i es combi ned and

10 20 mgg to 26 28 mgg for Hydri 1 1 a (Tabl e 3 4) Wi th several mi nor

except i ons potass i um content was a more vari abl e pl ant nutri ent than

e i ther phosphorus or n i trogen ( Fi gure 3 13 ) Thi s vari abi l i ty i n

potass i um content has al so been prev i ousl y reported by Sutton and Port i er

( 1983 )

A c o n s i d erabl e amou n t of the vari abi l i ty i n potas s i um

concentrat i ons was attri buted to the presence of other spec i es ( F i gures

3 1 4 and 3 1 5 ) but even when monocul tures of Hydri l l a are con s i dered a

h i gh amount of vari abi l i ty st i l l exi sts Kl opatek ( 1978) suggests that

3 - 9

vari at i on i n potass i um l evel s i n aquat i c macrophytes may refl ect h i gh

metabol i c demand duri ng the peri od of rap i d growth and that potass i um i s

not stored by pl ants s i nce th i s nutri ent i s read i l y avai l abl e from most

soi 1 s When grouped by cond i t i on factor the h i ghest potass i IJm contents

occurred i n the new or rapi d ly growi ng pl ants (cond i t i ons 1 2 and 3 )

( F i gure 2 - 1 6 ) Potass i um content decreases i n the l atter growth stages

assoc i ated wi th cond i t i on factors 4 and 5

I I I D CONCLUS IONS

The Hydri l l a b i omassnutri ent data anal yzed to date i nd i cates that

there are several important factors to be cons idered for future or

conti nued Hydri l l a harvest i ng programs

o Recogn i t i on and categori zati on of the rel ati ve maturi ty

state (cond i t i on factor) of the Hydri l l a mat i s i mportant

to sel ect sampl i ng l ocat i ons for nutri ent ana lys i s

o Anal ysi s of the nutri ent content of Hydri l l a i s most

preci se i e l owest sampl e vari at i on when col l ected from

areas of the mature mat The extremes of growth cond i t i on

new growth and senescence produced more vari abl e data

requ i ri ng l arger numbers of sampl es for rel i abl e mean

determi nat i ons

o Further testi ng of season a 1 d i fferences i n Hydri 1 1 a

nutri ent content and coup 1 i ng wi th harvest j ng-management

strateg i es cou l d s ign i ficantl y opt i m i ze the amount of

nutri ents removed through mechan i cal harvest i ng

I I I E RECOMMENDATIONS

Based on the data col l ected and anal yzed to date the fol l owi ng i s

the recommended course of act i on

Add i t i onal quant i tat i ve sampl i ng of Hydri l l a i n Lake Okeechobee i s

recommended Th i s add i t i onal sampl i ng effort shou l d be conducted at

3 - 10

1 ocat i ons both wi th i n the present study area as wel l as some 1 ocat i ons

out s i de of the study area Th i s general i zed pl an wi l l test for near

fi el d effects i e those effects that m ight be rel ated to harvest i ng

vs l akewi de effects Th i s sampl i ng effort shou l d be conducted quarterl y

to i nvest i gate the apparent seasonal changes i n Hydri l l a nutri ent

content Sampl i ng shou l d dupl i cate earl i er efforts and shou l d be

conducted at e i ght l ocat i on s four wi th i n and four outs i de of the present

study area

I I I F QUALITY ASSURANCE RESULTS

Tabl e 3 7 deta i l s the prec i s i on and accuracy of anal yt i cal resul ts

of dr i ed pl ant t i ssue Al l data were generated i n groups wi th

sat i sfactory qual i ty assurance cri teri a

3 - 1 1

LITERATURE CITED

Bowes G A S Hol aday W T Hal l er 1979 Seasonal vari ati on i n the b i omas s tuber dens i ty and photosynthet i c metabol i sm of Hydr i l l a i n three Fl ori d a l akes J Aquat i c Pl ant Mgt 17 61-65

Boyd C E 1978 Chemi cal Compos i t i on of Wetl and Pl ants IN Freshwater Ecol ogical Processes and Management Potenti al eds R E Good D F Wh i gham R L S i mpson C G Jackson J r Academi c Pres s N Y 378p

Freder i co A C K G D i c kson C R Kratzer F E Davi s 1981 Lake Okeechobee Water Qual i ty Stud i es and Eutroph i cat i on Assessment Techn i cal Publ i cati on 181-2 May 1981 Resource Pl ann i ng Department South Fl ori da Water Management D i stri c t West Pal m Beach FL 270pp + App

Kl opatek J M 1978 Nutri ent Dynami cs of Freshwater R i ver i ne Marshes and the Rol e of Emergent Macrophytes IN Freshwater Ecol og i cal Processes and Management Potent i al eds R E Good D F Wh i gham R L S i mpson C G Jackson Jr Academi c Press N Y 378p

ISampT 1987 Letter to Mr Ed Terczak dated Sep t 3 1987 Subj ect Chemi cal Anal yses resul ts of sampl es of Hydri l l a and mi crodeus

ISampT 1988 Letter to Mr Ed Terczak dated Jan 25 1988 Subj ect Compari son of nutri ent content i n Hydri l l a and water hyaci nth sampl es from the Demonstrat i on Project study area

Sutton D L and K H Port i e r 1983 Var i ati on of n i trogen phosphorus and potass i um contents of Hydri 1 l a i n South Fl orida J Aquat i c Pl ant Mgt 2 1 87 -92

3-12

Tabl e 3 1

Cond i t i on 1

Cond i t i on 2

Cond i t i on 3

Cond i t i on 4

Cond i t i on 5

Hvdrll l a Cond i t i on Factors to Descri be Pl ant Maturi ty i n the Lake Okeechobee Study Area

Areas of new pl ant growth rooted pl ants are l ess

than a foot h i g h

Pl ant growt h i s v igorou s but does not extend to the

surface P l ant s extend from 12 to 34 of the water

col umn i n height

Pl ant growth i s v igorous reaches the surface not

matted or at l east not brown and dyi ng on the

surface

Pl ant g rowth i s matted at the surfac e fl oat i ng

pl ants trapped s i gns of earl y decompos i t i on

P l ant mats are senescent and some open water i s

evident under mat

Source DSA Group I nc 1988

T-- 3 BiJS s_ bull aty 6 Sct irg 1tilt in _ Ia1 kee--gtee OJ --l l

my WEI lOOS lOOS

station GM2 so KGM2 so ArnE GM2 so KGM2 so ArnE

1 19 33 17 10 0 02 0 02 0 09 197 00 188 04 0 20 0 19 0 88

2 32 00 12 53 0 03 0 01 0 14 364 67 127 36 0 36 0 13 1 63

3 67 00 18 19 0 07 0 02 0 30 636 00 191 01 0 64 0 19 2 84

4 155 00 72 75 0 16 0 07 0 69 1660 33 733 09 1 66 0 73 7 41

5 195 33 85 82 0 20 0 09 0 86 1757 00 720 00 176 0 72 7 84

6 166 33 37 58 0 17 0 04 0 74 1695 33 335 67 1 70 0 34 7 56

7 263 33 56 70 0 26 0 06 1 18 2158 67 538 68 2 16 0 54 9 63

8 67 33 4067 0 07 0 04 0 30 676 33 302 63 0 68 0 30 3 02

9 184 67 94 85 0 18 0 09 0 77 1765 66 719 58 1 77 0 72 7 88

10 317 67 155 28 0 32 0 16 1 42 3165 33 1379 28 3 17 1 38 14 12

11 205 67 82 37 0 21 0 08 0 92 1716 00 500 11 1 72 0 50 7 66

12 200 67 47 60 0 20 0 05 0 90 2192 00 554 43 2 19 0 55 9 78

13 188 67 49 17 0 19 0 05 0 84 2326 00 492 11 2 33 0 49 10 38

14 116 00 29 82 0 12 0 03 0 52 1228 33 334 60 123 0 33 5 48

15 234 67 66 29 0 23 0 07 1 05 1997 33 527 08 2 00 0 53 8 91

Notes GM2= Grams Per Meter Square

SD= staOOald Deviation 1lGM2= Kilograms Per Meter Square

Dlta Ioolules Nan-Hydrilla Values for lhese stations

SOlllCe DSA Group Inc 1988

Tabl e 3 3

Cond i t i on

1

2

3

4

5

Sununary of Hydr i l l a Cond i t i on Factor by stat i on for the Lake Okeechobee study area August 18- 21 1987

Hydri 1 1 a Stat i ons

lt1 h i gh 1 2

12middot34 water col umn i n hei ght 2

at surface not matted 8 1 4 1 5

matted earl y decompos i t i on 4 6 7 1 0 1 1 1 2 1 3

senescent open water 5 9

Source DSA Group I nc 1987

Table 3 4 SUImlary ot Hyt1rllla Nl11rlent conumt nan Ole JaKe UKeeCnacee -oxty AJea 11

--- --------- - - ----- - -

Hydrilla Total Hydrilla Total Hydrilla Total p P TlltN TlltN K K

station I-CG so I-CG so I-CG so I-CG so I-CG so I-CG so

1 1 20 0 35 1 20 0 35 13 45 4 66 13 45 4 66 20 78 9 78 20 78 9 78

2 1 55 0 53 1 40 0 35 15 02 4 80 16 39 2 83 2156 12 06 16 45 6 23

3 1 43 0 06 1 43 0 06 15 78 1 37 15 78 1 37 19 66 6 19 19 66 6 19

4 2 36 0 27 2 36 0 27 20 67 2 76 20 67 2 76 20 57 4 81 20 57 4 81

5 1 28 0 14 1 47 0 30 16 49 0 88 16 93 1 10 19 09 2 11 18 99 1 98

6 1 60 0 02 1 60 0 02 17 16 028 17 16 0 28 23 56 5 57 23 56 5 57

7 0 91 0 07 0 91 0 07 15 58 0 38 15 58 0 38 10 20 0 53 10 20 0 53

8 1 37 0 15 1 37 0 15 13 60 2 50 13 60 2 50 26 28 8 25 26 28 8 25

9 1 45 0 36 1 48 0 39 17 60 2 38 17 73 2 56 18 34 5 30 18 59 5 35

10 1 96 0 14 1 96 0 14 21 35 1 69 21 35 1 69 18 71 2 73 18 71 2 73

11 1 63 0 13 1 63 0 13 16 71 0 37 16 71 0 37 16 60 5 06 16 60 5 06

12 1 81 0 12 1 81 0 12 21 97 1 04 21 97 1 04 14 43 1 37 14 43 1 37

13 2 67 0 27 2 68 25 26 15 2 29 26 34 1 97 15 89 4 52 15 89 4 52

14 2 14 0 09 2 14 0 09 20 68 1 12 20 68 1 12 23 68 1 72 23 68 1 72

15 1 33 0 11 1 33 0 11 14 01 0 47 14 01 0 47 15 82 1 99 15 82 1 99

Note All Values Expressed as Milligrams Per Gram of Dry Weight

50ur0e DSA Group Inc 1988

Tabl e 3 6

Sampl i ng Peri od Pl ant

August 1987

Tops

Steins

Whol e Pl ants

August 1987

Whol e P l ants

+January 1988

Who l e Pl ants

A Compari son of Hydri l l a Nutri ent Content for Samp l i ng Periods Conducted i n August 1987 and January 1987 i n t he Lake O keechobee Study Area

N i trogen Phosphorous (mgg-dry wei ght) (mgg-dry wei ght)

19 5 3 21

10 4 1 49

16 3 1 53

13 45 - 26 15 91 - 2 67

31 2 - 35 2 6 9 - 9 2

Source IST Augu s t 1987 Source DSA HHL August 1987

+Source IST January 1988

Tabl e 3 7 Bi omass anal ys i s qual i ty assurance resul ts

Prec i s i on Accuracy Parameter ( n X RSO SO) ( n X RSO SO)

Total phosphorus 6 3 8 1 4 4 1 0 1 7 6 5

Tota l Kje l dahl n i trogen 8 3 2 2 2 4 1 06 6 1 1 2

Potas s i um 6 3 1 1 8 5 12 1 2 43 5

zB

Figure middot3- 1 BIOMASS SAMPLING LOCATIONS

_c liOn Aalill LAaoaATOAV bullbull DA OAOb INC 18 bull

EVALUATION OF AQUATIC WEED HARVESTING DEMONSTRATION

IN LAKE OKEECHOBEE

Cl M EANS

B I O MAS S WET WE IG HT GRAS METER SQUARE

5--------------------------------------------------

45

4

3 5

3

25

1 5

1

05

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

+ UPPER CONFIDENCE STATION

o LOWER COIJADENCE

re 3 2

w a 4 J a tJ) lr w-ti

o M EANS

500

450-

40

350

300

2 50

20

1 50

1 00

50

0

1 2 3 4

+ UPPER CONfIDB-JCE

_ GPnl IP INC

81 0M-ASS D RY WEIGHT CRAMS METER SQUARE

-1-5 e 7 8 sa 1 0 1 1 1 2 1 3 1 4 1 5

STAriON o LOWER (ONlDENCE

ure 3 - 3

________________________________________________________ -____ G

c- -0 (I) (I) -laquo l 0 m J 0 I-

TOTAL BI O MASS VS HYDRI LLA C ONDITIO N DRY WEIGHT GlA2

3 00--------------------------------------------

2 80

1 80

1 60

1 40

1 20

1 00

80

6 0

40

20

middot0 1 2 3

CONDITION FACTOR IS I GM2 DRY NEIGHT

4 6

Figure 3-4

J laquo It w -It 0 L-a 0 -CL lt)

o M EAtJS

M I LLI G RAM S O F TOTA L P H O S PH O RUS

3--------------------------------------------

1

1 4

1 2

1

08 -1 2 3 4

+ UPPER CONFID ENCE

5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION gt LOWER CONFlDENCE

Figure 3-

z o tr 4 gt IL o

w o b IL W o o

C O EFFI C I ENT OF VARI ATION

TOTAL PHOSFHORUS 1 00-----------------------------------------------

90

80

70

60

50

40

30

2 0

1 0-

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION

i

z o ti gt b o

w o b h W o o

CO EFFIC I ENT OF VARIATION TOTAL PHOSA-lORUS (HtDRILLA ONLY)

I OO------------------------------------------------

90

80

70

60

50

40

30

20

1 0

1

IS I CONDlllON FACTORS STATION

9 1 0 1 1 1 2 1 3 1 4 1 5

Figure 3 -7

c - t) 2 0 -1 0 I-

TOTAL PH O S PH U RS VS H YDR I LLA C O N DITI ON

3--------------------------------------------

28

2

2

1 8

1 6 1 4

1

1 2 3

CONOrTJOt FACTOR -I I MGG my yenEIGHT

4 5

ure 3-8

J laquo cr

2 2 w l-e )- 20 (( 0 b 1 8 0 (-

z 1 6 t= 1 4

1 2

1 0

8

o M EANS

M ILLIGRAMS O F TOTAL KJELDAHL NITROGEN

1 2 3 4

+ UPPER CONFDE1CE

----r f 5 bull 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION ltgt LOWER COtADENCE

-ltlilirA 3-9

z 0

gt La 0

I-Z w

0 La La w

0 0

CO EFFIC I ENT OF VARI ATION

TOTAL l1ltJtJ

4

30

2

1 0

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

IS I CONDITlON FACTOR kZ 1 CV ()

Figure 3-1 0

z o t( tr laquo gt L o

tshyZ W o L L W o o

middot

CO EFFIC I ENT O F VARIATIO N 1lltN (HfDRlliA ONLY)

1 00-----------------------------------------------

90

80

70

80

50

40-

30

20

1 0

IS I CONDlllON FACTORS STATION WJ CV(7) 3- 1 1

0 -lt- z a

I--1 0 I-

30

28

28

24

22

2

1 8

1 8

1

1

2

0 1

TOTAL TKN VS HYDRI LLA CON DITION

2 3

CONDITION FACTOR r ] GG CRY WEIGHT

3- 1 2

-oJ ( tr W gt-cr n L 0 Cl - Cl E

o M EANS

M I LL IG RA M S O F TOTAL POTASSI U M

38---------------------------------------------

2

1

8--------------------- 1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

+ UPPER CONFDENCE STATION

ltgt LCJWER CONFIDENCE

z o n 4 gt LL o

I-shyZ bJ o LL LL W o o

1 00

90

80

70

80

50

40

30

20

1 0

0 -

CO EFFIC I ENT O F VARIATION POTASSIUU

-- _-_------ ------

1 2 3 4 5 8 7 8 1

IS I CONDITION FACTOR STATION ---

l2 J cv(-)

1 4 1 5

3- 1 4

z 0 t a oC gt Iamp-0

--

It

r z w 0 lamp-Iamp-w 0 0

C O EFFIC I ENT O F VARI ATION

POTASSlUA (HfffiILLA 011 Y) 1 00 - - - - - - -- - ---- - - - -- - -- - - - ---- --- - -- - - - - - - - - - - -- - - - - -

90

80

70

60

50

40

30 -

20

-

1 0

0 - 1 2 3 4

IS I CONDIllON FACTORS

l 7

J

r t

I 10 1 1 1 2 13

STATON LUd CV ( )

3- 1 5

TOTAL P OTASS I U M VS HYD RI L LA CON DITI ON

30------------------------------------------

28

28

1 2 3

CONDfTION FACTOR 1 I GG y WEIGHT

4 5

3- 1 8

IV WATER QUALITY SURVEYS

IV A INTRODUCTION

Concerns for water qual i ty i n Lake Okeechobee are pr i mar i l y

focused on nutri ent storage and cycl i ng between the water col umn

sedi ments and bi omass and the impl i cat i ons of these processes for the

current and future troph i c state of the l ake The harvest i ng

demonstrat i on project undertaken by the South Fl ori da Water Management

Di strict and conducted by I nternat i onal Sci ence and Technol ogy I nc

( ISampT) i s one of the remed i al measures proposed to arrest the apparently

i ncreas i ng troph i c state The harvest i ng and subsequent upl and d i sposal

of Hydrj l l a i s bei ng u sed to effect the removal of total nutri ents

( phos phorus in part i cul ar) from the aquat i c system The Di str i ct s

eval u at i on and research project ( EampR) conducted by Mote Mari ne Laboratory

(MML) was des i gned to del i neate other env i ronmental i mpacts and cost

benefi ts associ ated wi th mechan i cal weed removal

The goal of the water qual i ty task of the EampR s tudy was to

del i neate changes that cou l d be attri buted to the removal of dense stands

of Hydri l l a vert i c i l l ata ( Fi gure 4 1 ) Al though the i mmed i ate i mpacts of

weed harvest i ng on water qual i ty may be substant i al those wh i ch

perS i sted over a peri od of t i me were expected to be fai rl y smal l and

l ocal i zed due to the advect i ve barri er of the Hydri l l a mat Accord i ngl y

i n order t o resol ve these changes from background vari abi l i ty grad i ents

of water qual i ty were assumed to exi st across the s i te al though they may

be wea k

The sampl i ng program was desi gned t o al l ow the stat i st i c al

eval uat i on of water qual i ty d i fferences between stat i ons at any one poi nt

i n t i me prov id i ng enough anal yt i cal data to produce mean i ngful

compari sons As a resu l t a mi n i mum of tri pl i cate col l ect i on s per

stat i on were necessary Th i s approach was preferabl e to more frequent

sampl i ngs because i t centered on quant i fy i ng i mpacts at part i cul ar

i nstances rather than on a conti nu i ng bas i s when seasonal processes i n

the study area woul d compl i cate anal yses of data

4 - 1

Water qual i ty i nformati on i s al so necessary for the i nterpretat i on

and anal ys i s of many of the other tasks Phytopl ankton and pri mary

product i v i ty stud i es i n part i cul ar are heavi l y dependent on t h i s task and

wi l l exami ne ava i l abl e nutri ents tox i c compounds ( copper) as wel l as

phys i cal data produced by thi s tas k Accord i ng l y sampl i ngs for water

qual i ty were conducted on each of the days that Envi ronmenta 1 Qual i ty

Laboratory ( EQL) depl oyed primary producti v i ty equ i pment In add i t i on

certa i n parameters (d i ssol ved s i l i cates col or and i norgan i c carbon )

were added to the analyti c al su i te at stat i ons where product i v i ty was

be i ng determi ned Water qual i ty sampl i ngs were al so conducted wi th i n 24

hours of the communi ty metabol i sm task fi el d efforts and wi th i n two weeks

of l arval and juven i l e fi sh sampl i ngs

IV B METHODS

IV B l Water Qual i tv Stat i on locat i ons

The northern 1 200-m (4000 ft ) of Transect 3 was des i gnated as the

experimental transect where a majori ty of the tasks focused the i r

efforts Th i s harvested area was sel ected based upon central 1 ocat i on

wi th i n the study s i te representati veness of the study s i te as a whol e

wi th respect to depth fetch shore proxi mi ty and speci es compos i t i on

and the dens i ty of the Hydri l l a mat of the area

Stat i on l ocat i ons for most sampl i ng s of the water qual i ty task

were i l l ustrated i n F igure 4 2 a superi mposed on the Loran C l i nes mapped

for the study s i te dur i ng the August 1 987 reconnai ssance A tabul at i on

of Loran coordi nates of these stat i ons appears i n Tabl e 4 1 Stat i ons

were establ i shed to defi ne any ex i st i ng water qual i ty grad i ents across

the s i te as wel l as i mpacts due to harvest i ng and so extend beyond the

boundari es of the area schedul ed for harvest Stat i ons 1 2 3 13 1 5

and 1 6 represented the perimeter o f the study s i te Stat i ons 7 - 9 were

l ocated on the northern hal f of Transect 3 the experi mental transect

and represented the treatment stat i ons the treatment be i ng harvest i ng

Control ( unharvested ) stat i on 10- 1 2 were adj acent to the

experi mental transect i n the unharvested l ane between Transects 3 and 4

4 -2

( Stat i ons 4 -6 were al ternate control stati ons to be used onl y i f unusual

cond i t i ons at Stat i ons 10- 1 2 i nd i cated that they woul d not represent

und i sturbed cond i t i ons These stat ions have not been occup i ed to date )

Stat i ons 7 - 1 2 were al so the same areas sampl ed for phytopl ankto n benth i c

i nfauna and sed i ment chemi stry Stat i on 1 5 was or i g i nal l y establ i s hed

beyond the southern end of Transects 6 and 7 However dense growths of

Amer i can Lotus i n the area made i t l i kel y that water exchange was

mi n i mi zed wi th the rest of the study area Th i s stat i on was accord i ng l y

moved t o the north but kept between transects s o that i t represented

unharvested cond i t i ons

I V B 2 Parameters

In liY i nstrumentat i on (Hartek Hark V I I ) was used to determi ne

depth profi l es (at 0 2 and 0 5 meter i ncrements from the surface and at

bottom) of temperature conduct i v i ty pH and ox idat i on-reduct i on

potent i a l (ORP) bull Di ssol ved oxygen ( DO) meters ( YS I 57 pol arographi c

el ectrodes equ i pped wi th st i rrers ) were used to measure DO at the same

depths Heters ( and i nstruments ava i l abl e as backup equ i pment ) had been

bench cal i brated aga i nst known standards or phys i ca l constants pri or to

each sampl i ng Cal i brat i ons of the meters empl oyed were repeated

fol l owi ng each sampl i ng L i -Cor i ntegrat i ng photometers were ut i l i zed to

quant i fy i nc i dent and penetrant l i ght Care was taken i n performi ng

these measurements to mi n i mi ze weed d i sturbance i n l oweri ng the

i nstruments and ext i nct i on coeffic i ents were cal cul ated from both the

upper ( 0 5 m) and l ower ( bottom) read i ngs to provi de est i mates of both

weed mass and water col umn l i ght attenuati on Water sampl es were

col l ected for l aboratory analys i s outs ide of the i nfl uence of any meter

d i sturbances

Sampl es were secured us i ng a non -metal l i c i mpel l er-type pump wi th

a weed excl ud i ng cage mesh s i ze of 1 mm ( F i gure 9 3 ) The cage was

l owered wi th a mi n i mum of d i sturbance to the weed mat to prevent

resuspens i on and entrai nment of l oose ly attached al ga l materi al or other

pl ant debri s Th i s col l ecti on techn i que was empl oyed for al l sampl i ngs

Chemi cal parameters i ncl uded al l standard n i trogen and phosphorus

4-3

spec i es Inorgan i c forms - -orthophosphorus ammon i a- n i trate- and

n i tri te -n i trogen - - were determi ned on fi l tered sampl es ( 0 45 micon

effect i ve pore s i ze ) to ascerta i n the ava i l abl e amounts most mean i ngfu l

for b i ol og i cal assessments Potass i um and sodi um were quant i f i ed on a

fi l tered sampl e Trace metal concentrat i ons copper ( Cu ) and i ron ( Fe )

al so were determi ned o n fi l tered sampl es due t o the affi n i ty of these

e l ements for suspended part i cul ates

Total organ i c carbon total Kjel dahl n i trogen total phosphorus

and al kal i n i t i es were determi ned on unfi l tered s ampl es as was

bi ochem ica l oxygen demand Turb i d i ty and suspended l oads were quant i fi ed

and total col i form was analyzed by the membrane fi l ter techni que The

analys i s of sampl es for sod i um chl ori de and fl uori de concentrat i ons was

performed to permi t water mass cal cul at i ons and determi nat i on of water

qual i ty grad i ents across the s i te Anal yses necessary for the pri mary

product i v i ty task were col or d i ssol ved s i l i ca and i norgan i c carbon

Water qual i ty anal yt i ca 1 methods used were those approved by the

Envi ronmental Protect ion Agency ( EPA ) and the Fl orida Department of

Envi ronmental Regul ati on ( FDER) Method references anal yt i cal hol d i ng

t i mes and preservati ves are detai l ed i n Tabl e 4 2

Lake l evel s for spec i fi c dates were obtai ned from the Di stri ct and

represent 1 ake wide averages of stage recorders operated by both the

Di stri ct and the u s Army Corps of Eng i neers

IV B 3 Sampl i ng

There were four types of water qual i ty sampl i ngs each vary i ng i n

the numbers of stat i ons sampl ed t imi ng of col l ecti ons or parameters

anal yzed The s ampl i ngs were enti tl ed basel i ne short - term impacts

quarterl y and fi el d demonstrati on Col l ect i ons were focused around the

experimental transect Analyti cal sui tes i nc l uded both phys i cal and

chemi cal parameters Sampl i ngs performed to date appear i n Tabl e 4 3

4 -4

Basel i ne Sampl i ng

Basel i ne sampl i ng was conducted on August 18 1 987 pri or to any

harves t i ng act i v i ty wi t h i n the s i te The day was cl ear hot and cal m

Average l ake l evel for the day was 4 22 m ( 13 85 ft ) A total of n i ne

( 9 ) l ocati ons ( Figure 4 2 ) was sampl ed to establ i sh a grid of control

stat i ons ( Stat i ons sampl ed were 1 2 3 10 1 1 12 13 1 5 and 16 )

These stat i ons were al l i n areas where no harvest i ng act i v i t i es were

schedul ed Stat i ons 10 1 1 and 1 2 were l ocated i n a heavi l y weeded

area whi l e the rema i n i ng control stat i ons were outs i de the area to be

harvested and were i n comparati vely open water At each stati on a total

of three separate sampl es was col l ected from a depth of 0 2 m for

l aboratory analys i s

At Stati ons 1 3 13 and 16 sampl es were al so sec ured from 0 8

of the overal l depth Water depth ranged from 0 9 to 2 0 meters at al l

stat i on s These corners of the study si te represented the spat 1 a1

extremes and water qual i ty data from surface and at depth were used as

i nd i cat i ons of verti cal gradi ents over the s i te

One add i t i onal stat i on at the mouth of the K i s s i mmee R i ver

( Stati on 20) was sampl ed at the surface (0 2m ) The effect of thi s

tri butary on l ake nutri ent l oad i ng and resul tant spat i al grad i ents may

thus be cons i dered Th i s s i ng l e sampl e however was not i ncl uded i n

stat i st i cal anal yses

A total of fourteen ( 14) stati on-depths resul ted from thi s

sampl i ng for a total of forty ( 40 ) sampl es for anal ys i s In ll1Y and

l aboratory analyses i ncl uded al l wi th the except i on of col or s i l i cates

and org an i c carbon as no phytopl ankton sampl i ng was conducted duri ng

th i s epi sod e Sampl es for total col i form were col l ected from Stat i ons

10 1 1 and 1 2 onl y ( n i ne sampl es)

Short Term Impacts Sampl i ng

Two short term impacts water qual i ty sampl i ngs were conducted

i mmed i atel y after and approx i matel y one week fol l owi ng the compl et i on

of harvest on the exper imental transect These sampl i ngs were i n

4 - 5

conjunct i on wi th and on the same day as phytopl ankton and pr i mary

product i v i ty sampl i ngs Sampl es were col l ected from Stati ons 10 1 1 and

1 2 the control stat i ons and from Stat i ons 7 8 and 9 the experi mental

stat i ons ( F1 gure 4 5 ) Experimental stat i ons were l ocated approxi mately

150m 600m 1070m ( 500 ft 2000 ft and 3500 ft ) from the northern end of

the transect and were approximate ly 75 m ( 250 ft ) from e i ther edge of the

harvested area Contro 1 stat i ons were pa i red wi th each experi mental

stat i on and were adj acent approx1mate1y mi dway between Transect 3 and 4

1 n the center o f the unharvested are a Sampl es were col l ected from 0 2m

depth onl y

Aquat i c weed harvest1 ng on the experi mental transect began

September 3 1987 and the northern 1 220 m was compl eted on September 1 7

Dur1 ng th i s and the succeed 1 ng dayt 1 me sampl i ng events the ongo i ng

harvest of weeds cont i nued nearby An MHl fi el d crew conducted sampl i ng

on September 1 7 a hot cal m and cl ear day when l ake l evel s averaged 4 13

m ( 13 56 ft ) Th 1ck Hvdri 1 1 a growth was v 1 s i b1 e at depth w1 th i n the

tran sect Another sampl i ng occurred on September 22 1987 ( l ake l evel

4 1 2 m ( 1 3 51 ft raquo under s imi l ar cond i t i ons Regrowth of Hydri 1 1 a i n the

experiment al transect was extens ive by th i s date Sampl es were col l ected

near the mouth of the Ki s s immee Ri ver on both occas i ons Seven ( 7 )

stat i on depths resul ted 1 n the col l ect1 0n o f n i neteen ( 1 9 ) sampl es on

eah date Al l in si tu parameters and l aboratory anal yses were i nc l uded

Quarterl y Sampl i ng

As wi th the i mmed i ate i mpacts sampl i ng s quarterl y sampl i ngs were

conducted i n conjunct i on wi th phytopl ankton work Stat i ons sampl ed

i nc l uded 1 2 3 7 8 9 10 1 1 1 2 13 1 5 and 16 at 0 2m depth

( F i gure 4 2 ) and Stat i ons 1 3 1 3 and 16 at 0 8m overal l dept h

S i xteen ( 16 ) stat i on depth s pl us one ri ver sampl e resul ted i n at l east

49 sampl es duri ng each of the four efforts In s i tu and 1 aboratory

parameters i ncl uded al l those l i sted wi th the except i on that total

col i form d i s sol ved s i l i cates col or and i norgan i c carbon were anal yzed

on l y on sampl es from Stat i ons 7 8 9 1 0 1 1 and 12 onl y ( the

exper i mental stat i ons and the i r control pa i rs )

4 -6

Quarterly sampl i ngs took pl ace on September 30 1 987 and January

1 3 1 988 wi th the rema i n i ng sampl i ngs schedul ed for Apr i l and June 1988

Lake l evel s were 4 1 4 and 4 90m ( 1 3 60 and 16 07 ft ) i n September and

January respect i vel y The September event was conducted o n a bl ustery

day (wi nds from the west at 5- 10 kts ) wh i ch l ater produced a dr i v i ng

rai nstorm Vi s i b i l i ty both in and above the l ake was obscured currents

were al so noted Li ght and vari abl e w i nds from the NE to W were noted

duri ng the January sampl i ng Hydrilla had regrown to t he surface i n some

cases by th i s date but otherwi se was not often vi s I b1 e due to i ncreased

l ake l evel s

The northern 180m of the experi mental transect was reharvested

duri ng December 1987 Stati ons 7 and 10 were sampl ed i n January and thus

represented a t h i rd treatment ( 1 e harvested twi ce ) In order to

ma i nta i n a bal anced des i gn for stat i st i cal anal yses however two ( 2 )

stati ons were added t o the sampl i ng schedul e The pos i t i on of Stat i on

7 5 was just south of the mowed sect i on and another control ( 10 5 ) was

added i n a comparabl e l ocat i on south of Stat i on 1 0 Stat i ons 7 5 8 and

9 then became the experimental group to be consi dered i n data analyses

F i el d Demonstrat i on Sampl i ng

Water qua 1 i ty impacts duri ng the actual harvest i ng process were

expected to be pri mari l y a product of turbul ence generated by harvest i ng

These effects were al so expected to be fa i rl y l ocal i zed due to the

dens i ty of the weed mat Any temporary resuspen s i on of organ i c detr i tus

or el evat i on of sol i ds or nutri ent concentrati ons wou l d be establ i shed by

an i ntens i ve t i me seri es wh i ch woul d exami ne the degree and durat i on of

any d i sturbance

The fi el d demonstrat i on water qual i ty samp l l ng was conducted on

October 28-29 1 987 when l ake l evel s were at 14 26 ft Three pai rs of

stat i ons approxi matel y 100 ft apart were establ i shed at the northern edge

of the wi nd fence or harvested area l ocated between Tran sects 2 and 3

( Fi gure 4 6 ) Subsequent to preharvest sampl i ng a harvester made two

passe s each approx i mately 100m l ong A smal l barri er of Hydri l l a ( ca

3m w ide ) was l eft i ntact between the harvested area of Transect 2 and the

4 - 7

RharvestedR area for th i s study Stat i ons were i dent i fi ed as Rcut R (Cl

C2 C3 ) or R uncut R (UCl UC2 UC3 ) duri ng th i s effort

Fol l owi ng the two passes of the harvester over the experi mental

swath no more harvest i ng occurred in that area for at l east 24 hours A

t i me seri es of sampl es were col l ected from -each of the s i x ( 6 ) stat i ons

Data were to be compared from each of the two stat i on types for

quant i fyi ng i mpacts and traci ng the i r durat i o n

Sampl es were col l ected a t 0 2m and 0 8m o f the overal l depth us i ng

the pump and the weed excl ud i ng cage to el imi nate the l argest Hydri l l a

fragments from the sampl e Col l ect i ons took pl ace i mmedi atel y pri or to

the passage of the harvester immedi atel y subsequent to the harvest of

the experimental stat i ons (wi th i n approxi matel y 0 5 hr) and then aga i n

at roughl y 2 5 10 and 24 h r i nterval s after the harvest Sampl es were

not col l ected i n tri pl i cate i nstead the three stat i ons i n each

treatment type formed the basi s for stati sti cal compari son A total of

twel ve ( 1 2 ) stat i on depths and s i x (6) col l ect i ons resul ted i n seventyshy

two sampl es for ana lys i s The s i x col l ect i ons were i dent i fi ed as rounds

1 -6 i n data pri ntouts In 11Y parameters to be determi ned i ncl uded al l

l i sted with the except i on of l i ght penetrat i on and secchi depth

measurements Total col i form was not anal yzed due to the extremel y short

hol d i ng t i me of that parameter nor were repet i ti ve l i ght measurements

wh i ch have a h i gh potenti al for d i sturbance of the water mass due to the

actual sampl i ng process Suspended l oad and turbi d i ty anal yses were

ut i l i zed for est imates of l i ght attenuat i on S i l i cates col or and

i norgan i c carbon were not anal yzed as no phytopl ankton work was

conducted at th i s t i me

IV C INTER IM RESULTS

Al l water qual i ty data col l ected through the m idpo i nt of thi s

project appear i n Append i x 4 A and i ncl ude in s i tu and chemi cal anal yses

from the sampl i ngs performed on August 18 September 1 7 September 22

September 30 and October 28-29 1 987 and January 13 1 988 Means of

al l parameters measured i n the study s i te are presented i n Tabl es 4 4

and 4 5 by date but wi thout regard to treatment stat i on or depth

4 -8

The most notabl e of the in ll1Y parameters i s di ssol ved oxygen

More than 32 of al l observat i ons made were i n v i ol ati on of t he 5 0 mg1

i nstantaneous d i s so 1 ved oxygen cri teri on for C1 ass I waters and 20 of

a l l observat i ons were bel ow 4 0 mg1 (Tabl e 3 4 ) Samp1 i ng t i mes were

skewed toward the morn i ng hours and were thus abl e to record the effects

of pre-dawn resp i rati on of aquat i c vegetat i on at the s i t e

Surface sampl es were al so col l ected i n the Ki s s i mmee Ri ver

approximatel y midway between the S R 78 bri dge and Lake Okeechobee i n

add i t i on t o those sampl es spec i fi ed by the scope of work (Tabl e 4 6 )

Ion content ( sod i um potass i um chl ori de al kal i n i ty s i l i cates )

typi cal l y was l ower i n the ri ver than the s i te waters and i ncreased

sod i um and chl oride concentrat i ons were observed i n the southern port i on

of the study area The ri ver was general l y l ess turbi d ( turbid i ty total

suspended sol ids ) hi gher in col or and apparent ly represented a source

of d i ssol ved i ron to the area

Both throughout the s i te and i n the Ki ss immee Ri ver d i ssol ved

copper l evel s i f detected were only sl i ghtl y above the l i m its of

detect i on The same was true of n i trite-ni trogen wi th the excepti on of

the January sampl i ng On th i s date concentrati ons at the Ki ss inunee

stat i on were h i gher (0 027 mg1 ) than the rema i nder of the stat i on s and

concentrat i on grad i ents were apparent across the study s i te Data on

col or si l i cates and i norgan i c carbon al though presented i n the

append i x wi l l not be extens i vel y analyzed i n thi s sect i on as such data

were pri mari l y col l ected for use i n i nterpretat i on of phytopl ankton

anal yses

IV D DATA REDUCTIONS

Stati sti cal anal yses of i n s i ty and chemi cal data empl oyed one and

two-way analyses of vari ance where treatment effects ( harvested non shy

harvested stat i ons depths ) were consi dered as fi xed (Model I ANOVA)

Two-way anal yses were conducted empl oyi ng the same assumpt i ons when the

rel at i ve magni tude of effects was of i nterest S ign i fi cance l evel s were

set at 0 05 ( P 95) Except where noted anal yses ut i l i zed the

untransformed val ues of the vari ous parameters Log ( base e) data

4-9

trans format i ons were usual ly used to approxi mate normal d i stri but i ons

Parameters trans formed for analys i s i ncl uded orthophosphate ammoni a

n i trate -n i tri te-n i trogen potass i um i ron BOD turbi d i ty TSS and

sod i um

When vari ances among groups were s i gni fi cant i nd i v i dual means

were contrasted us i ng e i ther Student t-tests or Tukey s Student i zed Range

Test wh i ch computes the smal l est HSD ( honestly s ig n i fi cant d i fference )

for determi n i ng d i fferences Both were ap pl i ed at the P - 95 l evel

IV E DISCUSSION

IYr E I In 1i1Y Parameters

D i ssol ved oxygen l evel s and percent s aturat i on of d i ssol ved oxygen

were expected to show the most change from harvest i ng act i v i ti es W ide

d i urna 1 swi ngs shoul d be damped by the removal of 1 arge amounts of

Hydril l a D i urnal pH cycl es and to a l esser extent ORP woul d be

expected to fol l ow thi s pattern as l ess vegetat i on woul d be present to

con sume carbon d i ox ide Seasonal cycl es were expected i n temperature

data however d i urnal cycl es and verti cal thermal grad i ents were l ess

l i kely 1 n areas where dense stands of fl oat i ng Hydri l l a had been removed

For al l parameters wi nd generated m ix i ng i n harvested areas shou ld

1 es sen the degree of al l surface-to-bottom grad i ents Any changes i n

conduct i v i ty at a part i cul ar l ocat i on as a resul t of harvesti ng woul d be

i nd i rect and woul d l i kel y refl ect al terat i ons i n current structure by

removal of the Hvdri l1a mat and the i ncreased fl ush i ng i n harvested

areas

Due to the obv ious d i fferences between sampl i ngs anal yses of i n

tliY data empl oyed two -way ANOVAs usi ng date and treatment ( harvested

Stat i ons 7 8 and 9 and non-harvested Stati ons 10 1 1 and 1 2 ) as

factors Further as vert i cal grad i ents for some parameters appeared

substant i al data sets were al so subd i v i ded i nto surface and bottom

readi ngs and exami ned separately Data were anal yzed from the sampl i ngs

of September 1 7 22 and 30 and January 13 As ant ic i pated sampl i ng

date was a h i ghl y s i gn i fi cant factor for al l i n s i tu parameters

4 - 10

conduct i v i ty ORP pH temperature DO and percent saturat i on Those

parameters exh i bi t i ng d i fferences attri butabl e to harvest i ng impact were

DO and percent saturat i on at both surface and bottom and pH at bottom

No i nteract i ve terms were s i gn i fi cant i nd icat i ng a consi stent and

pred i ctabl e pattern of d i fferences

Di ssol ved oxygen l evel s averaged between 0 5 and 3 6 mgl h i g her

i n the experi mental ( harvested ) transect than i n the adj acent control

stat i ons Th i s pattern was general ly most ev i dent from read i ngs at the

bottom of the water col umn Overal l i ncreases i n percent saturat i on were

approxi mately 20

It shoul d be noted that the majori ty of these data were col l ected

before 1000 ( EST ) and that th i s t i mi ng affected both the magni tude and

the d i rect i on of d i fferences i n DO l evel s Had sampl i ng been conducted

predomi nantly dur i ng mid- to l ate afternoon i t i s most probabl e that the

unharvested and heav i l y weeded areas would have had s i gn i fi cant ly h i gher

DO val ues than the adj acent harvested areas The observed pattern i s

cons i stent wi th an enhanced pre-dawn DO middot sag middot i n areas wi th h i gher

dens i t i es of aquati c vegetat i on (control s ) To ensure that no bi as was

i ntroduced by sequence of sampl i ng on each date stat i ons were ranked by

t i me of sampl i ng the ranks summed by treatment and compared Duri ng that

sampl i ng with the most d i screpancy between treatment rank sums September

30 DO l evel s i ndi cated that thi s was not a seri ous factor

The overal l s i gni fi cance of date i n the previ ous anal yses was due

predomi nantl y to the i ncl us i on of the January data set as can be deduced

from the means presented i n Tabl e 4 4 W i th removal of th i s data set and

reanal ys i s of the three September sampl i ngs the onl y parameters where

date was a s i g n i fi cant factor were pH and ORP I n attempt i ng to quant i fy

the i mmed i ate i mpacts of harvest i ng the removal of the January data set

can be j ust i fi ed on the bas i s that the regrowth of Hydri l l a was

essent i al l y compl ete by th i s sampl i ng and that there were no obv i ous

d i fferences between experi mental and control stat i ons The s i gn i fi cant

d i fferences between experimental and control s for DO percent saturat i on

and bottom pH however were essent i al l y the same i n th i s reanal ysi s

i mpl y i ng that the i mpacts were most marked e i ther wi th i n the th i rty days

of harves t or duri ng that part i cul ar port i on of the growi ng season

4- 1 1

The i ntens i ve fi e l d demonstrat i on sampl i ng carr i ed out on October

28 and 29 1 987 to del 1 neate the invned i ate impacts of harvest i ng was

pr i mari ly desi gned to measure turbid i ty associ ated parameters or

nutri ents rel eased from the sed iments as a resul t of the passage of the

harvester The in 1iY data co 1 1 ected however were subjected to an

ana l ys i s s i mi l ar to the above (Tabl e 4 7 ) D i fferences between harvested

and unharve sted areas were s i gn i fi cant here for a l l parameters but

pri mar i l y for the val ues at depth D i ssol ved oxygen duri ng - th i s

samp 1 1 ng however was l ower overa 1 1 i n the harvested area As water

col umn oxygen demand (BOD ) was comparabl e between transects reference to

sampl i ng t imes the majori ty after 1000 EST cl ari fy thi s apparent

d i screpancy These d i urnal cycl es are apparent i n F i gure 3 7

Duri ng the i mmedi ate impacts sampl i ng conduct i v i t i es were

s i gn i fi cant ly h i gher i n the experimental area than at the control

stat i ons wi th i n one hour of the passage of the harvester ( F i gure 4 6)

Cond i t i ons i n both areas had been comparabl e just pri or to the harvest

Th i s may i l l ustrate the rap id i ty wi th wh i ch fl ush i ng rates are i ncreased

Al l other in 1i1Y parameters wi th the except i on of percent saturat i on

exh i b i ted s ign i f i cant changes over t ime part i cul arly a t the bottom of

the water col umn These are i l l u strated for the rema i n i ng parameters i n

F i gures 3 9 through 3 1 1 where subtl e di fferences produced by harvest i ng

are superi mposed upon d i urnal cycl es The magni tude and s i gn of

d i fferences for many parameters in add i t i on to DO between harvested and

control stat i ons were heav i l y dependent on the t i me of day

Vert i cal grad i ents i n vari ous parameters were expected to be

reduced as a resul t of the removal of the advect i ve barri er of the

Hydri l l a mat and the consequent i ncrease i n wi nd -generated mi x i ng

Anal yses of vari ance of surface mi nus bottom in s i tu val ues as a s i ng l e

vari abl e were performed wi th stati ons

( harvested ) and control ( unharvested

comparat i ve ly non -weeded stat i ons ) Of

categori zed i nto experi mental

i ncl ud i ng both weeded and

the s i x sampl i ngs anal yzed i n

th i s manner surface to bottom grad i ents were most often observed for pH

DO and percent satura t i on Surface DO val ues ranged between 0 3 and 3 8

mgl h i gher (4 -46 saturat i on ) and surface pH between 0 04 and 0 2 SU

h i gher

4 - 1 2

Surface to bottom grad i ents were a 1 so apparent i n both

experi mental and control areas duri ng the immed i ate i mpacts sampl i ng of

October 28 and 29 Except for conduct i v i ty vert i cal grad i ents for these

two treatments were not stat i st i cal l y d i fferent from one another when the

fi ve post -harvest sampl i ng rounds were consi dered as a un i t Thi s

s i mi l ari ty i n grad i ents however shoul d not be confused wi t h the

d i fferences previ ousl y demonstrated between treatment areas for th i s

sampl i ng as the grad i ent anal ys i s i s concerned onl y wi th the d i fference

between surface and bottom val ues and makes no statement concern i ng the

rel ati ve posi t i ons of i nd i v i dual val ues

The fact that gradi ents were present at al l i n the harvested area

duri ng October may impl y that the d i mensi ons of the pl ot from wh i ch

HydrjJ l a was removed ( approxi matel y 6 by 1 20 meters ) were i nsuffi c i ent

for exi st i ng wi nd d i rect i on and vel oc i ty to cause substanti al mix i ng

Water depths ranged between 1 2 and I Sm These grad i ents were present

for pH DO and percent saturat i on agai n for the January sampl i ng i n both

control and experi mental transects wh i ch i s not surpri s i ng i n l i ght of

the degree of regrowth over four months s i nce harvest and the phys i cal

s imi l ari ty of stat i ons at th i s t i me

E2 Chemical Parameters

The anal ys i s of chemi cal data was desi gned to answer the fol l owi ng

questi ons for the sampl i ngs to date

o Are there detectabl e water qual i ty d i fferences between the

experimental and control stat i ons

o If there are was thi s ei ther d i rect l y or i nd i rect ly a product of

harvest i ng act i v i ty or i s i t the byproduct of stat i on l ocat i on

and the resul t of natural d i l ut i on grad i ents ( i e l oad i ng from

the Ki s s immee Ri ver or other sources )

o I f there are no s ign i fi cant d i fferences between harvested and

unharvested areas were d i fferences to be expected on the bas i s of

water mass compos i t i on

4 - 13

Where chemi cal spec i es are not d i rect ly correl ated wi th a d i st i nct

water mass or where i nputs to the water col umn are d i ffuse enough to

prevent the ma i ntenance of a spat i a 1 grad i ent or the detect i on of a

s i ngl e sourc e data analysi s i s s i mpl i fi ed to a compari son of treatment s

experimenta1 s agai nst control s Seasonal trend s i f present can be

factored i nto the stat i st i cal ana lys i s A s i mpl e compari son of harvested

aga i nst unharvested area chemi stry can al so be performed shoul d i on

content and rat i os i ndi cate that these water masses were i denti cal duri ng

sampl e col l ect i on and that d i l ut i on grad i ents can be i gnored

However when nutri ents or other spec i es are i ntroduced i nto a

system a ssoc i ated wi th a di sti nct water mass and when d i l ut i on with

ex i st i ng waters produces detectabl e gradi ents the quest i on s become more

compl ex In add i t i o n b i ol og i cal uptake wi l l produce non - l i near

rel a t i on sh i ps and the separati on of harvesti ng impacts from expected

gradi ents becomes more d i ffi cul t

The compl ex i ty of these questi ons i n the presence of d i l ut i on

grad i ents can be i l l ustrated graph i cal l y by reference to Fi gure 4 1 2

where hypotheti cal data appear In the fi rst part parameter X i s a

l i near func t i on of sod i um or i n other word s X i s a l so a con servati ve

parameter so i ts absol ute l evel i s affected onl y by d i l uti on wh i ch

mai nta i n s a constant X Sod i um rat i o Th i s regress i on would be devel oped

u s i ng one day s data from the ent i re gri d of n i ne control stat i ons across

the study s i te The hypothet ical data from a harvested stat i on (Stat i on

7 ) and the control (Stat i on 10 ) are al so pl otted It i s apparent that

wh i l e the l evel s of parameter X at the harvested and control stat i on

shown are probabl y not stat i st i cal l y d i fferent from one another the

harvested stat i on c l earl y fal l s outside of the 95 confi dence i nterval of

the X Sod i um regress ion for thi s data set and d i fferences from the l evel s

expected may refl ect harvest i ng i mpacts

In the second port i on of Figure 4 1 2 an al ternate s i tuat i on i s

i l l ustrated where the 1 eve1 s of parameter X at h arvested and control

stat i ons are shown to be c l earl y d i fferent However it i s apparent that

the water mass at the harvested stat i on i s sl i ghtl y more d i l ute and that

the correspond i ngl y l ower l evel s of parameter X are to be expected I n

4 - 14

both s i tuat i ons any b i ol og i cal processes affect i ng parameter X wi l l

produce even more compl ex rel at i onsh i ps

Sod i um and chl ori de were fi rst exami ned for i ns i g ht i nto water

mass movement and d i l ut i on processes occurri ng across the study s i te

The sum of these two i ons ( i n mi l l i equ i va1ent s ) was empl oyed a s an

approxi mat i on of total i on content They were both assumed to be

conservat i ve i e not part i ci pat i ng to any substant i al degree i n

b i ol og i cal processes where they might be sequestered or added to t he

water col umn F i gure 4 13 i l l ustrates thi s d i l ut i on process as i t occurs

across the study s i te The rat i o of sod i um to chl oride was al so

cal cul ated as an i dent i fy i ng feature of a part i cul ar stat i on

The gri d of ni ne control stat i ons was sampl ed on three occas i ons

August 1 8 September 30 1987 and January 13 1988 These data were

exami ned as t hey represented the 1 argest spat i a 1 area Anal yses of

vari ance i nd i cated that both total i on content and sod i um ch1 0r ide rati os

vari ed s ign i fi cant ly wi th respect to sampl i ng date I n l i ght of the

seasonal pattern of preci p i tat i on and the i nfl uence of ri ver d i scharge on

the area th i s was not surpri s i ng I n add i t i on however stat i on was

h i gh l y s i gn i f icant as a factor In the case of sod i um pl us chl ori de

th i s represents a change i n total i on content or d i l ut i on occurri ng

across a spat i al grad i ent ( Fi gure 4 14 ) I n the case of sod i um ch 1 0r i de

rat i os the fact that rat i os are di fferent at d i fferent stat i ons impl i es

that two or more separate water bod ies are represented across the s i te

( F i gure 4 1 5) I nteract i ve terms were al so s i gn i fi cant for each

parameter i nd i cat i ng that d i fferences were not cons i stent across t i me or

space Th i s i s apparent i n compari ng Fi gure 4 13 wi th Fi gure 4 14

As the mi xi ng of more than two water masses together woul d make

ana l ys i s of the rema i n i ng parameters extreme ly mathemat i cal l y compl ex

regress i ons of sodi um aga i n st chl ori de were performed for al l control

stat i ons on the three sampl i ng dates On each date correl at i ons for

l i near rel at ionshi ps were s ign i fi cant at pgt99 9 Th i s resul t al l owed

the use of the assumpt i on that onl y two water masses were mi x i ng across

the s i te Parameters associ ated wi th one of the two water masses coul d

therefore be detected by regress i ons on sod i um or some other conservat i ve

parameter

4 - 1 5

Anal yses of water qual i ty impacts were i n i t i al l y restri cted to

four sampl i ngs September 1 7 22 and 30 1 987 and January 13 1 988

Stat i ons 7 - 9 for experimental and Stat i ons 10 - 1 2 for control s (Stat i on

7 5 and 10 5 were used for the J anuary data set as an area wh i ch

i nc l uded Stat i on 7 had been reharvested shortl y before the sampl i ng )

S i gn i fi cant amounts of vari ati on between experi mental (Stat i on s 7

8 9 ) and control s ( Stati ons 1 0 1 1 1 2 ) as groups were found us i ng

two-way ANOVAs wi th date and treatment as factors (Tabl e 4 8 ) Al l

n i trogen and phosphorus spec i es (wi th the except i on of orthophosphate )

conta i ned s i gn i fi cant amounts of vari at i on d i stri buted between the

harvested and unharvested control stat i ons In add i t i on for BOD

turb id i ty and total suspended sol i d s d i fferences were present as wel l

As expected potassi um fl uoride chl ori de and sod i um d i d not d i spl ay

s i gn i fi cant vari ati ons between data from harvested and unharvested

stat i ons I ron copper total organ i c carbon and al kal i n i ty were al so

not s i gn i fi cant ly d i fferent between treatments

As d i scussed above however d i fferences between harvested and

unharvested areas are strai ghtforward onl y i f I water masses i n each of

the two treatment areas were identi cal or 2 the anal yzed parameter has

no s i gn i fi c ant rel ati onsh i p to a part i cul ar water mas s or to sod i um

Al though n o s ign i fi cant d i fferences i n sod i um o r chl ori de

concentrat i ons were observed between harvested and unharvested stat i ons

as a group di 1 ut i on grad i ents of these parameters were present wh i ch

paral l el ed the axi s of the harvested transects ( Fi gure 4 1 4 ) As a

resul t the data envel ope for the stati ons of a s i ngl e treatment was

l arge i n compar i son to any subtl e d i fferences between transects (F i gure

4 16 ) The fact that any di fferences were detected between experi mental

and control transects (Tabl e 4 8) impl i ed that they were substanti al

enough to overr ide the wi th i n -treatment vari abi l i ty expected from the

sod i um grad i ent S i gn i fi cance of i nteract i ve tems i n these model s

i nd i cated that d i fferences were not cons i stent from sampl i ng to sampl i ng

To d i rect l y compare harvested and non-harvested water qual i ty the

water of the two treatments must represent i dent i cal d i l ut i ons of source

and rece i v i ng waters As d i l ut i on gradi ents were roughly paral l el to the

transect axes stat i ons were pa i red and the d i fferences of experimental s

4 - 1 6

l ess control s cal cul ated for each pa i r of sod i um and chl ori de data

( Stat i ons 7 - 1 0 8- 1 1 9 - 1 2 Tabl es 4 9 4 10 ) The mean d i fferences

computed for al l sampl i ngs or for each date were on no occas i on d i fferent

from zero ( t - tests ) I n add i t i on no cons i stent pattern of d i fferences

was observed The conc1 us i on was that wh l l e di fferences 1 n the water

mass were present between stat i ons w ith i n a s i ngl e treatment harvested

stat i ons and t he i r adjacent control pai rs represented i dent i cal waters on

each date w i th respect to d i l ut i on

As water masses were i dent i cal the d i fferences i n parameter

concentrat i ons were cal cul ated for each stat i on pa i r as for sod i um and

chl ori de above These d i fferences are summari zed i n Tabl e 4 1 1 for those

parameters for wh i ch treatment was a s i gn i f icant factor i n the two-way

ANOVAs descri bed above (Tabl e 4 8 ) The magn i tudes of the d i fferences on

i nd i v i dual dates when not stat i st i cal l y equ i val ent to zero are al so

presented

Us i ng the pai red compari sons of stat i ons al l n i trogen s peci es and

total phosphorus exh i bi ted s i gn i fi cant al though subtl e d i fferences

between harvested and unharvested areas for the sampl i ngs to date (The

only date where orthophosphorus showed treatment d i fferences was on

September 22 and on th i s occas i on the magni tude was onl y 0 002 11191

1 ess than the 1 im i t of detect i on ) These d i fferences are most notabl e

for n i trate and ammon i a n i trogen and are i n add i t i on to any d i l ut i on

grad i ents across the s i te They can be presumed to refl ect the i mpacts

e i ther d i rect or i nd i rect of harvest i ng

Concentrat i ons where d i fferent were typi cal l y l arger i n the

unharvested control transect Th i s may be attri buted to e i ther uptake by

regrowth at harvested stat i ons or to the rel ease of nutri ents by

senescent macrophytes or peri phyton at the unharvested l ocat i ons

Fl oat i ng mats of Hydrj 1 1 a i n vari ous cond i t i ons were present through the

September 30 sampl i ng

B i ochemi cal oxygen demand turbi d i ty and suspended sol i d s al so

showed d i fferences us i ng stat i on pa i rs al though i n the i n stance of

suspended sol i ds concentrat i ons were sl i ghtl y h i gher at the harvested

stat i ons Wi nd -generated sed i ment resuspensi on i n harvested areas and

suspended senescent pl ant materi al i n the unharvested areas (contri but i ng

4- 1 7

to turbi d i ty and oxygen demand but wi th rel at i vely l i ttl e dry we i ght ) are

postul ated to account for these d i fferences Th i s i s supported

c i rcumstant i al l y by the l argest d i fference i n suspended sol ids be i ng

observed on September 30 when w i nd cond i t i ons were the most extreme of

any of the days sampl ed

The l argest number of parameters d i fferent between harvested and

weeded areas was al so observed on September 30 wh i l e the fewest were

seen on January 1 3 1 988 Whether th i s d i stri but i on across t ime i s a

res ul t of 1 ) vary ing nutri ent uptake rates throughout the growi ng season

2 ) the essent i al l y compl eted regrowth observed by the January s ampl i ng

3 ) the h i gher l ake l evel s and l ack of a fl oati ng mat of Hydri l l a perhaps

reduc i ng res idence t i mes of water across the s i te duri ng January or

4) the h i gher January nutri ent l evel s maki ng d i fferences more d i ff icul t

to d i scern i s i mposs i bl e to resol ve

Another techn i que for data anal ys i s was empl oyed on the September

30 and January 13 data sets for those parameters wh i ch were associ ated

wi th d i l ut i on grad i ents across the s i te Bri efl y i f the grid of control

stat i on s d i spl ayed s i gn i fi cant regress i ons with sod i um theoret ical

parameter concentrat i ons were cal cul ated for al l control and experimental

stati ons based on the observed sod i um data and that funct i on wi th the

h i ghest regress i on coeffi ci ent Res i dual s (V i - V hat) were then

compared by t - tests between means of experimental and control groups to

determi ne i f popul ati ons were the s ame (no impacts F i gure 3 1 2B) or

d i fferent ( i mpacts Fi gure 4 1 2A)

L i sted i n Tabl e 4 1 2 by date are the regres s i on types and

coeffi c i ents of the vari ous parameter concentrat i ons wi th sod i um Onl y

surface data from control stat i ons were used The vari ed nature of i nputs

to the s i te i s exempl i fi ed by F igures 4 1 7 and 4 18 dep i cti ng the vast l y

d i fferent d i stri buti ons of orthophosphorus between September and January

Whi l e rel at i vel y few parameters were apparentl y associ ated wi th

d i l ut i on duri ng the August sampl i ng the h i gher l oads i n September and

January perhaps coupl ed with sl owed uptake and growth rates duri ng the

l atter part of the year may produce l onger water col umn res idence t i mes

for nutri ent spec i es and permi t the detect i on of d i l ut i on grad i ents i n

4 - 18

these parameters Chl ori de and potas s i um and any other parameter onl y

s l ightl y affected by bi ol og i cal act i v i ty shoul d certa i nl y produce

s i gn i fi cant rel ati onsh i ps (The l ack of s i gn i fi cance of fl uor i de wi th

res pect to sod i um i s attri buted to the extremel y l ow l evel s encountered

e g concentrat i ons at or bel ow the l i mi t of detect i on for th i s

parameter )

Overal l the res i dual s anal ys i s of sod i um dependency proved l es s

sens i t i ve than that o f the pai red stat i ons anal yses O f the twenty-two

parameter-date combi nati ons where a s i gn i fi cant regress i on wi th sod i um

was obtai ned res i dual s of experimental stat i ons were s i gn i fi cant ly

d i fferent from res i dual s from control stat i ons for onl y three parameters

- - orthophosphorus and al kal i n i ty duri ng September 30 1 987 and n i tri teshy

n i trogen dur i ng January 13 1 988 Figure 4 19 superimposes the

experi mental stat i on orthophosphorus concentrati ons upon the rel at i onsh i p

devel oped for control stati ons i n September I t can be seen here that

the experimental stat i ons (X) are not evenl y d i stri buted around the

regress i on l i ne

Orthophosphorus concentrat i ons on th i s occas i on were l ower i n

the experi mental transect but onl y by 0 002 mgl l ess than the l i mi t of

detect i on Al kal i n i t i es at these stat i on s were h i gher than sod i um

concentrat i on s mi ght pred i ct by about 9 mgl as CaC03 Duri ng January

n i tri te - n i trogen was al so l ower at the harvested stat i ons than woul d be

expected on the bas i s of d i l ut i on al one but aga i n by l ess than the l imi t

of detect i on

As troph i c states and nutri ent l i mi tati ons wi thi n Lake Okeechobee

area of concern rati os of d i ssol ved and i norgan i c n i trogen to phosphorus

spec i es were cal cul ated and summari zed i n Tabl e 4 1 3 On a we ight bas i s

systems wi th rat i os l ess than 1 0 are typ i cal l y cons i dered n i trogen

1 i mi ted wh i l e phosphorus 1 im i tat i ons occur at rat i os greater than 1 7

( Sakamoto 1 966) Wi th th i s cr i teri on the waters o f the study s i te are

cl earl y n i trogen l imi ted i n contrast to al gal assays performed i n the

v i c i n i ty duri ng 1 974 and 1 975 ( Dye et al 1975 ) These resul ts have the

most consequences for phytopl ankton popul ati ons rather than macrophytes

as the rooted pl ants are capabl e of extracti ng at l east some i f not the

majori ty of thei r requ i red nutri ents from the hydroso i l

4 - 19

The stati st i cal anal yses d i scussed earl i er for the i ndi vi dual

parameters determi ned i norgan i c ni trogen spec i es to be h i gher i n the

unharvested control stat i ons and orthophosphorus to be s l i ghtl y l ower

ANaYA s of N P rat i os al so found s i gni fi cant d i fferences The treatment

( harvested or unharvested ) or stat i on was more important than date i n

account i ng for vari ati on Al l September and January sampl i ngs combi ned

produced mean N P rat i os for the harvested stat i ons ( 7 - 9 ) of 3 0 and for

the unharvested d i fferences coul d be attri buted e i ther to uptake by

act i vel y growi ng p l ants or to rel ease of nutri ents by senescent p l ant

materi a 1 Oi fferences between harvested and nonharvested areas were

l east apparent duri ng the January sampl i ng when ri s i ng l ake l evel and

Hydri l l a regrowth combi ned to i ncrease stat i on to stat i on phys i cal

s i m i l ari t i es

E 2 Bacteri ol ogi cal Parameters

Resul ts of total col i form anal yses (membrane fi l ter techn i que) of

sampl es col l ected on August 18 September 1 7 22 30 1987 and January 13

1 988 appear in Tabl es 4 1 4 After the August fi e ld effort sampl es were

col l ected i n conjuncti on wi th the phytopl ankton work and al l sampl es were

anal yzed by EQL Overal l bacteri ol ogi cal qual i ty was qu i t e good wi th

on ly a s i ngl e sampl e exceed i ng the 1000 counts per 100 ml cri teri on for

Cl ass I waters Th i s s i ngl e val ue of 5000 (Stat i on 1 1 September 30

1 987 ) was cl as sed as a stat i st i cal outl i er for the study as a whol e The

other two val ues from sampl es col l ected s i mul taneously were 900 and

100100 ml Most stat i on means were bel ow 200 countslOa ml

Stat i st i cal anal yses of these data empl oyed natural l og

transformat i on s Two way ANaYA s (by date and treatment and by date and

s t at i o n ) prod uced s i gn i fi cant terms for date and i nteract i ve

rel at i onsh i ps however nei ther harvesti ng nor stat i on accounted for

s ign i fi cant amounts of vari at i on Further anal yses cons i sted of mul t i pl e

l i near regress i ons of l og transformed total col i form counts aga i nst BOD

turb i d i ty total suspended sol i d s sod i um and chl ori de content ( as water

mass i ndi cators ) col or and s i l i cates A s i gn i fi cant regress i on model

whi ch i ncl uded BOD col or and TSS was obtai ned (r2 = 0 255 n 72) A

4 -20

d i rect rel ati onsh i p wi th BOD was not surpri s i ng The vari at i on wi th

col or val ues may be support for runoff control l ed bacteri a l evel s in the

l ake i ncreas i ng duri ng peri ods of h i gh d i scharge or backpump i ng (wh ich

are themsel ves characteri zed by i ncreased col or l evel s from t he

accumul ated surface waters An i nverse rel at i onsh i p w i th TSS l evel s was

l ess amenabl e to i nterpretat i on and i s l i kely to have been an art i fact of

some other control l i ng i nfl uence

IV E WATER QUALITY IMPACTS - QUALITY ASSURANCE OBJECTIVES

Prec i s i on and accuracy targets and resul ts for in ll1Y water

qual i ty parameters are presented in Tabl e 4 1 5 Prec i s i on est i mates were

based on dupl i cate in 1iY determi nat i ons expressed as percent rel ati ve

standard devi at i on (S RSD) Measurements at one stat i on per day were

typ i cal l y repl i cated i n thi s fash i on Prec i s i on est i mates for fi el d

measurements necessari l y i nc l uded the representati veness of the sampl i ng

as any non - homogene i ty of the s i te bei ng sampl ed appeared i n these

resul t s

Accuracy was determi ned from both pre- and post - sampl i ng

cal i brat i on of i nstrumentati on and where appl i cabl e the s i mu l taneous

col l ect i on of sampl es for l aboratory analysi s wi th al ternate procedures

or equ i pment Thi s was expressed as percent recovery ( R) of

f i el dl aboratory val ues t i mes 1 0 Col l ect i on of sampl es for

veri f icat i on was typi cal l y conducted at a rate of 1 for every 1 0 stati ons

samp l ed For th i s project di ssol ved oxygen and conducti v i ty were so

veri fi ed

Comparabi l i ty o f data was veri fi ed duri ng the pre- and postshy

sampl i ng cal i brati ons of i nstrumentat i on aga i nst standard sol ut i ons or

phys i c al constants Compl eteness of in 1iY data was esti mated to be

greater than 88 throughout the sampl i ngs to date

The qual i ty assurance object i ves for l aboratory anal yses were

anal ogous to those d i scussed for the i n s i tu parameters and are l i sted i n

Tabl e 4 14 Prec i s i on esti mates were determi ned from the anal yt i cal

resul ts and SRSD between the concentrati ons of two al i quots of a s i ng l e

conta i ner Dupl i cate analyses were performed at a rate of at l east one

4 - 2 1

for every ten sampl es The RSD between sampl es only sl i ghtly above the

l i mi t of detect i on i s often qu i te h i gh al though the analys i s i s

extremel y prec i se ( L e 0 001 and 0 002 11191 47 1 RSD ) Some mean

tRSD val ues and SD val ues are skewed by these seemi ngl y i mprec i se

dupl i cates that are actual l y wi th i n QA l i mi ts Accuracy of analyses was

assessed by the analys i s of sampl es to wh i ch known amounts of standard

materi al s had been added

IVG I NTERIM SUMMARY AND CONCLUSIONS

The study area i mmedi ately south of the entrance of the Ki s s 1mee

R i ver i nto Lake Okeechobee represents a compl ex combi nat i on of factors

wi t h regard to water qual i ty Vari at i ons with t i me were observed for

almost al l parameters measured D i ssol ved oxygen v i ol at i ons of the 5 0

11191 i nstantaneous cri teri on were common and d i urnal cycl es of DO and

rel ated parameters were apparent The skew i n sampl i ng t i mes toward the

morn i ng hours undoubtedly i ncreased the number of observed v i ol at i ons

a l though sampl i ng l ater i n the afternoon woul d i ncrease the percent

saturat i on of d i ssol ved gases and val ues i n excess of the 1 10 cri terion

wou l d have resul ted

In li1Y parameters were i n i t i al l y eval uated for stat i st i cal

d i fferences between harvested and unharvested stat i ons as a grou p

Di fferences i n DO percent saturat i on and p H were observed and were most

marked at the bottom of the water col umn and duri ng the September

sampl i ngs Pred i ct abl y harvesti ng reduced the ampl i tude of the d i urnal

DO cycl e such that DO concentrat i ons were h i gher i n the harvested

transect i n the morn i ng hours and l ower duri ng the afternoon Both the

magn i tude and the d i rect i on of the observed d i fferences were therefore a

funct i on of the t i me of sampl i ng

A rap i d change i n water masses was al so observed at harvested

stat i ons and th i s was attri buted to the i ncreased fl ush i ng potent i al

produced by Hydri l l a removal Inten s i ve surveys detected vert i cal

grad i ents of s i mi l ar magn i tudes for i n s i tu parameters at both harvested

and control stati ons The s i ze of the harvested transect may have been

too smal l to al l ow wi nd-generated vert i cal mi xi ng to be effect i ve

4-22

Bacteri ol og i cal water qual i ty at the s i te was good overal l wel l

wi th i n the 1000 1100 ml cri teri on and correl at i ons w ith col or BOD and

TSS were present Col or rel at i onshi ps i ndi cate a functi onal rel at i onsh i p

of total col i form wi th d i scharge i nto the l ake whi l e the rel at i onsh i p

wi th TSS was i nverse

Chemi cal water qual i ty d i stri but i ons at the s i te were a l so qu i te

compl ex Spat i al and d i l uti on grad i ents produced by the i nfl uence of the

K i s s i mmee Ri ver were qu i t e apparent as determi ned by conservat i ve

parameters such as sod i um and chl ori de The d i l ut i on grad i ents were

roughl y paral l el wi th the l ong axi s of the harvested transects such that

a progress i on of i ncreas i ng strengths of Lake Ri ver d i l ut i ons were

observed al ong both the experimental harvested transect and the adjacent

unharvested control transect Thi s transl ated to a h i gh wi th i n -treatment

va ri a b n i ty of water masses compared to the between- treatment

vari abi l i ty wh i ch i n turn may obscure d i fferences between harvested and

unharvested areas i n stra ightforward stat i st i cal compari sons

Overal l stat i sti cal techni ques were sat i sfactory because the

number of sampl es adequate for determi ni ng di fferences i n concentrat i ons

was at or near the analyt i cal l imi ts of detect i on The three stat i st i cal

anal yses were 1 ) d i rect compari sons (means test i ng and ANOVA s ) of

harvested to unharvested data sets 2) ana lys i s by d i fference of stat i on

pa i rs ( harvested l ess the adjacent control stati on) and whether

d i fferences were stat i sti cal l y d i fferent from zero and 3) res i dual s

anal ysi s of those parameters wi th a s ign i fi cant rel at i onsh i p w i th sod i um

and whether the popul ati on of res i dual s from control stati ons was

equ i val ent to those from the harvested stati ons

Ana lys i s of harvested versus unharvested data groups by parameter

reveal ed s i gn i fi cant d i fferences between treatments for al l n i trogen

spec i es total phosphorus BOD turb id i ty and total suspended sol i ds

These d i fferences are i n sp i te of the broad envel ope i n water qual i ty

conta i ned wi th i n each treatment type However d i rect compari sons and

correct est i mati on of the magni tude of harvest i ng impacts are poss i bl e

onl y where the water masses of the two treatments can be assumed to

represent equ i val ent po i nts on the d i l ut i on grad i ent

The d i fference i n sod i um and chl ori de concentrat i ons between each

harvested stat i on and i ts adjacent unharvested stat i on was cal cul ated

For al l dates these d i fferences were equ i val ent to zero mean i ng that

the water mass was i dent i cal at Stati ons 7 and 10 at Stat i ons 8 and 1 1

and at Stat i ons 9 and 1 2 The d i fferences i n concentrat i ons between the

stat i on pai rs cou l d then be calcul ated Al l n i trogen spec i es and total

phosphorus concentrat i ons were typ i cal l y h i gher i n the unharvested

transect On the one occas i on where orthophosphorus d i ffered between

treatments i t was s l i ghtl y h i gher i n the harvested transect Turbid i ty

and BOD were al so h i gher at the control stat i ons wh i l e total suspended

sol i ds were sl ightly l ess Uptake by macrophytes i n act i ve regrowth

rel ease o f nutri ents by senescent and matted pl ant mater i al and wi nd shy

generated resuspens i on may account for thi s pattern

Ana lys i s of those parameters associ ated wi th d i l u t i on and of those

wi th s i gn i fi cant correl at i ons wi th sod i um proved l ess sens i t i ve for

detect i ng d i fferences Al though many parameters d i spl ayed s i gn i f icant

rel at i onsh i ps the i r d i stri but i on around the regress i on l i ne was

cons i derabl e and res i dual popul at i ons were s i gn i fi cantly d i fferent

between treatments for only three parameters

The s i te as a whol e appeared to be n i t rogen 1 i mi ted based on

we i g ht r at i os of i norgan i c n i trogen forms to orthophosphorus

O i fferences between harvested and unharvested areas were apparent here

al so w i th average rat i o s of 3 0 and 9 4 respect i vely

IVG RECOMMENDATIONS - FINAL REPORT

For the rema i n i ng two quarterly sampl i ngs i n th i s task a

real l ocat i on of effort i s proposed wh i ch woul d del ete copper and fl uori de

from the anal yt i cal su i tes These two parameters were e i ther at or near

the 1 im i ts of analyt i cal detect i on for al most al l s ampl es and

stat i sti cal analyses were not effect i ve i n determi n i ng any d i fferences

attri butabl e to harvest i ng at these l ow concentrat i ons N i tri teshy

n i trogen however shoul d be reta i ned Al though l evel s were l ow they

are i mportant i n th i s n i trogen 1 i mi ted system and d i fferences between

treatments were apparent The Ki ss i mmee R i ver stat i on shou l d cont i nue to

4-24

be sampl ed and another stat i on shou l d be added to the west of Stat i on 1

toward Buckhead Ridge as an i ntermi ttent nutri ent i nput may be present

there Mon i tori ng of these two add i t i onal stat i ons shou l d cont i nue for

al l parameters In pl ace of copper and fl uor ide anal yses d i ssol ved

cal c i um i s suggested as a repl acement to prov ide a bas i s of compari son

wi th other work done prev i ously i n the l ake and to exam i ne i ts behav i or

across the s i te The poss i b i l i ty of mov i ng the exper imental and control

stat i on pai rs ( Stat i ons 7 - 1 2 ) to the most recently harvested area for the

subsequent sampl i ng i s currentl y be i ng d i scussed wi th the task l eaders of

the i nter-rel ated tasks

Future data exami nat i ons wh i ch wi 1 1 be conducted for the fi nal

report of th i s project i ncl ude the deta i l ed assessment of l i ght

penetrat i on profi l es and the effect of the weed mat upon these The data

from the 24 hour fi el d demonstrat i on sampl i ng wi l l be eval uated w ith

regard to chemi cal parameters and the i mmedi ate effects produced by

harvest i ng S i l i cates col or and i norgan i c carbon data wi l l be

processed as wi l l the rema i n i ng parameters for d i fferences between

experi mental and control stat i on s and a further anal ys i s of d i ssol ved

oxygen wi th cons i derat i ons for t i me of day vegetat i on and even sed i ment

type wi l l be conducted

4-25

LITERATURE CITED

Dye C W D A Jones L T Ros s R L Wi l l more 1 975 L imi t i ng nutri ents i n the Ki ss i llll1ee Ri ver - Lake Okeechobee Bas i n based on al gal assay techni ques Fl a Dept Envi ronmental Regul at i on Sakamoto H 1 966 Pri mary product i on by phytopl ankton conununi ty i n some Japanese l akes and i ts dependence on l ake depth Arch Hydrobi ol 62 1 - 28

4-26

Table 4 1 Mean IDran coordinates of water quality staticns

STATIOO NO

1 2 3 7 7 5 8 9 10 10 5 11 12 13 15 16

Ipound)RAN 1 JPRAN 2

14313 2 45453 2 14312 6 43449 1 14312 4 43445 9 14313 6 43449 1 14313 4 43448 2 14313 2 43447 7 14312 9 43446 1 14313 7 43448 5 14313 5 43447 7 14313 4 43447 3 14312 9 43445 7 14315 1 43444 6 14313 9 43443 2 143109 43437 8

Table 4 2 water Quality parameters methods ard holdirq times

Parameter

TeJlFerature Corrluctivity pi ORP Dissolved Oxygen Light Penetratim Secxhl laboratory 0rthqil0spl0rus (D) Total AlosJtIorus (D) AImalia-Nitrogen (D) Nitrite-Nitrogen (D) Nitrate-Nitrogen (D) Total Kjeldahl Nitrogen ium (D) Ccgler (D) Iran (D) Total OJgan1c carbon Alkalinity Biochemical Oxygen DeuanI lu1)idity SUspenled Solids Ibtal Ollifonn auoride Scdium Fluoride Color silicates (D) Inorganic Cartlon

MetbodlInstrument

Martek Mark VII Martek Mark VII Martek Mark VII Martek Mark VII YSI 57 LiOlr Secxhl Disk (LiDngtlogical)

EPA 365 1 365 3 EPA 365 3 365 4 SM 417F EPA 350 3 EPA 353 3 353 3 EPA 353 2 353 3 EPA 351 2 SM 30lA SM 303A B SM 303A B EPA 415 1 8M 403 4C EPA 3102 EPA 405 1 EPA 180 1 SM 2090 8M 908A 909A SM 4070 EPA 325 3 SM 303A EPA 3402 SM 204A B EPA 370 1 SM 425C EPA 415 1

Holdirg TimePreservative Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable

Filter iDmSdiately 48 hrs4Oc 28 daYSH2S04 to pllt2 40c Filter bImadiately 28 daYSH2S04 to pllt2 40c Filter bImadiately 48 hrsH4 to pllt2 40c Filter iDmSdiately 28 daYSH4 to pHlt2 40c 28 daYSH2S04 to pllt2 40c Filter iDmSdlately 6 1IDSIftll) to pllt2 40c Filter iDmSdiately 6 1IDSIftll) to pllt2 40c Filter inmediately 6 1IDSIftll) to pHlt2 40c 28 daYSH2S04 to pIlt2 40c 14 days4oC 48 hrs4Oc 48 hrs4Oc 7 days4Oc 6 hrs4Oc 28 days4Oc Filter inmdiately 6 lOOIlthslftll) to pIlt2 40c 28 days4Oc 48 hrs4Oc 28 days4Oc 28 days4Oc

EPA = EPA 6004-7920 Methods for OJemical Analysis of water ard wastes SM = stanIard Methods for the Examination of water ard wastewater 15th Fdition 1980 (D) = Dissolved

Tabl e 4 3

Date

Aug 18 1987

Sept 17 1987

Sept 22 1987

Sept 30 1987

Oct 28-29 1987

Jan 13 1988

Sampl i ng efforts and dates Water Qual i ty Tas k

Sampl i ng Type

Basel i ne

Short Term Impacts

Short Term Impacts

Quarterly

F i el d Demonstrat i on

Quart erly

No of Stat i ons

9

6

6

12

6

12

No of V i al s

1

1

1

1

6

1

Table 4 4 site averages of in situ parameters by sanplirg date all stations all depths

1987 1988

AU 18 SEP 17 SEP 22 SEP 30 ocr 28-29 JAN 13

n 28 18 18 36 144 68

2 SD 2 S D 2 S D S( S D S( S D 2 SD

onluctivity 0 5350 0661 0 5397 0351 0 5074 0550 0 4985 0517 0 3921 0731 0 3017 0895

ORP 493 109 441 42 298 77 293 47 295 31 247 55

Pi 8 02 0 55 8 27 0 34 7 56 027 7 47 043 7 72 0 51 7 59 0 30

lenperature 28 95 144 27 34 0 50 27 23 054 26 67 041 23 11 099 16 67 078

Dissolved Oxygen (00) 5 02 3 20 3 51 2 20 2 87 1 32 5 11 2 28 664 2 25 8 16 1 58

PeJta1t SaturatiCBl 66 1 42 9 44 4 27 9 36 3 16 7 64 0 28 6 77 8 269 84 0 16 7

00 cbs lt1 0 nql 128 318 218 336 0144 168

00 cbs lt4 0 nql 1428 U18 1318 936 14144 168

00 cbs lt5 0 ugII 1428 1218 1618 1536 41144 268

Table 4 5 Site averages of water quality parameters by sanplirg date all stations all depths

1987 l2sectsect AU 18 SEP 17 SEP 22 SEP 30 ocr 28-29 JAN 13

n 39 18 18 48 7 3 54 K SD K SD I SD K S D K SD K SD

0rthqil0sJil0 0 019 0 007 0 017 0 005 OOll 0 003 O OlS 0 014 0 033 0 011 0 082 0 045 Total rus 0 07 0 11 0 10 0 01 0 08 0 01 0 09 0 03 0 12 0 06 0 15 0 05

Anrncnia-nitrogen 0 039 0 018 0 04 5 0 042 0 017 0 012 0 012 0 017 0 040 0 029 0 04 6 0 036 Nitrite-nitrogen 0 004 0 001 0 005 0 004 0 004 0 001 0 003 0 003 0 004 0 001 0 008 0 004 Nitrate-nitrite-nitrogen 0 009 0 003 0 034 0 036 0 039 0 021 0 048 0 046 0 038 Q 019 0 190 0 039 Total Kjeldahl nitrogen 1 52 0 26 1 75 0 15 1 55 0 28 1 47 0 18 1 29 0 20 1 20 0 17 Potassium 4 4 0 9 4 7 0 3 4 5 0 3 4 2 1 0 2 9 0 5 3 9 1 0

Cqpar 0 003 0 002 0 003 0 002 0 003 0 001 0 002 0 001 0 001 0 001 0 002 0 002 Iron 0 002 0 002 0 014 0 007 0 014 0 007 0 015 0 019 0 048 0 018 0 090 0 031 ampxlium 4 8 9 7 6 47 3 4 6 46 9 4 7 49 0 9 4 31 0 8 9 28 2 8 1 Olloride 8 5 8 13 1 79 6 6 4 76 5 8 6 76 2 10 0 55 9 14 9 48 2 16 7 Fluoride 0 3 0 03 0 3 0 05 0 3 0 03 0 3 0 04 0 1 0 03 0 2 0 03 lbtal organic carlxln 2 1 7 1 6 17 9 0 9 18 1 0 8 18 4 1 0 19 7 2 5 18 4 3 0 Alkalinity 105 14 117 5 113 8 1U 10 7 3 15 68 lS Biochemical oxygen deHard 1 9 1 0 2 7 1 3 2 2 0 6 2 3 1 2 1 5 0 7 1 1 0 6 lubidi ty 2 4 1 9 4 2 0 9 4 1 1 5 4 0 2 9 3 1 2 5 3 7 2 1 Total susperded solids 3 3 3 3 6 0 2 3 5 7 2 4 6 3 4 7 4 5 3 9 3 1 4 1 Oller 61 5 66 9 81 9 113 10 silicates 12 8 2 2 13 1 2 2 12 0 3 0 5 4 0 5 Inorganic carlon 17 4 4 3 19 9 2 8 20 4 4 4 11 9 5 2

11=18

Table 4 6 site averages of water quality parameters for the KissiJulse River by sanpling date

1987 1988

AU 18 SEP 17 SEP 22 SEP 30 JAN 13

0 032 0 096 0 12 7 0 116 0 063 Total (ilcsphorus 0 09 0 18 0 20 0 20 0 12 Almalia-nitrcgen 0 021 0 036 lt0 005 0 017 0 069 Nitrite-nitrcgen lt0 005 lt0 005 lt0 005 lt0 005 0 027 Nitrate-nitrite-nitrogen 0 012 0 009 0 072 0 188 0 151 Total Kje1dahl nitrogen 0 51 1 39 1 40 1 12 1 08 Ibtassium 3 7 3 6 3 5 2 9 3 2

((gler 0 003 0 003 0 004 0 001 lt0 001 Iron 0 008 0 085 0 095 0 172 0 225 Sodium 3 3 4 2 6 5 24 2 2 1 0 15 0 Olloride 60 6 47 8 4 1 9 38 7 23 7 Fluoride 0 3 0 3 0 3 0 2 0 2 Total organic cartxn 19 6 19 5 19 9 18 8 17 4 Alkalinity 89 7 3 66 57 34 Biochemical oxygen daDaM 2 4 3 0 1 5 1 3 0 5 lJnbidity 3 0 3 9 2 7 2 3 2 3 Total suspenied solids J 9 4 8 4 0 2 5 2 0 Color 110 130 130 125 Silicates 6 58 6 42 5 67 3 17 Iooxganic carbon 4 4 9 6 7 2 1 1

Tabl e 4 7 S i g n i f icant F middot test rat i os for two-way ANOVA s by treatment and samp 1 1 ng round for in illY data co 1 1 ected duri ng fi el d demonstrat i on samp l i ng October 28-29 1987

FmiddotTET RAT IOS

TREATMENI ROUND INTERACTION (Exp vs control ) (1-5 only ) (Treatment x Round )

CONDUCTI V lTV Surface 25 99 1 14 56 Bottom 28 3 5 4 26 1 6 73

ORP Surface 2 1 10 Bottom 5 35

pH Surface 32 67 33 10 Bottom 1 1 1 5 4 5 1 4 48

Temperature Surface 104 64 Bottom 21 95 1 1 73 8 17

D i s sol ved Surface Oxygen Bottom 14 1 5 7 98 5 20

Saturat i on Surface Bottom 7 66 3 87

df df error bull 20 F 0 05 [df 20 ] bull

1

4 35

4

2 87

4

2 87

Table 4 8 Significant F-test ratios fnD two way analysis of variane by date ani treatment statiCllS 7-12 only Septedler 17 22 30 1987 ani JanJaIY 13 1988 data

rus dissolved Total pnsphorus Anroonia-nitrogen di ssolved Nitrite-nitrogen dissolved Nitrate-nitrite-nitrogen dissolved Total Kjeldahl nitrogen RltassilDU di ssel ved Cqpr di ssolved Iron dissolved Total organic car1xXl Alkalinity Biochemical oxygen demard TUlbidi ty Total suspenied solids Chloride SOdilDU Fluoride

Degrees of freedaD

Degrees freedan of error = 64

F 0 05 [df 60]

595 12 31 05

4 09 96 71 51 06 31 28

225 02 6 34

424 47 23 36 18 32 28 69

171 46 145 71

49 55

3

2 76

lREMMENl ( vs cxmR)L)

10 24 4 81

17 59 12 57

6 75

6 31 24 03 22 36

1

4 00

3 89

4 64 4 94 5 08

3

2 76

unharvested areas on the bas i s of spec i es compos i t i on Vari at i ons i n

chl orophyl l content al so were affected more by seasonal cond i t i ons than

by harvest i ng

The conunun i ty metabol i sm measurements conducted durlng September

1 987 i nd i cate probabl e d i fferences i n oxygen budgets for control and

harvested areas al though i n i t i al stat i st i cal methods d i d not establ i sh

the s i gni f i cance of such d i fferences Th i s was attri buted to anomal ous

data col l ected at a stat i on with unusual sed iment character i s t i cs ( h i ghly

organ i c unconsol idated f i ne grai ned mater i al in contrast to f i ne

grai ned sand ) Add i t i onal data analyses wi l l excl ude thi s stat i on from

cons i derat i on and future sampl i ngs wi l l be conducted at al ternate

l ocat i ons Di fferences by treatment duri ng the January sampl i ng were not

as pronounced as i n September and i nd i cate that regrowth of Hvdri 1 1 a with i n t hat peri od had offset harvest i ng e ffects

Sed i ment heterogenei ty was marked wi th i n the s i te with organ i c

w ith nutri ent content were fa i rl y l ow Organ i c content averaged 0 7

n i trogen 0 27 mgg total phosphorous 0 08 mgg and potass i um 0 49 mgg

on a dry we ight basi s Ni trate-n i tri te -n i trogen concentrati ons were l ess

than 1 of the total present Total n i trogen tota1 phosphorous rat i os

averaged 3 1 and were markedl y l ower than comparabl e rat i os i n e i ther t he

water col umn or the bi omass sampl es refl ect i ng a preferenti al

mobi l i zati on of n i trogen from s i te sed iments Few stat i st i cal l y

s i gn i f i cant d i fferences were detected a s a resul t o f w ith i n - stat i on

vari ati ons and the col l ect i on of more total phosphorus and total n i trogen

val ues are proposed for the second effort of th i s tas k

Data anal yses t o date for benth i c i nfauna i ncl ude preharvest and

postharvest cond i t i ons duri ng August and October respect i vel y The

August fauna was notabl y depauperate both i n taxa and numbers of

i nd i v i dual s wh i l e pronounced i ncreases in both were observed for

October D i urnal l y oxygen - poor cond i t i ons part i cul arl y duri ng August

may l i mi t benth i c fauna Spati al grad i ents were al so noted w ith

decreas i ng s pec i es ri chness and faunal dens i ti es at the southern end of

the study area Experimental and control stat i ons exh i bi ted s i mi l ar

faunal densi t i es and spec i es richness pri or to harvest wh i l e both

1 -3

parameters were substant i al ly greater at the harvested stat i ons duri ng

the October sampl i ng

Based on sampl i ngs i n September and J anuary the l arval and

juven i l e f i sh task col l ected 44 ( 2 1 ) of al l spec i es prev i ously reported

for Lake Okeechobee F i ve habi tats represent i ng both natural and

harvested edges and open water as wel l as heav i ly vegetated areas

were sampl ed Heterandria formosa LeDomi s sp and Gambus i a aff i nis

were the most abundant spec i es Centrarch i ds were the most abundant eggs

recovered The col l ect i on methods were f a i rly specif i c for part i cul ar

l i fe stage juven i l es were taken primari ly i n l i g ht trap sampl es whereas

postl arvae and eggs were taken i n pl ankton tows and Hvdri l l a sampl es

col l ected by the harvester LeDomi s s p appears to ut i l i ze al l fi ve

hab i tats dependent on l i festage No vert i cal strat i fi cat i on of organ i sms

was detected i n the weeded hab i tat and spec i es d i vers i t i es were

equ i val ent at both natural and harvested RedgesR of the Hydri l l a mat No

stat i s t i ca l ly s i gn i f i cant short term i mpacts of harvesti ng on spec i es

abundance or d i str i buti on are apparent

The cost-benefi t analys i s i s restri cted to eval uati ng mechan i cal

harvest i ng al one Benefi ts of thi s techni que wi th the except i on of

sal eabl e byproducts or costs assoc i ated wi th harvested mater i al are

pr i mari l y non -quanti fi abl e ( i mproved habi tat and water qual i ty boater

access nutri ent removal ) Therefore ranges of econom i c parameters wi l l

be ut i 1 i zed together wi th operat i ona 1 data from harvest i ng and

env i ronmental vari abl es from th i s project to present an economi cal l y

opt im i zed harvest i ng pl an to the Di stri ct

I n sunvnary no catastroph i c impacts due to mechan ical harvest i ng

have been detected i n the foregoi ng categori es al though subtl e

d i fferences have been determi ned by the study des ign Harvest i ng reduces

the amount of oxygen stress i n the study area and the nutri ent content of

the water col umn i s l ower i n the harvested than the unharvested areas

The s i te i s n i trogen l i mi ted based on water col umn sed i ment and pl ant

t i ssue anal yses Seasonal vari at i ons are l arge wi th respect to

d i fferences between harvested and unharvested areas for a l gal and l arval

fi sh popUl at i ons Spati al grad i ents were apparent i n many parameters

1 -4

The qual i ty assurance program associ ated wi th thi s project has

thus far conducted a systems aud i t for the pl an of study and at l east one

performance aud i t on f i e l dwork A Qual i ty Assurance Project Pl an has

been prepared and i s i n use as a project control document Aud i ts of

data management and anal ysi s are pl anned for the fi nal report i ng phase

At mi d -course sampl i ng anal yses and del i verabl es are on

schedul e and the project is operati ng wi th i n the budget No probl ems are

foreseen to prevent t imely compl eti on of the remai nder of the schedul ed

work Where al terati ons to speci f ic tasks have been recommended the

support for these efforts wi l l be obtai ned by real l ocati on of funds

wi th i n the project rather than by add i t i onal fund i ng

1-5

o 18 bullbull UNnar tllllllllI UINL UNnan

_ bull 0111 II wilD LlMi

lAKE (J(EECH08EE

Figure 11 Stu dy site l ocation Evaluation and research of impacts o f mechanical harves ting in Lake Okeechobee

I

I I LAKE OKEECHOBEE LITERATURE REV I EW

I I A INTRODUCTION

A 1 i terature rev i ew was conducted as a d i screte task of the

research project The Eval uat i on and Research of Impacts of Aquat i c Weed

Harvest i ng Demonstrat i on i n Lake Okeechobee cond ucted by Mote Mari ne

Laboratory The purpose of the l i terature rev i ew was to provide project

team members wi th economi c geol og i c hydrol og i c chemi cal and

b i ol og i cal i nformat i on on Lake Okeechobee wi th part i cu l ar emphas i s on

water qual i ty probl ems concern i ng phosphorus storage and cycl i ng between

the water col umn sed i ments and aquat i c weeds

I I B METHODS

Three techn i cal el ements were undertaken i n compl et i ng the

l i terature rev i ew 1) ident i fy i ng and search i ng i nformat i on 2) creat i ng

f i l es and 3 ) devel opi ng outputs

I nformati on was obtai ned by rev i ewi ng journal s for art i cl es

search i ng card catal ogs of area l i brar ies contact i ng major authors

conduct i ng research and request i ng key word searches of avai l abl e

computer l i brari es Journal s searched i ncl uded The Journal of Aquat i c

Pl ant Management Quarterly Journal o f the Fl ori da Academy o f Sci ences

( and Fl ori da Sc i ent i st ) L i mnol ogy and Oceanography Hydrobi ol og i a and

North Amer i can Journal of F i sher i es Management L i brari es vi s i ted

i ncl uded Un i vers i ty of South Fl or ida Uni vers i ty of Fl orid a Mote Mari ne

Laboratory Southwest Fl or ida Reg i onal Pl ann i ng Counci l South Fl ori da

Water Management D i str i c t and the Okeechobee off i ce of the Fl ori da Game

and Freshwater Fi sh Commi ss i on Key word l i terature searches were

c o n d u c t e d on d i qu at Lake O keechobee Hyd r i l l a and

nutr i entsaquat i c pl ants u s i ng searches avai l abl e from the Fl ori da

Department of Env i ronmental Regul at i on the Un i vers i ty of Fl ori da Aquati c

Weed Program and the U S Fi sh and Wi l d l i fe Servi ce

2-1

I I C PRODUCT

After rev i ew each publ icat i on was cited keyworded and annotated

u s i ng ARTF I LE vers i on 3 02 software for l i brar i es and b i bl i ographic

storage

Two outputs were devel oped from the comp i l ed i nformat i on 1 )

annotated c i tation s of each i nd i v i dual report and 2 ) Lake Fact Sheets

wh ich summari ze ava i l abl e i nformat i on on a spec i fic top ic requested by

members of t he study team Lake Fact Sheets and keyword b i bl i ographies

were d i stri buted t hroughout the course of the study as requested by

i nd i vi dual project members Lake Fact Sheets and a key word l i st

fol l ow Annotated c i tat i ons appear i n Append i x 2 A

2-2

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on AQUATIC PLANTS

Entri es i n Bi bl i ography 69

( For more deta i l s on spec i fic top ics pl ease see other fact sheets i e

hydri l l a b i omass harvest i ng etc )

Types of stud i es noted

- -Aquat ic pl ant ecol ogy (Moss 1980 23 Lugo and Snedaker 1971 113

Bl ackburn n 11 1968 128 Canfi el d et J 1983 260 Cassan i and

Caton 1985 352 Marshal l 1984 386)

- -Informat i on on aquat i c pl ant communi t i e s as habi tat (Wi l ey etI 1984

34 Durocher niI 1984 38 Mi l l eson nI 1980 40 Watki ns et I

1983 45 Ager and Kerce 1974 190 Sav i no et il 1985 196 Richard

n iI 1985 262)

- -Aquatic pl ant and sed i ment rel ati onsh i ps (Engel and N ichol s 1984 44

Barko and Smart 1986 106 Barko et 11 1983 147 L i et I 1974

108)

- -Aquat i c p l ant management ( Fl or ida DER nI 1986 415)

- - Nutrjent removal by aquat i c pl ants ( Reddy and DeBusk 1985 132)

- -Stud i es on harvest i ng aquat i c pl ants and the effects of harvest i ng

( Carpenter and Adams 1978 17 Sabol 1987 37 Mi ko l 1985 41

Wi l e 1978 57 Neel n 11 1973 114 N ichol s 1974 115

Smal l et

I 1985 130 Wi l e 1975 135)

- -Stud i es on chemical and other control s of aquat i c pl ants ( H i l t i bran n

J 1972 105 Ganstad 1978 110 deNoyel l es and Kett l e 1980 118

M i l on n 11 1986 119 Smal l et I 1985 130 Sutton and Vand i ver

1986 139 Lesl i e and Kobyl i nsk i 1985 255 Langel and and DeMont

1986 227 Barrett 1981 342 Barrett and Murphy 1982 344 Cl ayton

and Tanner 1982 355 Frank and Comes 1967 364 Graham 1976 369

Hughes and McCol l 1980 377 Richard et I 1984 426)

- -Aquat i c pl ant chem i s try and phys i ol ogy ( LaLonde 1970 107 Gerl off

1978 111 Gerl off 1973 112 Bri stow and Wh i tcombe 1971 136)

- - Chl orophyl l a concentrat i ons and aquat i c macrophytes ( Canfi e l d et I

1984 263)

2-3

Produced by Mote Marine Laboratory for South Florida Water Management District

- -B i omass stud i es and methods ( Schl oesser and Manny 1984 14 Mace i n a

J il 1984 33)

- -Uses for aquat i c weed s such as cattl e s i l age ( Bagnal l n l 1978

18) and compost (Wi l e g1 Jl 1978 19)

--Stud i es concern i ng Hydrilla vertic1llata ( Bagnal l 1980 18 Bol e and

Al l an 1978 15 P i erterse J il 1984 42 Bruner and Batterson 1984

43 Bowes 11 il 1979 47 Sutton 1982 52 Sutton and Port i er 1985

53 Sutton and Port i er 1983 57 McGhehee 1979 57 Bal c i unas 1985

116 Mart i n 1983 146 Johnston n Jl 1983 36 Canfi el d et l

1983 265 Mace i n a and Shi reman 1982 281 Hodgson and Carter 1982 423)

2-4

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fa c t She e t on BIOMASS

Entri es i n B i bl i ography 14

Types of stud i es noted

- -A troph i c state i ndex for l akes based on al gal bi omass (Carl son 1977

2)

- -Chl orophyl l -b i omas s - nutri ent rel ati onsh i ps for phytopl ankton (Canfi el d

et gl 1985 4)

--An assessment of bi omass control for water qual i ty management (Wong et

li 1979 9) --Methodol og ies for est imat i ng or measuri ng bi omass (Schl oesser and

Manny 1984 14 Mace i na g1 li 1984 33)

--Effects of harvest i ng or other weed control methods on aquat i c

vegetat i on b i omass (Mi kol 1985 41 Wi l e 1978 57 Cassani and Caton

1985 352 Hughes 1974 378 Sch i l l er 1983 398)

--B i omass measurements rel ati ng seasonal and b i otype vari at i ons i n

Hydr i l l a (Bowes et 11 1979 47 Steward 1987 408)

--Seasonal b i omas s of sel ected spec i es (Bowes et li 1979 47 Dewey et

l 19a1 266)

SUMMARY

Several stud i es use b iomass as a measure of aquat i c pl ant control

and as part of overal l assessments of water qual i ty management Mi ko 1

(1985) uses total pl ant bi omass measurements to asses s the effects of

mechan i cal harvesti ng on aquat i c vegetati on Wi l e (1978) al so presents

bi omass data as part of an assessment of envi ronmental effects of

mechan i cal harvesting Cassine and Caton (1985) asses s the same for

chem i cal and b i ol og i cal weed control Mace i na et li (1984) present a

method for est i mat i ng submersed pl ant bi omass by us i ng a record i ng

fathometer The i r data showed that the tech n i que i s not equal l y rel i abl e

for al l water bod i es However accurate b iomass determi nat i ons cou l d be

obt ai ned i f fathometer traci ngs are cal i brated w i th actual b i omas s data

Add i t i onal b iomass data for aquat i c p l ants are presented by Hughes

2-5

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

( 1974) Sch i l l er ( 1983 ) and Steward ( 1987 ) Bowes n il ( 1979) and

Steward ( 1987 ) present bi omass data for Hydri l l a i n Fl ori da

Canfi e l d et il ( 1985 ) address chl orophyl l - bi omass - nutri ent

rel at i onsh i ps for n atural assembl ages of Fl ori da phytopl ankton Carl son

( 1977 ) presents a troph i c state i ndex for l akes and uses al gal b i omass as

a parameter for the i ndex

2-6

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STU DY

Fact Sheet on D IQUAT

Entr i es i n B i bl i ography 84

Types of stud i es noted

- -Taxi c i ty data ( Mayer and El l ers i eck 1986 270 Berry and Schreck

1976 346 Funderburk and Lawrence 1967 366 Howe and Wri gt 1965

376 Kam W i ng and Furtado 1977 381 Naqui et Ai 1980 390)

- - Effects of d i quat on aquat i c commun i t i es ( H i l t i bran I 1972 105

Berry sl 1964 347 Cas san i and Caton 1985 352 Cal derban k 1972

351 C l ayton 1986 356 Dan i el 1972 358 G i l derhus 1967 368

Haag 1986 370 H i l senhoff 1966 372 Hughes and McCol l 1980 377

Joyce and Thayer 1986 379 Marshal l 1984 386 M i chaud 1979 387)

- -General chem i cal control gu i des and control of spec i fi c aquat i c

pl ants (Abery 1986 339 Barrett 1981 342 Barrett and Murphy 1982

344 Barrett and Logan 1982 345 Chevron Chemi cal Corp 1978 354

Hi l t i bran 1971 373 H i mel n li 1981 375 Ki l l gore 1984 383

Mac kenz i e 1966 385 Mobl ey n il 1971 388)

- -Di quat accumul ati on i n pl ants and sed i ments ( B i rmi ngham and Colman

1983 348 Dav i s and Seaman 1968 359 Frank and Comes 1967 364

Langeland and Warner 1986 384)

- - Experi mental data on herb i c i de treatments (Bri t i sh Col umbi a 1975

350 Clayton and Tanner 1982 355 Dunn et I 1983 362 Hal l er

1982 371 K i l l gore 1981 382 Newroth and L i m 1980 392)

- -Di quat u se wi th other types of control s (Charudattan 1986 353 Frank

AI 1979 365 Ganstad 1986 367 Graham 1976 369 Newroth

1974 391)

SUMMARY

I n add i t i on to the above noted stud i es three l i terature summari es and

rev i ews prov ide good i nformat i on on d i quat stud i es

Joyce and Ramey (1986) prov ide a good annotated rev i ew of 1 i terature

concern i ng research on the fate of aquat i c herb i c i de s i n water w i th

emphas i s on Fl ori d a s freshwater ecosystems Tucker (1980) rev i ews 50

c i tat i ons on d i quat c i tat i ons and prov ides a deta i l ed summary on the

2-7

Produced by Mote Marine Laboratory for South Florida Water Management District

foll ow i ng aspects of d i quat env i ronmental chemi stry adsorpt i on by so il

and cl ay mi neral s aerob i c and anaerob i c soi l stud i es soi l stud i es under

fi el d cond i t i ons aquat i c studi es soi l l eaching stud i es rotat i onal crop

stud i es photochem i cal degradat i on stud i es and mi croorgan i sm stud i es

Langel and and DeMont ( 1986 ) prov i de a thorough rev i ew of the l i terature

on the detect i on tox i c i ty and pers i stence of d i quat endotha1 1 and

f1 uri done They al so present speci fi c data on stud i es of the pers i stence

of d i quat endothal l and f1 uridone i n North Carol i na ponds and water

movement patterns i n Lake Wheel er North Carol i na

2-8

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fact Sheet on EUTROPHICATION

Entr i es i n Bi bl i ography 12

Types of stud i es noted

- -Eval uati ons of nutri ents i n eutroph i c l akes (Canfi el d 1983 5

Schi ndl er 1971 131 Michaud n ll 1979 387 Lee and Jones 1980

175)

- -Aquati c pl ant probl ems i n eutroph i c l akes (Graham 1976 369 Hughes

and McCol l 1980 377)

--Assess i ng eutroph i cati on based on water qual i ty stud i es ( Federi co et

Al 1981 67)

--Troph i c structure assessments and changes i n eutroph i c l akes ( Gayl e

1975 181 US Envi ronmental Protect i on Agency 1975 161)

SUMMARY

A number of stud i es address eutroph i cati on i n Lake Okeechobee

US Env i ronmental Protect i on Agency (1975 161) reports on Lake

Okeechobee as part of the Nat i onal Eutroph i cat i on Survey and a number of

state gency commi ttee stud i es and eng i neeri ng reports provi de anal yses

of Lake Okeechobee eutroph i cati on (MacGl l n AI 1976 174 Bl ack Crow

Ei dsness Inc 1976 185 Lee and Jone s 1980 175)

Us i g seven years of water qual i ty data Federi co et it 1 (1981

67) i dent i fy annual and seasonal l mnet i c water qual i ty trends exami ne

the re l at i o n s hi p to t r i but ary i n fl ow s i d en tify trends and

quali tyd i scharge rel ati onsh i p s cal cul ate annual l ake materi al budgets

for each year and assess the trophi c status of the 1 ake Gayl e (1975

181) presents a systems model for understanding eutrophicat i on i n Lake

Okeechobee

2-9

Produced by Mote Marine Laboratory for South Flori da Water Management District

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on HARVESTING

Entr i es i n B i bl i ography 15

Types of stud i es noted

--Effects of harvesti ng aquat i c pl ants on nutr i ent removal ( Bol e and

Al l an 1978 15 Wi l e 1978 57 Neel et AI 1973 114)

--Compari sons of mechan ical and b i ol og i cal harvest i ng wi th herbi c i de

control ( Carpenter and Adams 1978 17 Smal l et AI 1985 130

Sch i l l er 1983 398)

--Di sposal of and uses for harvested hydri l l a ( Bagnal l et AI 1978 18

Sabol 1987 37)

--Harvest i ng effects on aquat i c fl ora and fauna (Mi kol 1985 41 Wi l e

1978 57 N i chol s 1974 115 Wi l e 1975 135 Schramm et AI 1985

212 Lesl i e and Kobyl i nsk i 1985 255)

- - Economi c s of mechani cal harvest i ng (McGhehee 1979 57)

- - Phys i cal propert i es of hydri l l a for harvesti ng ( Bagnal l 1980 59)

SUMMARY

Most of the stud i es address the effects of mechan i cal ly harvest i ng

aquat i c pl ants Bol e and Al l an (1978) report that the harvest i ng of

Hydr i l la vert i c illata woul d result i n the d i rect transfer of onl y a smal l

amount of phosphorus i n the soi l i nto the water and the organ i cal l y-bound

phosphorus removed i n harvested pl ants woul d be deri ved l argely from the

sed i ment and not the water body W i l e (1978) and Neel n AI (1973)

present data and anal yses on l ake nutri ent dynam i cs resul t i ng from

harvest i ng aquat i c pl ants W i l e (1978) al so presents data on al gae

phytopl an kton fi sh and water qual i ty changes

A number of other stud i es address harvest i ng affects on fl ora and

fauna Mi kol (1985) reports that harvest i ng pl ants al so removed from 2-

8 of the total stand i ng crop of juven i l e fi sh Lesl i e and Kobyl i ns ki

(1985) address benth i c macro i nvertebrate response to aquat i c vegetat i on

removal wh il e Sabol (1087) addresses the env i ronmental effects of aquat i c

d i sposal o f chopped hydr i l l a

2-10

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

Compar i sons of mechan i cal harvest i ng and herbi c i des address

phosphorus cycl i ng (Carpenter and Adams 1 978) and Smal l et Jl ( 1 985)

report that herbi c i des reduced aquat i c vegetat i on but d i d not el i mi nate

i t Us i ng grass carp as bi ol og i cal control s el im i nated or red uced the

vegetat i on depend i ng on the stocki ng rat i o ( Smal l et AI 1985 )

2-11

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fact Sheet on Hydrjlla vertic11l ata

Entri es i n B i bl i ography 37

Spec i fi c stud i es on hydri l l a i n Lake Okeechobee i ncl ude a

compari son of dens i ty data for Lake Okeechobee and three other areas of

Fl ori da wi th stud i es spec i fi c to the speci a l i zed reproducti ve structures

of hydri l l a (Sutton and Port i er 1985 53) and an ana lys i s of potass i um

n i trogen and phosphorus content i n hydri 11 a from Lake Okeechobee and

three other areas of Sout h Fl ori da ( Sutton and Porti er 1983 56)

Pl ants from Lake Okeechobee had the h i ghest concentrat i on s of each

Other types of stud i e s on hydri l l anoted

--Phys i cal and mechani cal propert i es of hydri l l a (Bagnal l 1980

59)

--Nutri ent uptake stud i es of hydri l l a (Bol e and Al l an 1978 15)

--Us i ng hydri l l a for s i l age ( Bagnal l et Al 1978 18)

--Methods for determi n i ng or est i mat i ng pl ant biomass (Maceina et

li 1984 33)

--Growth reproduct i on and l i fe hi story of hydril l a ( Langel and and

Sutto 1980 35 Bruner and Batterson 1984 43 Spencer et li 1987

48 Sutton 1982 52)

--Habi tat i mportance and ecol ogy of hydril l a communit i es and

al terations to hydril l a communities (Watkins et li 1983 45middot

Bowes et

li 1979 47 Bl ackburn et li 1968 128 Sutton and Vandiver 1986

139 Can f i el d n Al 1983 265 Mace i na and Sh i reman 1982 281

R i chard i1 Al 1985 396)

--Biol ogical control s of hyd ri l l a (Bal ciunas and Minno 1985 46

Bal ciunas 1985 116 Johnston et li 1983 36 Cas sani and Caton

1985 352)

--Mechanical control s of hydril l a (McGhehee 1979 57)

--Chemical control of hydri l l a (Martin 1983 146 Cassani and

Caton 1985 352 Frank et li 1979 365 Hughes 1974 378 Small et

Al 1985 404 Steward 1972 405 Steward 1982 406 Steward 1976

407 Steward 1987 408 Van 1985 419 Van et Al 1987 420)

2-12

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

SUMMARY

Most of the stud i es deal w ith ways to control Hydr i l l a

verticilJata as a nui sance weed The effects of harvest i ng Hydri l l a i s

frequent l y addressed wi th mi xed resul ts Bol e and Al l an ( 1978) report

that the harvest i ng of Hydri 1 1 a woul d resul t i n the d i rect transfer of

onl y a smal l amount of phosphorus in the so i l i nto the water and the

organ i cal ly-bound phosphorus removed i n the harvested pl ants woul d be

deri ved l argel y from the sed i ment and not the water body

Johnston g1 il ( 1 983 ) report on the recol oni zat i on of a smal l pond

wi th aquat i c vegetat i on where grass carp have been used to control

Hydrill a They demonstrate the feas i b i l i ty o f reduc i ng the compet i t i ve

advantage of Hydri l l a i n order to l l ow other spec i es to become

establ i shed but al so note that care must be exerc i sed i n sel ect i ng

repl acement spec i es Other aquat i c pl ants may grow as prol i fi cal l y as

the Hydri 1 1 a bei ng repl aced

Sabol ( 1 987) and Langel and and Sutton ( 1 980 ) report on the

regrowth of fragmented Hydri l 1 a w i th confl i ct i ng resul t s In f iel d

stud i es Sabol ( 1 987) tested the re -growth potent i al of chopped Hydri 1 1 a

and found that a very smal l port i on of fragments cou1 d produce new

g rowth Conversely Langel and and Sutton ( 1980 ) under control l ed

l aboratory and f i e l d cond i t i ons demonstrated that 40 of the pl ant

fragments wi th one or two nodes were capabl e of vegetat i ve reproduct i o n

Bagnal l 11 il ( 1984 ) eval uated the feas i b i l i ty o f us i ng Hydri l 1 a

for cattl e feed and Macei na 1 il ( 1 984 ) present a method for pred i cti ng

pl ant b i omass us i ng a record i ng fathometer

2-13

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on N ITROGEN

Entri es i n B i bl i ography 27

Types of stud i es noted

- - Land userunoff rel at i onsh i ps w i th nutri ents i ncl ud i ng n i trogen

( Feder i c o 1 977 3 )

- - Nutri ent i n fluences on aquat i c pl ants and phytopl ankton (Canfi el d et

li 1985 4 Can fi el d 1 983 5 Davi s 1980 20 Dav i s 1 982 27

P i eterse 1 984 42 Sutton and Port i er 1 983 56 Bl ac kburn et il

1 968 1 28 Reddy and DeBus k 1 985 13 2 Jones and Federi co 1 984 1 )

- - Water qual i ty stud i es that i ncl ude nitrogen parameters ( Lutz 1 977a

7 Lutz 1 977b 16 M i l ler 1 980 20 Mi l l er et li 1982 26 Dav i s

and Marshal l 1 975 65 Peverl y and Johnson 1 979 394 Jones 1 983

9 )

- - Nutri ent rel at i onsh i ps w i th the troph i c structure of l akes (Henri kson

11 il 1 980 32 Dye 11 il 1975 138)

- - N i trogen and other water qual i ty data for Lake Okeechobee ( Di c kson et

li 1978 66 Davi s and Marshal l 1975 65 Federi co g1 li 1981 67

Fre i betger 1972 69 Mi l l er 1975 70 Jones and Federi co 1984 1

Jones 1 983 9)

- -N i t rogen i nputs and l ake eutroph i cat i on ( Sch i ndl er 197 1 13 1

Feder i co et il 1981 67 Canfi el d 1 983 5 )

- -Den i tri ficat i on i n Lake Okeechobee (Messer et li 1979 1 43 Messer

and Brezon i c 1 984 1 58)

- -Geochemi cal exchanges across the sed i ment -water i nterface ( Burton et

il 1975 1 45 Messer and Brezon i c 1984 158 )

- -Model s pred i ct i ng n i t rogen concentrat i ons (Jones 1983 9 )

SUMMARY

Several stud i es prov i de data on n i trogen for Lake Okeechobee

(M i l l er 1 980 20 Di c kson et li 1978 66 ) Many of these prov ide

n i trogen data as part of l arger studies for i nstance Federi co et li

( 1981 67 ) summari ze seven years of water qual i ty data i n order to

ident i fy annual and seasonal trends cal cu l ate annual budgets and assess

2-14

Produced by Mote Marine Laboratory for South Florida Water Management District

the troph i c state of the l ake Two stud ies ( Fre i berger 1 972 69

Mi l l er 1 97 5 70) i ncl ude lake Okeechobee as part of l arger wet and dry

season nutri ent surveys of South Fl ori d a

Jones ( 1 983 9 ) eval uates the qual i ty o f d i scharges t o Lake

Okeechobee nutr i ent concentrat i ons affects of var i ous changes i n l ake

l evel s and the abi l i ty of var i ous model s to accuratel y pred i ct n i trogen

and phosphorus concentrat i ons Jones and Federi co ( 1984 I) al so apply

nutr i ent model smiddot to Lake Okeechobee Dav i s and Marshal l ( 1 975 65)

present i nformat i on on areal and seasonal vari at i on s of n i trogen l evel s

nutri ent l oad i ngs and budgets for Lake Okeechobee and other chemi stry

d ata

Sutton and Port i er ( 1 983 56) eval uate the potass i um n i trogen

and phosphorus content of Hydri l l a from fi ve l ocat i on s i n South F l ori da

Sampl es were eval uated for wi th i n 1 ocat i on vari abi l i ty and for between

l ocat i on vari abi l i ty and resul ts showed that pl ants from lake Okeechobee

had h i gher concentrat i ons of nutri ents than pl ants from other areas

2-15

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on PHOSPHORUS

Entr ies i n Bi bl i ography 135

Phosphorus stud i es speci fi c to Lake Okeechobee i ncl ude

- -An anal ys i s o f the effect o f reduced nutri ent l oad i ngs on Lake

Okeechobe chl orophyl l (Jones and Feder i co 1984 )

- -An eval u at i on of the qual i ty of d i scharges to l ake nutri ent

concentrat i on s (Jones 1983 )

- -An analys i s of the abi l i ty of vari ous model s to accurately pred i ct

phosphorus concentrat i on s (Jones 1983 )

- -A comp ari son of phosphorus content i n hydri l l a from Lake Okeechobee and

four other l ocat i ons (Sutton and Porter 1 983 )

- -Aer i a 1 and seasonal vari at i ons of phosphoru s 1 eve 1 s i n Lake Okeechobee

(Davi s and Marshal l 1975 )

-A survey of total ortho p l us aci d - hydrol yzabl e phosphorus ( P- P04)

dur i ng a peri od of h igh water and a peri od of l ow water at 1 1 stat i on s i n

Lake Okeechobee and several stat i ons el sewhere i n South Fl or1 da

(Fre i berger 1972 )

- -An anal ys i s of l i mi t i ng factors based on al gal assays on water sampl es

from 30 s i tes i n the Ki s s i mmee R i ver- Lake Okeechobee Bas i n (Dye tl AI

1 975 )

- - Stud i es on nutri ent exchange across the sed i ment-water i nterface

(Burton et il 1975 )

Add i t i onal l y spec i fi c phosphorus d ata for Lake Okeechobee and i t s

watershed are presented i n a number o f reports (Jones and Feder i co 1984

Jones 1983 Mil l er 1980 Davi s and Marshal l 1975 Fre i berger 1 972

Messer et il 1 979 Dye et il 1975 Burton et Al 1975 Lee and Jones

1975 Lutz 1 977 Mi l l er et il 1982 Di ckson et Al 1978 M i l l er 1975)

Regard i ng management pl an s for phosphorus l evel s t he Lake

Okeechobee Techni cal Commi ttee ( 1 986 ) recommended to reduce phosphorus

l oads by at l east 40 (based on the mod i fi ed Vol l enwe i der nutri ent

l oad i ng model s ) through a program of d i vers i ons and treatment

2-16

Produced by Mote Marine Laboratory for South Florida Water Management District

Stud i es out s i de the lake Okeechobee area wh i ch prov i de i nformat i on

val uabl e to the study of phosphorus i ncl ude

- - Uptake of phosphorus from sed i ment and the water col umn by pl ants ( Bol e

and Al l an 1978 Dav i s 1984 Dav i s 1982 Reddy and DeBus k 1985 Dav i s

and Harri s n d li i1 Al 1974)

- -The i nfl uence of 1 and use patterns and other control s on phosphorus

l evel s ( Federi co 1977 Mi chal ski i1 Al 1975)

- -The correl at ion of nutri ent l evel s w i th chl orophyl l and phytopl ankton

l evel s ( Canfi el d i1 Al 1985 )

- - I ndexi ng and model l i ng techn i ques for l akes us i ng phosphorus and

rel ated data ( Carl son 1977 Canfi el d 1983 Meri cas and Mal one 1984)

- - Data on removal of phosphorus by mechan i ca l l y harvest i ng pl ants

( Carpenter and Adams 1978 Wi l e 1978 )

- -Rel ati on sh i p between nutri ents and b i ol og i cal parameters ( Henri kson g1

Al 1980 Pi eterse 1984 Enn i s 197 5 Re i nertsen 1 986 )

- - Phosphorussed i ment i nteract i ons (Twi nch and Peters 1984 li et li

1 97 1

- -laboratory and other control l ed stud i es on the propert i es of phosphorus

( Shannon and lee 1966 li et li 197 1 )

--Other l i terature stud i es ( Sch i ndl er et Al 197 1 )

2-17

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet on PHYTOPLANKTON

Entr i es i n B i bl i ography 8

Types of stud i es noted

- - Phytopl ankton stud i es for Lake Okeechobee (Marshal l 1977 1 2 Dav i s

and Marshal l 1975 65 Marshal l 1977 424 Jones and Federi co 1 984

1 )

- - Phytopl anktonnutri entl ake eutroph i cat i on rel at i onsh i ps (Canfi el d et

AI 1985 4 Sch i ndl er 1971 13 1 Hughes and McCol l 1 980 377 Jones

and Federi co 1 984 1 )

- - Phytopl ankton pri mary producti on methodol ogy ( Schearer et AI 1985

278)

--Phytopl ankton responses to aquat i c pl ant removal (R i chard et AI 1985

426)

SUMMARY

Dav i s and Marshal l ( 1975 65) present 2 - 12 years of

phytopl an kton dens i ty data for Lake Okeechobee as wel l as i nformat i on on

n i trogn and phosphorus l evel s ( areal and season al vari at i on s ) pri mary

product i v i ty changes in al gal popul at i on s nutr i ent l oad ings and

budgets ra i n fal l chemi stry dat a regress i on anal yses on bi ol og i cal

act i v i ty and chemi cal or phys i cal propert i e s and trophic state

Marshal l s ( 1 977 1 2 ) phytopl ankton dens i ty data for 1974 show peaks i n

May and September i n Lake Okeechobee Marshal l concl udes that Lake

Okeechobee exh i b i t s seasonal patterns and peri od i c i ty typ i cal of

temperate l akes al though the seasonal vari at i on i n den s i t i es i s typi cal

of a trop i cal l ake

Jones and Federi co ( 1984 1 ) present over four years of d ata on

chl orophyl l a pri mary product i v i ty phytopl ankton dens i t i es and domi nant

species They al so an al yze the effect of reduced nutri ent l oad i ng s on

L a ke Okeechobee chl orophyl l and concl ude that chl orophyl l and

product i v i ty l evel s have not changed substanti al l y dur i ng the study

peri od except that peak val ues were h i gher i n 1981

2-18

Produced by Mote Marine Laboratory for South Florida Water Management District

Canfi el d n li ( 1985 4) col l ected data from 165 Fl ori da l akes

and reported a s i gn i fi cant correl at i on between chl orophyl l a

concentrat i ons and phytopl ankton bi omass Mul t i pl e repress i on anal yses

i nd i cated that phytopl ankton bi omass was dependent on both the total

phosphorus and total n i trogen concentrati on Nutri ent-phytopl ankton and

Secch i - phytopl ankton rel ati onsh i ps for the Fl orida l akes had h i gher

coeffi c i ents of determi nat i on i f chl orophyl l a concentrat i ons rather than

bi omass data were used

2-19

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY Fa ct Sheet on PRIMARY PRODUCTIVITY

Entries in Bibl iography 11

Types of studies noted

- -General ecol ogy studies incl uding primary productivity (Fontaine and

Ewe l 1981 31)

- -Trophic studies of l akes (Henrikson it 11 1980 32)

--Nutrient infl uences on primary productivity (Davis and Harris no date

141)

- -Primary production methodol ogy (Shearer l1 11 1985 278)

--Primary production data in Fl orida (Odum 1974 169 Brezonic et 11

1979 155 Jones and Federico 1984 1 Davis and Marshal 1975 65

Marshal l 1974 424)

- -Seasonal primary productivi ty cycl es (Comita 1985 1195 Marshal l

1974 424)

SUMMARY

Severa 1 stud i es concern primary production in Lake Okeechobee

Brezonjc l1 11 (1979 155) report to the Fl orida Sugar Cane League on

factors affect i ng primary product ion n Lake Okeechobee Jones and

Federico (1984 1) present primary productivity data on Lake Okeechobee

for 1974-76 and 1979-82 as wel l as information on chl orophyl l a

phytop 1 ankton dens i ties and domi nant spec 1 es and an anal ys s of the

effect of reduced nutrient l oadings Their report concl udes that

ch l orophyl l and productivity l evel s have not c hanged substantial l y during

the study period except for peak val ues that were higher in 1981 and

overal l val ues were higher In the Lake s north end Marshal l (1974

424) add resses seasonal changes for primary productivity and

phytopl ankton He concl udes that considering primary productivity and

other factors Lake Okeechobee phytopl ankton dynamics resembl e temperate

l akes Davis and Marshal l (1975 65) present over two years of data on

chemical and biol ogical investigations of Lake Okeechobee incl uding

primary productivity

2-20

Produced by Mote Marine Laboratory for South Florida Water ManaQement District

LAKE OKEECHOBEE AQUATIC WEED DEMONSTRATION STUDY

Fact Sheet o n SED IMENTS

E ntr i es i n B i bl i ography 21

Types of stud i es noted

Most of the stud i es i nvol ve sedi ment nutr i ent ava i l abi l i ty fl uxes

and uptake by pl ants These i ncl ude reports on

-- Laboratory experiments to determi ne phosphorus uptake from the

sed i ments by Myri ophyl l ym and Hydri l l a ( Bol e and Al l an 1978 1 5 )

- - Phosphate exchange i n l ake sed i ments (Twi nch and Peters 1984 295 L i

et l 197 1 1 49 li Al 1973 )

- -Ava i l ab i l i ty of sedi ment phosphorus for macrophytes ( L i et l 1974

108)

- - Phosphorus fl uxes i n south Fl ori da marshes (Dav i s and Harri s no date

143 )

- -The i mportance of den i tr i fi cati on i n lake Okeechobee (Messer et l

1979 1 43 )

- -Geochemi cal exchanges across the sed i ment -water i nterface i n the

Ki s s i mmee Ri ver- Lake Okeechobee watershed ( Burton g1 l 1975 145)

- - lak sed i ment den i tri f i cat ion model s (Messer and Brezon i c 1 984 1 58)

There are al so a number of stud i es concern i ng the rel at i onsh i p of

sedi ment type and other factors to pl ant growth ( Bruner and Batterson

1984 43 Mart i n 1983 146 Barko et il 1983 147 Engel and

N i chol s 1 984 44 Barko and Smart 1986 106) pest i c i de and other

chemi cal res i dues i n sedi ments ( Pfeuffer 1985 298 Hughes and McCol l

1980 377 S i ms i man and Chesters 1976 402 )

SUMMARY

BUrton et l ( l979) documents the rol e of sed i ments i n determi n i ng

water qual i ty i n the Ki s s immee Ri ver-lake Okeechobee watershed wi th an

emphas i s on nutri ent exchange across the sed i ment -water i nterface They

a l so prov ide survey i nformat i on on sediment d i str i but i on and transport

Mes ser et l ( 1979) summari zes the i mportance of den i tr if i cat i on i n lake

Okeechobee i ncl ud i ng a d i scuss i on on the rol e of sedi ments i n the

2-21

Produced by Mote Marine Laboratory for South Florida Water Mana ement District

den i tr i fi cat i on process

eval uat i on o f l ake sed i ment

Lake Okeechobee

Messer and Brezon i c ( 1 984 ) present an

den i tri fi cat i on model s and i ncl ude data from

Dav i s and Harri s ( n d ) provi de est i mates of phosphorus fl uxes

wh i ch d i rectly contri bute to uptake through pl ant growth and to retent i on

through pl ant detri tus sed i mentat i on for the Evergl ades Conservat i on Area

2

2-22

LAKE OKEECHOBEE LITERATURE REVIEW

LIST OF KEY WORDS

ABUNDANCE ( 2 ) ADSORPTION ( 2 ) AGE (1) AGRICULTURE (1) ALGAE (14) ALGAL BIOASSAY (1) ALGICIDES ( 2 ) ALKALI N I TY (1) ALKALOIDS (1) ALTERNANTHERA ( 2 ) ALTERNATHERA (1) AMMONIA (1) AMPH I PODS (1) ANALYSIS OF COVARIANCE (1) ANIMAL BEHAVIOR (1) ANIMALS ( 2 ) AQUATHOL (1) AQUATIC PLANT CHEMISTRY (1) AQUATIC PLANTS (76) AQUATIC ORGANISMS ( 2 ) AQUATIC ( 1 ) AQUIFER ( 2 ) ARGULUS ( 1 ) ARTHROPODS ( 1 ) ATHERINE FISH (1) BACKPUMPING ( 2 ) BACTERIA ( 3 ) BASS (18) BEACH HAB ITATS ( 2 ) BEHAVIOR ( 2 ) BENTHOS (9 ) BEST MANAGEMENT PRACTICES (1) B IOACCUMULATION (1) BIOASSAY (1) BIOLOGICAL CONTROL (8) BIOLOGY ( 6 ) BIOMASS (15) BIOTIC ASSESSMENT (1) BIOTYPES (1) BIRDS ( 2 ) BLACK CRAPPIE (19) BLACK BULLHEADS (1) BLUEGILL ( 1 2 ) BODY FORM ( 2 ) BREEDING (1) BROMAC I L (1) BROOK SILVERSIDE (1) CABOMBA (1)

2-23

CADDISFLIES (1) CADMIUM (1) CALLITRICHE (1) CALOOSAHATCHEE RIVER (5) CANALS ( 2 ) CARBON (1) CARBONATE ROCKS (1) CARBOXYLASE (1) CAREX (1) CATTAI LS (1) CATTLE FEED (1) CENTRARCHIDS (5) CERATOPHYLLUM (5) CHAIN PICKEREL ( 1 ) CHANN ELS ( 1 ) CHAOBORUS (1) CHARA ( 6 ) CHEMICAL CONTROL ( 66 ) CHEMISTRY (10) CHIRONOMID LARVAE (1) CHIRONOMIDS (1) CHLORIDE (4) CHLORINATED HYDROCARBONS (1) CHLOROPHYLL (11) CLADIUM ( 2 ) CLASSIFICATION (1) COEFFICIENT OF DETERMINATION (1) COMMERCIAL FISHERY (2 ) COMMUNI TIES (1) COMMUNITY STRUCTURE ( 7 ) COMPETITION ( 3 ) COMPOST (1) COMPUTER MODELS (1) CONFINING BEDS (1) CONTOUR MAPPING (1) CONTROLLED RELEASE (1) COPEPODS (1) COPPER ( 9 ) COPPER SULFATE (1) CORE SAMPLER (1) COST BENEFIT ANALYSIS (1) CRUSTACEANS ( 2 ) CTENOPHARYNGODON IDE (2 ) CULTURAL CONTROL ( 2 ) CYANATRYN (1) DALAPON (4) DEGRADATION ( 3 ) DEMOGRAPHY (1)

DENITRIFICATION (1) DENSITY (6) DESORPTION (1) DETENTIONRETENTION ( 1 ) DETRITUS (1) DEVELOPMENT (2) DIATOMS (1) DICHLOBENIL (2) DIPOTASSIUM ENDOTHAL ( 1 ) DIQUAT (89) DISCHARGE ( 1 ) DISPERS ION (1) DISSOLVED OXYGEN (14) DISSO LVED SOLIDS (2) DISTRIBUTION (16) DIURNAL (1) DRAINAGE (4) DREDGING (1) DYSTROPHIC (1) EARLY DEVELOPMENT (2) ECOLOGY (15) ECONOMIC ANALYSIS (1) ECONOMICS (1) ECOSYSTEM (1) EFFLUENT REDUCTION (1) EFFLUENT (1) EGERIA (6) EICHHORNIA (13) ELODEA (20) EMBRYO ( 1 ) ENDOTHAL-POTASSIUM ( 1 ) ENDOTHALL (20) ENTRAINMENT (2) EPIPHYTES (1) EUTROPHICATION (12) EVERGLADES ( 9 ) EVERGLADES COUNTY (1) EXOGENOUS FEEDING (2) EXPLORATION (2) FAUNA (2) FEEDING ( 9 ) FEEDING RELATIONSHIPS (2) FENAC (5) FIRST YEAR SURVIVAL ( 1 ) FISH (130) FLOOD CONTROL (1) FLOODING ( 1 ) FLORIDA (31) FLORIDA EVERGLADES (1) FLORIDA LAKES (4) FLORIDA DUCK (1) FLORIDAN AQUIFER (2)

2-24

F LOW RATES (1) F LURIDONE (9) FOOD CHA I NS (1) FOOD HABITS (2) FOOD (6) FORAGE ( 1 ) FORAGING ( 1 ) FREQUENCY ANALYSIS (1) FRESHWATER SPECIES (1) FRESHWATER DISCHARGE ( 1 ) FRESHWATER (27) FRESHWATER MARSH (1) GEOLOGY ( 9 ) GERMINATION (1) GIZZARD F I SH (1) GIZZARD SHAD (2) GLADES COUNTY (9) GLYPHOSATE ( 6 ) GRAPNEL SAMPLER (3) GRASS CARP (8 ) GREAT BRITAIN ( 6 ) GROUNDWATER (5) GROWTH (11) GROWTH INHIBITORS (1) HABITAT (2) HABITAT PARTITION ING (1) HARVESTING (7) HAUL SEINE ( 1 ) HENDRY COUNTY (9) HERBICIDES (47) HEXAZINONE ( 1 ) HIGHlANDS COUNTY (1) HISTORY (3) HOST SPECIFICITY (1) HYDRILLA (42) HYDROCARBONS (1) HYDROCOTYLE (1) HYDROGEOLOGY (2) HYDROLOGY (17) HYDROPERIOD CHANGES (1) HYGROPHILA (1) HYPERmiddotEUTROPHIC (1) ICHTHYOFAUNA (1) ICHTHYOPLANKTON (2) IDENTIFICATION KEY (1) IDENTIFICATION GUIDE (10) IMAZAPYR (1) IMPOUNDMENTS (3) IMPROVING CATCH (1) INDICATOR SPECIES (1) INORGANIC PHOSPHATE (1) INSECT CONTROL (1)

INSECTS (4) INVERTEBRATES (9) IRON (2) IRON CHELATE (1) IRR IGAT ION (2) ISOPODS (1) JASM INE (1) JUNCUS (2) JUVEN ILE F ISH (5) K ISS IMMEE R IVER (11) LABORATORY STUD IES (1) LAGAROS I PHON (3) LAKE LEVELS (2) LAKE WANAKA (1) LAKE CONWAY (1) LAKE OKEECHOBEE (89) LAKE DRAWDOWN (1) LAKES (75) LAND USE (6) LARGEMOUTH BASS (16) LARVAE (1) LARVAL F ISH (25) LEAF PRODUCTION (1) LEMNA (8 ) LEPOMIS (1) L IFE HISTORY ( 9 ) L IGHT INTENSITY (1) L IGHT TRAPS (1) L IMNOLOGY (2) LI MNO PH I LA (1) L ITERATURE SURVEY (5) L ITHOLOG IC ANALYSIS (3) L ITTORAL (12) L ITTORAL ZONE (9) LOTAC (3) MACRO INVERTEBRATES (12) MACROPHYTES (18) MANAGEMENT PLAN (3) MANGANESE (3) MARION COUNTY (3) MARSH PLANTS (3) MARTIN COUNTY (27) MASS BALANCE MODEL (3) MATERIAL BUDGET (3) MATHEMAT ICAL MODELLING (3) MATHEMATICAL MODELS (3) MECHAN ICAL CONTROL (15) MECHANICAL HARVEST ING (24) METHODS ( 9 ) M ICROBES (3) MICROPTERUS (6) MINERAL RETENTION (3)

2-25

MINERAL ADSORPTION (3) M INERAL NUTRITION (3) MINERALIZATION (3) M ISS ISSI PPI S ILVERSIDE (3) MODELING (6) MODELS (12) MOLLUSKS (3) MONITOR ING (15) MORPHOLOGY (3) MORTALITY (12) MOTHS (3) MOWING (3) MYOMERE NUMBERS (3) MYR IOPHYLLUM (84) MYSIDS (3) NAIDIDAE (3) NAJAS (18) NEKTON (3) NEMATODES (3) NEOCHETINA (6) NETS (6) N ICKEL (3) N ITRATES (3) N ITROGEN (81) NORTHERN P IKE (3) NUPHAR ( 9 ) NUTR IENTS (141) OCALA GROUP (3) OKEECHOBEE COUNTY (33) OKLAWAHA R IVER (3) OL IGOCHAETES (3) OLIGOTHROPHIC (6) ORANGE LAKE (3) ORGANIC MATTER (3) OSCEOLA COUNTY (3) OXYGEN (9) PALAEOLIMNOLOGY (3) PALM BEACH COUNTY (30) PAN ICUM (67) PARAQUAT (39) PARTICULATE MATTER (3) PASPALUM (3) PATHOGENS (3) PERI PHYTON (3) PERSISTENCE (9) PESTICIDES (27) PH ( 9 ) PHOSPHATE (15) PHOSPHORUS (135) PHOTOSYNTHES IS (12) PHYS IOLOGY (12) PHYTOPLANKTON (27)

PHYTOTOXICITY (3) PIKE (3) PISCIVOROUS FISH ( 6 ) PISTIA (15) PLANKTON (15) PLANNING (3) PLANT SUCCESSION (9) PLANT HARVESTING (9) PLANT ABUNDANCE ( 6 ) PLANT DENSITY (3) PLANT COMMUNITIES (9) PLANT SURVEY TECHNIQUES (9) PLANT COMPOSITION (9) PLANT NUTRITION (3) PLANT GROWTH ( 6 ) PLANT BIOMASS (3) POLLUTION (3) POLLUTION CONTROL (3) POLYCHAETES (3) POLYMER ( 6 ) POMACEA (3) POHOXIS ( 6 ) PONAR GRAB SAMPLER (9) PONDS ( 6 ) POPULATION DYNAMICS (9) POPULATION (21) POTAMOGETON (57) POTASSIUM (9) PREDATION (3) PREDATOR - PREY (15) PRIMARY PRODUCTION (36 ) PROPAGU1ES (3) PUMP STATIONS (3) PUMPING (3) RADAR (3) RADIOPHOSPHORUS (3) RAINFALL (18) RANUNCULUS ( 6 ) RATS (3) RECLAMATION ( 3 ) RECORDING FATHOMETER (3) RECRUITMENT (3) REDBREAST SUNFISH (3) REDEAR SUNFISH (3) REFERENCES (3) REGRESSION ANALYSIS (15) RELEASE RATES (3) REMOTE SENSING (3) REPRODUCTION (12) RESERVOIRS (51) RESIDUES (27) RESOURCE PARTITIONING (9)

2-26

RESPIRATION (3) REVIEW (3) RIVERS (42) RUNOFF (33) SAGITTARIA (3 ) SALVINIA (18) SAMPLING (15) SAMPLING METHODS ( 6 ) SAMPLING GEAR (3) SCIRPUS (3) SEA LEVEL RISE (3) SEASONAL EFFECTS (12) SEASONAL SUCCESSION (3 ) SEASONAL (9) SECCHI DISK (9) SEDIMENTARY ROCKS (3 ) SEDIMENTS (78) SEEPAGE (12) SEWAGE DISCHARGES (3) SHAD (15) SHINERS (3) SHOREFLIES (3) SHORELINE AREAS (3 ) SILICA (3) SILICON (3) SIZE CLASS ( 6 ) SNAILS (3) SODIUM ALGINATE ( 6 ) SODIUM (3) SOILS (9) SOUTH FLORIDA (24) SPARGANIUM (3 ) SPAWNING (21) SPECIES DIVERSITY (3 ) SPECIES COMPOSITION (3 ) SPECIFIC CONDUCTANCE (15) SPOTTED BASS (3 ) ST LUCIE ESTUARY (3 ) ST JOHNS RIVER (3 ) ST LUCIE COUNTY (3 ) STANDING CROP (15) STOCHASTIC LAKE MODELS (3 ) STORHWATER (3) STRATIGRAPHY ( 6 ) STREAMS (9) SUNFISH (18) SURFACE DISCHARGES (3) SURFACE WATER (21) SURFACTANTS ( 6 ) SURVIVAL ( 3 ) SUSPENDED SOLIDS (3 ) SWIM PROGRAM ( 3)

TAYLOR CREEK (6) TAYLOR CREEK WATERSHED (3) TEMPERATURE (9) TENNESSEE (6) TERRESTRIAL (6) THREADFIN SHAD (15) TILAPIA (3) TOXICITY (36) TRACE METALS (3) TRANSMISSIBILITY (3) TRANSPARENCY (6) TROPHIC STRUCTURE (30) TUBER PRODUCTION (3) TUBER DENSITY (3) TURBIDITY (12) TURION (9) TYPHA (9) UPPER TAYLOR CREEK (3) USGS (3) UTILIZATION (3) UTRICULARIA (3) VALLISNERIA (15) VAUCHERIA (3) VEGETATED HABITATS (3) VEGETATION (15) VEGETATIVE PROPAGULES (3) VEGETATIVE REPRODUCTION (6) VELOCITY (3) VERTEBRATES (3) WASTELOAD ALLOCATION (6) WASTEWATER TREATMENT (6) WASTEWATER (3) WATER SUPPLY (12) WATER RECYCLING (3) WATER LEVELS (6) WATER CONSERVATION AREA 2A (3) WATER CHEMISTRY (21) WATER QUALITY (Ill) WATER MANAGEMENT (6) WATER LEVEL (9) WATER CIRCULATION (3) WATER BUDGET (3) WATERSHED ANALYSIS (3) WEIGHT DISTRIBUTION (3) WEIR BOX (3) WET AND DRY SEASON (9) WETLANDS (9) WHITE CRAPPIE (6) WILDLIFE (3) WITHLACOOCHEE RIVER (6) WOLFFIA (3) XYLENE (6)

2-27

ZINC (3) ZOOLOGY (3) ZOOPLANKTON (21)

I I I BIOMASS - M ID-COURSE SUMMARY

I I I A INTRODUCT ION

The experimental removal of Hydr i l l a vert i c i 1 1 ata R i s bei ng

conducted to prov ide removal of nutr i ents phosphorus i n part icul ar from

Lake Okeechobee as wel l as the anc i l l ary benefi ts of i ncreased fi sh

hab i tat and nav igat i onal acces s To determi ne benefi ts and costs of

removal an i ndependent est i mate of both b i omass and nutri ent content of

vert i ci l l ata has been conducted

The bi omass sampl i ng effort was conducted i n August 1987 and was

compl eted pri or to the actual harvest i ng Stat i ons were concentrated i n

the area of the Hydri l l a mat but some non -Hydr i 1 1 a spec i es were al so

col l ected Sampl i ng l ocat i ons were sel ected on the bas i s of qual i tat i ve

cl ass i ficati ons of Hydri l l a growth character i s t ics

Based on fi e l d reconna i ssance i n Aprll and Ju l y 1987 a

s ubstant i al amount of spati al nonhomogene i ty i n both weed dens i ty and

spec i es compos i t i on was observed throughout the proposed s tudy s i te A

vari ety of env i ronmental factors such as substrate compos i t i on water

qual i ty and to a l es ser degree l i ght penetrat i on and water depth may

have been respons i bl e for these observed d i fferences Any past

appl icat i on and poss i bl e res i dual effects of weed control herb ic i des may

al so be contr i buti ng envi ronmental factors As growth character i st ics

w i th i n th i s area were not un i form i t was assumed un l i ke ly that nutri ent

content was evenly d i stri buted To quanti fy these area -wi de var i ati ons

a s ampl i ng scheme emphas iz i ng the range of Hydril l a growth cond i t i ons was

des i gned

III B MATER IALS AND METHODS

I I I B 1 Sampl e Col l ecti on

Prec i s i on measurement of Hydri l l a bi omass i s h igh l y dependent upon

the representat i veness of the sampl es as wel l as evenness of growth

character i st ics wi thi n the study s i te As di fferences i n dens i ty had

3 - 1

been observed duri ng reconnai ssance surveys fi ve Hydri l l a cond i t i on

factors were establ i shed ( see Tabl e 3 1 ) Stat i ons were apport i oned

among these fi ve categor i es rat i ng sel ected s i tes accord i ng to these

cond i t i on factors to i nsure that comparabl e representat i ve sampl es were

col l ected

As a resul t fi fteen ( 1 5 ) stat i ons were establ i shed wi th i n the

weed harvest i ng area ( Fi gure 3 1 ) Sampl i ng l ocat i ons were fi xed and

recorded i n the fi e l d us i ng Loran C (Apel co model DXL -6000 ) Sampl e

col l ect i on at each stat i on con s i sted of three repl i cated cl i pped - pl ots of

Hydri l l a removed from wi thi n a 202Sm2 sampl i ng dev i ce pl aced on the

substrate The sampl i ng box was constructed of steel pl ate 3 mm th ick

The overal l des i gn was s imi l ar to that descri bed by Mart i n and Sherman

( 1979 ) The top of the box however was covered by a d i amond pattern

screen wi th an attached hook to fac i l i tate l i ft i ng the sampl er wh i ch

contai ned the Hydr i l l a sampl e i nto the boat

The sampl er was l owered to the substrate and the Hydri l l a adjacent

to the edge of the box was cut by the d i ver wi th a kn i fe The bottom

sl i d i ng pl ate was then i nserted to conta i n the Hydri l l a sampl e and the

sampl er was then retri eved to the surface

Onl y the above- substrate port i ons of the pl ant were col l ected

s i nce thi s was cons i dered to be the port i on of the pl ant subject to

removal by the mechan i cal harvester Unconsol i d ated detri tal materi al

and roots were not col l ected Any non -Hydri J 1 a macrophytes col l ected

were separated from the Hydri l l a sampl es and treated as d i screte sampl es

Each l abel l ed repl i cate sampl e was we i ghed separatel y to the nearest gram

to determ i ne fresh wet we i ght s The i nd i v i dual repl i cates were then

i ced and shi pped to the l aboratory for dry we ight and nutr i ent content

analys i s

Add i t i onal fi el d procedures i ncl uded a near-fi el d and obl i que

photograph taken at each bi omass sampl i ng stat i on

3-2

I I I B 2 Anal yt i cal Methods

Percent mo i sture was determi ned on al l sampl es Sampl es were

dri ed at 103 - 1050C and the dri ed materi al was used i n n i trogen

phosphorus and potass i um anal yses A total of 52 sampl es were processed

(45 Hydri l l a and 7 non - Hydrjl l a fract i ons ) by MML Total Kjel dahl

n i t rogen and total phosphorus were analyzed from dri ed ground pl ant

materi al Methods ut i l i zed were from the AOAC Methods of Anal ysi s 13th

Ed i t i on 1980 Kjel dahl d i gesti on i n a bl ock d i gester of l ess than O lg

pl ant materi al was fol l owed by sampl e reconst i tut i on automated d i l ut i on

and col ori metri c determi nati on o f amon i a and phosphate by Techn i con

AutoAnal yzer II The resul tant n i trogen and phosphorus concentrat i ons

were converted to a dry we i ght basi s

Procedures for the potass i um anal ysi s are deri ved from the AOAC

Methods of Ana lys i s 13th Ed i t i on 1980 Less than 0 3g of dri ed ground

p l ant materi al was d i gested wi th n i tr ic and perchl ori c ac i ds d l l utjed

wi th 1+1 hydrochl ori c ac i d and anal yzed by atomi c adsorpt i on

1 1 1 B 3 Dat a Management

B i omass data col l ected duri ng thi s study was used to generate the

fol l ow i ng types of data

o Wet and dry wei ghts of Hydri l l a expressed as gm2

o Nutri ents [n i trogen ( N ) phosphorous ( P) potas s i um (K ) ]

per we i ght of Hydri l l a

I I I C I NTERMIM RESULTS - BIOMASS

I I I C l B IOMASS ANALYSIS

Monocul tures of Hydri l l a were present except at Stat i ons 1 2 5

9 and 13 At these fi ve l ocat i ons i nc i dental col l ect i ons of

Ceratoohyl l um sp were made I n i t i al process i ng of these sampl es

cons i sted of separat i ng Hydril l a and non -Hydri l l a spec i es and anal yzi ng

and eval uati ng each fract i on as a d i screte sampl e Once the eval uati on

3 -3

was compl eted b i omass val ues from both sets of sampl es were combi ned to

represent the overal l b i omass harvested from the study are a

B i omass val ues (dry we ights a l l spec i es combi ned ) ranged from

1 9 33 gm2 ( 02 kgm2 ) to 3 1 7 67 gmm2 (0 32 kgm2 ) (Tabl e 3 2 ) The

l ower b i omass val ues were found at stat i ons 1 and 2 wh i ch were nearshore

stat i ons The h i ghest b i omass general l y occurred at the stati ons l ocated

i n the central port i ons of the Hydri 1 1 a mat The range i n wet and dry

b i omass val ues wi th i n a confi dence i nterval of 1 plusmn standard dev i at i on

( SO ) are graph i cal l y presented i n F i gures 3 2 and 3 3 The cons iderabl e

var i at i on i n b i omass val ues among the stati ons i s rel ated to onshy

shoreoff-s hore d i fferences in stat i on l ocat i on and var i at i on in b i omass

maturi ty wh i ch i s descri bed by the prev i ous ly l i sted cond i t i on factors

rhe Hydri 1 1 a cond i t i on factors have been devel oped to prov ide an

i nd i cat i on of the vari abi l i ty of pl ant maturi ty and were used to prov ide

a prel i mi nary eval uati on of the rel ati onsh i p between pl ant maturi ty and

nutrient content The cond i t i on factors recorded at each stat i on dur i ng

b i omass sampl i ng are summari zed i n Tabl e 3 3

The Hydr i 1 1 a b i omass val ues for each sampl i ng stat i on were grouped

accord i ng to the i r respecti ve cond i t i on factor and pl otted ( F i gure 3 4 )

The resul ts of th i s group i ng dep i cts a cl ear pattern of the d i stri but i on

of b i omass versus p 1 ant maturi ty or cond i t i on factor The new growth

cond i t i ons (1 and 2) had the l owest mean bi omass val ues whi l e cond i t i on

4 (mature cond i t i on ) had the h i ghest val ue and cond i t i on 5 (senescence )

i nd i cated a decl i n i ng b i omass of the Hydri 1 1 a mat at the stati on

l ocat i ons The stat i ons sampl ed and the study area were pr i mari l y

con s idered to be represented by a mature growth cond i t i on duri ng the

August col l ecti on Cond i t i on factors ( pl ant maturi ty) are al so rel ated

to nutri ent content as i s subsequently d i scussed

A gross esti mate of b i omass i n terms of areal extent was projected

us i ng the wei ghtarea rat i o for each stat i on and then averag i ng the

rat i os It shoul d be noted however that stat i on sel ect i on for thi s

task was not random and stat i ons were del i beratel y chosen wh i ch

refl ected a range of growth cond i t i ons By the same l og i c l ocat i ons of

transects to be harvested were not random and were chosen i n an attempt

to sel ect maxi mum dens i t i es of Hydri l l a Wi th these qual i fi ers the

3 -4

average b i omass sampl ed ranged from l ess than 1 to over 14 tons per acre

and averaged 7 tonsacre Esti mates for tons of b i omass i n fres h both

wet and dry cond i ti ons al so appear i n Tabl e 3 2 The wet b i omass val ues

represent we ights of the pl ant materi al after surface water has been

removed from the pl ant by bl ott i ng wi th a dry med i um Because of t h i s

handl i ng procedure a d i rect compari son wi th the harvest contractor s

fi el d est i mates (of merely dra i ned materi al ) are not val i d s i nce the

water associ ated wi th the Hydri l 1 a cou l d add a con s i derabl e but unknown

amount to the esti mated total we ight

B iomass sampl i ng i n the study area has been l i mi ted to a s i ng l e

event and the resul t s of the samp l i ng effort do not refl ect seasonal

vari at i ons However Bowes et al ( 1 979) i nvest i g ated the seasonal

Hydri lJ a b i omass product i on of three Fl ori da l akes Lake Trafford

Orange and Jackson Thei r study i ndi cated that the t i me for seasonal

peaks i n bi omass vari ed wi th the southern most 1 ake Lake Trafford

produc i ng the max i mum Hydri l l a bi omass i n August wh i l e the more northern

l akes Orange and Jackson produced more Hydri l l a b i omass i n Novernber

I 1 I C 2 NUTRI ENT REMOVAL

Phosphorus content of Hydri 1 1 a and the potent i al for removi ng

phosphorus from the l ake system was the pri mary focus of the data

anal ys i s Secondary aspects were quant i fyi ng n i trogen and potass i um as

they rel ate to the overal l nutri ent content of the study area and

prov i d i ng i nformat i on for any poss i bl e uses for the harvested materi a l

Tabl e 3 4 summari zes the analyti cal data for bi omass sampl es

col l ected Hydri l l a and total b i omass are tabul ated separatel y s i nce

Hydri l J a i s the target spec i es of the harvest i ng program and i t compri ses

the majori ty of the pl ant materi al i n the study area Inter-spec i fi c

d i fferences i n pl ant chemi cal compos i t i on are al so reported by Boyd

( 1978) as the greatest source of vari at i on i n characteri zat i on stud i es of

aquat i c macrophytes

3 - 5

I I I C 2 1 Phosphorus

Total phosphorus ranged from 9 1 mgg to 2 68 mgg for al l spec i es

comb i ned and 91 mgg to 2 67 mgg for Hvdrill a only (Tabl e 3 4) The

comb i ned data wi th confidence i nterval s ( 1plusmn SO) are shown i n F i gure 3 5

The somewhat h i gher var i at i on i n phosphorus content at Stat i on s 2 5 9

and 13 i s est imated to occur as a resul t of the presence of non -Hvdri l l a

spec i e s at these l ocat i ons Therefore the presence of other spec i es i n

the sampl es ( i f not separated ) i s ant i c i pated to produce data that have a

greater vari abi l i ty and consequently are not as rel i abl e an est i mate of

nutri ent content as des i red for management dec i s i ons

Coeffi c i ents of var i at i on I n phosphorus content were cal cul ated

and pl otted by stat i on for comb i ned pl ants and for Hydr i l l a on l y ( F i gures

3 6 and 3 7) A compari son o f F i gures 3 6 and 3 7 however i ndi cates

that a rel at i vely smal l amount of the vari at i on observed can be

attri buted to the presence of two spec i es at a s i ngl e stat i on F i gure

3 7 demonstrates an i mportant con s iderat i on for any future sampl i ng and

asses sment effort s Sampl es o f Hydri l l a from the extremes of the

cond i t i on factors i e 1 and 5 produce data that may vary from 20 to

more than 30 i n est i mates of phosphorus content

The comb inat i on of cond i t i on factors and means for phos phorous

content at each stat i on i ndi cate a rel ati onsh i p between cond i t i on i e

re l at i ve maturi ty and phosphorus content ( F i gure 3 8) Stati ons wh i ch

cons i st pr imari ly of new pl ant growth (cond i t i on 1 ) contai n the l east

amount of phosphorus on a mgg (p l ant mater i al ) bas i s wh i l e stati on s

wi th pl ants that are descri bed as bei ng i n cond i t i on 4 (mature) have the

greatest amount of phosphorous A dec 1 i ne in phosphorus content al so

apparently accompan i es pl ant senescence

RegreSS i on anal ys i s was conducted to determ i ne the rel at i onsh i p

between b i omass and phosphorus content Because onl y one i ndependent

vari abl e (b i omas s ) was used i n the regress i on mode i t is necessary to

report only the resul ts of the two-tai l ed test u s i ng Student s t shy

stat i ons The nul l hypothes i s for the two -tai l ed test i s that there i s

no rel at i onsh i p between the dependent vari abl e and a spec i fi c i ndependent

vari abl e namel y bi omas s The t -stati st ic generated by the model

3-6

i nd i cated that b i omass s i gn i fi cantly effects phosphorus content at a 43

confidence l evel That i s there i s a 57 chance of i nd i cat i ng there i s

no rel ati onsh i p between b i omass and phosphorus i f the nul l hypothes i s i s

rejected

Add i t i onal stat i st i cal model i ng and an al ys i s i nd i cated that

b i omass at stati ons categori zed as Cond i t i on 4 were s i gn i fi cant ly rel ated

to phosphorous content at onl y a 75 confi dence l evel or a 25 chance

that a re 1 at i onshi p between b i omass and phosphorous content does not

exi st The h i gher confi dence l evel provi des some support for the use of

Hydrj 1 1 a cond i t i on factors part i cul arl y cond i t i on 4 for est i mat i ng the

nutri ent content of Hydri 1 1 a

To prov i de some prel i mi nary est i mates of potent i al phosphorous

removal rel ated to Hydri 1 1 a matur i ty each sampl i ng stat i on s phosphorous

we i ght to area rat i o was determi ned (Tabl e 3 5 ) These rat ios were then

averaged by cond i t i on factor The resu1 tant overal l phosphorus content

ranged from 16 1 bacre (cond i t i on 1 ) to 3 40 1 bacre (cond i t i on 4) and

dupl i cated the trend observed i n the b i omass data ( F i gure 3 4 )

The range of Hydri 1 1 a cond i t i ons factors and the presence o f other

macrophyte spec i es wi thi n the harvest area i nd i cates that further

defi n i t i on of the nutri ent removal est i mates are requ i red Th i s further

quant i fi cati on can be accompl i shed i n part through the use of aeri al

photographs The i nter im report by 15ampT ( 1 987 ) i nd i cates that sca1 ed

true col or and fa1 se col or i nfrared photographs of the study area have

been rout i ne1 y fl own Cop i es of these photographs and vegetat i on maps

wi 1 1 be requested from 15ampT The vegetati on maps produced from these

photographs by 15ampT wi l l be computer d i g i t i zed and acreage measurements

cal cul ated I t shoul d be noted that remote resource sens i ng techn i ques

part i cul arl y stud i es i nvol v i ng submerged pl ants have l i mi tati ons rel ated

primari l y to water depth and cl ari ty These 1 im i tati ons restri ct the

quant i ficat i on of i mmature Hydri 1 1 a represent i ng cond i t i on factors 1 and

2 because i t i s unl i ke1 y these p1 ants can be detected due to thei r

submerged cond i t i on Hydri ll a exh i bi t i ng cond i t i on factors 3 4 and 5

shoul d be v i s i bl e i n the l ate summer aeri al photographs as emergent mats

The fal se col or i nfrared aeri al photographs wi l l al so be anal yzed to

3 - 7

further separate the area i nto cond i t i on factors (3 4 and 5 ) These

refi ned est imates wi l l be i ncl uded in the fi nal report

An i ntegrated seasonal data base on nutri ent content of Hydri l l a

i n Lake Okeechobee i s l acki ng However recent data ( 1 5ampT 1988 )

i nd i cates there may be a pronounced seasonal d i fference i n t he chemi cal

compos i t i on of Hydrll l a from the l ake Hydri l l a sampl es col l ected by

15ampT duri ng January 1988 had phosphorus and n i trogen val ues that were

two to t hree t i mes h igher than the val ues reported for Aug ust 1987

(Tabl e 3 6 )

Spl i t sampl es anal yzed by the same l aboratory wh i ch prov i ded the

I SampT data provi ded veri fi cati on for the August phosphorus data reported

i n th i s study Therefore i t appears to be reasonabl e to assume that an

i ncrease i n Hydri l l a nutri ent content has occurred between August 1 987

and January 1988 The spec i fi c causes for th i s i ncrease are present ly

unknown but Federi co et al 1981 have suggested a nutri ent i nput

mechan i sm for the l ake based on l ake management W i th the fal lwi nter

i ncrease i n l ake surface area nutri ents conta i ned i n the l i ttoral zone

cou l d be transported l ake-ward by the fl ood i ng of the l i ttoral zone

Water qual i ty data from the present study does i n fact i nd i cate an

i ncrease i n i norgan i c phosphorus (P04- P ) from August 1 987 to January

1988 I t may be specul ated that i ncreased nutri ent avai l ab i l i ty may have

produced t h i s i ncrease i n Hydri l l a nutri ent content I t shoul d al so be

noted however that a seasonal i ncrease i n Hydri l l a phosphorus and

n i trogen content may occur i ndependent of any l ake management reg i me

Th i s seasonal vari at i on i n Hydri l l a nutri ent content has i mportant

rami fi cat i ons for any cont i nued or future harvest i ng programs I t al so

creates some add i t i onal quest i ons For exampl e i s th i s Hydri l l a

nutri ent i ncrease a l akewi de phenomenon or i s i t a near fi el d effect that

might be rel ated to the recent harvest i ng I f th i s i s a l akewide

i ncrease i n nutri ent content does it al so produce a correspond i ng

i ncrease i n bi omass so that phosphorus removal per acre cou l d be

max i mi zed I f th i s were true then the seasonal t i m i ng of any future

harvest i ng efforts need s to be careful l y cons i dered

Converse l y i f the wi nter i ncrease i n phosphorus content i s a near

fi el d effect rel ated to harvest i ng then perhaps harvest i ng des i gn i e

3 - 8

n umber and widths of harvested l anes needs to be re -exami ned and t i mi ng

of the harvest i ng may become l ess i mportant S i nce Hydri l l a i s a

n u i s ance spec i es al l prev i ous harvest i ng strateg i es have been a i med

toward weed el i mi nat i on for n av igat i onal purposes Because of th i s

nu i sance status management strateg i es have not been dev i sed or tested to

ut i l i ze Hydrj l l a as a nutri ent removal middotcrop middot For exampl e a seri es of

narrow but cl osely spaced cuts may be v i ewed as crop th i nn i ng wh i ch may

resul t i n greater nutri ent uptake by the adjacent unthi nned port i on of

the middotcrop middot Th i s act i on cou l d al so be coord i nated wi th n av i gat i onal

concerns and where appropri ate habi tat restorat i on or ma i ntenance

1 1 1 C 2 2 Ni trogen

As previ ous l y noted n i trogen has al so been eval uated as part of

the nutri ent analys i s N i trogen (TKN) ranged from 13 45 mgg to 26 34

mgg for al l spec i es combi ned and 13 45 mgg to 26 1 5 mgg for Hydri l l a

onl y (Tabl e 3 4) I ts d i stri but i on among stat i ons ( F i gure 3 9 ) fol l owed

the pattern prev i ousl y d i scussed for phosphorus Thi s pattern i ncl uded

the h i gh vari at i on attri buted to the presence of other spec i es ( F i gures

3 10 and 3 1 1 ) as wel l as the cond i t i on factornutri ent content

rel ati onsh i p of Hydri l l a ( F i gure 3 1 2 )

1 1 1 C 2 3 Potas s i um

The rema l n l ng nutri ent i ncl uded i n the anal ys i s was potass i um

wh i ch vari ed from 10 20 mgg to 26 28 mgg for al l spec i es combi ned and

10 20 mgg to 26 28 mgg for Hydri 1 1 a (Tabl e 3 4) Wi th several mi nor

except i ons potass i um content was a more vari abl e pl ant nutri ent than

e i ther phosphorus or n i trogen ( Fi gure 3 13 ) Thi s vari abi l i ty i n

potass i um content has al so been prev i ousl y reported by Sutton and Port i er

( 1983 )

A c o n s i d erabl e amou n t of the vari abi l i ty i n potas s i um

concentrat i ons was attri buted to the presence of other spec i es ( F i gures

3 1 4 and 3 1 5 ) but even when monocul tures of Hydri l l a are con s i dered a

h i gh amount of vari abi l i ty st i l l exi sts Kl opatek ( 1978) suggests that

3 - 9

vari at i on i n potass i um l evel s i n aquat i c macrophytes may refl ect h i gh

metabol i c demand duri ng the peri od of rap i d growth and that potass i um i s

not stored by pl ants s i nce th i s nutri ent i s read i l y avai l abl e from most

soi 1 s When grouped by cond i t i on factor the h i ghest potass i IJm contents

occurred i n the new or rapi d ly growi ng pl ants (cond i t i ons 1 2 and 3 )

( F i gure 2 - 1 6 ) Potass i um content decreases i n the l atter growth stages

assoc i ated wi th cond i t i on factors 4 and 5

I I I D CONCLUS IONS

The Hydri l l a b i omassnutri ent data anal yzed to date i nd i cates that

there are several important factors to be cons idered for future or

conti nued Hydri l l a harvest i ng programs

o Recogn i t i on and categori zati on of the rel ati ve maturi ty

state (cond i t i on factor) of the Hydri l l a mat i s i mportant

to sel ect sampl i ng l ocat i ons for nutri ent ana lys i s

o Anal ysi s of the nutri ent content of Hydri l l a i s most

preci se i e l owest sampl e vari at i on when col l ected from

areas of the mature mat The extremes of growth cond i t i on

new growth and senescence produced more vari abl e data

requ i ri ng l arger numbers of sampl es for rel i abl e mean

determi nat i ons

o Further testi ng of season a 1 d i fferences i n Hydri 1 1 a

nutri ent content and coup 1 i ng wi th harvest j ng-management

strateg i es cou l d s ign i ficantl y opt i m i ze the amount of

nutri ents removed through mechan i cal harvest i ng

I I I E RECOMMENDATIONS

Based on the data col l ected and anal yzed to date the fol l owi ng i s

the recommended course of act i on

Add i t i onal quant i tat i ve sampl i ng of Hydri l l a i n Lake Okeechobee i s

recommended Th i s add i t i onal sampl i ng effort shou l d be conducted at

3 - 10

1 ocat i ons both wi th i n the present study area as wel l as some 1 ocat i ons

out s i de of the study area Th i s general i zed pl an wi l l test for near

fi el d effects i e those effects that m ight be rel ated to harvest i ng

vs l akewi de effects Th i s sampl i ng effort shou l d be conducted quarterl y

to i nvest i gate the apparent seasonal changes i n Hydri l l a nutri ent

content Sampl i ng shou l d dupl i cate earl i er efforts and shou l d be

conducted at e i ght l ocat i on s four wi th i n and four outs i de of the present

study area

I I I F QUALITY ASSURANCE RESULTS

Tabl e 3 7 deta i l s the prec i s i on and accuracy of anal yt i cal resul ts

of dr i ed pl ant t i ssue Al l data were generated i n groups wi th

sat i sfactory qual i ty assurance cri teri a

3 - 1 1

LITERATURE CITED

Bowes G A S Hol aday W T Hal l er 1979 Seasonal vari ati on i n the b i omas s tuber dens i ty and photosynthet i c metabol i sm of Hydr i l l a i n three Fl ori d a l akes J Aquat i c Pl ant Mgt 17 61-65

Boyd C E 1978 Chemi cal Compos i t i on of Wetl and Pl ants IN Freshwater Ecol ogical Processes and Management Potenti al eds R E Good D F Wh i gham R L S i mpson C G Jackson J r Academi c Pres s N Y 378p

Freder i co A C K G D i c kson C R Kratzer F E Davi s 1981 Lake Okeechobee Water Qual i ty Stud i es and Eutroph i cat i on Assessment Techn i cal Publ i cati on 181-2 May 1981 Resource Pl ann i ng Department South Fl ori da Water Management D i stri c t West Pal m Beach FL 270pp + App

Kl opatek J M 1978 Nutri ent Dynami cs of Freshwater R i ver i ne Marshes and the Rol e of Emergent Macrophytes IN Freshwater Ecol og i cal Processes and Management Potent i al eds R E Good D F Wh i gham R L S i mpson C G Jackson Jr Academi c Press N Y 378p

ISampT 1987 Letter to Mr Ed Terczak dated Sep t 3 1987 Subj ect Chemi cal Anal yses resul ts of sampl es of Hydri l l a and mi crodeus

ISampT 1988 Letter to Mr Ed Terczak dated Jan 25 1988 Subj ect Compari son of nutri ent content i n Hydri l l a and water hyaci nth sampl es from the Demonstrat i on Project study area

Sutton D L and K H Port i e r 1983 Var i ati on of n i trogen phosphorus and potass i um contents of Hydri 1 l a i n South Fl orida J Aquat i c Pl ant Mgt 2 1 87 -92

3-12

Tabl e 3 1

Cond i t i on 1

Cond i t i on 2

Cond i t i on 3

Cond i t i on 4

Cond i t i on 5

Hvdrll l a Cond i t i on Factors to Descri be Pl ant Maturi ty i n the Lake Okeechobee Study Area

Areas of new pl ant growth rooted pl ants are l ess

than a foot h i g h

Pl ant growt h i s v igorou s but does not extend to the

surface P l ant s extend from 12 to 34 of the water

col umn i n height

Pl ant growth i s v igorous reaches the surface not

matted or at l east not brown and dyi ng on the

surface

Pl ant g rowth i s matted at the surfac e fl oat i ng

pl ants trapped s i gns of earl y decompos i t i on

P l ant mats are senescent and some open water i s

evident under mat

Source DSA Group I nc 1988

T-- 3 BiJS s_ bull aty 6 Sct irg 1tilt in _ Ia1 kee--gtee OJ --l l

my WEI lOOS lOOS

station GM2 so KGM2 so ArnE GM2 so KGM2 so ArnE

1 19 33 17 10 0 02 0 02 0 09 197 00 188 04 0 20 0 19 0 88

2 32 00 12 53 0 03 0 01 0 14 364 67 127 36 0 36 0 13 1 63

3 67 00 18 19 0 07 0 02 0 30 636 00 191 01 0 64 0 19 2 84

4 155 00 72 75 0 16 0 07 0 69 1660 33 733 09 1 66 0 73 7 41

5 195 33 85 82 0 20 0 09 0 86 1757 00 720 00 176 0 72 7 84

6 166 33 37 58 0 17 0 04 0 74 1695 33 335 67 1 70 0 34 7 56

7 263 33 56 70 0 26 0 06 1 18 2158 67 538 68 2 16 0 54 9 63

8 67 33 4067 0 07 0 04 0 30 676 33 302 63 0 68 0 30 3 02

9 184 67 94 85 0 18 0 09 0 77 1765 66 719 58 1 77 0 72 7 88

10 317 67 155 28 0 32 0 16 1 42 3165 33 1379 28 3 17 1 38 14 12

11 205 67 82 37 0 21 0 08 0 92 1716 00 500 11 1 72 0 50 7 66

12 200 67 47 60 0 20 0 05 0 90 2192 00 554 43 2 19 0 55 9 78

13 188 67 49 17 0 19 0 05 0 84 2326 00 492 11 2 33 0 49 10 38

14 116 00 29 82 0 12 0 03 0 52 1228 33 334 60 123 0 33 5 48

15 234 67 66 29 0 23 0 07 1 05 1997 33 527 08 2 00 0 53 8 91

Notes GM2= Grams Per Meter Square

SD= staOOald Deviation 1lGM2= Kilograms Per Meter Square

Dlta Ioolules Nan-Hydrilla Values for lhese stations

SOlllCe DSA Group Inc 1988

Tabl e 3 3

Cond i t i on

1

2

3

4

5

Sununary of Hydr i l l a Cond i t i on Factor by stat i on for the Lake Okeechobee study area August 18- 21 1987

Hydri 1 1 a Stat i ons

lt1 h i gh 1 2

12middot34 water col umn i n hei ght 2

at surface not matted 8 1 4 1 5

matted earl y decompos i t i on 4 6 7 1 0 1 1 1 2 1 3

senescent open water 5 9

Source DSA Group I nc 1987

Table 3 4 SUImlary ot Hyt1rllla Nl11rlent conumt nan Ole JaKe UKeeCnacee -oxty AJea 11

--- --------- - - ----- - -

Hydrilla Total Hydrilla Total Hydrilla Total p P TlltN TlltN K K

station I-CG so I-CG so I-CG so I-CG so I-CG so I-CG so

1 1 20 0 35 1 20 0 35 13 45 4 66 13 45 4 66 20 78 9 78 20 78 9 78

2 1 55 0 53 1 40 0 35 15 02 4 80 16 39 2 83 2156 12 06 16 45 6 23

3 1 43 0 06 1 43 0 06 15 78 1 37 15 78 1 37 19 66 6 19 19 66 6 19

4 2 36 0 27 2 36 0 27 20 67 2 76 20 67 2 76 20 57 4 81 20 57 4 81

5 1 28 0 14 1 47 0 30 16 49 0 88 16 93 1 10 19 09 2 11 18 99 1 98

6 1 60 0 02 1 60 0 02 17 16 028 17 16 0 28 23 56 5 57 23 56 5 57

7 0 91 0 07 0 91 0 07 15 58 0 38 15 58 0 38 10 20 0 53 10 20 0 53

8 1 37 0 15 1 37 0 15 13 60 2 50 13 60 2 50 26 28 8 25 26 28 8 25

9 1 45 0 36 1 48 0 39 17 60 2 38 17 73 2 56 18 34 5 30 18 59 5 35

10 1 96 0 14 1 96 0 14 21 35 1 69 21 35 1 69 18 71 2 73 18 71 2 73

11 1 63 0 13 1 63 0 13 16 71 0 37 16 71 0 37 16 60 5 06 16 60 5 06

12 1 81 0 12 1 81 0 12 21 97 1 04 21 97 1 04 14 43 1 37 14 43 1 37

13 2 67 0 27 2 68 25 26 15 2 29 26 34 1 97 15 89 4 52 15 89 4 52

14 2 14 0 09 2 14 0 09 20 68 1 12 20 68 1 12 23 68 1 72 23 68 1 72

15 1 33 0 11 1 33 0 11 14 01 0 47 14 01 0 47 15 82 1 99 15 82 1 99

Note All Values Expressed as Milligrams Per Gram of Dry Weight

50ur0e DSA Group Inc 1988

Tabl e 3 6

Sampl i ng Peri od Pl ant

August 1987

Tops

Steins

Whol e Pl ants

August 1987

Whol e P l ants

+January 1988

Who l e Pl ants

A Compari son of Hydri l l a Nutri ent Content for Samp l i ng Periods Conducted i n August 1987 and January 1987 i n t he Lake O keechobee Study Area

N i trogen Phosphorous (mgg-dry wei ght) (mgg-dry wei ght)

19 5 3 21

10 4 1 49

16 3 1 53

13 45 - 26 15 91 - 2 67

31 2 - 35 2 6 9 - 9 2

Source IST Augu s t 1987 Source DSA HHL August 1987

+Source IST January 1988

Tabl e 3 7 Bi omass anal ys i s qual i ty assurance resul ts

Prec i s i on Accuracy Parameter ( n X RSO SO) ( n X RSO SO)

Total phosphorus 6 3 8 1 4 4 1 0 1 7 6 5

Tota l Kje l dahl n i trogen 8 3 2 2 2 4 1 06 6 1 1 2

Potas s i um 6 3 1 1 8 5 12 1 2 43 5

zB

Figure middot3- 1 BIOMASS SAMPLING LOCATIONS

_c liOn Aalill LAaoaATOAV bullbull DA OAOb INC 18 bull

EVALUATION OF AQUATIC WEED HARVESTING DEMONSTRATION

IN LAKE OKEECHOBEE

Cl M EANS

B I O MAS S WET WE IG HT GRAS METER SQUARE

5--------------------------------------------------

45

4

3 5

3

25

1 5

1

05

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

+ UPPER CONFIDENCE STATION

o LOWER COIJADENCE

re 3 2

w a 4 J a tJ) lr w-ti

o M EANS

500

450-

40

350

300

2 50

20

1 50

1 00

50

0

1 2 3 4

+ UPPER CONfIDB-JCE

_ GPnl IP INC

81 0M-ASS D RY WEIGHT CRAMS METER SQUARE

-1-5 e 7 8 sa 1 0 1 1 1 2 1 3 1 4 1 5

STAriON o LOWER (ONlDENCE

ure 3 - 3

________________________________________________________ -____ G

c- -0 (I) (I) -laquo l 0 m J 0 I-

TOTAL BI O MASS VS HYDRI LLA C ONDITIO N DRY WEIGHT GlA2

3 00--------------------------------------------

2 80

1 80

1 60

1 40

1 20

1 00

80

6 0

40

20

middot0 1 2 3

CONDITION FACTOR IS I GM2 DRY NEIGHT

4 6

Figure 3-4

J laquo It w -It 0 L-a 0 -CL lt)

o M EAtJS

M I LLI G RAM S O F TOTA L P H O S PH O RUS

3--------------------------------------------

1

1 4

1 2

1

08 -1 2 3 4

+ UPPER CONFID ENCE

5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION gt LOWER CONFlDENCE

Figure 3-

z o tr 4 gt IL o

w o b IL W o o

C O EFFI C I ENT OF VARI ATION

TOTAL PHOSFHORUS 1 00-----------------------------------------------

90

80

70

60

50

40

30

2 0

1 0-

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION

i

z o ti gt b o

w o b h W o o

CO EFFIC I ENT OF VARIATION TOTAL PHOSA-lORUS (HtDRILLA ONLY)

I OO------------------------------------------------

90

80

70

60

50

40

30

20

1 0

1

IS I CONDlllON FACTORS STATION

9 1 0 1 1 1 2 1 3 1 4 1 5

Figure 3 -7

c - t) 2 0 -1 0 I-

TOTAL PH O S PH U RS VS H YDR I LLA C O N DITI ON

3--------------------------------------------

28

2

2

1 8

1 6 1 4

1

1 2 3

CONOrTJOt FACTOR -I I MGG my yenEIGHT

4 5

ure 3-8

J laquo cr

2 2 w l-e )- 20 (( 0 b 1 8 0 (-

z 1 6 t= 1 4

1 2

1 0

8

o M EANS

M ILLIGRAMS O F TOTAL KJELDAHL NITROGEN

1 2 3 4

+ UPPER CONFDE1CE

----r f 5 bull 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

STATION ltgt LOWER COtADENCE

-ltlilirA 3-9

z 0

gt La 0

I-Z w

0 La La w

0 0

CO EFFIC I ENT OF VARI ATION

TOTAL l1ltJtJ

4

30

2

1 0

1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

IS I CONDITlON FACTOR kZ 1 CV ()

Figure 3-1 0

z o t( tr laquo gt L o

tshyZ W o L L W o o

middot

CO EFFIC I ENT O F VARIATIO N 1lltN (HfDRlliA ONLY)

1 00-----------------------------------------------

90

80

70

80

50

40-

30

20

1 0

IS I CONDlllON FACTORS STATION WJ CV(7) 3- 1 1

0 -lt- z a

I--1 0 I-

30

28

28

24

22

2

1 8

1 8

1

1

2

0 1

TOTAL TKN VS HYDRI LLA CON DITION

2 3

CONDITION FACTOR r ] GG CRY WEIGHT

3- 1 2

-oJ ( tr W gt-cr n L 0 Cl - Cl E

o M EANS

M I LL IG RA M S O F TOTAL POTASSI U M

38---------------------------------------------

2

1

8--------------------- 1 2 3 4 5 8 7 8 9 1 0 1 1 1 2 1 3 1 4 1 5

+ UPPER CONFDENCE STATION

ltgt LCJWER CONFIDENCE

z o n 4 gt LL o

I-shyZ bJ o LL LL W o o

1 00

90

80

70

80

50

40

30

20

1 0

0 -

CO EFFIC I ENT O F VARIATION POTASSIUU

-- _-_------ ------

1 2 3 4 5 8 7 8 1

IS I CONDITION FACTOR STATION ---

l2 J cv(-)

1 4 1 5

3- 1 4

z 0 t a oC gt Iamp-0

--

It

r z w 0 lamp-Iamp-w 0 0

C O EFFIC I ENT O F VARI ATION

POTASSlUA (HfffiILLA 011 Y) 1 00 - - - - - - -- - ---- - - - -- - -- - - - ---- --- - -- - - - - - - - - - - -- - - - - -

90

80

70

60

50

40

30 -

20

-

1 0

0 - 1 2 3 4

IS I CONDIllON FACTORS

l 7

J

r t

I 10 1 1 1 2 13

STATON LUd CV ( )

3- 1 5

TOTAL P OTASS I U M VS HYD RI L LA CON DITI ON

30------------------------------------------

28

28

1 2 3

CONDfTION FACTOR 1 I GG y WEIGHT

4 5

3- 1 8

IV WATER QUALITY SURVEYS

IV A INTRODUCTION

Concerns for water qual i ty i n Lake Okeechobee are pr i mar i l y

focused on nutri ent storage and cycl i ng between the water col umn

sedi ments and bi omass and the impl i cat i ons of these processes for the

current and future troph i c state of the l ake The harvest i ng

demonstrat i on project undertaken by the South Fl ori da Water Management

Di strict and conducted by I nternat i onal Sci ence and Technol ogy I nc

( ISampT) i s one of the remed i al measures proposed to arrest the apparently

i ncreas i ng troph i c state The harvest i ng and subsequent upl and d i sposal

of Hydrj l l a i s bei ng u sed to effect the removal of total nutri ents

( phos phorus in part i cul ar) from the aquat i c system The Di str i ct s

eval u at i on and research project ( EampR) conducted by Mote Mari ne Laboratory

(MML) was des i gned to del i neate other env i ronmental i mpacts and cost

benefi ts associ ated wi th mechan i cal weed removal

The goal of the water qual i ty task of the EampR s tudy was to

del i neate changes that cou l d be attri buted to the removal of dense stands

of Hydri l l a vert i c i l l ata ( Fi gure 4 1 ) Al though the i mmed i ate i mpacts of

weed harvest i ng on water qual i ty may be substant i al those wh i ch

perS i sted over a peri od of t i me were expected to be fai rl y smal l and

l ocal i zed due to the advect i ve barri er of the Hydri l l a mat Accord i ngl y

i n order t o resol ve these changes from background vari abi l i ty grad i ents

of water qual i ty were assumed to exi st across the s i te al though they may

be wea k

The sampl i ng program was desi gned t o al l ow the stat i st i c al

eval uat i on of water qual i ty d i fferences between stat i ons at any one poi nt

i n t i me prov id i ng enough anal yt i cal data to produce mean i ngful

compari sons As a resu l t a mi n i mum of tri pl i cate col l ect i on s per

stat i on were necessary Th i s approach was preferabl e to more frequent

sampl i ngs because i t centered on quant i fy i ng i mpacts at part i cul ar

i nstances rather than on a conti nu i ng bas i s when seasonal processes i n

the study area woul d compl i cate anal yses of data

4 - 1

Water qual i ty i nformati on i s al so necessary for the i nterpretat i on

and anal ys i s of many of the other tasks Phytopl ankton and pri mary

product i v i ty stud i es i n part i cul ar are heavi l y dependent on t h i s task and

wi l l exami ne ava i l abl e nutri ents tox i c compounds ( copper) as wel l as

phys i cal data produced by thi s tas k Accord i ng l y sampl i ngs for water

qual i ty were conducted on each of the days that Envi ronmenta 1 Qual i ty

Laboratory ( EQL) depl oyed primary producti v i ty equ i pment In add i t i on

certa i n parameters (d i ssol ved s i l i cates col or and i norgan i c carbon )

were added to the analyti c al su i te at stat i ons where product i v i ty was

be i ng determi ned Water qual i ty sampl i ngs were al so conducted wi th i n 24

hours of the communi ty metabol i sm task fi el d efforts and wi th i n two weeks

of l arval and juven i l e fi sh sampl i ngs

IV B METHODS

IV B l Water Qual i tv Stat i on locat i ons

The northern 1 200-m (4000 ft ) of Transect 3 was des i gnated as the

experimental transect where a majori ty of the tasks focused the i r

efforts Th i s harvested area was sel ected based upon central 1 ocat i on

wi th i n the study s i te representati veness of the study s i te as a whol e

wi th respect to depth fetch shore proxi mi ty and speci es compos i t i on

and the dens i ty of the Hydri l l a mat of the area

Stat i on l ocat i ons for most sampl i ng s of the water qual i ty task

were i l l ustrated i n F igure 4 2 a superi mposed on the Loran C l i nes mapped

for the study s i te dur i ng the August 1 987 reconnai ssance A tabul at i on

of Loran coordi nates of these stat i ons appears i n Tabl e 4 1 Stat i ons

were establ i shed to defi ne any ex i st i ng water qual i ty grad i ents across

the s i te as wel l as i mpacts due to harvest i ng and so extend beyond the

boundari es of the area schedul ed for harvest Stat i ons 1 2 3 13 1 5

and 1 6 represented the perimeter o f the study s i te Stat i ons 7 - 9 were

l ocated on the northern hal f of Transect 3 the experi mental transect

and represented the treatment stat i ons the treatment be i ng harvest i ng

Control ( unharvested ) stat i on 10- 1 2 were adj acent to the

experi mental transect i n the unharvested l ane between Transects 3 and 4

4 -2

( Stat i ons 4 -6 were al ternate control stati ons to be used onl y i f unusual

cond i t i ons at Stat i ons 10- 1 2 i nd i cated that they woul d not represent

und i sturbed cond i t i ons These stat ions have not been occup i ed to date )

Stat i ons 7 - 1 2 were al so the same areas sampl ed for phytopl ankto n benth i c

i nfauna and sed i ment chemi stry Stat i on 1 5 was or i g i nal l y establ i s hed

beyond the southern end of Transects 6 and 7 However dense growths of

Amer i can Lotus i n the area made i t l i kel y that water exchange was

mi n i mi zed wi th the rest of the study area Th i s stat i on was accord i ng l y

moved t o the north but kept between transects s o that i t represented

unharvested cond i t i ons

I V B 2 Parameters

In liY i nstrumentat i on (Hartek Hark V I I ) was used to determi ne

depth profi l es (at 0 2 and 0 5 meter i ncrements from the surface and at

bottom) of temperature conduct i v i ty pH and ox idat i on-reduct i on

potent i a l (ORP) bull Di ssol ved oxygen ( DO) meters ( YS I 57 pol arographi c

el ectrodes equ i pped wi th st i rrers ) were used to measure DO at the same

depths Heters ( and i nstruments ava i l abl e as backup equ i pment ) had been

bench cal i brated aga i nst known standards or phys i ca l constants pri or to

each sampl i ng Cal i brat i ons of the meters empl oyed were repeated

fol l owi ng each sampl i ng L i -Cor i ntegrat i ng photometers were ut i l i zed to

quant i fy i nc i dent and penetrant l i ght Care was taken i n performi ng

these measurements to mi n i mi ze weed d i sturbance i n l oweri ng the

i nstruments and ext i nct i on coeffic i ents were cal cul ated from both the

upper ( 0 5 m) and l ower ( bottom) read i ngs to provi de est i mates of both

weed mass and water col umn l i ght attenuati on Water sampl es were

col l ected for l aboratory analys i s outs ide of the i nfl uence of any meter

d i sturbances

Sampl es were secured us i ng a non -metal l i c i mpel l er-type pump wi th

a weed excl ud i ng cage mesh s i ze of 1 mm ( F i gure 9 3 ) The cage was

l owered wi th a mi n i mum of d i sturbance to the weed mat to prevent

resuspens i on and entrai nment of l oose ly attached al ga l materi al or other

pl ant debri s Th i s col l ecti on techn i que was empl oyed for al l sampl i ngs

Chemi cal parameters i ncl uded al l standard n i trogen and phosphorus

4-3

spec i es Inorgan i c forms - -orthophosphorus ammon i a- n i trate- and

n i tri te -n i trogen - - were determi ned on fi l tered sampl es ( 0 45 micon

effect i ve pore s i ze ) to ascerta i n the ava i l abl e amounts most mean i ngfu l

for b i ol og i cal assessments Potass i um and sodi um were quant i f i ed on a

fi l tered sampl e Trace metal concentrat i ons copper ( Cu ) and i ron ( Fe )

al so were determi ned o n fi l tered sampl es due t o the affi n i ty of these

e l ements for suspended part i cul ates

Total organ i c carbon total Kjel dahl n i trogen total phosphorus

and al kal i n i t i es were determi ned on unfi l tered s ampl es as was

bi ochem ica l oxygen demand Turb i d i ty and suspended l oads were quant i fi ed

and total col i form was analyzed by the membrane fi l ter techni que The

analys i s of sampl es for sod i um chl ori de and fl uori de concentrat i ons was

performed to permi t water mass cal cul at i ons and determi nat i on of water

qual i ty grad i ents across the s i te Anal yses necessary for the pri mary

product i v i ty task were col or d i ssol ved s i l i ca and i norgan i c carbon

Water qual i ty anal yt i ca 1 methods used were those approved by the

Envi ronmental Protect ion Agency ( EPA ) and the Fl orida Department of

Envi ronmental Regul ati on ( FDER) Method references anal yt i cal hol d i ng

t i mes and preservati ves are detai l ed i n Tabl e 4 2

Lake l evel s for spec i fi c dates were obtai ned from the Di stri ct and

represent 1 ake wide averages of stage recorders operated by both the

Di stri ct and the u s Army Corps of Eng i neers

IV B 3 Sampl i ng

There were four types of water qual i ty sampl i ngs each vary i ng i n

the numbers of stat i ons sampl ed t imi ng of col l ecti ons or parameters

anal yzed The s ampl i ngs were enti tl ed basel i ne short - term impacts

quarterl y and fi el d demonstrati on Col l ect i ons were focused around the

experimental transect Analyti cal sui tes i nc l uded both phys i cal and

chemi cal parameters Sampl i ngs performed to date appear i n Tabl e 4 3

4 -4

Basel i ne Sampl i ng

Basel i ne sampl i ng was conducted on August 18 1 987 pri or to any

harves t i ng act i v i ty wi t h i n the s i te The day was cl ear hot and cal m

Average l ake l evel for the day was 4 22 m ( 13 85 ft ) A total of n i ne

( 9 ) l ocati ons ( Figure 4 2 ) was sampl ed to establ i sh a grid of control

stat i ons ( Stat i ons sampl ed were 1 2 3 10 1 1 12 13 1 5 and 16 )

These stat i ons were al l i n areas where no harvest i ng act i v i t i es were

schedul ed Stat i ons 10 1 1 and 1 2 were l ocated i n a heavi l y weeded

area whi l e the rema i n i ng control stat i ons were outs i de the area to be

harvested and were i n comparati vely open water At each stati on a total

of three separate sampl es was col l ected from a depth of 0 2 m for

l aboratory analys i s

At Stati ons 1 3 13 and 16 sampl es were al so sec ured from 0 8

of the overal l depth Water depth ranged from 0 9 to 2 0 meters at al l

stat i on s These corners of the study si te represented the spat 1 a1

extremes and water qual i ty data from surface and at depth were used as

i nd i cat i ons of verti cal gradi ents over the s i te

One add i t i onal stat i on at the mouth of the K i s s i mmee R i ver

( Stati on 20) was sampl ed at the surface (0 2m ) The effect of thi s

tri butary on l ake nutri ent l oad i ng and resul tant spat i al grad i ents may

thus be cons i dered Th i s s i ng l e sampl e however was not i ncl uded i n

stat i st i cal anal yses

A total of fourteen ( 14) stati on-depths resul ted from thi s

sampl i ng for a total of forty ( 40 ) sampl es for anal ys i s In ll1Y and

l aboratory analyses i ncl uded al l wi th the except i on of col or s i l i cates

and org an i c carbon as no phytopl ankton sampl i ng was conducted duri ng

th i s epi sod e Sampl es for total col i form were col l ected from Stat i ons

10 1 1 and 1 2 onl y ( n i ne sampl es)

Short Term Impacts Sampl i ng

Two short term impacts water qual i ty sampl i ngs were conducted

i mmed i atel y after and approx i matel y one week fol l owi ng the compl et i on

of harvest on the exper imental transect These sampl i ngs were i n

4 - 5

conjunct i on wi th and on the same day as phytopl ankton and pr i mary

product i v i ty sampl i ngs Sampl es were col l ected from Stati ons 10 1 1 and

1 2 the control stat i ons and from Stat i ons 7 8 and 9 the experi mental

stat i ons ( F1 gure 4 5 ) Experimental stat i ons were l ocated approxi mately

150m 600m 1070m ( 500 ft 2000 ft and 3500 ft ) from the northern end of

the transect and were approximate ly 75 m ( 250 ft ) from e i ther edge of the

harvested area Contro 1 stat i ons were pa i red wi th each experi mental

stat i on and were adj acent approx1mate1y mi dway between Transect 3 and 4

1 n the center o f the unharvested are a Sampl es were col l ected from 0 2m

depth onl y

Aquat i c weed harvest1 ng on the experi mental transect began

September 3 1987 and the northern 1 220 m was compl eted on September 1 7

Dur1 ng th i s and the succeed 1 ng dayt 1 me sampl i ng events the ongo i ng

harvest of weeds cont i nued nearby An MHl fi el d crew conducted sampl i ng

on September 1 7 a hot cal m and cl ear day when l ake l evel s averaged 4 13

m ( 13 56 ft ) Th 1ck Hvdri 1 1 a growth was v 1 s i b1 e at depth w1 th i n the

tran sect Another sampl i ng occurred on September 22 1987 ( l ake l evel

4 1 2 m ( 1 3 51 ft raquo under s imi l ar cond i t i ons Regrowth of Hydri 1 1 a i n the

experiment al transect was extens ive by th i s date Sampl es were col l ected

near the mouth of the Ki s s immee Ri ver on both occas i ons Seven ( 7 )

stat i on depths resul ted 1 n the col l ect1 0n o f n i neteen ( 1 9 ) sampl es on

eah date Al l in si tu parameters and l aboratory anal yses were i nc l uded

Quarterl y Sampl i ng

As wi th the i mmed i ate i mpacts sampl i ng s quarterl y sampl i ngs were

conducted i n conjunct i on wi th phytopl ankton work Stat i ons sampl ed

i nc l uded 1 2 3 7 8 9 10 1 1 1 2 13 1 5 and 16 at 0 2m depth

( F i gure 4 2 ) and Stat i ons 1 3 1 3 and 16 at 0 8m overal l dept h

S i xteen ( 16 ) stat i on depth s pl us one ri ver sampl e resul ted i n at l east

49 sampl es duri ng each of the four efforts In s i tu and 1 aboratory

parameters i ncl uded al l those l i sted wi th the except i on that total

col i form d i s sol ved s i l i cates col or and i norgan i c carbon were anal yzed

on l y on sampl es from Stat i ons 7 8 9 1 0 1 1 and 12 onl y ( the

exper i mental stat i ons and the i r control pa i rs )

4 -6

Quarterly sampl i ngs took pl ace on September 30 1 987 and January

1 3 1 988 wi th the rema i n i ng sampl i ngs schedul ed for Apr i l and June 1988

Lake l evel s were 4 1 4 and 4 90m ( 1 3 60 and 16 07 ft ) i n September and

January respect i vel y The September event was conducted o n a bl ustery

day (wi nds from the west at 5- 10 kts ) wh i ch l ater produced a dr i v i ng

rai nstorm Vi s i b i l i ty both in and above the l ake was obscured currents

were al so noted Li ght and vari abl e w i nds from the NE to W were noted

duri ng the January sampl i ng Hydrilla had regrown to t he surface i n some

cases by th i s date but otherwi se was not often vi s I b1 e due to i ncreased

l ake l evel s

The northern 180m of the experi mental transect was reharvested

duri ng December 1987 Stati ons 7 and 10 were sampl ed i n January and thus

represented a t h i rd treatment ( 1 e harvested twi ce ) In order to

ma i nta i n a bal anced des i gn for stat i st i cal anal yses however two ( 2 )

stati ons were added t o the sampl i ng schedul e The pos i t i on of Stat i on

7 5 was just south of the mowed sect i on and another control ( 10 5 ) was

added i n a comparabl e l ocat i on south of Stat i on 1 0 Stat i ons 7 5 8 and

9 then became the experimental group to be consi dered i n data analyses

F i el d Demonstrat i on Sampl i ng

Water qua 1 i ty impacts duri ng the actual harvest i ng process were

expected to be pri mari l y a product of turbul ence generated by harvest i ng

These effects were al so expected to be fa i rl y l ocal i zed due to the

dens i ty of the weed mat Any temporary resuspen s i on of organ i c detr i tus

or el evat i on of sol i ds or nutri ent concentrati ons wou l d be establ i shed by

an i ntens i ve t i me seri es wh i ch woul d exami ne the degree and durat i on of

any d i sturbance

The fi el d demonstrat i on water qual i ty samp l l ng was conducted on

October 28-29 1 987 when l ake l evel s were at 14 26 ft Three pai rs of

stat i ons approxi matel y 100 ft apart were establ i shed at the northern edge

of the wi nd fence or harvested area l ocated between Tran sects 2 and 3

( Fi gure 4 6 ) Subsequent to preharvest sampl i ng a harvester made two

passe s each approx i mately 100m l ong A smal l barri er of Hydri l l a ( ca

3m w ide ) was l eft i ntact between the harvested area of Transect 2 and the

4 - 7

RharvestedR area for th i s study Stat i ons were i dent i fi ed as Rcut R (Cl

C2 C3 ) or R uncut R (UCl UC2 UC3 ) duri ng th i s effort

Fol l owi ng the two passes of the harvester over the experi mental

swath no more harvest i ng occurred in that area for at l east 24 hours A

t i me seri es of sampl es were col l ected from -each of the s i x ( 6 ) stat i ons

Data were to be compared from each of the two stat i on types for

quant i fyi ng i mpacts and traci ng the i r durat i o n

Sampl es were col l ected a t 0 2m and 0 8m o f the overal l depth us i ng

the pump and the weed excl ud i ng cage to el imi nate the l argest Hydri l l a

fragments from the sampl e Col l ect i ons took pl ace i mmedi atel y pri or to

the passage of the harvester immedi atel y subsequent to the harvest of

the experimental stat i ons (wi th i n approxi matel y 0 5 hr) and then aga i n

at roughl y 2 5 10 and 24 h r i nterval s after the harvest Sampl es were

not col l ected i n tri pl i cate i nstead the three stat i ons i n each

treatment type formed the basi s for stati sti cal compari son A total of

twel ve ( 1 2 ) stat i on depths and s i x (6) col l ect i ons resul ted i n seventyshy

two sampl es for ana lys i s The s i x col l ect i ons were i dent i fi ed as rounds

1 -6 i n data pri ntouts In 11Y parameters to be determi ned i ncl uded al l

l i sted with the except i on of l i ght penetrat i on and secchi depth

measurements Total col i form was not anal yzed due to the extremel y short

hol d i ng t i me of that parameter nor were repet i ti ve l i ght measurements

wh i ch have a h i gh potenti al for d i sturbance of the water mass due to the

actual sampl i ng process Suspended l oad and turbi d i ty anal yses were

ut i l i zed for est imates of l i ght attenuat i on S i l i cates col or and

i norgan i c carbon were not anal yzed as no phytopl ankton work was

conducted at th i s t i me

IV C INTER IM RESULTS

Al l water qual i ty data col l ected through the m idpo i nt of thi s

project appear i n Append i x 4 A and i ncl ude in s i tu and chemi cal anal yses

from the sampl i ngs performed on August 18 September 1 7 September 22

September 30 and October 28-29 1 987 and January 13 1 988 Means of

al l parameters measured i n the study s i te are presented i n Tabl es 4 4

and 4 5 by date but wi thout regard to treatment stat i on or depth

4 -8

The most notabl e of the in ll1Y parameters i s di ssol ved oxygen

More than 32 of al l observat i ons made were i n v i ol ati on of t he 5 0 mg1

i nstantaneous d i s so 1 ved oxygen cri teri on for C1 ass I waters and 20 of

a l l observat i ons were bel ow 4 0 mg1 (Tabl e 3 4 ) Samp1 i ng t i mes were

skewed toward the morn i ng hours and were thus abl e to record the effects

of pre-dawn resp i rati on of aquat i c vegetat i on at the s i t e

Surface sampl es were al so col l ected i n the Ki s s i mmee Ri ver

approximatel y midway between the S R 78 bri dge and Lake Okeechobee i n

add i t i on t o those sampl es spec i fi ed by the scope of work (Tabl e 4 6 )

Ion content ( sod i um potass i um chl ori de al kal i n i ty s i l i cates )

typi cal l y was l ower i n the ri ver than the s i te waters and i ncreased

sod i um and chl oride concentrat i ons were observed i n the southern port i on

of the study area The ri ver was general l y l ess turbi d ( turbid i ty total

suspended sol ids ) hi gher in col or and apparent ly represented a source

of d i ssol ved i ron to the area

Both throughout the s i te and i n the Ki ss immee Ri ver d i ssol ved

copper l evel s i f detected were only sl i ghtl y above the l i m its of

detect i on The same was true of n i trite-ni trogen wi th the excepti on of

the January sampl i ng On th i s date concentrati ons at the Ki ss inunee

stat i on were h i gher (0 027 mg1 ) than the rema i nder of the stat i on s and

concentrat i on grad i ents were apparent across the study s i te Data on

col or si l i cates and i norgan i c carbon al though presented i n the

append i x wi l l not be extens i vel y analyzed i n thi s sect i on as such data

were pri mari l y col l ected for use i n i nterpretat i on of phytopl ankton

anal yses

IV D DATA REDUCTIONS

Stati sti cal anal yses of i n s i ty and chemi cal data empl oyed one and

two-way analyses of vari ance where treatment effects ( harvested non shy

harvested stat i ons depths ) were consi dered as fi xed (Model I ANOVA)

Two-way anal yses were conducted empl oyi ng the same assumpt i ons when the

rel at i ve magni tude of effects was of i nterest S ign i fi cance l evel s were

set at 0 05 ( P 95) Except where noted anal yses ut i l i zed the

untransformed val ues of the vari ous parameters Log ( base e) data

4-9

trans format i ons were usual ly used to approxi mate normal d i stri but i ons

Parameters trans formed for analys i s i ncl uded orthophosphate ammoni a

n i trate -n i tri te-n i trogen potass i um i ron BOD turbi d i ty TSS and

sod i um

When vari ances among groups were s i gni fi cant i nd i v i dual means

were contrasted us i ng e i ther Student t-tests or Tukey s Student i zed Range

Test wh i ch computes the smal l est HSD ( honestly s ig n i fi cant d i fference )

for determi n i ng d i fferences Both were ap pl i ed at the P - 95 l evel

IV E DISCUSSION

IYr E I In 1i1Y Parameters

D i ssol ved oxygen l evel s and percent s aturat i on of d i ssol ved oxygen

were expected to show the most change from harvest i ng act i v i ti es W ide

d i urna 1 swi ngs shoul d be damped by the removal of 1 arge amounts of

Hydril l a D i urnal pH cycl es and to a l esser extent ORP woul d be

expected to fol l ow thi s pattern as l ess vegetat i on woul d be present to

con sume carbon d i ox ide Seasonal cycl es were expected i n temperature

data however d i urnal cycl es and verti cal thermal grad i ents were l ess

l i kely 1 n areas where dense stands of fl oat i ng Hydri l l a had been removed

For al l parameters wi nd generated m ix i ng i n harvested areas shou ld

1 es sen the degree of al l surface-to-bottom grad i ents Any changes i n

conduct i v i ty at a part i cul ar l ocat i on as a resul t of harvesti ng woul d be

i nd i rect and woul d l i kel y refl ect al terat i ons i n current structure by

removal of the Hvdri l1a mat and the i ncreased fl ush i ng i n harvested

areas

Due to the obv ious d i fferences between sampl i ngs anal yses of i n

tliY data empl oyed two -way ANOVAs usi ng date and treatment ( harvested

Stat i ons 7 8 and 9 and non-harvested Stati ons 10 1 1 and 1 2 ) as

factors Further as vert i cal grad i ents for some parameters appeared

substant i al data sets were al so subd i v i ded i nto surface and bottom

readi ngs and exami ned separately Data were anal yzed from the sampl i ngs

of September 1 7 22 and 30 and January 13 As ant ic i pated sampl i ng

date was a h i ghl y s i gn i fi cant factor for al l i n s i tu parameters

4 - 10

conduct i v i ty ORP pH temperature DO and percent saturat i on Those

parameters exh i bi t i ng d i fferences attri butabl e to harvest i ng impact were

DO and percent saturat i on at both surface and bottom and pH at bottom

No i nteract i ve terms were s i gn i fi cant i nd icat i ng a consi stent and

pred i ctabl e pattern of d i fferences

Di ssol ved oxygen l evel s averaged between 0 5 and 3 6 mgl h i g her

i n the experi mental ( harvested ) transect than i n the adj acent control

stat i ons Th i s pattern was general ly most ev i dent from read i ngs at the

bottom of the water col umn Overal l i ncreases i n percent saturat i on were

approxi mately 20

It shoul d be noted that the majori ty of these data were col l ected

before 1000 ( EST ) and that th i s t i mi ng affected both the magni tude and

the d i rect i on of d i fferences i n DO l evel s Had sampl i ng been conducted

predomi nantly dur i ng mid- to l ate afternoon i t i s most probabl e that the

unharvested and heav i l y weeded areas would have had s i gn i fi cant ly h i gher

DO val ues than the adj acent harvested areas The observed pattern i s

cons i stent wi th an enhanced pre-dawn DO middot sag middot i n areas wi th h i gher

dens i t i es of aquati c vegetat i on (control s ) To ensure that no bi as was

i ntroduced by sequence of sampl i ng on each date stat i ons were ranked by

t i me of sampl i ng the ranks summed by treatment and compared Duri ng that

sampl i ng with the most d i screpancy between treatment rank sums September

30 DO l evel s i ndi cated that thi s was not a seri ous factor

The overal l s i gni fi cance of date i n the previ ous anal yses was due

predomi nantl y to the i ncl us i on of the January data set as can be deduced

from the means presented i n Tabl e 4 4 W i th removal of th i s data set and

reanal ys i s of the three September sampl i ngs the onl y parameters where

date was a s i g n i fi cant factor were pH and ORP I n attempt i ng to quant i fy

the i mmed i ate i mpacts of harvest i ng the removal of the January data set

can be j ust i fi ed on the bas i s that the regrowth of Hydri l l a was

essent i al l y compl ete by th i s sampl i ng and that there were no obv i ous

d i fferences between experi mental and control stat i ons The s i gn i fi cant

d i fferences between experimental and control s for DO percent saturat i on

and bottom pH however were essent i al l y the same i n th i s reanal ysi s

i mpl y i ng that the i mpacts were most marked e i ther wi th i n the th i rty days

of harves t or duri ng that part i cul ar port i on of the growi ng season

4- 1 1

The i ntens i ve fi e l d demonstrat i on sampl i ng carr i ed out on October

28 and 29 1 987 to del 1 neate the invned i ate impacts of harvest i ng was

pr i mari ly desi gned to measure turbid i ty associ ated parameters or

nutri ents rel eased from the sed iments as a resul t of the passage of the

harvester The in 1iY data co 1 1 ected however were subjected to an

ana l ys i s s i mi l ar to the above (Tabl e 4 7 ) D i fferences between harvested

and unharve sted areas were s i gn i fi cant here for a l l parameters but

pri mar i l y for the val ues at depth D i ssol ved oxygen duri ng - th i s

samp 1 1 ng however was l ower overa 1 1 i n the harvested area As water

col umn oxygen demand (BOD ) was comparabl e between transects reference to

sampl i ng t imes the majori ty after 1000 EST cl ari fy thi s apparent

d i screpancy These d i urnal cycl es are apparent i n F i gure 3 7

Duri ng the i mmedi ate impacts sampl i ng conduct i v i t i es were

s i gn i fi cant ly h i gher i n the experimental area than at the control

stat i ons wi th i n one hour of the passage of the harvester ( F i gure 4 6)

Cond i t i ons i n both areas had been comparabl e just pri or to the harvest

Th i s may i l l ustrate the rap id i ty wi th wh i ch fl ush i ng rates are i ncreased

Al l other in 1i1Y parameters wi th the except i on of percent saturat i on

exh i b i ted s ign i f i cant changes over t ime part i cul arly a t the bottom of

the water col umn These are i l l u strated for the rema i n i ng parameters i n

F i gures 3 9 through 3 1 1 where subtl e di fferences produced by harvest i ng

are superi mposed upon d i urnal cycl es The magni tude and s i gn of

d i fferences for many parameters in add i t i on to DO between harvested and

control stat i ons were heav i l y dependent on the t i me of day

Vert i cal grad i ents i n vari ous parameters were expected to be

reduced as a resul t of the removal of the advect i ve barri er of the

Hydri l l a mat and the consequent i ncrease i n wi nd -generated mi x i ng

Anal yses of vari ance of surface mi nus bottom in s i tu val ues as a s i ng l e

vari abl e were performed wi th stati ons

( harvested ) and control ( unharvested

comparat i ve ly non -weeded stat i ons ) Of

categori zed i nto experi mental

i ncl ud i ng both weeded and

the s i x sampl i ngs anal yzed i n

th i s manner surface to bottom grad i ents were most often observed for pH

DO and percent satura t i on Surface DO val ues ranged between 0 3 and 3 8

mgl h i gher (4 -46 saturat i on ) and surface pH between 0 04 and 0 2 SU

h i gher

4 - 1 2

Surface to bottom grad i ents were a 1 so apparent i n both

experi mental and control areas duri ng the immed i ate i mpacts sampl i ng of

October 28 and 29 Except for conduct i v i ty vert i cal grad i ents for these

two treatments were not stat i st i cal l y d i fferent from one another when the

fi ve post -harvest sampl i ng rounds were consi dered as a un i t Thi s

s i mi l ari ty i n grad i ents however shoul d not be confused wi t h the

d i fferences previ ousl y demonstrated between treatment areas for th i s

sampl i ng as the grad i ent anal ys i s i s concerned onl y wi th the d i fference

between surface and bottom val ues and makes no statement concern i ng the

rel ati ve posi t i ons of i nd i v i dual val ues

The fact that gradi ents were present at al l i n the harvested area

duri ng October may impl y that the d i mensi ons of the pl ot from wh i ch

HydrjJ l a was removed ( approxi matel y 6 by 1 20 meters ) were i nsuffi c i ent

for exi st i ng wi nd d i rect i on and vel oc i ty to cause substanti al mix i ng

Water depths ranged between 1 2 and I Sm These grad i ents were present

for pH DO and percent saturat i on agai n for the January sampl i ng i n both

control and experi mental transects wh i ch i s not surpri s i ng i n l i ght of

the degree of regrowth over four months s i nce harvest and the phys i cal

s imi l ari ty of stat i ons at th i s t i me

E2 Chemical Parameters

The anal ys i s of chemi cal data was desi gned to answer the fol l owi ng

questi ons for the sampl i ngs to date

o Are there detectabl e water qual i ty d i fferences between the

experimental and control stat i ons

o If there are was thi s ei ther d i rect l y or i nd i rect ly a product of

harvest i ng act i v i ty or i s i t the byproduct of stat i on l ocat i on

and the resul t of natural d i l ut i on grad i ents ( i e l oad i ng from

the Ki s s immee Ri ver or other sources )

o I f there are no s ign i fi cant d i fferences between harvested and

unharvested areas were d i fferences to be expected on the bas i s of

water mass compos i t i on

4 - 13

Where chemi cal spec i es are not d i rect ly correl ated wi th a d i st i nct

water mass or where i nputs to the water col umn are d i ffuse enough to

prevent the ma i ntenance of a spat i a 1 grad i ent or the detect i on of a

s i ngl e sourc e data analysi s i s s i mpl i fi ed to a compari son of treatment s

experimenta1 s agai nst control s Seasonal trend s i f present can be

factored i nto the stat i st i cal ana lys i s A s i mpl e compari son of harvested

aga i nst unharvested area chemi stry can al so be performed shoul d i on

content and rat i os i ndi cate that these water masses were i denti cal duri ng

sampl e col l ect i on and that d i l ut i on grad i ents can be i gnored

However when nutri ents or other spec i es are i ntroduced i nto a

system a ssoc i ated wi th a di sti nct water mass and when d i l ut i on with

ex i st i ng waters produces detectabl e gradi ents the quest i on s become more

compl ex In add i t i o n b i ol og i cal uptake wi l l produce non - l i near

rel a t i on sh i ps and the separati on of harvesti ng impacts from expected

gradi ents becomes more d i ffi cul t

The compl ex i ty of these questi ons i n the presence of d i l ut i on

grad i ents can be i l l ustrated graph i cal l y by reference to Fi gure 4 1 2

where hypotheti cal data appear In the fi rst part parameter X i s a

l i near func t i on of sod i um or i n other word s X i s a l so a con servati ve

parameter so i ts absol ute l evel i s affected onl y by d i l uti on wh i ch

mai nta i n s a constant X Sod i um rat i o Th i s regress i on would be devel oped

u s i ng one day s data from the ent i re gri d of n i ne control stat i ons across

the study s i te The hypothet ical data from a harvested stat i on (Stat i on

7 ) and the control (Stat i on 10 ) are al so pl otted It i s apparent that

wh i l e the l evel s of parameter X at the harvested and control stat i on

shown are probabl y not stat i st i cal l y d i fferent from one another the

harvested stat i on c l earl y fal l s outside of the 95 confi dence i nterval of

the X Sod i um regress ion for thi s data set and d i fferences from the l evel s

expected may refl ect harvest i ng i mpacts

In the second port i on of Figure 4 1 2 an al ternate s i tuat i on i s

i l l ustrated where the 1 eve1 s of parameter X at h arvested and control

stat i ons are shown to be c l earl y d i fferent However it i s apparent that

the water mass at the harvested stat i on i s sl i ghtl y more d i l ute and that

the correspond i ngl y l ower l evel s of parameter X are to be expected I n

4 - 14

both s i tuat i ons any b i ol og i cal processes affect i ng parameter X wi l l

produce even more compl ex rel at i onsh i ps

Sod i um and chl ori de were fi rst exami ned for i ns i g ht i nto water

mass movement and d i l ut i on processes occurri ng across the study s i te

The sum of these two i ons ( i n mi l l i equ i va1ent s ) was empl oyed a s an

approxi mat i on of total i on content They were both assumed to be

conservat i ve i e not part i ci pat i ng to any substant i al degree i n

b i ol og i cal processes where they might be sequestered or added to t he

water col umn F i gure 4 13 i l l ustrates thi s d i l ut i on process as i t occurs

across the study s i te The rat i o of sod i um to chl oride was al so

cal cul ated as an i dent i fy i ng feature of a part i cul ar stat i on

The gri d of ni ne control stat i ons was sampl ed on three occas i ons

August 1 8 September 30 1987 and January 13 1988 These data were

exami ned as t hey represented the 1 argest spat i a 1 area Anal yses of

vari ance i nd i cated that both total i on content and sod i um ch1 0r ide rati os

vari ed s ign i fi cant ly wi th respect to sampl i ng date I n l i ght of the

seasonal pattern of preci p i tat i on and the i nfl uence of ri ver d i scharge on

the area th i s was not surpri s i ng I n add i t i on however stat i on was

h i gh l y s i gn i f icant as a factor In the case of sod i um pl us chl ori de

th i s represents a change i n total i on content or d i l ut i on occurri ng

across a spat i al grad i ent ( Fi gure 4 14 ) I n the case of sod i um ch 1 0r i de

rat i os the fact that rat i os are di fferent at d i fferent stat i ons impl i es

that two or more separate water bod ies are represented across the s i te

( F i gure 4 1 5) I nteract i ve terms were al so s i gn i fi cant for each

parameter i nd i cat i ng that d i fferences were not cons i stent across t i me or

space Th i s i s apparent i n compari ng Fi gure 4 13 wi th Fi gure 4 14

As the mi xi ng of more than two water masses together woul d make

ana l ys i s of the rema i n i ng parameters extreme ly mathemat i cal l y compl ex

regress i ons of sodi um aga i n st chl ori de were performed for al l control

stat i ons on the three sampl i ng dates On each date correl at i ons for

l i near rel at ionshi ps were s ign i fi cant at pgt99 9 Th i s resul t al l owed

the use of the assumpt i on that onl y two water masses were mi x i ng across

the s i te Parameters associ ated wi th one of the two water masses coul d

therefore be detected by regress i ons on sod i um or some other conservat i ve

parameter

4 - 1 5

Anal yses of water qual i ty impacts were i n i t i al l y restri cted to

four sampl i ngs September 1 7 22 and 30 1 987 and January 13 1 988

Stat i ons 7 - 9 for experimental and Stat i ons 10 - 1 2 for control s (Stat i on

7 5 and 10 5 were used for the J anuary data set as an area wh i ch

i nc l uded Stat i on 7 had been reharvested shortl y before the sampl i ng )

S i gn i fi cant amounts of vari ati on between experi mental (Stat i on s 7

8 9 ) and control s ( Stati ons 1 0 1 1 1 2 ) as groups were found us i ng

two-way ANOVAs wi th date and treatment as factors (Tabl e 4 8 ) Al l

n i trogen and phosphorus spec i es (wi th the except i on of orthophosphate )

conta i ned s i gn i fi cant amounts of vari at i on d i stri buted between the

harvested and unharvested control stat i ons In add i t i on for BOD

turb id i ty and total suspended sol i d s d i fferences were present as wel l

As expected potassi um fl uoride chl ori de and sod i um d i d not d i spl ay

s i gn i fi cant vari ati ons between data from harvested and unharvested

stat i ons I ron copper total organ i c carbon and al kal i n i ty were al so

not s i gn i fi cant ly d i fferent between treatments

As d i scussed above however d i fferences between harvested and

unharvested areas are strai ghtforward onl y i f I water masses i n each of

the two treatment areas were identi cal or 2 the anal yzed parameter has

no s i gn i fi c ant rel ati onsh i p to a part i cul ar water mas s or to sod i um

Al though n o s ign i fi cant d i fferences i n sod i um o r chl ori de

concentrat i ons were observed between harvested and unharvested stat i ons

as a group di 1 ut i on grad i ents of these parameters were present wh i ch

paral l el ed the axi s of the harvested transects ( Fi gure 4 1 4 ) As a

resul t the data envel ope for the stati ons of a s i ngl e treatment was

l arge i n compar i son to any subtl e d i fferences between transects (F i gure

4 16 ) The fact that any di fferences were detected between experi mental

and control transects (Tabl e 4 8) impl i ed that they were substanti al

enough to overr ide the wi th i n -treatment vari abi l i ty expected from the

sod i um grad i ent S i gn i fi cance of i nteract i ve tems i n these model s

i nd i cated that d i fferences were not cons i stent from sampl i ng to sampl i ng

To d i rect l y compare harvested and non-harvested water qual i ty the

water of the two treatments must represent i dent i cal d i l ut i ons of source

and rece i v i ng waters As d i l ut i on gradi ents were roughly paral l el to the

transect axes stat i ons were pa i red and the d i fferences of experimental s

4 - 1 6

l ess control s cal cul ated for each pa i r of sod i um and chl ori de data

( Stat i ons 7 - 1 0 8- 1 1 9 - 1 2 Tabl es 4 9 4 10 ) The mean d i fferences

computed for al l sampl i ngs or for each date were on no occas i on d i fferent

from zero ( t - tests ) I n add i t i on no cons i stent pattern of d i fferences

was observed The conc1 us i on was that wh l l e di fferences 1 n the water

mass were present between stat i ons w ith i n a s i ngl e treatment harvested

stat i ons and t he i r adjacent control pai rs represented i dent i cal waters on

each date w i th respect to d i l ut i on

As water masses were i dent i cal the d i fferences i n parameter

concentrat i ons were cal cul ated for each stat i on pa i r as for sod i um and

chl ori de above These d i fferences are summari zed i n Tabl e 4 1 1 for those

parameters for wh i ch treatment was a s i gn i f icant factor i n the two-way

ANOVAs descri bed above (Tabl e 4 8 ) The magn i tudes of the d i fferences on

i nd i v i dual dates when not stat i st i cal l y equ i val ent to zero are al so

presented

Us i ng the pai red compari sons of stat i ons al l n i trogen s peci es and

total phosphorus exh i bi ted s i gn i fi cant al though subtl e d i fferences

between harvested and unharvested areas for the sampl i ngs to date (The

only date where orthophosphorus showed treatment d i fferences was on

September 22 and on th i s occas i on the magni tude was onl y 0 002 11191

1 ess than the 1 im i t of detect i on ) These d i fferences are most notabl e

for n i trate and ammon i a n i trogen and are i n add i t i on to any d i l ut i on

grad i ents across the s i te They can be presumed to refl ect the i mpacts

e i ther d i rect or i nd i rect of harvest i ng

Concentrat i ons where d i fferent were typi cal l y l arger i n the

unharvested control transect Th i s may be attri buted to e i ther uptake by

regrowth at harvested stat i ons or to the rel ease of nutri ents by

senescent macrophytes or peri phyton at the unharvested l ocat i ons

Fl oat i ng mats of Hydrj 1 1 a i n vari ous cond i t i ons were present through the

September 30 sampl i ng

B i ochemi cal oxygen demand turbi d i ty and suspended sol i d s al so

showed d i fferences us i ng stat i on pa i rs al though i n the i n stance of

suspended sol i ds concentrat i ons were sl i ghtl y h i gher at the harvested

stat i ons Wi nd -generated sed i ment resuspensi on i n harvested areas and

suspended senescent pl ant materi al i n the unharvested areas (contri but i ng

4- 1 7

to turbi d i ty and oxygen demand but wi th rel at i vely l i ttl e dry we i ght ) are

postul ated to account for these d i fferences Th i s i s supported

c i rcumstant i al l y by the l argest d i fference i n suspended sol ids be i ng

observed on September 30 when w i nd cond i t i ons were the most extreme of

any of the days sampl ed

The l argest number of parameters d i fferent between harvested and

weeded areas was al so observed on September 30 wh i l e the fewest were

seen on January 1 3 1 988 Whether th i s d i stri but i on across t ime i s a

res ul t of 1 ) vary ing nutri ent uptake rates throughout the growi ng season

2 ) the essent i al l y compl eted regrowth observed by the January s ampl i ng

3 ) the h i gher l ake l evel s and l ack of a fl oati ng mat of Hydri l l a perhaps

reduc i ng res idence t i mes of water across the s i te duri ng January or

4) the h i gher January nutri ent l evel s maki ng d i fferences more d i ff icul t

to d i scern i s i mposs i bl e to resol ve

Another techn i que for data anal ys i s was empl oyed on the September

30 and January 13 data sets for those parameters wh i ch were associ ated

wi th d i l ut i on grad i ents across the s i te Bri efl y i f the grid of control

stat i on s d i spl ayed s i gn i fi cant regress i ons with sod i um theoret ical

parameter concentrat i ons were cal cul ated for al l control and experimental

stati ons based on the observed sod i um data and that funct i on wi th the

h i ghest regress i on coeffi ci ent Res i dual s (V i - V hat) were then

compared by t - tests between means of experimental and control groups to

determi ne i f popul ati ons were the s ame (no impacts F i gure 3 1 2B) or

d i fferent ( i mpacts Fi gure 4 1 2A)

L i sted i n Tabl e 4 1 2 by date are the regres s i on types and

coeffi c i ents of the vari ous parameter concentrat i ons wi th sod i um Onl y

surface data from control stat i ons were used The vari ed nature of i nputs

to the s i te i s exempl i fi ed by F igures 4 1 7 and 4 18 dep i cti ng the vast l y

d i fferent d i stri buti ons of orthophosphorus between September and January

Whi l e rel at i vel y few parameters were apparentl y associ ated wi th

d i l ut i on duri ng the August sampl i ng the h i gher l oads i n September and

January perhaps coupl ed with sl owed uptake and growth rates duri ng the

l atter part of the year may produce l onger water col umn res idence t i mes

for nutri ent spec i es and permi t the detect i on of d i l ut i on grad i ents i n

4 - 18

these parameters Chl ori de and potas s i um and any other parameter onl y

s l ightl y affected by bi ol og i cal act i v i ty shoul d certa i nl y produce

s i gn i fi cant rel ati onsh i ps (The l ack of s i gn i fi cance of fl uor i de wi th

res pect to sod i um i s attri buted to the extremel y l ow l evel s encountered

e g concentrat i ons at or bel ow the l i mi t of detect i on for th i s

parameter )

Overal l the res i dual s anal ys i s of sod i um dependency proved l es s

sens i t i ve than that o f the pai red stat i ons anal yses O f the twenty-two

parameter-date combi nati ons where a s i gn i fi cant regress i on wi th sod i um

was obtai ned res i dual s of experimental stat i ons were s i gn i fi cant ly

d i fferent from res i dual s from control stat i ons for onl y three parameters

- - orthophosphorus and al kal i n i ty duri ng September 30 1 987 and n i tri teshy

n i trogen dur i ng January 13 1 988 Figure 4 19 superimposes the

experi mental stat i on orthophosphorus concentrati ons upon the rel at i onsh i p

devel oped for control stati ons i n September I t can be seen here that

the experimental stat i ons (X) are not evenl y d i stri buted around the

regress i on l i ne

Orthophosphorus concentrat i ons on th i s occas i on were l ower i n

the experi mental transect but onl y by 0 002 mgl l ess than the l i mi t of

detect i on Al kal i n i t i es at these stat i on s were h i gher than sod i um

concentrat i on s mi ght pred i ct by about 9 mgl as CaC03 Duri ng January

n i tri te - n i trogen was al so l ower at the harvested stat i ons than woul d be

expected on the bas i s of d i l ut i on al one but aga i n by l ess than the l imi t

of detect i on

As troph i c states and nutri ent l i mi tati ons wi thi n Lake Okeechobee

area of concern rati os of d i ssol ved and i norgan i c n i trogen to phosphorus

spec i es were cal cul ated and summari zed i n Tabl e 4 1 3 On a we ight bas i s

systems wi th rat i os l ess than 1 0 are typ i cal l y cons i dered n i trogen

1 i mi ted wh i l e phosphorus 1 im i tat i ons occur at rat i os greater than 1 7

( Sakamoto 1 966) Wi th th i s cr i teri on the waters o f the study s i te are

cl earl y n i trogen l imi ted i n contrast to al gal assays performed i n the

v i c i n i ty duri ng 1 974 and 1 975 ( Dye et al 1975 ) These resul ts have the

most consequences for phytopl ankton popul ati ons rather than macrophytes

as the rooted pl ants are capabl e of extracti ng at l east some i f not the

majori ty of thei r requ i red nutri ents from the hydroso i l

4 - 19

The stati st i cal anal yses d i scussed earl i er for the i ndi vi dual

parameters determi ned i norgan i c ni trogen spec i es to be h i gher i n the

unharvested control stat i ons and orthophosphorus to be s l i ghtl y l ower

ANaYA s of N P rat i os al so found s i gni fi cant d i fferences The treatment

( harvested or unharvested ) or stat i on was more important than date i n

account i ng for vari ati on Al l September and January sampl i ngs combi ned

produced mean N P rat i os for the harvested stat i ons ( 7 - 9 ) of 3 0 and for

the unharvested d i fferences coul d be attri buted e i ther to uptake by

act i vel y growi ng p l ants or to rel ease of nutri ents by senescent p l ant

materi a 1 Oi fferences between harvested and nonharvested areas were

l east apparent duri ng the January sampl i ng when ri s i ng l ake l evel and

Hydri l l a regrowth combi ned to i ncrease stat i on to stat i on phys i cal

s i m i l ari t i es

E 2 Bacteri ol ogi cal Parameters

Resul ts of total col i form anal yses (membrane fi l ter techn i que) of

sampl es col l ected on August 18 September 1 7 22 30 1987 and January 13

1 988 appear in Tabl es 4 1 4 After the August fi e ld effort sampl es were

col l ected i n conjuncti on wi th the phytopl ankton work and al l sampl es were

anal yzed by EQL Overal l bacteri ol ogi cal qual i ty was qu i t e good wi th

on ly a s i ngl e sampl e exceed i ng the 1000 counts per 100 ml cri teri on for

Cl ass I waters Th i s s i ngl e val ue of 5000 (Stat i on 1 1 September 30

1 987 ) was cl as sed as a stat i st i cal outl i er for the study as a whol e The

other two val ues from sampl es col l ected s i mul taneously were 900 and

100100 ml Most stat i on means were bel ow 200 countslOa ml

Stat i st i cal anal yses of these data empl oyed natural l og

transformat i on s Two way ANaYA s (by date and treatment and by date and

s t at i o n ) prod uced s i gn i fi cant terms for date and i nteract i ve

rel at i onsh i ps however nei ther harvesti ng nor stat i on accounted for

s ign i fi cant amounts of vari at i on Further anal yses cons i sted of mul t i pl e

l i near regress i ons of l og transformed total col i form counts aga i nst BOD

turb i d i ty total suspended sol i d s sod i um and chl ori de content ( as water

mass i ndi cators ) col or and s i l i cates A s i gn i fi cant regress i on model

whi ch i ncl uded BOD col or and TSS was obtai ned (r2 = 0 255 n 72) A

4 -20

d i rect rel ati onsh i p wi th BOD was not surpri s i ng The vari at i on wi th

col or val ues may be support for runoff control l ed bacteri a l evel s in the

l ake i ncreas i ng duri ng peri ods of h i gh d i scharge or backpump i ng (wh ich

are themsel ves characteri zed by i ncreased col or l evel s from t he

accumul ated surface waters An i nverse rel at i onsh i p w i th TSS l evel s was

l ess amenabl e to i nterpretat i on and i s l i kely to have been an art i fact of

some other control l i ng i nfl uence

IV E WATER QUALITY IMPACTS - QUALITY ASSURANCE OBJECTIVES

Prec i s i on and accuracy targets and resul ts for in ll1Y water

qual i ty parameters are presented in Tabl e 4 1 5 Prec i s i on est i mates were

based on dupl i cate in 1iY determi nat i ons expressed as percent rel ati ve

standard devi at i on (S RSD) Measurements at one stat i on per day were

typ i cal l y repl i cated i n thi s fash i on Prec i s i on est i mates for fi el d

measurements necessari l y i nc l uded the representati veness of the sampl i ng

as any non - homogene i ty of the s i te bei ng sampl ed appeared i n these

resul t s

Accuracy was determi ned from both pre- and post - sampl i ng

cal i brat i on of i nstrumentati on and where appl i cabl e the s i mu l taneous

col l ect i on of sampl es for l aboratory analysi s wi th al ternate procedures

or equ i pment Thi s was expressed as percent recovery ( R) of

f i el dl aboratory val ues t i mes 1 0 Col l ect i on of sampl es for

veri f icat i on was typi cal l y conducted at a rate of 1 for every 1 0 stati ons

samp l ed For th i s project di ssol ved oxygen and conducti v i ty were so

veri fi ed

Comparabi l i ty o f data was veri fi ed duri ng the pre- and postshy

sampl i ng cal i brati ons of i nstrumentat i on aga i nst standard sol ut i ons or

phys i c al constants Compl eteness of in 1iY data was esti mated to be

greater than 88 throughout the sampl i ngs to date

The qual i ty assurance object i ves for l aboratory anal yses were

anal ogous to those d i scussed for the i n s i tu parameters and are l i sted i n

Tabl e 4 14 Prec i s i on esti mates were determi ned from the anal yt i cal

resul ts and SRSD between the concentrati ons of two al i quots of a s i ng l e

conta i ner Dupl i cate analyses were performed at a rate of at l east one

4 - 2 1

for every ten sampl es The RSD between sampl es only sl i ghtly above the

l i mi t of detect i on i s often qu i te h i gh al though the analys i s i s

extremel y prec i se ( L e 0 001 and 0 002 11191 47 1 RSD ) Some mean

tRSD val ues and SD val ues are skewed by these seemi ngl y i mprec i se

dupl i cates that are actual l y wi th i n QA l i mi ts Accuracy of analyses was

assessed by the analys i s of sampl es to wh i ch known amounts of standard

materi al s had been added

IVG I NTERIM SUMMARY AND CONCLUSIONS

The study area i mmedi ately south of the entrance of the Ki s s 1mee

R i ver i nto Lake Okeechobee represents a compl ex combi nat i on of factors

wi t h regard to water qual i ty Vari at i ons with t i me were observed for

almost al l parameters measured D i ssol ved oxygen v i ol at i ons of the 5 0

11191 i nstantaneous cri teri on were common and d i urnal cycl es of DO and

rel ated parameters were apparent The skew i n sampl i ng t i mes toward the

morn i ng hours undoubtedly i ncreased the number of observed v i ol at i ons

a l though sampl i ng l ater i n the afternoon woul d i ncrease the percent

saturat i on of d i ssol ved gases and val ues i n excess of the 1 10 cri terion

wou l d have resul ted

In li1Y parameters were i n i t i al l y eval uated for stat i st i cal

d i fferences between harvested and unharvested stat i ons as a grou p

Di fferences i n DO percent saturat i on and p H were observed and were most

marked at the bottom of the water col umn and duri ng the September

sampl i ngs Pred i ct abl y harvesti ng reduced the ampl i tude of the d i urnal

DO cycl e such that DO concentrat i ons were h i gher i n the harvested

transect i n the morn i ng hours and l ower duri ng the afternoon Both the

magn i tude and the d i rect i on of the observed d i fferences were therefore a

funct i on of the t i me of sampl i ng

A rap i d change i n water masses was al so observed at harvested

stat i ons and th i s was attri buted to the i ncreased fl ush i ng potent i al

produced by Hydri l l a removal Inten s i ve surveys detected vert i cal

grad i ents of s i mi l ar magn i tudes for i n s i tu parameters at both harvested

and control stati ons The s i ze of the harvested transect may have been

too smal l to al l ow wi nd-generated vert i cal mi xi ng to be effect i ve

4-22

Bacteri ol og i cal water qual i ty at the s i te was good overal l wel l

wi th i n the 1000 1100 ml cri teri on and correl at i ons w ith col or BOD and

TSS were present Col or rel at i onshi ps i ndi cate a functi onal rel at i onsh i p

of total col i form wi th d i scharge i nto the l ake whi l e the rel at i onsh i p

wi th TSS was i nverse

Chemi cal water qual i ty d i stri but i ons at the s i te were a l so qu i te

compl ex Spat i al and d i l uti on grad i ents produced by the i nfl uence of the

K i s s i mmee Ri ver were qu i t e apparent as determi ned by conservat i ve

parameters such as sod i um and chl ori de The d i l ut i on grad i ents were

roughl y paral l el wi th the l ong axi s of the harvested transects such that

a progress i on of i ncreas i ng strengths of Lake Ri ver d i l ut i ons were

observed al ong both the experimental harvested transect and the adjacent

unharvested control transect Thi s transl ated to a h i gh wi th i n -treatment

va ri a b n i ty of water masses compared to the between- treatment

vari abi l i ty wh i ch i n turn may obscure d i fferences between harvested and

unharvested areas i n stra ightforward stat i st i cal compari sons

Overal l stat i sti cal techni ques were sat i sfactory because the

number of sampl es adequate for determi ni ng di fferences i n concentrat i ons

was at or near the analyt i cal l imi ts of detect i on The three stat i st i cal

anal yses were 1 ) d i rect compari sons (means test i ng and ANOVA s ) of

harvested to unharvested data sets 2) ana lys i s by d i fference of stat i on

pa i rs ( harvested l ess the adjacent control stati on) and whether

d i fferences were stat i sti cal l y d i fferent from zero and 3) res i dual s

anal ysi s of those parameters wi th a s ign i fi cant rel at i onsh i p w i th sod i um

and whether the popul ati on of res i dual s from control stati ons was

equ i val ent to those from the harvested stati ons

Ana lys i s of harvested versus unharvested data groups by parameter

reveal ed s i gn i fi cant d i fferences between treatments for al l n i trogen

spec i es total phosphorus BOD turb id i ty and total suspended sol i ds

These d i fferences are i n sp i te of the broad envel ope i n water qual i ty

conta i ned wi th i n each treatment type However d i rect compari sons and

correct est i mati on of the magni tude of harvest i ng impacts are poss i bl e

onl y where the water masses of the two treatments can be assumed to

represent equ i val ent po i nts on the d i l ut i on grad i ent

The d i fference i n sod i um and chl ori de concentrat i ons between each

harvested stat i on and i ts adjacent unharvested stat i on was cal cul ated

For al l dates these d i fferences were equ i val ent to zero mean i ng that

the water mass was i dent i cal at Stati ons 7 and 10 at Stat i ons 8 and 1 1

and at Stat i ons 9 and 1 2 The d i fferences i n concentrat i ons between the

stat i on pai rs cou l d then be calcul ated Al l n i trogen spec i es and total

phosphorus concentrat i ons were typ i cal l y h i gher i n the unharvested

transect On the one occas i on where orthophosphorus d i ffered between

treatments i t was s l i ghtl y h i gher i n the harvested transect Turbid i ty

and BOD were al so h i gher at the control stat i ons wh i l e total suspended

sol i ds were sl ightly l ess Uptake by macrophytes i n act i ve regrowth

rel ease o f nutri ents by senescent and matted pl ant mater i al and wi nd shy

generated resuspens i on may account for thi s pattern

Ana lys i s of those parameters associ ated wi th d i l u t i on and of those

wi th s i gn i fi cant correl at i ons wi th sod i um proved l ess sens i t i ve for

detect i ng d i fferences Al though many parameters d i spl ayed s i gn i f icant

rel at i onsh i ps the i r d i stri but i on around the regress i on l i ne was

cons i derabl e and res i dual popul at i ons were s i gn i fi cantly d i fferent

between treatments for only three parameters

The s i te as a whol e appeared to be n i t rogen 1 i mi ted based on

we i g ht r at i os of i norgan i c n i trogen forms to orthophosphorus

O i fferences between harvested and unharvested areas were apparent here

al so w i th average rat i o s of 3 0 and 9 4 respect i vely

IVG RECOMMENDATIONS - FINAL REPORT

For the rema i n i ng two quarterly sampl i ngs i n th i s task a

real l ocat i on of effort i s proposed wh i ch woul d del ete copper and fl uori de

from the anal yt i cal su i tes These two parameters were e i ther at or near

the 1 im i ts of analyt i cal detect i on for al most al l s ampl es and

stat i sti cal analyses were not effect i ve i n determi n i ng any d i fferences

attri butabl e to harvest i ng at these l ow concentrat i ons N i tri teshy

n i trogen however shoul d be reta i ned Al though l evel s were l ow they

are i mportant i n th i s n i trogen 1 i mi ted system and d i fferences between

treatments were apparent The Ki ss i mmee R i ver stat i on shou l d cont i nue to

4-24

be sampl ed and another stat i on shou l d be added to the west of Stat i on 1

toward Buckhead Ridge as an i ntermi ttent nutri ent i nput may be present

there Mon i tori ng of these two add i t i onal stat i ons shou l d cont i nue for

al l parameters In pl ace of copper and fl uor ide anal yses d i ssol ved

cal c i um i s suggested as a repl acement to prov ide a bas i s of compari son

wi th other work done prev i ously i n the l ake and to exam i ne i ts behav i or

across the s i te The poss i b i l i ty of mov i ng the exper imental and control

stat i on pai rs ( Stat i ons 7 - 1 2 ) to the most recently harvested area for the

subsequent sampl i ng i s currentl y be i ng d i scussed wi th the task l eaders of

the i nter-rel ated tasks

Future data exami nat i ons wh i ch wi 1 1 be conducted for the fi nal

report of th i s project i ncl ude the deta i l ed assessment of l i ght

penetrat i on profi l es and the effect of the weed mat upon these The data

from the 24 hour fi el d demonstrat i on sampl i ng wi l l be eval uated w ith

regard to chemi cal parameters and the i mmedi ate effects produced by

harvest i ng S i l i cates col or and i norgan i c carbon data wi l l be

processed as wi l l the rema i n i ng parameters for d i fferences between

experi mental and control stat i on s and a further anal ys i s of d i ssol ved

oxygen wi th cons i derat i ons for t i me of day vegetat i on and even sed i ment

type wi l l be conducted

4-25

LITERATURE CITED

Dye C W D A Jones L T Ros s R L Wi l l more 1 975 L imi t i ng nutri ents i n the Ki ss i llll1ee Ri ver - Lake Okeechobee Bas i n based on al gal assay techni ques Fl a Dept Envi ronmental Regul at i on Sakamoto H 1 966 Pri mary product i on by phytopl ankton conununi ty i n some Japanese l akes and i ts dependence on l ake depth Arch Hydrobi ol 62 1 - 28

4-26

Table 4 1 Mean IDran coordinates of water quality staticns

STATIOO NO

1 2 3 7 7 5 8 9 10 10 5 11 12 13 15 16

Ipound)RAN 1 JPRAN 2

14313 2 45453 2 14312 6 43449 1 14312 4 43445 9 14313 6 43449 1 14313 4 43448 2 14313 2 43447 7 14312 9 43446 1 14313 7 43448 5 14313 5 43447 7 14313 4 43447 3 14312 9 43445 7 14315 1 43444 6 14313 9 43443 2 143109 43437 8

Table 4 2 water Quality parameters methods ard holdirq times

Parameter

TeJlFerature Corrluctivity pi ORP Dissolved Oxygen Light Penetratim Secxhl laboratory 0rthqil0spl0rus (D) Total AlosJtIorus (D) AImalia-Nitrogen (D) Nitrite-Nitrogen (D) Nitrate-Nitrogen (D) Total Kjeldahl Nitrogen ium (D) Ccgler (D) Iran (D) Total OJgan1c carbon Alkalinity Biochemical Oxygen DeuanI lu1)idity SUspenled Solids Ibtal Ollifonn auoride Scdium Fluoride Color silicates (D) Inorganic Cartlon

MetbodlInstrument

Martek Mark VII Martek Mark VII Martek Mark VII Martek Mark VII YSI 57 LiOlr Secxhl Disk (LiDngtlogical)

EPA 365 1 365 3 EPA 365 3 365 4 SM 417F EPA 350 3 EPA 353 3 353 3 EPA 353 2 353 3 EPA 351 2 SM 30lA SM 303A B SM 303A B EPA 415 1 8M 403 4C EPA 3102 EPA 405 1 EPA 180 1 SM 2090 8M 908A 909A SM 4070 EPA 325 3 SM 303A EPA 3402 SM 204A B EPA 370 1 SM 425C EPA 415 1

Holdirg TimePreservative Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable Not awlicable

Filter iDmSdiately 48 hrs4Oc 28 daYSH2S04 to pllt2 40c Filter bImadiately 28 daYSH2S04 to pllt2 40c Filter bImadiately 48 hrsH4 to pllt2 40c Filter iDmSdiately 28 daYSH4 to pHlt2 40c 28 daYSH2S04 to pllt2 40c Filter iDmSdlately 6 1IDSIftll) to pllt2 40c Filter iDmSdiately 6 1IDSIftll) to pllt2 40c Filter inmediately 6 1IDSIftll) to pHlt2 40c 28 daYSH2S04 to pIlt2 40c 14 days4oC 48 hrs4Oc 48 hrs4Oc 7 days4Oc 6 hrs4Oc 28 days4Oc Filter inmdiately 6 lOOIlthslftll) to pIlt2 40c 28 days4Oc 48 hrs4Oc 28 days4Oc 28 days4Oc

EPA = EPA 6004-7920 Methods for OJemical Analysis of water ard wastes SM = stanIard Methods for the Examination of water ard wastewater 15th Fdition 1980 (D) = Dissolved

Tabl e 4 3

Date

Aug 18 1987

Sept 17 1987

Sept 22 1987

Sept 30 1987

Oct 28-29 1987

Jan 13 1988

Sampl i ng efforts and dates Water Qual i ty Tas k

Sampl i ng Type

Basel i ne

Short Term Impacts

Short Term Impacts

Quarterly

F i el d Demonstrat i on

Quart erly

No of Stat i ons

9

6

6

12

6

12

No of V i al s

1

1

1

1

6

1

Table 4 4 site averages of in situ parameters by sanplirg date all stations all depths

1987 1988

AU 18 SEP 17 SEP 22 SEP 30 ocr 28-29 JAN 13

n 28 18 18 36 144 68

2 SD 2 S D 2 S D S( S D S( S D 2 SD

onluctivity 0 5350 0661 0 5397 0351 0 5074 0550 0 4985 0517 0 3921 0731 0 3017 0895

ORP 493 109 441 42 298 77 293 47 295 31 247 55

Pi 8 02 0 55 8 27 0 34 7 56 027 7 47 043 7 72 0 51 7 59 0 30

lenperature 28 95 144 27 34 0 50 27 23 054 26 67 041 23 11 099 16 67 078

Dissolved Oxygen (00) 5 02 3 20 3 51 2 20 2 87 1 32 5 11 2 28 664 2 25 8 16 1 58

PeJta1t SaturatiCBl 66 1 42 9 44 4 27 9 36 3 16 7 64 0 28 6 77 8 269 84 0 16 7

00 cbs lt1 0 nql 128 318 218 336 0144 168

00 cbs lt4 0 nql 1428 U18 1318 936 14144 168

00 cbs lt5 0 ugII 1428 1218 1618 1536 41144 268

Table 4 5 Site averages of water quality parameters by sanplirg date all stations all depths

1987 l2sectsect AU 18 SEP 17 SEP 22 SEP 30 ocr 28-29 JAN 13

n 39 18 18 48 7 3 54 K SD K SD I SD K S D K SD K SD

0rthqil0sJil0 0 019 0 007 0 017 0 005 OOll 0 003 O OlS 0 014 0 033 0 011 0 082 0 045 Total rus 0 07 0 11 0 10 0 01 0 08 0 01 0 09 0 03 0 12 0 06 0 15 0 05

Anrncnia-nitrogen 0 039 0 018 0 04 5 0 042 0 017 0 012 0 012 0 017 0 040 0 029 0 04 6 0 036 Nitrite-nitrogen 0 004 0 001 0 005 0 004 0 004 0 001 0 003 0 003 0 004 0 001 0 008 0 004 Nitrate-nitrite-nitrogen 0 009 0 003 0 034 0 036 0 039 0 021 0 048 0 046 0 038 Q 019 0 190 0 039 Total Kjeldahl nitrogen 1 52 0 26 1 75 0 15 1 55 0 28 1 47 0 18 1 29 0 20 1 20 0 17 Potassium 4 4 0 9 4 7 0 3 4 5 0 3 4 2 1 0 2 9 0 5 3 9 1 0

Cqpar 0 003 0 002 0 003 0 002 0 003 0 001 0 002 0 001 0 001 0 001 0 002 0 002 Iron 0 002 0 002 0 014 0 007 0 014 0 007 0 015 0 019 0 048 0 018 0 090 0 031 ampxlium 4 8 9 7 6 47 3 4 6 46 9 4 7 49 0 9 4 31 0 8 9 28 2 8 1 Olloride 8 5 8 13 1 79 6 6 4 76 5 8 6 76 2 10 0 55 9 14 9 48 2 16 7 Fluoride 0 3 0 03 0 3 0 05 0 3 0 03 0 3 0 04 0 1 0 03 0 2 0 03 lbtal organic carlxln 2 1 7 1 6 17 9 0 9 18 1 0 8 18 4 1 0 19 7 2 5 18 4 3 0 Alkalinity 105 14 117 5 113 8 1U 10 7 3 15 68 lS Biochemical oxygen deHard 1 9 1 0 2 7 1 3 2 2 0 6 2 3 1 2 1 5 0 7 1 1 0 6 lubidi ty 2 4 1 9 4 2 0 9 4 1 1 5 4 0 2 9 3 1 2 5 3 7 2 1 Total susperded solids 3 3 3 3 6 0 2 3 5 7 2 4 6 3 4 7 4 5 3 9 3 1 4 1 Oller 61 5 66 9 81 9 113 10 silicates 12 8 2 2 13 1 2 2 12 0 3 0 5 4 0 5 Inorganic carlon 17 4 4 3 19 9 2 8 20 4 4 4 11 9 5 2

11=18

Table 4 6 site averages of water quality parameters for the KissiJulse River by sanpling date

1987 1988

AU 18 SEP 17 SEP 22 SEP 30 JAN 13

0 032 0 096 0 12 7 0 116 0 063 Total (ilcsphorus 0 09 0 18 0 20 0 20 0 12 Almalia-nitrcgen 0 021 0 036 lt0 005 0 017 0 069 Nitrite-nitrcgen lt0 005 lt0 005 lt0 005 lt0 005 0 027 Nitrate-nitrite-nitrogen 0 012 0 009 0 072 0 188 0 151 Total Kje1dahl nitrogen 0 51 1 39 1 40 1 12 1 08 Ibtassium 3 7 3 6 3 5 2 9 3 2

((gler 0 003 0 003 0 004 0 001 lt0 001 Iron 0 008 0 085 0 095 0 172 0 225 Sodium 3 3 4 2 6 5 24 2 2 1 0 15 0 Olloride 60 6 47 8 4 1 9 38 7 23 7 Fluoride 0 3 0 3 0 3 0 2 0 2 Total organic cartxn 19 6 19 5 19 9 18 8 17 4 Alkalinity 89 7 3 66 57 34 Biochemical oxygen daDaM 2 4 3 0 1 5 1 3 0 5 lJnbidity 3 0 3 9 2 7 2 3 2 3 Total suspenied solids J 9 4 8 4 0 2 5 2 0 Color 110 130 130 125 Silicates 6 58 6 42 5 67 3 17 Iooxganic carbon 4 4 9 6 7 2 1 1

Tabl e 4 7 S i g n i f icant F middot test rat i os for two-way ANOVA s by treatment and samp 1 1 ng round for in illY data co 1 1 ected duri ng fi el d demonstrat i on samp l i ng October 28-29 1987

FmiddotTET RAT IOS

TREATMENI ROUND INTERACTION (Exp vs control ) (1-5 only ) (Treatment x Round )

CONDUCTI V lTV Surface 25 99 1 14 56 Bottom 28 3 5 4 26 1 6 73

ORP Surface 2 1 10 Bottom 5 35

pH Surface 32 67 33 10 Bottom 1 1 1 5 4 5 1 4 48

Temperature Surface 104 64 Bottom 21 95 1 1 73 8 17

D i s sol ved Surface Oxygen Bottom 14 1 5 7 98 5 20

Saturat i on Surface Bottom 7 66 3 87

df df error bull 20 F 0 05 [df 20 ] bull

1

4 35

4

2 87

4

2 87

Table 4 8 Significant F-test ratios fnD two way analysis of variane by date ani treatment statiCllS 7-12 only Septedler 17 22 30 1987 ani JanJaIY 13 1988 data

rus dissolved Total pnsphorus Anroonia-nitrogen di ssolved Nitrite-nitrogen dissolved Nitrate-nitrite-nitrogen dissolved Total Kjeldahl nitrogen RltassilDU di ssel ved Cqpr di ssolved Iron dissolved Total organic car1xXl Alkalinity Biochemical oxygen demard TUlbidi ty Total suspenied solids Chloride SOdilDU Fluoride

Degrees of freedaD

Degrees freedan of error = 64

F 0 05 [df 60]

595 12 31 05

4 09 96 71 51 06 31 28

225 02 6 34

424 47 23 36 18 32 28 69

171 46 145 71

49 55

3

2 76

lREMMENl ( vs cxmR)L)

10 24 4 81

17 59 12 57

6 75

6 31 24 03 22 36

1

4 00

3 89

4 64 4 94 5 08

3

2 76