Are Seagrasses in Charlotte Harbor Migrating Landward in Response to

Expected Sea Level Rise?

Charlotte Harbor Watershed SummitMarch 27, 2008

Judy Ott FDEP South District Laboratory

Environmental Assessment & Restoration& Partners

Environmental Assessment & RestorationCharlotte Harbor Aquatic Preserves

Background

Questions Relating to Sea Level Rise

Field & Analysis Methods

Results

Discussion

Conclusions

This Presentation Briefly DescribesSeagrass Transect Monitoring in

Charlotte Harbor:

BACKGROUNDFDEP Charlotte Harbor Aquatic Preserves

Coordinates Seagrass Transect Monitoring:

To Assess Seagrass Conditions Throughout

Charlotte Harbor.

At 50 Fixed Transects.

Every Fall Since 1999.

Consistent with SWFWMD Protocols.

With Help From Many Partners.

Source: CHAPs

CHAPs Seagrass Transects Compliment Other

Seagrass Monitoring & Aerial Mapping

Programs…

Source: SWFWMD

ON-GOING SEAGRASS TRANSECT MONITORING

  #     Times

Agency Sites Location Start /Year

FDEP/CHAPs 50 Charlotte Harbor APs 1999 1

FDEP/EBAP 5 Estero Bay AP 2002 2

SCCF 7 Caloosahatchee R 2004 6-12

San Carlos Bay (1999)

FDEP/EAR 6 Caloosahatchee R 2007 4

San Carlos Bay (2000)

… & Water Quality Monitoring Programs…

FDEP, SCCF & WMDContinuous Data

LoggersCharlotte Harbor

Estuaries Volunteer Water

Quality Monitoring Fixed Sites

Coastal Charlotte Harbor

Monitoring Network

Random Grids

... To Help Manage the

Estuaries for Long Term Health &

Balanced Uses.

Source: CHAPs

Studies Show Seagrasses have been Relatively Stable in Charlotte Harbor in the Last Decade:

Seagrass Deep Edge Hasn’t Change Significantly. (Stearns et al 2007, Boswell et al 2006, Ott et al CEHR 2006)

0.0

0.5

1.0

1.5

2.0

Estuary

Sea

gras

s D

eep

Edg

e (m

)

(m)

1999 -2005 Mean Depth at Deep Edge of Seagrasses for Each Estuary

From: Ott 2006

7YearMean

1.61.8

0.8

1.3 1.3

1.7

1.3

1.8

1.0

Studies Show Seagrasses have been Relatively Stable in Charlotte Harbor in the Last Decade:

Seagrass Deep Edge Hasn’t Change Significantly. (Stearns et al 2007, Boswell et al 2006, Ott et al CEHR 2006)

0.0

0.5

1.0

1.5

2.0

Estuary

Sea

gras

s D

eep

Edg

e (m

)

(m)

1999 -2005 Mean Depth at Deep Edge of Seagrasses for Each Estuary

From: Ott 2006

7YearMean 1999 2000 2001 2002 2003 2004 2005

Seagrass Acreage Hasn’t Change Significantly. (Corbett et al 2006, Kaufman/SWFWMD 2007)

1982 – 2003 Change in Seagrass Acres in Charlotte Harbor

From: Corbett 2006

Seagrass Acreage Hasn’t Change Significantly. (Corbett et al 2006, Kaufman/SWFWMD 2007 )

● 18,364 acres● 225 acres increase● 1% change

2004 – 2006 Change in Seagrass Acres in Charlotte Harbor

From: SWFWMD/Kaufman 2007

But Seagrass Density is Declining in Some Estuaries.(Boswell et al 2006, Stearns et al 2007)

1999 – 2004 Change in Seagrass Density in Charlotte Harbor

From: Boswell et al 2006

Freq

uenc

y of

Qua

drat

s Su

rvey

ed

Estuary

But Seagrass Density is Declining in Some Estuaries.(Boswell et al 2006, Stearns et al 2007)

From: Boswell et al 2006

1999 – 2006 Change in Seagrass Species Density in Charlotte Harbor

Mea

n B

B A

bund

ance

Mea

n B

B A

bund

ance

Mea

n B

B A

bund

ance

From: Stearns et al 2007

Seagrass Transect Data is Used by CHNEP to Set Resource Based Water Quality Targets:

Based on Seagrass Deep Edge & Water Clarity.Allows Flexibility in Reaching Water Quality Targets.

Col

or (P

CU

)

Turbidity (NTU) Chlorophyll a

Calculate Levels of Color + Turbidity + Chl a Needed to Sustain Water Clarity.

Plane of Adequate

Water Clarity

Set Water Clarity Targets Based on

Seagrass Light Requirements at

Deep Edge.

Source: CHNEP/Corbett

But Sea Level is Rising

Oyster Research in Estero Bay (Volety et al).

Mangrove Restoration in Charlotte Harbor (Tattar et al).

& Anecdotal Observations….

SWFRPC Analyses in Charlotte & Lee Co.

Water Resource Planning in Sarasota Bay (Clark et al.)

…& the NEPs are Incorporating Sea Level Rise in CCMPs & Goals.

QUESTIONS

BIGGY: How will Sea Level Rise Affect Seagrass Depths, Acres, Abundance &

Water Quality Targets in Charlotte Harbor?

SPECIFICALLY: Have Seagrasses in Charlotte Harbor Migrated Landward in Since 1999?

Source: CHAPs

METHODSCHAPs Seagrass Monitoring Protocols:

Monitored Each Fall.

50 Fixed Sites in Charlotte Harbor Estuaries.

Sites Grouped by Estuary.Estuary

# Sites

Lemon Bay 6

Gasparilla Sound 7

Myakka River 5

Peace River 5

Charlotte Harbor West 5

Charlotte Harbor East 5

Pine Island Sound 9

Matlacha Pass 4

San Carlos Bay 4

Few = + < 5% = 1 6-25% = 2 26-50% = 3 51-75% = 4 > 75% = 5

Braun Blanquet Abundance Categories

Fixed Transects from Shore to Seagrass Deep Edge.1 m2 Grids at Defined Intervals Along Each Transect.

5 Seagrass & 6 Physical Parameters.Use Braun Blanquet Abundance Categories.

Tide Stage Observed Relative to MHWL (Barnacles).

Water Depths are Corrected to Mid-Tide using Observed Tides Stages & Tide Ranges from

Nearest NOAA Tide Gauge.

1.3’

0.9’

0.9’

1.0’1.3’ 1.3’1.2’

1.3’

1.5’

1.4’1.7’

1.5’1.5’

CHAPs Data Analyses Use Access & SPSS.

Today’s Analyses made with Excel.

Based on 44 Stations, Excluding those with No Seagrass or Data

for > 3 Years:

MYR01 & MYR02

PR01 & PR02

MC01 & PIS08

XX X

X

X

X

RESULTS

Location of Shoreward Edge of Seagrasses Did Not Move Significantly from 1998 – 2007.

Only 4 of 44 Seagrass Transect Sites Showed the Shallow Edge of Seagrasses Moved

Significantly Shoreward.

?

CHANGE LOCATION OF SHALLOW EDGE OF SEAGRASS 1998 - 2007

  Total # # Sites # Sites # Sites

Estuary Sites Changing Shoreward Waterward

Lemon Bay 6 2 GAS01 ICW05

      (R2=.410 P=.05) (R2=.991 P=.000)

Gasparilla Sound 6 1 GAS05  

      (R2=.738 P=.00)  

Myakka+Peace R 6 0    

         

Charlotte Harbor 9 2 PIS01 PIS03

      (R2=.869 P=.00) (R2=.690 P=.00)

Pine Island Sound 9 2 PIS05 PI04

      (R2=.390 P=.05) (R2=.657 P=.01)

Matlacha Pass 4 0    

         

San Carlos Bay 4 1   MP05

        (R2=.722 P=.00)

Total 44 8 4 4

GAS01 Shoreward 5 m

GAS05 Shoreward 4 m

MP05 Shoreward 2 m

PIS01 Shoreward 15 m

PIS05 Shoreward 4 m

ICW05 Waterward 5 m

PI04 Waterward 2 m

PIS03 Waterward 12 m

Water Depth Did Not Increase Significantly From 1998 – 2007.

All Estuaries

Mean SE

1999 -49 4.12

2000 -51 3.83

2001 -47 3.78

2002 -50 2.75

2003 -47 2.63

2004 -53 2.59

2005 -57 2.71

2006 -50 2.73

2007 -55 3.34

All Years -51 1.06

R2 0.239  

P 0.15  

MEAN DEPTH AT SHALLOW EDGE REFERENCE POINT

No Estuaries Showed Significant Changes in Water Depth at Shallow Edge Reference Point.

Mean Depth (cm) at Seagrass Shallow Edge Refrence Location ("0 Stake") 1999 - 2007

-70

-60

-50

-40

-30

-20

-10

0

Estuary

Dep

th (cm

)

41 cmSE=1.6R2=.060P=.08

54 cmSE=3.8R2=.000P=.89

52 cmSE=2.3R2=.000P=.97

48 cmSE=1.4R2=.014P=.31

58 cmSE=2.7R2=.018P=.24

52 cmSE=2.5R2=.002P=.80

48 cmSE=4.8R2=.022P=.40

51 cmSE=1.1R2=.239P=.15

But 1 Estuary & Region as a Whole Showed Significant Increases in Water Depth at

Deep Edge of Seagrasses.

Mean Depth (cm) at Seagrass Deep Edge 1999 - 2007

-200

-150

-100

-50

0

Estuary

Dep

th (cm

)

158 cmSE=5.3R2=.030P=.22

176 cmSE=6.7R2=.05P=.12

87 cmSE=2.1R2=.01P=.43

124 cmSE=4.6R2=.01P=.54

169 cmSE=5.5R2=.03P=.15

128 cmSE=5.2R2=.03P=.36 186 cm

SE=4.8R2=.37P=.00

147 cmSE=2.3R2=.01P=.05

DISCUSSION

Improved Accuracy of Seagrass Transect Locations Each Year with GPS.

Improved Analysis & Availability of Seagrass Data Access Data Base & Summary Reports.

Improved Precision of Seagrass Transect Locations Improved Each Year with More Stakes.

Improved Description of Seagrass Abundance Since 2005 with Addition of Shoot Counts &

Total Abundances.

CONCLUSIONS

Based on Preliminary Analysis of Seagrass Transect Data, Seagrasses Do not Appear to

have Moved Shoreward since 1998.

More Precise Tide Measurements During Seagrass Monitoring will Enhance the Ability to Detect

Smaller Changes in Water Depth.

Depth Measurements Collected with Seagrass Transect Data Did Not Find a Significant Increase in

Water Levels in Charlotte Harbor since 1998.

More Rigorous Statistical Analyses are Needed to Relate Seagrass Changes to Sea Level Rise..

CONCLUSIONS

Continuing Seagrass Transect Monitoring & Improving Tide Estimations will Enhance Links

between Seagrass Health, Water Quality Targets & Sea Level Rise.

Based on this & Recent Seagrass Reports, Mean Deep Edge of Seagrass Growth is An

Effective Tool for Evaluating Water Quality Targets.

Seagrass Distribution & Abundance Reflect Seasonal Changes in Seagrass Conditions Related

to Rainfall & Changes in Salinity Regimes.

Thank You to All the Many People Who Helped with “Seagrassing” Since 1998:

FDEP: Neil Ayers, Erin Dykes, Stephanie Erickson, Trink Fletcher, Debbie Horner, Carla Kappmeyer, Ray

Leary, Jennifer Nelson, Mindy Schneider-Brown, Heather Stafford, Jennifer Thera & Celia Stearns

CHEC: Renee Duffey & Jason Hale

CHNEP: Catherine Corbett

& MANY OTHERS INCLUDING: Rick Bartleson, Jaime Boswell, Brian Cotterill, Ken Cummins,

Katie Fuhr, Kris Kaufmann, Ray Kurz, Jim Lacascio, Ronda McKenzie, Bob Repenning, Tom Ries, Karen Shudes, Betty Staugler, Kendra Willett,

Peggy Wilzbach & Bill Van Oyen

FDEP in Punta Gorda:

South Distinct LaboratoryEnvironmental Assessment & Restoration

(941) 575-5810

&

Charlotte Harbor Aquatic Preserves(941) 575-5861

or

Judy OttUntil April 2: judith.ott@dep.state.fl.us

Starting April 3: jott@swfrpc.org (239) 338-2550 Ext 230

For More Information, Please Contact: