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Chapter 33. Preliminary study on the ecology of ostracods from the moat of a coral reef off Sesoko Island, Okinawa, Japan

Chapter 33. Preliminary study on the ecology of ostracods from the moat of a coral reef off Sesoko Island, Okinawa, Japan

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430



R.TABUKI

AND T. NOMA



118.



128.



130°



1p'



TEXT-FIG.1-Location map of Sesoko Island.



The study area occupies the northeastern part of the moat where abundant sea weeds and sea

grasses grow. Text-fig. 2 shows the topography and substrates of the study area and is based on

preliminary data obtained by the authors form November 1984 to April 1985. In the moat, there

is a deep area extending almost parallel to the shore line where loose sediments such as gravel and

sand are accumulated. Macroalgae and sea grasses are distributed widely in the moat. There were

many species and numbers of individuals in spring, but from spring to summer they decreased

gradually and, in autumn, only three species could be found; those were UZva pertusa (green algae),

Jania decussato-dichotoma (red algae) and Thalassia hemprichii (sea grass). Text-fig. 3 shows the

distributions of these three species in the northern part of the study area from November to

December 1984.

Water temperature and salinity were measured for coastal water at Sesoko Marine Science

Center, University of the Ryukyus, located on the eastern coast of Sesoko Island. There, the mean

monthly maximum temperature of 1982 was 28.6"C in August and the mean monthly minimum

was 2O.l"C in February. The mean salinity ranged from 34.6 to 35.3 %O (Nakamura 1983).



Ostraeodafrorn Coral Reef of Okinawa 431



water dapth (at law wator of

March 27 1886)

wntour intorvat: 10 cm



substmu



grmt



grrwtb



tJ



rrnd



TEXT-FIG. 2-Topography and substrates of the study area. The location of sampling localities is shown on the

map. The part with oblique lines indicates the lowest marine terrace.



METHODS

Sampling localities 1 to 4 are shown in Text-fig. 2. Localities 1 to 3 are located in the lower part

of the intertidal zone, and locality 4 is in the subtidal zone. Ulva samples were collected in the tide

pool of locality 1, and Jan& samples were collected on the rock platform of locality 2. Ulva has

smooth and flat fronds. Jania gives a hemisphere-like appearance as the product of complex intergrowth of filamentous plant bodies. At localities 3 and 4, we collected the gravels on which lilamentous algae were growing. Filamentous algae grow densely on some cobble to boulder size

gravels and on parts of rock, and trap sand grains. They are frequently found to be covered with a

thin sand layer. There seems to be no marked decrease of filamentous algae at any particular season. Samples were collected with surrounding sea water by means of plastic bags and agitated in

the bags with a 10% solution of formaline. Then the contents in the bags were put through a

Taylor's 425 mesh sieve. The remains in the sieve were dried up and partitioned into samples which

contained approximately 200 ostracods.

RESULTS



We selected 16 samples among the monthly samples which were collected since May 1984.

Thirty-eight species of Podocopa and two species of Myodocopa were identified but the Myodocopa are not listed in Table 1. As a whole, the genera Xestoleberis, Paradoxostoma and Loxocorniculum were predominant in the samples from the moat. Xestoleberis cf. X. hanaii and X. sp.

A were dominant species, and Loxocorniculum sp. A, Paradoxostoma sp. B, P. sp. C and P. sp. D

also occurred abundantly.



432 R. TABIJKIAND T. NOHARA



Ulva pertusa Kjellman

Jania decussato-dichotoma Yendo

Thalassia hemprichii(Ehrenberg1

TEXT-FIG.

3-Distribution of representative macroalgae and sea grasses in the northern part of the study area

during the period from November to December, 1984.



Table 2 represents the number of individuals per species per unit sample. Ostracod species in this

list are divided into two species groups; one group relevant to the nature of the substrates or the

water depth, and the other group which has no distinct relation to particular substrates or water

depth or which occurs infrequently. The boundary between these two groups is drawn between

Paradoxostoma lunatum and Hermanites sp.

Among the former group, the upper four species from Semicytherura? sp. to Aurila sp. occur

mainly from the UIva samples from locality 1. Paradoxostoma sp. E is confined to the intertidal

samples. The following five species of Paradoxostoma are characteristically found in the Jania

samples, locality 2. The species from Xestoleberis cf. X. sagamiensis to Paradoxostoma lunatum

are found at localities 2 to 4, and, in particular, the last three species are characteistic in the filamentous algae samples at localities 3 and 4.

Some species show grominent increase in individual number at particular seasons. ParadoxoPLATE1-Figs. 1,2. Perissocyfheridea inabai Okubo, 1983. 1. Lateral view of right valve (LOC. 1, sample 0521).

X 80.2. Lateral view of left valve (LOC.1, sample 0521). x 80. Figs. 3,4. Pecfocythere? sp. 3. Lateral view of right

valve (LOC.1, sample 0817). x 105.4. Lateral view of left valve (LOC.1, sample 0817). x 105. Figs. 5,6. Aurila sp.

5. Lateral view of right valve(l0c. 1, sample0817). x 75.6. Lateral view of left valve(Loc. 1,sample 0817). x 75.

Figs. 7,8. Hermanites sp. 7. Lateral view of right valve (Loc. 2, sample 0521). x 80. 8. Late ralview of left valve

(Loc. 2, sample 0521). ~ 8 0 Figs.

.

9,lO. Caffistocythere sp. A. 9. Lateral view of right valve (Loc. 3, sample

1109). x 105. 10. Lateral view of left valve (LOC.3, sample 1109). x 105. Figs. 11,12. Loxoconcha (Loxoconrha)

uranouchiensisIshizaki, 1968. 11. Lateral view of right valve (Loc. 1, sample 0817). ~ 1 0 5 12.

. Lateral view of

left valve (LOC. 1, Sam le 0817). x 105. Figs. 13, 14. Loxocornicufum sp. A. 13. Lateral view of right valve

(Loc. 1, sample 0817). 105. 14. Lateral view of left valve (LOC.1, sample 0817). x 105.



4



434 R. TAEUKI

AND T. NOHARA



TABLELIST OF LIVINGOSTRACOD SPECIESFROM THE MOATOF S W K O ISLAND. SAMPING LOCALITIES ARE ARRANGED

FROM HIGHER

TO LOWER LEVELS;LOCALmEs 2 AND 3 ARE ALMOST

AT THE SAME LEVEL,AND LOCALITY

1 IS

SOMEWHAT HIGHER IN LEVEL.SAMPLING NUMBERS

ARE REPRESENTED BY SAMPLING DATES.

I



Loca1iti.s



.ql*S__]0817



R o p ~ " t o * l p r i r ( R o p ~ n t ~ ~ap.

~p~i~l



I



I



I



I



LOC. 1 (=I

TOO. 2 1-(

LOC. 3 (f. algae)

IPC. 4 ( f . algae)

1 2 2 1 0 2 2 1 0 5 2 1 1 0 8 1 5 1109 0 2 2 1 0 5 2 1 1 0 8 1 6 1 1 0 9 0 2 2 1 0 5 2 1 1 0 9 2 2 1 1 0 9 0 2 2 2 0 5 2 1

2



21



I



1



2



P. lskpontooiyprinl ap.

P.rissoo#th.ridw

inabni Okubo, 1 9 8 3

Peotooythore? lip.

CaZli*too#them sp. A

c. sp. B

c. sp. c

Aurtl. sp.

lurizo? sp.

Copuinba ap.

8.mmanit.s sp.

Euqithere up.

Sernio#th8rura? n i u r e n d s ( H a n a i , 1 9 5 7 1

s. 7 sp.

Pame#th#ridea sp.

Lorooon~h=lL~roconohrr)uranouohienaia m h i z a k i , 1 9 6 8

L. IL.) sp.

L O r o o o r n ~ o u Z u Up.

~ A

L. sp. B

L. sp. c

X*#toZeberis r e t o u o h i e n e i s Okubo, 1 9 7 9

x. c f . X. h a n a i i I a h i z a k i , 1 9 6 8

X . cf. X. eogarnionsie Kajiyama, 1 9 1 3

X . sp. A

I. sp. B

1. .p.



4

2



2



3



1



2

2



8



P. Sp. 0

P. ap. u



3



6



1



9



31



15



13



1



3

23



2



2



5



3



1



5



1

1



14



11



2



5



1



1



1



I



1



6



2



1



4



14



5



2



2



I 1



1



2



2



0



9



1



2



3



1



1



3



12



45



208



64



25



6



1

8



5



2



1



1



1

1



83



17



4



28



1

47



66



4



1



3



13



23



2



1



9



5



6



3



4



9



3



3



6



67

13



103

3



50



45



135



69



45



80



136



18

153



49

68



19

68



6



6



2



1



1



2

1



3



2



148



101



100



16



25



I



1

145



7



1



6



73



2

16



77

9



34

3



9



2



29



124



158



8



80



1



2



3



3



2



3

1



1



l7



15

3



1

36



14;



:1



14



142



17



5



113



34



1



1



1



1



4



k



3



4



9



4



1



451

3



1

19



5

4



6



11

5



6)



6



5 1

3



1



2

2



,



8

1



1



2



38



11



Paradoroatom affine



P. Up. P



3



1



c



o k u b , 1977

P. tunatun okubo, 1 9 7 7

P. c f . P. gibberurn S c b m i k o v , 1 9 7 5

P. sp. A

P. B p . B

P. up. c

P. sp. 0

P. up. E



2



12



1



43



7



2



1

27



15



30



21



20



27



2



15



43



3



1

1



attain a maximum individual number in the November sample at locality 2. Unfortunately, we

could not take a sample of Ulva in November, because the plant bodies were too few and small

to be collected. It is likely that these three species of Paradoxostoma occur in great abundance at

the same time. Paradoxostoma sp. A and P. sp. F, both of which are also characteristic in the Jania

samples as well as P. sp. B and P. sp. D, occur in great abundance in February. Hermanites sp. and

Loxocorniculum sp. A show a distinct abundance in the August samples, but this tendency is not

clear in the subtidal samples at locality 4. It seems that the patterns of seasonal change in individual number of some species are not the same at all localities. This is well represented by the

occurrences of the two dominant species of Xestoleberis. For example, X. cf. X. hanaii attains a

maximum individual number in the December sample at locality 1, and in the February samples

at localities 2 and 4, and in the May sample at locality 3. It is important to note that the ratio of

adults to juveniles in individual number ranges about from 10 to 45 % in the samples at locality

1, and as contrasted with this result, in the samples of other localities, adults show only a very small

ratio, generally less than 10%, or are not found. At present, however, we can not decide the cause

of this difference of age structure of Xestoleberis cf. X. hanaii in those localities.

The seasonal rangwf the total individual number per unit sample is much wider in the intertidal

samples at locality 1 to 3 than in the subtidal samples at locality 4. This results from the marked



Ostracoda from Coral Reef of Okinawa 435

OF OSTRACOD SPECIES REPRESENTING THE NUMBER

OF INDIVIDUALS

PER U N I T SAMPLE. THEAMOUNT

OF UNITSAMPLE

WAS DECIDED

so THAT ABOUT SEVERAL

HUNDRED

OSTRACODS

COULD BE COLLECTED

FROM IT;

THB UNIT SAMPLE IS THE PLANT SAMPLE OF 50 GRAMS

IN WET WEIGHT FOR MACROALGAE,

AND IS THE PLANT

SAFAPLE

FROM ABOUT 100 CMZIN SUPERSCRIPT

SURFACE

AREA OF GRAVEL

FOR FILAMENTOUS

ALGAE.



TABLE %LIST



localities

spcier



samp1.a



m c . 1(L!ue)

I LOC. 2 (gaania) I LOC. 3 ( f . algaell LOC. 4 (t. alpas)

817 1221 0221 05211 0815 1109 0221 05211 0816 1109 0221 05211 0922 1109 0222 0521

4

5

5

161

2

0

3

2

18

1

3

0

1

2

5

21

2

11 513

46

2

21

2

0

50

3

31

11

9

2

9

1

1

4 4 330 160 141

16

5

53

13

4

2

1

4

4

0

17 328 181

9

4

69

1

34

32

4

13

5

1

0

44 117

38

43

3

32

43

3

16

46

7

6

2

25

96

9

3

3

3

29

52

20

18

5

18

1

0

10

8

10

3

I

1

7

10

6

13

50

3

14

2

37

2

3

13

19

9

89

27

4

30

6

2

10

3

1

17

5 1 1

6 8 5 1 4

0

2

8

5

1

2

13

1

80

9

888 102

5

21

37

2

1

104

144

74

72

110

80

13

61

107

38

88

37 819

329 459 135

45

73

245

73

86

218

128

9

496

34

13

67

1319

36 114

9

9

9

5

1 1 6

15

1 5 3 2

1

2

9

1

6

2 1 0

5

5

6

2

14

3

5

1 1 1 4

1

4

11

6

3

5

9



I



I



P. up.



0



P. Ip. A

P . sp. D

P. .p. B

P. affininr okubo, 1977

X,rtoZeberi# cf. X . eagaairnais Kajiyama, 1913

Pmadoro8torn.z cf. P. gibbemm Sclnrnikov, 1975



Lorooornioulua s p .



c



CaZli.too#there

sp. A

Loroo~noho(Lorooon~haJvranouohisnsia Ishiraki, 1961

Paradosostoma tunaturn Okuho, 1977

8.monit.a

sp.

Lorosomioulum sp. A

Xiitoteberis cf. X . hanaii Ishizaki, 1968

I . sp. A



I . ap. B

X. ,etouohisnais Okubo, 1979

Peotooythws? sp. A

Lozoaomioulurn lip. 0

P=,pontooupri.IPropontoaypri.)

SP.

Zos~oon~ho/L0ro*onoh=Jsp.

R..J".*id*'7

sp.

P = , p o n t o ~ y p r i s l E k p r o p o n t o c u p r i a J SP.

Euuouthorura sp.

Isatolsboris sp. C

Pmadarostoma SP. G

P. np. n

Catlietocythere sp. C

Coquimba sp.



4



S m i c ~ t h e ~ u r nm?i z m m d a (Wanai, 1957)

A u r i l a ? sp.

612 1169



210



I



,



681 286



856 2831



I



88911118



544



53



1

2

3831 469



490



325



286



seasonal changes in the individual number of several species in the intertidal samples; examples of

such species are Paradoxostoma sp. C at locality 1 and Loxocorniculum sp. A at locality 3. This

wider range of individual number in the intertidal samples may reflect the influence of greater

fluctuations of environmental factors on ostracods found there.

We have been collecting surface sand samples at irregular intervals near locality 4 by means of a

soil-net sampler, since September 1984. We were unable to collect living ostracods from sand samples until January 1985. We also found some living ostracods from the sand sample in February

1985, and were able to collect about 50 ostracods alive from the sand sample in June 1985. Only

three species were recognized (in order of dominance): Loxoconcha uranouchiensis, Perissocytheridea inabai and Xestoleberis sp. A. It is probable that the species composition of ostracods from

the sand area is rather different from that of the sea plant samples, and that the density of ostracods

is very low in the sand area.



Ostracoda from Coral Reef of Okinawa 437



CONCLUSIONS

Among the ostracods from the moat, there were many species which showed a distinct areal or

seasonal change in their occurrences, so that the species composition of ostracods from the moat

was greatly changeable areally and seasonally.

The moat is situated landward in the coral reef area and is considerably isolated from the open

sea at low water. This peculiar situation results in the highly variable water temperature, salinity,

and strength and direction of water movement. On the other hand, the moat is protected from the

direct influence of the open sea such as strong wave action, and sea weeds and sea grasses, which

are thought to be important habitats for ostracods, flourish there.

The marked areal and seasonal changes in species composition of ostracods from the moat

may be the product of adaptation to this characteristic environment of the moat.

In the future, we are going to study the life cycles of ostracod species and observe and measure

physical, chemical, and biological environmental factors. We may also take into consideration the

migration of ostracods, which was emphasized by Whatley and Wall (1979, within the moat and

from other areas into the moat.



ACKNOWLEDGEMENTS

The authors would like to thank the students of our department, the staff of Sesoko Marine

Science Center of University of the Ryukyus and Mr. Shinya Matsuda of University of the Ryukyus for their help in many ways in the course of this study. The authors are deeply indebted to

Professor Ernest H. Williams of University of Puerto Rico, Puerto Rico, for reading the manuscript.



REFERENCES

NAKAMURA,



s. 1983. Record of air temperature, surface water temperature and chlorinity at Sesoko. Galaxea, 2,



75-76.

SKAUMAL, u. 1977. Preliminary

and DANIELOWL, D. (eds.).



account of the ecology of ostracods on the rocky shore of Helgoland. In L~FFLER,H.

Aspects of Ecology and Zoogeography of Recent and Fossil Ostracoda, 197-205. W.



Junk, The Hague.

1966. The Life History of Seven Species of Ostracods from a Danish Brackish-water Locality. Meddeelser fra Danmarks. Fiskeri-og Havunderson gelser N.S. 4 (8), 21 5-270.

WATLEY,

R.C. and WALL, D.R. 1975. The relationship between Ostracoda and algae in littoral and sublittoral marine

environments. In SWAIN, F.M. (ed.). Biology and Paleobiology of Ostracoda. Bull. Am. Paleontol. 65 (282), 173-203.

WILLIAMS, R. 1969. Ecology of the Ostracoda from selected marine intertidal localities on the Coast of Anglesey. In

NEALE, J.W. (ed.). The taxonomy, morphology and ecology of Recent Ostracoda. 299-329. Oliver and Boyd, Edinburgh.



THEISEN, B.T.



1



2-Fig. 1. Neonesidea sp. Lateral view of left immature valve (Loc. 3, sample 0221). x 75. Figs. 2,3. Xestoleberis cf. X.hanaii Ishizaki, 1968. 2. Lateral view of right valve (Loc. 1, sample 0817). x 80. 3. Lateral view of

left valve (Loc. 1, sample 0817). X 80. Figs. 4,5. Xestoleberis sp. A. 4. Lateral view of right valve (Loc. 2, sample

0521). x 180. 5. Lateral view of left valve (LOC.2, sample 0521). x 180. Figs. 6,7. Xestoleberis 6.

X. sagamiensis

Kajiyama, 1913. 6. Lateral view of right valve (LOC.2, sample 0521). x 80. 7. Lateral view of left valve (LOC.

2, sample 0521). x 80. Fig. 8. Paradoxostoma sp. A. Lateral view of right valve (LOC.2, sample 0221). x 105.

Fig. 9. Paradoxostoma sp. B. Lateral view of right valve (LOC.2, sample 1109). x 105. Fig. 10. Paradoxostoma

sp. C. Lateral view of right valve (LOC.1, sample 1221). x80. Fig. 11. Paradoxostoma sp. D. Lateral view of

right valve (Loc. 2, sample 0815). x 105. Fig. 12. Paradoxostoma ufine Okubo, 1977. Lateral view of right

valve (Loc. 2, sample 0521). x80.



PLATE



This Page Intentionally Left Blank



Podocopid Ostracods of Brisbane Water,

Near Sydney, South-Eastern Australia

CHRISTOPHER

BENTLEY

Canberra C.A.E., Canberra, Australia



ABSTRACT

The distribution of ostracods in Brisbane Water is controlled firstly by substrate type and secondly by salinity. The fauna of Brisbane Water (fifty-one species in thirty-eight genera is more

closely related to that of Heron Island than to that of Port Phillip Bay. For Botany Bay to the

south the reverse is true. This is in agreement with Hartmann’s (1981) idea of the East Coast of

Australia as a “large tropical-subtropical transition zone”. One new genus (Mckenziartia) is described.

Fifty one species in thirty-eight genera of podocopid ostracod were found in Brisbane Water

(see species list). They represent fifteen families-Bairdiidae, Bythocytheridae, Osticytheridae,

Cytheromatidae, Hemicytheridae, Krithidae, Leptocytheridae, Loxoconchidae, Paradoxastomatidae, Pectocytheridae, Trachyleberididae, Xestoleberididae, Pontocyprididae and Candonidae.

The Trachyleberididae, with eleven genera, dominate the fauna in terms of number of genera, with

the Bythocytheridae (seven genera) and Hemicytheridae (five genera) next in rank. The remaining

families have one or two genera each. In numbers of individuals it is the Osticytheridae (Osficythere), Bairdiidae (Neonesidea), Xestoleberididae (Xestoleberis) and Trachyleberididae (Ponticocythereis) which dominate, each with hundreds of individuals.

Brisbane Water itself is an estuary in a drowned valley (see Text-fig. 1). It consists of a broad

shallow area known as the Broadwater, smaller shallow areas to either side (Cockle Creek and Woy

Woy Bay) and narrow channels connecting them to Broken Bay and thence to the ocean. The maior

channel has been excavated to a depth of thirty-five metres at its narrowest point by tidal currents,

which reach velocities of 1.70 mlsec.

Previous work in the immediate vicinity has been scant. To the south, Brady (1880) collected

ostracods in Port Jackson. The fauna of Botany Bay was examined by Urbaczewski (1977, unpub.). McKenzie (1967) described a fauna from Port Phillip Bay, near Melbourne. He has also

described Tertiary Ostracoda from Victoria (1974) and South Australia (1979). To the north, the

fauna of Heron Island was studied by Labutis (1977, unpub.). Hartmann has described ostracods

collected at many points around the Australian coast (1978, 1979, 1980, 1981, 1982). McKenzie

and Pickett (1984) described faunas from the Pleistocene of the Richmond River valley, north of the

study area. One new genus, Papillatabairdia, has been described from Brisbane Water (Bentley,

1981) and a second (Mckenziartia) is described herein.

The sediments of Brisbane Water range from clean quartz and shell fragment sands in the tidal

channels to faecal pellet muds in the broad shallow areas, mud flats and channel edges, with

439



440 C.BENTLEY

Nararn Crook



d

Tasmen Sua

Porl Jackson



Horon Island

xmoulh Cull



AUSTRALIA

Rlchmond Rlvar Valley



Ro ckln g h am



(a1



Bolany Bay



Kllomalros



TEXT-FIG.l - ( a ) Map of Australia showing the points at which specimens referred to Mckenziurtiu porrjacksonensis have been found; (b) Location of Brisbane Water with regard to Sydney, Port Jackson and Botany Bay;

(c) Bathymetric map of Brisbane Water, with mud banks shaded.



admixtures between these substrate types at their boundaries and in the less strongly flowing channels. The greatest diversity of ostracods is found in the muddy sands (86.5 % of total species). The

fauna in the clean sands (51.4%) is comparable in number to that found in the most populous of

the muds (range 5.4 to 54%).

Six ostracod assemblages can be distinguished, the apparent primary distribution factor being

substrate type. These assemblages have been named for the substrate type, with the mud assemblages being further separated and named for their location.

A second factor which affects the ostracod fauna in a more general way than substrate type is

salinity or degree of marine influence. This is obviously strongest near the tidal race of the Rip and

decreases as distance from the Rip increases. This correlates generally with substrate type, the

sandier substrates corresponding to more nearly marine conditions and the muds correlating with

the lower salinities due to the input of fresh water from the creeks and towns. The salinity range

found in Brisbane Water is from 30.2 parts per thousand near the Rip to 24.2 parts per thousand

near Gosford.

The SAND assemblage contains nineteen genera (51 % of the total genera), one of which (Bultraella sp.) does not occur in any other assemblage. This group is dominated by trachyleberid

genera.

The MUDDY SAND assemblage contains thirty-two genera (86.5%), seven of which are unique

to this faunule. These are Keijia sp., Australimoosella sp., Cytheropteron sp., Bythocythere



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