INDIAN J. MAR. SC1., VOL. 5, JUNE 1976

First zoea: with 4 carapacidal spines; the dorsalspine IOllg with a curved tip; the straight and point­ed rostral spine is shorter than the dorsal; lateralspines are short one on each side of the carapace

(Fig. 1I~. The details concerning- the appendagesare giver in Table 1.The incubation period in P. vigil is 12-13 days

which is!similar as in Scylla serrata. The behaviourof berried females and the hatching processes ofthe eggs are also more or less similar to that ofS. serrata9 and Portunus pelagicus1o• Salient fea­tures o~ corresponding stages of some importantPortunids are given in Table 2.

Fisher~ -P. vigil was caught along with otherportunids and prawns by trawl nets, operated ata depth range of 10-20 fm off Porte Novo, mainlyduring premonsoon and monsoon months (July­December) with a peak catch during August toOctober (1974). The average daily landing wasabout 125 kg (numbering c. 2500) in the size rangeof 41-120 mm carapace width, which also includes alarge number of ovigerous females. Most of thecrabs w<jrefound to be infested by the goose barna­cles, Octolosmis warwickii and the acorn barnacles,Chelonob¥a patula. Smallest berried crab measured58 mm lin carapace width. Pillay7 reported onlyspecimens of 47-61 mm size whereas Stephensonand Campbe1l4 recorded specimens of 55-142 mmsize.

Locally this crab is known as Visha nandli (poison­ous crab) and not eaten by the people of PortoNovo arb previously. But in recent times it hasbecome popular and is noW consumed without anyill effects. There are 8 species of Indian ediblemarine qrabs, viz. Scylla serrata, Portunus pelagicus,P. sanquinolent~~s, Charybdis cruciata, C. annulata,C. natat(')n, Matuta lunaris and Varuna litteretall•PodoPhthalmus vigil may also be added to this list,as it is now caught and consumed in large quantitiesin and around Porto Novo. The supply of thiscrab is far below the local demand and thus it hasa ready Imarket at the landing place itself. Thisinteresting species, which is so far considered un­edible, dlls for further commercial exploitation andan assessment of this resource is worthwhile.

One of the authors (S.S.) is grateful to lCAR,New Delhi, for the award of a junior fellowship.References

1. SHEN, C. J., Bull. Raffles Mus., 13 (1937), 96.

2. STEPH~NSON, K, Dan. Sci. Invest. Iran, 4 (1945), 57.3. EDMONDSON,C. H., Gee. Pap. Bernice P. Bishop Muz.,21 (1~54), 217.

4. STEPHENSON,W. & CAMPBELL,B., Aust. J. mar. freshw.Res., ill (1960), 73.

5. SAKAI,'T., The crabs of Sagami Bay (Maruzen Co. Ltd,TOky@, Japan), 1965, 111 & 126.

6. PREMKUMAR,V. K., Crustaceana, 3 (1962), 319.

7. PILLAYri K K., J. mar. biol. Ass. India, 6 (1964),169.8. BRYANT, T. S., Crustaceana. 11 (1966), 185.9. SIN, 0; K, Proc. Indo-Pacific Fish. Coun., 11 (1969),

139.10. PRASAD,R. R. & TAMPI, P. R. S., J. Bombay nat. Rist.

Soc., 51 (1953), 674.11. VEDAVYASARAO, P., THOMAS,M. M. & SUDHAKARRAO,

G., Proceedings of the s)·mposium on living resources ofthe seJ.; around India (Central Marine Fisheries ResearchInstitute, Cochin), 1973. 58!.

12. NAIDU,!K G. R. B., Indian J. Fish., 2 (1955), 67 ..

Seasonal Variation in Zooplankton frem theCoastal Waters off Saurashtra

M. 1. PATEL

Marine Biological Research Station, Port Okha 361350

Received 20 August 1975; revised received 13 APril 1976

Seasonal variation in hydrography and zooplanktonfrom 3 stations (off Rozi, Port Okha and Dwarka) inthe coastal waters off Saurashtra was studied for 2 yr.Primary peaks of zooplankton were recorded during,south-west monsoon (July-October) and secondarypeak in north-east monsoon (January) jn both theyears. Predominant copepods were confined to 8·genera, viz. Paracalanus Boeck, Acrocalanus Gies­brecht, Centropages Herrick, Acartia Dana, OithonaBaird, Oncaea Philippi, Corycaeus Dana and EterpinaNorman. The major planktonic larvae were of cope­poda, mollusca, cirripedia, decapoda and polychaeta.

FLUCTUATIONS in plankton abundance and hy-drological factors off Port Kandla Oat. 23°01' N;

long. 70013'E) in the Gulf of Kutch have beenreported1,2. Bhaskaran and Gopalakrishnan3 havegiven a general account of plankton from PortOkha (lat. 22°28'N; long. 69°05'E), Gulf of Kutch.The present paper describes hydrological condiitons,abundance and variaticn of the zooplankton andtheir possible relationship with diatom maxima inthe waters off Saurashtra coast.

The study area extends between the latitude22°N and 22°35'36"N and longitude 68°E and70004'E, covering a stretch of 178 km of the coast.Three surface stations off Rozi, Port Okha andDwarka were sampled monthly from November1972 to October 1974 (Fig. 1). Collections weremade by 20 min horizontal surface hauls, using al ill net of organdy cloth having 36 strands/em,towed from a fishing vessel at a set speed of 3 knot/hr except in the monsoon months when a sailingboat was used. As fishing season off Dwarkacommences from September and ends in April,samples for 7 months only were obtained.

69- 700 ~ n~

Fig. 1 - Saurashtra coast showing sam?ling stations[A, off Rozi; B, off Port Okha; C, off Dwarka]

140

..,

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6257

1553

OffDwarka.

Locality

Off OffRozi

Port Okha

8

91·5

2·52·5

1'54

45

56

1253

2220

819

6,554

29·518

156

4

(Values are expressed in ml)

Jan.Feb.MarchAprilMayJuneJulyAug.Sept.Oct.Nov.Dec.

TABLE 2 - MONTHLY DISPLACEMENT VOLUME

Month

pre~ent study, Paracalanus parvus, CentopagesdorsisPinatus, Acartia sPinicauda, EuterP1'na acuti­frons, Oithona brevicornis and Oithona similis showedhigh abundance during July, October and January.The~e periods of copepod maxima differ frem tho~eof earlier report~1-3. Thus, in the pre~mt studycopepods showed more than one major peak duringthe south-west monsoon (July-October) and minorpeak during the north-east mon~oon (January)at Rozi and Port Okha, while at Dwarka the pri­mary peak was ob~erved during October and the~econdary peak in January for both the years.The~e peaks more or le~s followed the maxima ofdiatom~3o.

Amongst planktonic larv2"e, copepod naupliidominated in numbers as well in occurrence asreportedl-3. Larval forms of polychaeta, cirripedia,gastropoda and bivalve al~o showed good occurrencebut were less in numbus. Zoeae of the crabPortunus pe~agicus w€:re found in high numbers offRozi but their occurrence was very restricted.High abundance of zoea of Portunus pelagicus was~ignificant taking into consideration the under­developed crab fishery of Gujarat31.

It may be noted (Table 3) that fish eggs andlarvae were abundant during July to Septemberat Rozi as also observed earlier1,2.

All plankton samples were pre~erved in 5%formaldehyde. The volume of the plankton samplewas determined by the displacement method. Eachsample was then diluted to 200 ml from which 3 mlsubsample was taken to Bogorov counting tray bystempel pipette for enu.meration of zooplanktonand an aliquot (1 ml) was taken separately to Sedg­wick rafter cell for counting planktonic diatoms.Macroplankton organisms were, however, countedfrom the entire haul.

Temperature of the surface water was taken witha centigrade thermometer. Salinity was determinedby Mohr metod' and dissolved oxygen by Winklermethod'.

Hydrological data collected at various ~amplingstations on the Saurashtra coa~t during the presentinvestigation are presented in Table 1. Surfacetemperature showed a unimodal oscillation at allthe stations as observed earlier1,2,5 unlike the bimo­dal pattern shown at some other parts of Indiancoast3,26-28. Its minima and maxima coincidedwith winter and summer seasons respectivelyl,2.

Salinity values showed narrow fluctuations andalways remained above 34'4%0' Salinity distributionin the areas studied differ from the general patternalong the west coast of India1,2,26,29, which may beattributed to the weaker monsoons.

The dissolved oxygen content was found maximumduring winter months (January and February)as also reported by Dhawan2.

Monthly displacement volumes are shown inTable 2. Maximum standing crop was obtainedin October from all the 3 stations. Minimum wasin February off Rozi and Dwarka, and in March offOkha.

At Rozi, the minimum standing crop rosesteadily reaching maximum in July and then show­ed a decline up to September and again showed apeak in October and subsequently fell down. Thesame pattern in standing crop of zooplankton wasobserved off Port Okha. In general, the minorand major peaks coincided with north-east andsouth-west monsoons respectively for both theyears.

Zooplankton population of Saurashtra watersis mainly composed of copepods and planktoniclarvae (Table 3) as compared to earlier reponsl-3.Out of the 12 dominant copepods found during the

TABLE 1 - HYDROLOGICAL DATA OFF RozI (OR), OFF PORT OKRA (OP) AND OFF DWARKA (OD)

Month

Temperature (0C) Salinity (%0)Dissolved oxygen (mi/litre)

OR

OPOD OROPOD OROPOD

Jan.

20·219·219·8 37·736,437·1 5,75,36·6Feb.

2219·921 3736·135,8 4,656March

22·921·323·5 35,634·73504 3·24'3504April

252426·4 3634·535,8 4·23-84,6May

2728·8-3735·8- 4·44,7June

29·629-37-836,6- 4·65·1July

2928·1-3837'75- 5,65·2Aug.

28-426·9-37"636,45- 4,54Sept.

2826'5-38-436·7- 5044,7Oct.

272626·4 37,636·336·7 53·43·7Nov.

26·924-825·5 37·1736·1536 4-63-85·5Dec.

242323 36·834·435·4 5·24,85·4

141

INDIAN J. MAR. SCl., VOL. 5, JUNE 1976

TABLE 3 - SEASONAL VARIATION OF ZOOPLANKTON OFF RozI (A), OFF PORT OKHA (B) AND OFF DWARKA (C)

Zooplankton

Jan.Feb.MarchAprilMayJuneJulyAug.Sept.Oct.Nov.Dec.

FORMINIFERA 6Globoquadrina conglomerata

A- 3-----24(Schwager)

B- 2--2------3

Globigerina pachydermaA-------44-20

(Ehrenberg)

C--4------Globigerina quinqueloba

B- -238--44Natland Globigerina bulloides

B--4-4-32d'Orbigny Globigerina rubescens

A- -2----24-4Hofker Globorotilia rneanardii

A--2----2--6

(d'Orbigny) Globorotilia hirsutaB--2- 1--23--2 ),(d'Orbigny) Globorotilia tumida (Brady)

B--3----32---Orbulina universa

B2----43----2d'Orbigny Globigerinell'a aequilateralis

B4-4----53(Brady)

TINTINNIDS' ,6Tintinnopsis dadayi

A------2---820Kofoid valj. loricata

B---12Brandt

C---20

Tintinnopsis dadayi var.

A4--------416c. of Brandt Tintinnopsis radix (Imhof)

A5-----6---46Brandt

B11111- 2--211C

--21-----6--Tintinnopsi's tocantinensis

A----------207Kofoid and Campbell

B43- 1-------2C

--2-------13Tintinnopsi'fs gracilis

A- -----4---612Kofoid and Campbell

C4311--------Tintinnopsis karajacensis

C---1-------6

Brandt Tintinnopsif; mortenseniiB411-------22

Schmidt Tintinnopsis nordqvistiA3- 11-----216

var. a of IBrandt Tintinnopsis nordqvistiA11- 1-----516

var. b of ;Brandt Cyttarocylis ehrenbergi

B3412-------2

(Claparede and Lachmann) C4--------204

Codonella ostenfeldiiB- --4

Schmidt Codonellopsis orthocerasC- 34

(Haeckel) Joergensen HYDROIDS'Obelia commissuralis

B---221McCrady SCHYPHOMEDUSA10Pelagia no'ctiluca (Forskal)

C- --------490

SIPHONOPHORA 11PorPita pabifica Lesson

C- 1

CTENOPHORAPleurobrac'ftia sp.

A20 201842-448102020

CHAETOGNATHA12,13Sagitta regularis Aida

A-----44

Sagitta bombayensis Lele

A-----21

and Gaej Sagitta en'ftata GrassiB25 2010444--10302422

Sagitta neglecta AidaB10 21344--3421 )

Sagitta bedoti BeraneckA2 120204--33321

Sagitta robusta DoncasterB544414424455

142

.I

•J

SHORT COMMUNICATIONS

TABLE 3- SEASONAL VARIATION OF ZOOPLANKTON OFF ROZI (A), OFF PORT OKRA (B) AND OFF DWARKA (C) - Contd

Zooplankton

Jan.Feb.MarchAprilMa.yJuneJulyAug.Sept.Oct.Nov.Dec.

CLADOCERAEvadne sp.

B--1---161415544C

412-----2123Penilia ap.

C22-------2-1

OSTRACODACypt'idina sp.

B421424----22C

2222------42COPEPODAU-16Paracalanus parvus

A740 525548504548860524830154)~

Giesbrecht B472 5414226116108383432303030,j C268 645636 803612,- -----Paracalanus aculeatus

A20 234183060402041614Giesbrecht

B141844688462018188C

4234-----1443Acrocalanus longicornis

A202014162238456040461416Giesbrecht

B64647278969252202018C

401844-----41818Acracalanus gibber

A4410-238--6-4Giesbrecht

B8812-343--6-8C

16104------4-12Acrocalanus gracilis

B4444443--344Giesbrecht

C18 324-----433Centropages dorsisPinatus

B2432432242041818Thompson and Scott A

40 32 234 12Acarlia spinicauda--301816

GiesbrechtB234-2024- 62052420

C43218-----48412

Euterpina acutifrons

A2018121030143001801201014232(Dana)

B323040485260452100116985446C

232 201812-----10418Oithona brevicornis

A260 2224181648101618120124Giesbrecht

B2226306102541416666104C

8020184-----401860Oithona similis claus

A280 20103648438431416B

402 1418745426510154886C

602044-----3810Oncaea venusta Philippi

A6262018-4- 3- 444B

4161020-22--444C

2025224-----201616Corycaeus catus F. Dahl

A250584016244430316B

2124248604448422C

16121024-----4812CUMACEA

Eocuma sp.

B64-12-2--7AMPRIPODA17-19Ce1'apus abdius Templeton

B4--------2844Vibilia viatrix Bovallius

C2

Euthamneus platyrhynchus

C----------3(Stebbing)

C22Synopia scheebeana

-Bovallius Phatis sp.

B- 1126----114C

----------3MVSIDACEAMysidopsis sp.

A42------1320DEcAPoDA2oLucifer hanseni Nobili

A3-----424131B

-------16322

CAPRELLIDEA21Paradeutella bidentata Mayer B

23-------42143

INDIAN J. MAR. sel., VOL. 5, JUNE 1976

TABLE 3 - SEASONAL VARIATION OF ZOOPLANKTON OFF RoZl (A), OFF PORT OKHA (B) AND OFF DWARKA (C) - Contd

Zoop~nkton Jan. Feb. March April May June July Aug. Sept. Oct. Nov. Dec.

GASTROPODA22

Clio acicula (Souleyet) BC 6

44

16

4 48 4

THALIACEA 23,24

SalPa cylindrica Cuvier CDoliolum tritonis Herdman C

62 1 1

ApPENDICULARIA

OikoPleura sp.

Appendicularia sp.

ACC

12 1

111

PLANKTONIC LARVAE

2

43

90 704 -

20 2614 2044,4,

2020- 184 10

16 20--:.. 11.8,20- -

86

60

4

4

104

20020

3,

200

120

4

6

80

22

28

17

182

202

173

60

43

4

23

4

420

4

18

4

9

4

20

4

214

38

440

4

4

440

44

1620

47

4

416

4

111

4

41

8

445

195

40444

61

2817

205

1024

ABC

Larvae of polychata

Fish eggs and larvae

Bivalve veliger larvae

Barnacle nauplii

Copepod nauphi

Gnathia larvaeGastropod Ilarvae

ABCABC

Portunus pelagicus _zoea25 AOther crab~ - zoea and A

Megalopa Ilarvae - BCBABCABCABC

The author is grateful to Shri Moosa Raza,Commissioner of Fisheries, Government of Gujarat,for facili~ies and to Shri M. Bhaskaran, ResearchOfficer, for guidance and confirming the identifica­tions of zooplankton.

References

1. RAMA¥URTHY, S. & DHAWAN, R M., Indian I Fish.,10 (1963), 94:

2. DHAWJ\N, R. M .• Indian J. Fish., 17 (1970), 122.3. BHASK:ARAN, M. & GOPALAKRISHNAN. P .• Indian J. Fish.,

18 (1972), 99.4. BARNES, H., Apparatus and methods of oceanograPhy,

Parti I (George Allen & Unwin Ltd, London), 1959,85, 179.

5. PRASAD, R. R, Indian J. Fish., 4 (1957), 20.6. RAo, K. K, Indian J. mar. Sci., 1 (1972), 1.7. PRASAD, R R., Indian J. Fish., 3 (1956), 23.8. TAYLOR, F. J. R, J. mar. biol. Ass. India, 14 (1972), 55.9. RAo, K. V. R. & RAo, K V. S., I mar. biol. Ass. India,

13 (1972), 144.10. RAo, }-r. S., Rec. Indian Mus., 33 (1931), 29.11. RAJ, B. S., Bull. Madras Govt Mus. n.s. nat. Hist.,

1 (1?27), 21.12. SILAS, E. G. & SRINIVASAN, M., Proc. Indian Acad. Sci.,

71 (1970), 177.13. JOHN, C. C., Bull. Madras Govt Mus. n.s. nat. Hist.,

3 (1933), 1.14. KASTeRIRANGAN, L. R, A key for the identification of the

more common Planktonic copepoda of Indian coastal

15.16.17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.28.

29.30.31.

waters (Council of Scientific & Industrial Research,New Delhi), 1963, 8.

SEWELL, RB. S., Mem. Indian Mus., 10 (1929), 1.KRISHNASWAMY, S., J. zool. Soc. India, 5 (1953),73.NAYAR, K. N., Bull. Madras Govt Mtts. n.s. nat. Hist.,

6 (1959), 41.PILLAI, N. K., Proceedings of the Symposium on Crustacea,

Part I (Marine BiologicJ.l Association of India, Manda­pam Camp, India), 1965, 205.

THOMAS, R R & STEBBING, M. A., Rep. Scient. ResultsVoyage H.M.S. 'Challenger' 1873-76, 29 (1888), 799.

MENON, M. K., Bull. Madras Govt n.s. nat. Hist., 3(1940), 7 ..

RAJ, B. S., Bull. Madras Govt Mus. n.s. nat. Hist., 1(1927), 126.

LANKESTER, E. R, Treatise on zoology, Part V (Adam &Charles Black, London), 1906, 171.

NAIR, R. V., Bull. Madras Govt Mus. n.s. nat. Hist.,6 (1949), 22.

HERDMAN, W. A., Rep. Scient. Results Voyage H.M.S., Challenger' 1873-76,27 (1888), 47.

PRASAD, R R & TAMPI, P. R S., I Bombay nat. Hist.Soc., 51 (1953), 674.

CHIDAMBARA.M, K. & MENON, M. D., Proc. Indian Acad.Sci., 22B (1945), 355.

PILLAI, V. K, J. mar. biol. Ass. India, 10 (1968), 237.SUBRAHMANYAN, R; Proc. Indian Acad. Sci., 50B

(1959), 113.GEORGE, P. C., J. zool. Soc. India, 5 (1953), 76.MAHYAVANSHI, 1. N., unpublished work.TRIVEDI, Y. A. & PATEL, N. M., Seafood Exp. I, 7

(1975), 17.

144