analysis of irrigation pond ecosystems. ii....

Hyogo University of Teacher Education Journal Vol. 9, Ser. 3, 51-68 (1988)

Analysis of Irrigation Pond Ecosystems.

II. Seasona,1 Changes of the Concentrations of

Photosynthetic Pigments.

51

Osamu YAMAGUCHI, Noriko INOUYE, Osamu IMANISHI

and Shigeru SHIRANITA

(Received September 30, 1988)

Abstract

Four irrigation ponds were analyzed for the density of plankton and the concentr-

ations of photosynthetic pigments in every month over a year in order to estima-

te the capacity of productivity in the ecosystems. The averages of concentration

of chlorophyll a were 1.98〟 g/ 1 in Showa pond, 2.75 in Haibaraguchi pond and

3.35 inOhjiga pond respectively. Diatoms were the most dominant plankton in

these three ponds in common. While the average concentration of chlorophyll a

was 47.66llg/ 1 , and the dominant plankton were protozoans in Sara pond. The

magnitudes of diatom quotient paralleled the concentrations of chlorophyll a. The

estimated productivityinSarapondseems tobetwentytimes higher than thoseof

the former three ponds.

Introduction

Photosynthesis is the ultimately biologiacal energy source to ecosystems. Using

this energy, any functions of ecosystem are able to operate. Photosynthetic pigm-

ents are the primary light energy acceptors or the primary step of photosynthesis,

and their total amount is an indicator of the potential of productivity in a given

ecosystem. Each floral phytoplankton has its own supplemental photosynthetic

pigments, thus the amount is also an indicator of biomass of a specific plankton

flora. So far, we have described population dynamics of the constituent plankton

in some irrigation ponds (Yamaguchi et al. 1988). Here in this paper, we report

a monthly survey of the potential of productivity and the population dynamics

of its contributory plankton considered from a variation in the concentrationsof

photosynthetic pigments.

Materials and methods

Descriptionof the water-sampled ponds: The following four irrigation ponds

were examined for amounts of photosynthetic pigments during a period of ayear.

All of them are in Yashiro Town, Hyogo Prefecture. The irrigation capacities

Department of Biology, Hyogo Universtiy of Teacher Education, Yashiro, Hyogo

673-14, Japan

52

Table 1. Capacities for irrigation of four ponds examined.

pond Showa pond Haibaraguchi pond Ohjiga pond Sara pond

Surface area (ha) 15.50 0.99 6.25 0.97

Maximum storage (t) 1500000 34700 150000 21000

Dam length (m) 205.4 99.7 275.5 90.0

Dam height (m) 29.0 12.4 7.2 5.0

Depth Cm) 20.0 7.0 5.0 2.0

Covered area (ha) 178.0 22.0 102.6 48.5

Data from the records of the Office of Yashiro Town.

are summerized in Table 1. (1) Showa pond is located at an altitude of 180

meters above the sea level and is surrounded by a red pine forest. The pond

was constructed for irrigation by the damming of a natural valley, and has no

feeders upstream. No aquatic higher plants grow there. Rainfall is the sole

source of inflow of water (also see Hikime et al. 1986). ( 2 ) Haibaraguchi

pond is located at an altitude of 110 meters above the sea level and adjacent to

the campus of Hyogo University of Teacher Education. The environment sur-

rounding this pond is quite similar to that of Showa pond (also see Yamaguchi

et al. 1988). (3) Ohjiga pond is located at an altitude of 99 meters above the

sea level. This reservoir works as a part of the source of water supply to

Yashiro Town, and is connected with Tojyo lake by a canal (Hikime et al. 1986).

Reeds (Phragmites mommunis) grow in some corners of the pond. ( 4 ) Sara

pond is located in the town center of Yashiro. The pond is situated at an alti-

ude of 60 meters and has no inflow from the neighboring streams. No aquatic

higher plants grow there. It is surrounded by houses and therefore has some in-

flow through drainage from kitchens (Yamaguchi et al. 1988).

Sampling of the pond water: Periodic sampling of the water was done once a

month from February of 1987 to January of 1988. For all samplings two liters

of the surface water was removed at a location near the floodgate at around 9

0'clock in the morning and put into a plastic tank. At the same time, the water

temperature was measured with a thermometer. The transparency was measured

with the use of Secchi's white plastic disc having a diameter of 30 centimeters.

The sampled water was immediately taken into our laboratory, and its pH was

measured with a pH meter. Soon after that, the samples were placed in a deep

freezer at -80C and kept for 24 hours in order to kill all the plankton. The sam-

pling dates are shown in Table 2.

Scoring of number of plankton per I milliliter of pond water: This process was

essentially same as that described in Yamaguchi et al. (1988). Two liters of the pond

water were concentrated into 200 microliters by centrification at 3000 rpm for 5 min-

utes. Number of plankton was measured in 0.1 microliter of this concentrated

solution using EKDS Thoma haemocytometer (Na 390, Kayagaki Med. Sci Ins.

CO.).

Measurement of concentrations of photosynthetic pigments: Fifty microhters of

the centrifuged pond water were put into a ceramic grinder containing a small

amount of quartz sand and homogenized in 10 milliliters of 90% acetone. After

transuding of chlorophylls and carotenoid into acetone at 0 C for30 minutes,

Tab一e 2. Monthly changes inもentperat.ilre, transparency, and pH ofもhe surface l抱ter in four irrigation ponds.

Pond Showa pond Hai baraguchi pond Oh、i iga pond Sara pond

Sampl ing Temp. Transparency pH Temp. Transparency pH Temp. Transparency pH Temp. Transparency pH

date

Feb. 18, 1987

Mar. 17, 1987

Apr.22, 1987

May 21,1987

Jun.17,1987

.lui. 4,1987

Aug. 3,1987

Sep. 16,1987

0ct.13.1987

Nov. 12, 1987

Dec. 10, 1987

Jan. 6,1988

7.9℃ 115cm

7.5 120

17.5 120

23.0 150

23.0 210

26.0 300

29.0 300

23.5 110

19.5 135

15.0 160

9.5 215

7.0 140

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蝣Not examined.

Irrigationpondecosystems

Crl

CJD

Table 3. 【listribution of photosynthetic pigments in different taxons of al岩ae (cf. Sudo 】983). The de苫r・氾s of the aimiounts are expresst・d id one clf

the four classes of +++, ++, +, and -.

Taxon Chlorophyta En岩Ienophyta Phaeophyceae Dialomeae Chrysophyceae lleterocontae Dinoflagellata Rhodophyta Cyanophyta

Piwent

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a

b

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+ +++

Table 4. Monthly changes of the concentrations of plankton in the surfacer water of four irri岩ation ponds examined, classification of planktonon into phy一a followed

the criteria of Mizuno (1964), and expressed in abbrev atioru blue-green algae as Cyan., diatoms as Bad., reerl algae as Chlr., and proto2aas as Prot.

Ponii lrowa pond Haibaraguchi pond Ohj iga pond Sara pond

Plallkton二yan. Bad. Chlr. ProL Total Cyan. Bad. Ch】r. P「ot. Total Cyan- Bad. Chir. Prot. Total Cyan. Bad. Chir. Prot. Total

Sa叫Iing date (No. of plankton !印J)


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Noヤ. 12.王087

Dec. 】0,日〕P7

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Yl也6-J.04.50.614.31.0225.14.995.0326.0s.n.--4.69.012.80.924.02.3592.415.0144.6722.7

"Not examined.

‥Anbiased standard deviation.

Table 5. Monthly changes of the concentrations of photosynthetic pig向ents in the surfacer lJater of four irrigation ponds examined. Photosynthetic pigi山ents are

expressed in abbreviations; chloropiulls a, b, and c as Chi. a, Chi. b, and Chi. c, phycocyanin as Cya., and carotenoid as Car.

PoI Showa pond Hai baraguchi pond Ohj i岩a pond Sara pond

Pi即Ient Chi.a Ch上b Chi.o Cya. Car. Chi.a Chi.b Chi.c Cya. Car. Chi.a Chi.b Chi.c Cya. Car. Chi.a Chl.b CH.c Cya. Car.

Samp! ing date (u幕/I)

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May 21,1987

ノun. 17, 1987

Jul. 4,1987

Au葛. 3,1987

Sep- 16. 1987

Oct. 13, 1987

Nov.i2,】987

Dec. 10, 1987

Jan. 6.1988

Mean 1.98 3.0 10.22 2.57

S.Cl.= 3.43 ll.R9 4.75

* Not examined.

"Anbiased standard deviation.

Irrigation pond ecosystems 57

the homogenates were centrifuged at 3000 rpm for 5 minutes. Two milhliters

of the supernatant solution was decanted into a quartz cell, and light absorp-

tion was examined at 750,663,645,630, and 480 nm wave lengths witha spectr0-

photometer (Shimazu UV-120-02). Estimation of the concentrations of chlo-

rophylls (Chi. a, b, and c) and carotenoid (Car.) was done following the

methods of SCOR/UNESCO (1966) and Strickland and Parsons (1968).

Chi. a dug/ml) -ll.64E663-2.16E645+0.10E<

Chi. b (〟g/ml) --3.94Ee63+20.97E6(s-3.66Ee3o

Chi. c (〟g/ml) --5.53Ei -14.81E645+54.22E,

Car. 〟g/ml) -10.0E48

There E means the real absorption at specific wave lengths written in subscript

after sulDtracting the absorption at 750 nm.

Another 50 microliters of the centrifuged pond water were ground in 10 milli-

liters of distilled water. The concentration of phycocyamn was measured in the

same way as carotenoid substituting Ee2s for E480 (cf. Shibata 1974).

Concentrations of the photosynthetic pigments in the actual pond water sam-

pled (C 〟g/ 1) are given in the following formula when the measured value

is x (〝g/ml) ;

C(〝g/1)-Ⅹ.Ⅴ

Ⅴ

There V means the volume of 90% acetone solution or distilled water (ml) used

for extraction of the pigments, and V stands for the volume of the correspond-

ing pond water examined (1).

Results

Monthly survey_ of parameters of the ecosystems

Abiotic conditions of the pond ecosystems were surveyed once a month for one

year from February of 1987 to January of 1988; temperature of the surface

water, transparency, and pH. The results are shown in Table 2. The tempera-

ture had a range from 5.6℃ to 31.0-C with the grand mean of 18.1。C. The min-

1mum transparency was 40cm, and the maximum was 300cm with the grand mean

of 140.8cm. The concentrations of hydrogen ions (pH) ranged from 5.0 to 8.1

with the grand mean of 6.4. The biotic components were surveyed to assess

the dynamics of the planktonic population, and the plankton mass was described

as the observed number of individual organisms in one milhliter of the pond

water and the concentrations of photosynthetic pigments specific to the com-

posing taxons. Distribution of the pigments among different taxons are seen in

Table3 (Sudo 1983). The results are shown in Tables 4 and 5. The detailed

analyses were done in the following sections with regard to each independent

pond.

Seasonal succession in the ecosystem of Showa pond

Diatoms (Bacillariophyta) dominated over the other plankton throughout the

58

No.p一ankton/ml p一ankton in Showa pond

234567891'g

Month in 1987 or 1988

!

S

J

&

i

n

-

n

88堊ヨCyanophyta78 EヨBaci I larioph如

・こ悪∵∴r-il・=i50 -・ tota一 p一ankton

n

U

n

U

n

U

n

U

^<OC¥JT-i

Fig. 1 Distributions of the numbers of individual plankton classified into four

major phyla in 1 milliliter of the surface pond water in Showa pond.

Months are expressed in abbreviation; from 1 as January to12asDecember.

p9-'】

甜柑

Photosリnthet ic pigments in Shoレga pond

LL/'!

-1

!

!

-

′

56T89柑i1121

-ChlorophリH a

ChlorophリIl b

一--ChiorophリH c

PhリCOCゝ.'a n i n

-- Caroteneid

「蝣tenth in 1987 or 1988

Fig. 2 Distributions of the concentrations of photosynthetic pigments in Showa

pond.

E:琵ヨChl a(y

Temp. (

I--Trans.(

pH

234567891011121


Fig. 3 Distributions of the concentration of chlorophyll a, the temperature of

surface water, transparency and pH in Showa pond.


year in this pond. Green algal plankton (Chlorophyta) were observed only inthe

cold season under direct observation with a micsroscope. Blue-green algal plank-

ton (Cyanophyta) had also a similar distribution pattern as of the green algae.

The distribution is seen in Fig. 1. However, this seems not to be the case,

because the concentration distribution of chlorophyll b which is specific to green

algae (Table 3) had peaks in April (6.! 〃g/1) and July (6.90〝 1) as

well as February (38.13 〝g/1) as shown in Fig. 2. The contradiction ap-

pears to be ascribed to the small sample volume of the former assay. Similarly,

the concentration distribution of pycocyanin, specific to blue-gree algae (Table

3), had a sigle peak in November (17.54 〟g/ 1 ) in the pigment assay. The

concentration distribution of carotenoid paralleled that of chlorophyll c which

is specific to diatoms, thus the majority of carotenoid were contributed from

the diatoms. The pigments discussed above are of supplementals in the process

of energy acception in photosynthesis. Chlorophyll a, on the contrary, is the

core pigment in photosynthesis and every phytoplankton contains this pigment

(Table 3 ). Therefore, its concentration seems to be an indicator of capacity

of photosynthesis. Its concentration distribution is represented by a bold line in

Fig. 2. The peaks were seen in the eary spring (5.97〝g/ 1 ) and summer

(4. 06〝 1 ), but not so drastic fluctuation was observed throughout the year.

The concentration distribution of chlorophyll a was also analyzed along with the

distributions of the abiotic components in Fig. 3. The amounts of chlorophyll

a did not parallel with the variation of temperature of the surface water, but

paralleled with the magnitudes of pH. Clear circulation periods in spring and

autumn and stagnation in summer were not observed (cf. Hogetsu 1974).

Seasonal succession in the ecosystem of Haibaraguchi pond

The maximum number of plankton per ml was 2600 in November, and faily

small numbers were observed in the remaining samples. The average number

was 326.0 in this pond. The distribution of number of plankton per ml is

shown in Fig. 4. The most dominant plankton were diatoms, especially, Melosira

distans and Cyclotella stelligera. Species structures of the diatom community

were analyzed by using the following indices (Odam 1971).

Index of dominance (C)

C-∑ (n./N)5

Index of similarity (S)

s-2C/(A+B)

Index of species diversity (H)

H--∑ (n,/N) 10gォ(rii/N)

Where n; means the number of individuals found in some drops of the concen-

trated sample solution. N is a total of the number of diatom individualsexam-

ined. A and B mean numbers of species found in samples A and B,respectively

C stands for a unmber of species common to both samples. The results are

shown in Table 6. The high diversity and low dominance values were seen in the

60

恥・planktorv′nl plankton in Haibaraguchトpond

234567891011121

lionth in 1987 or 1988


major phyla in 1 milliliter of the surface pond water in Haibaraguchi

pond.

Haibaraguchi pond

・Chlorophリtl a

Chlorophリ11 b

-一一ChlorophリH c

PhlJCOCリa n i n

・- Carotenoid


Fig. 5 Distributions of the concentrations of photosynthetic pigments in Distribu-

tions of the concentrations of photosynthetic pigments in Haibaraguchi

pond.

ChlorophiI

6

5

4

3

2

I

8

E=ヨChl.a(ug/I>Temp. <-C)

Trans. (m)

・‥一・一pH

2345 7891の11121

Month in 1987 0「 1988


surface water, transparency and pH in Haibaraguchi pond.

Table 6. Month一y changes of species diversity of diatoms in Haibaraguchi pond- Tl把constant Volume of pond Ualer was not examned for this analysis;

thus the frequencies are expressed as relative values.

Diatom species

Centra l es

Cyclotel la g塑垣

Cyclo.tel la aenexhinia伯

Cyclotel la岨L幽rtelosira ambigua

Melosira distant;

Penna l es

Achnanthes lanceo ata

Achn払nthesホinutissima

Cymbella affinis

Cynbel la

Cvmbel la microceptiala

包吐出_担tunidaEpithemia墾竺tunotia sp.

Gomphone爪a parvu lum

Navicula c「yptocephala

Navicula tndentula

Navio.ila vindula

Navicula sp.

Mtzschia幽Ni一.zschia sinuata

Pinnulana braunii

PH増iotropis l印i血p如Rhopalod ia &[b垣Synedra parasi tica

Synedra吐型Tabel laria fl0cculosa

Diato¶ quotient (Dq)

Index of doninance (c)

Simi一arity indexくS)

lr山ex of species diversity (H)


Apr May Jun Ju l Aug Sep Oct Nov Dec Jan Mean

12 14

1 4 3 3 1

15 27

2

33 1 6 18 69 15 10 42 75 35

1

L

C

-

つ

・

I

0.50 0.43 0.50 0.75 0.I 1.60 1.00 0.75 >3.00 1.33

0.32 0.36 ,54 0.83 0.23.27 0.28 0.69 0.90 0.47

0.32 0.R3 0.31 0. 13 0.50 0.57 0.46 0.10 0.60

1.45 ち.40 1.03 0.47 】.73 1.B4 1.49 0.76 0.24 I.05

WOilI3

o

j

ォ

r

A

.

I

C

3

0

0

-

・


62

summer season.

The high concentration of chlorophyll a was observed in spring (4.44〃g/ 1 in

April) and autumn (6.75〟 1 in November) as shown in Fig. 5. This con-

centration distribution is also represented along with the distributions of the

abiotic parameters in Fig. 6.

Seasonal succession of the ecosystem of Ohjiga pond

The maximum number of plankton per ml was observed to be 637.4 in January

and the average was 146. 9. The dominant planktonic taxon was Bacillariophyta

(diatoms) throughout the year as seen in Fig. 7. The concentration distributions

of photosynthetic pigments are represented in Fig. 8. The maximum concentra-

tion of chlorophyll a was in September (13.09 〟g/ 1 ) , and the average value

was 3.35lJg/ L The variation of amount of this pigment was shown together

with those of the temperature of the surface water, transparency and pH in Fig,

9. There was no clear correlation between them.

Seasonal succession of the ecosystem of Sara pond

From November of 1987 to January of 1988, the pond was almost dried up

owing to little rainfall, therefore the water sampling could not be made. The

planktonic community and structure was quite different qualitatively and quan-

titatively from the forementioned ponds. The maximum density of plankton was

27781/ml in June arid the minimum was 216/ml in January as shown in Fig.

10. The mean was 7010 and was at least twenty times higher than those of the

forementiond ponds. The concentration distribution of chlorophyll a followed

that of the planktonic density as seen in Fig.ll. The maximum value was

132.22〃g/ 1 in April, and the average was 47.66〟g/ 1. This is also

twenty times higher than those of the remaining ponds. The concentration dis-

tribution of chlorophyll a is also represented together with those of abiotic fac-

tors in Fig. 12.

Species of Euglenidae popularly found in irrigation ponds

Throughout the survey of plankton in the irrigation pond ecosystems, Euglenidae

species were one of the most popularly observed plankton. They share the

characters both of phytoplanktonic and zooplanktonic, thus they are one of the

most suitable teaching materials for plankton. Here we describe some of them

in Plates 1 and 2. In addition to this, Euglena proxima, for instance, has a

form of cyst covered with special pigments as an adaptive strategy avoidingan

obstruction by powerful sunlight and high temperature in summer. Some of

them form s0-called "water bloom" in summer season.

Discussion

The present irrigation pond ecosystems were analyzed in number of planktonic

individuals in certain volume of the pond water and the concentrations of photo-

synthetic pigments, especially chlorophyll a. There was no identical distribution

patterns between these two quantities. A part of the reasons came from the

卜わ. planktoivml

Irrigation pond ecosystems

Plankton in Ohjiga pond

7四匹冠Cゝjanoph如匠≡ヨBaci llariophリta

表■ chlorophリta58の田Protozoa

蝣・・蝣total plankton

四

四

開

E

^

K

i

H

日

伝

2345 7891011121

Month in 1987 or 198専


major phyla in 1 milliliter of the surface pond water in Ohjiga pond.

-ChlorophリH a

Chlorophllll b

一一一Chlorophl月l c

-i- PhリCOcl唱nin

・・-- Caroteno id

3456789柑11121

110nth in 1987 0「 1988

Fig. 8 Distributions of the concentrations of photosynthetic pigments in Ohiiga

pond.


surface water, transparency and pH in Ohjiga pond.

63

64

differences in the sample volumes for examination, 0.1 〟 1 0f concentrated

pond water for the former and 2 ml for the latter. However, the mam reason

is due to the difference in body sizes of planktomc species. The amount

of chlorophyll a is more accurate esmitate for the biomass of planktomc com-

munity (Odam 1971). This quantity is also a good indicator of the capacity of

productivity in certain ecosystem.

High concentration of chlorophyll a, or high capacity of productivity was ob-

served in early spring, summer and late autumn commonly in the present four

ponds. The high productivity in early spring and in late autumn seems to cor-

respond to the outcome of "water-circulation period" (e.g. Hogetsu 1974,

Yamaguchi et al. 1988).

Throughout the present survey of four irrigation pond ecosystems, it is note-

worthy that Showa pond, Haibaraguchi pond and Ohjiga pond have similar ecolo-

gical features in common, whereas Sara pond has the unique features. Diatoms

were the dominant phytoplankton throughout the year in the former three pond

(Figs. 1, 4 and 7). Protozoans replaced them in Sara pond (Fig. 10). The

average concentrations of chlorophyll a were 1.98〟g/ 1 , 2. 75 and 3.35, respec-

tively for the former three ponds, and it was 47.66 for Sara pond (Table 5 ).

Diatom quotient, the number of species of Centrales versus that of Pennals

(Nygaard 1949, see Mizuno 1964), were 0.29, 0.24 and 0.30, respectively for the

former three ponds. That was 0. 34 for Sara pond. For these ecological analyses,

it is concluded that Sara pond is highly eutropic and has high productivity.

References

Hikime, S., Y. Onoue, I. Naka and T. Ozeki (1986) Studies of the seasonary

changes of water of the irrigation ponds in Ureshino Height, (in Japanese).

Hyogo Univ. Teacher Edu. Jour. , 6:49-73.

Hogetsu, K. (1974) Aquatic ecosystems, (in Japanese). Kyoritsu Shuppan, Tokyo.

Mizuno, T. (1964) Illustrations of the freshwater plankton of Japan, (in Japan-

ese). Hoikusha, Osaka.

Odum, E. P. (1971) Fundamentals of ecology. W.B. Saunders CO‖ Philadelphia,

U.S.A.

The SCOR/UNESCO working group on photosyntheitc pigments (1966) Mono-

graphs on oceanographic methodology, No.1 , Publ. Unesco, U. S. A.

Shibata, K. (1974) Measurement of spectrum and spectrophotometer. (in Japan-

ese). Kodansha Scientific, Tokyo.

Strickland, J. D. H. and T. R. Parsons (1968) A practical handbook of sea

water analysis. Fish. Res. Bd. Canada Bull. Nal67, Canada.

Sudo, R. ed. (1983) Microbiology for clarification of environment, (in Japanese).

Kodansha Scientific, Tokyo.

Yamaguchi, 0. , S. Morimoto, N. Inouye, O. Imanishi and M. Kasahara (1988)

Analysis of irrigation pond ecosystems. I. Population dynamicsof the plank-

Irrigation pond ecosystems

3匂88の団CyanophytaE∃ Baoillariophyta軍遜chlorophリta四Protozoa

-・ tota一 p一ankton

65

No. planktoivml Plankton in Sara pond

234567 910 2!


Fig.10 Distributions of the numbers of indi、/idual plankton classified into four

major phyla in 1 milliliter of the surface pond water in Sara pond.

・Chlorophリ11 a

- - 1Chlorophyl1 b

-・-ChlorophリlI c

PhゝICOCリ∂ni n

-蝣Carotenoid

Month in 1987 or 19S3

Fig.ll Distributions of the concentrations of photosynthetic pigments in Sara

pond.

Chlorophisou 39匹ヨChi.叫g/i)一一Temp.( C)

--- Trans. 、m)

一一・ pH

28

2 3 4 5 6 7 8 9 1の

Month in 1987

Fig.12 Distributions of the concentration of chlorophyll a, the temperature of

surface water, transparency and pH in Sara pond.

66

Plate 1. Some species of the genus Euglena popularly found in irrigation pon-

ds. A. Euglena proxima observed in Hasu pond in Saga city. B.

Euglena acus found in Sara pond and in Hasu pond. C. Euglena

oxy?ris (in the center) observed in Sara pond. D. Euglena proximo, incystic forms which are seen as water bioom in summer. The water

surface is covered with brick color. E. An epifluorescent view of the

cystic forms of Euglena proximo. Chloroplasts are not degenerated

even in cyst and seen as round particles in the cysts.


Plate 2. Some species of the genera Phacus and Trachelomonas popularly

found in irrigation ponds. A. Phacus pleuronectes observed in Sara

pond andHasu pond. B. Phacus undulatus observed in Hasu pond.

C. Phacus longicauda observed in Sara pond. D. Trachelomonas

armata observed in Hasu pond. E. Trachelomonas hispida observed

in Hasu pond.

68

ton and a seasonal succession of the main producers and consumers. Hvogo

Univ. Teacher Edu. Jour. , 8:89-106.

analysis of irrigation pond ecosystems. ii....

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