Faunal Diversity in Prawns and Crabs in Digha and Adjacent Coast in West Bengal with Notes on the Relationship of Their Abundance with Physico chemical Parameters

2007·2.2 MB·

by  T K Chatterjee

Journalofthe Bombay Natural HistorySociety, 104(3), Sep-Dec 2007 311-315
FAUNALDIVERSITY IN PRAWNS AND CRABS IN DIGHAAND ADJACENT COAST
IN WEST BENGALWITH NOTES ON THE RELATIONSHIP OF THEIR ABUNDANCE
WITH PHYSICO-CHEMICAL PARAMETERS'
T. K. Chatterjee23'4 AkmalHusain2'5and Santanu Mitra36
,
'AcceptedMay02,2007
2ZoologicalSurveyofIndia,MarineAquarium& ResearchCentre,Digha721 428,WestBengal,India.
’ZoologicalSurveyofIndia,27,J.L. NehruRoad,Kolkata700016, India.
JEmail: [email protected].
’Email: [email protected]
6Email: [email protected]
Studies on the diversity ofprawns andcrabs in Dighaand its adjacentcoast inWest Bengal, which are rich in fauna,
were carried out from April 2000-December 2005. Twenty-four species of prawns, two species of lobsters, twenty
threespeciesofbrachyurancrabsandfourteenspeciesofanomurancrabswererecorded.Attemptswerealsomadeto
determine the relationshipofthe abundance ofsome species with the physico-chemical parameters.
Key words: prawns, crabs, diversity, Dighacoast, abundance, physico-chemical parameters
INTRODUCTION MATERIALAND METHODS
Chandrasekhara Rao and Misra (1986) made a The present study is based on monthly collection of
preliminary investigationonthedistribution andecologyof samples fromApril 2000 to December2005 in Digha and the
theintertidal faunaofDighaBeach located inWest Bengal. adjacentcoast.DighaissituatedclosetothemouthoftheGanga
They studied the composition, density and distribution of at21°36'Nand87°30'E.Sampleswerecollectedusingshrimp
the meiofauna and macrofauna ofthis beach during 1979- seedcollection nets (shoot nets)from thefollowing locations:
1980. This paper aims at giving a detailed account of the 1)PaschimGadadharpur,about6kmwestofDigha,2)Udaipur,
diversity in prawns and crabs found on Digha beach, based about 5 km west ofDigha, 3) OngariaGhat, about 3 km west
on studies conducted from April 2000 to December 2005. from Digha, 4)JatranalaGhat, about 3 km west ofDigha and
Attemptshavealsobeenmadetocorrelatetheabundanceof 5)NewDigha,about2kmwestofDigha.Theprawnsandcrabs
these animals with somephysico-chemical parameters. were counted from the beach collections and Drag net hauls.
A variety of prawns and one species of lobster Buried crabs were collected from sand flats during low tide.
belonging to the genus Panulirus dominate Digha and the Specimenswerecollectedusingasquaremetallicframeof25x
adjacent coast. The important species of prawn include 25cm,whichwas5cmdeep.Thequadrantwaspushedintothe
Penaeus monodon Penaeus indicus, Penaeusmerguiensis, sediment and the enclosed deposit dug out. This process was
,
Penaeus semisulcatus, Metapenaeus monoceros, repeatedatthesamespottogetanother5cmlayerofsediment
Metapenaeusbrevicornis andMacrobrachium rosenbergii. belowthetop5 cmofdeposit.
Crabs constitute one of the most dominant
RESULTS
macrobenthic faunal components in the ecosystem; they
play several significant roles. The feeding activities of
detritivore crabs, particularly of the genera Uca, CoastalWestBengalhasarichcrustaceanfaunaininshore
Macrophthalmus, Dotilla, Sesarma and Metaplax help in (including estuaries and mangroves) and offshore waters.
,
thedegradationofplantmattertodetritusparticles,andthey Around Digha, 26 species ofprawns and 37 species ofcrabs
are themselves preyed upon by a numberofpredators such were recorded (Tables 1 and 2). The prawns belong to three
as fish, reptiles, birds and mammals. The crabs also have a families, Penaeidae, Palaemonidae and Sergestidae. The
positive effect on the brackish water zone of mangrove penaeids form the bulk of the crustacean catch, contributing
ecosystem, due totheirburrowingactivities, the aeration of morethan50%ofthetotalproduction. Inthelasttwodecades,
soil increases.Anotherimportantroleofcrabsin mangrove crabshaveemergedasanimportantcommodityofexport.Apart
environmentsistheproductionofmillionsofmeroplankton from prawns and crabs, there is a great demand for lobsters,
which serve as potential source offood for a wide variety especiallyintheinternationalmarket.
of planktophagous organisms, including a rich fish Prawnsconstitutealargegroupofcrustaceansvarying
population. in sizefrommicroscopic toabout 35 cmlong. Nearly 2,500
FAUNAL DIVERSITY IN PRAWNSAND CRABS IN DIGHAAND ADJACENTCOAST
species are known (FAO 1984). The body is almost always Table2: ListofCrabspecies recordedfrom Dighacoast
laterally compressed, the rostrum usually compressed and
Brachyuran Crabs (TrueCrabs)
toothed, and the abdomen longer than the carapace. The
Family: Leucosiidae
antennules in most species bear a small scale or spine, the Philyrasyndactyla (Ortmann)
stylocerite,attheirbase,andtheantennalscalesofthesecond
pair of feelers, the antennae, are generally large and plate- Family: Calappidae
like. The pereopods or legs are usually slender, but in some Matutalunaris(Hilgendorf)
Matutaplanipes(Fabricius)
species a single leg ora pairoflegs may be stout, and some
Calappalophos(Herbst)
pereopods (the chelipeds) end in pincers or chelae. The
pleopods are well developed and usually present on all the Family: Majidae
five anteriorabdominal segments. Docieacanalifera(Stimpson)
Prawns are widely distributed, occurring in marine, Docleaovis(Fabricius)
brackishandfreshwaterbodiesfrom theequatortothepolar
Family: Parthenopidae
regions.Manyarepelagic,butthemajorityarebyfarbenthic, Parthenope(Platylambrus)prensor(Herbst)
living on a large variety ofbottoms such as rock, mud, peat,
sand, fragments of shells or mixtures of these materials. Family: Xanthidae
Twenty-four species of prawns and two species of lobsters Galenebispinosa(Herbst)
wererecordedfromtheDighacoast(Table 1).Thesespecies Family: Ocypodidae
Ocypodemacrocera(Milne-Edwards)
Table 1: Listof Prawn and Lobsterspecies recorded Uca Deltuca rosea(Tweedie)
from Digha Coast ( )
Ucadussumieri(Milne-Edwards)
Ucalactea(de Hann)
Prawns
Ucatriangularis(Milne-Edwards)
Family: Penaeidae
DotillablanfordiAlcock
Metapenaeusaffinis(Milne-Edwards)
Metapenaeusbrevicornis(Milne-Edwards)
Family: Portunidae
Metapenaeusdobsoni(Miers)
Scyllaserrata(Forskal)
Metapenaeuslysianassa(de Man)
Metapenaeusmonoceros(Fabricius) Portunus(Portunus)pelagicus(Linnaeus)
Portunus Portunus sanguinolentus(Herbst)
Parapaenaeopsissculptilis(Heller) ( )
Charybdis Charybdis rostrata(Milne-Edwards)
Parapaenaeopsisstylifera(Milne-Edwards) ( )
Charybdis(Charybdis) affinis(Dana)
Penaeusindicus(Milne-Edwards)
Charybdis(Charybdis) natator(Herbst)
Penaeusjaponicus(Bate)
Charybdis(Charybdis) feriatus(Linnaeus)
Penaeusmerguiensis(de Man)
Penaeusmonodon(Fabricius)
Family: Grapsidae
Penaeuspenicillatus(Alcock)
Varunalitterata(Fabricius)
Penaeussemisulcatus(de Man)
Metaplaxdentipes(Heller)
Family: Sergestidae
Aceteserythrina (Nobili) Anomuran Crabs (HermitCrabs)
Acetesindicus(Milne-Edwards) Family: Diogenidae
Family: Palaemonidae Clibanariusclibanarius(Herbst)
Exopalaemonstyliferus(Milne-Edwards) Clibanariusinfraspinatus(Heligendorf)
Macrobrachiumequidens(Dana) Clibanaruspadavensis(de Man)
Macrobrachiumjavanicum(Heller) Clibanarusolivaceus(Henderson)
Macrobrachiumlamarrei(Milne-Edwards) Diogenescustos(Fabricius)
Macrobrachiummalcomsonii(Milne-Edwards) Diogenesaffinis(Henderson)
Macrobrachiumrosenbergii(de Man) Diogenesplanimanus(Henderson)
Macrobrachiumrude(Heller) Diogenesavarus(Heller)
Diogenescostatus(Henderson)
Family: Hippolytidae
Diogenesinvestigatoris(Alcock)
Hippolysmata(Exhippolysmata) ensirostris(Kemp)
Diogenesdiogenes(Herbst)
AlpheusmalabaricusFabricius
Diogenesmiles(Hersbt)
Lobsters Diogenesrectimanus(Miers)
Family: Palinuridae
Panulirusornatus(Fabricius) Family:Coenobitidae
Thenusorientallis(Lund) Coenobitacavipes(Stimpson)
312 J. Bombay Nat. Hist. Soc., 104 (3), Sep-Dec 2007
FAUNAL DIVERSITY IN PRAWNSAND CRABS IN DIGHAAND ADJACENT COAST
are abundant from June to August, with the peak in July.
—
Coastal aquaculture of prawns and other crustaceans is
'Temperature
commonly practiced in the region. The demand for prawns
pH
in the world market is rapidly increasing. India has rich -—•—Salinity
crustaceanresources which areexploitedforexport. - - DO.
Lobsters
Lobsters include a variety of crustaceans ranging in
size from a few centimeters to more than 60 cm. They are
more orless elongate animals with cylindrical and flattened
Fig. 1: Averagetemperature, pH, salinity, dissolved oxygen
bodies, and a prominent tail or abdomen consisting of six (D.O.), recorded from the studyarea duringthe study period
movable segments andaterminal fan. (April2000-December2005)
DISCUSSION December2005 are given in Fig. 1.The monthly abundance
of four prawn and crab species during 2001 and 2004 are
The mean monthly values of the physico-chemical given in Fig. 2 and Fig. 3 respectively. The density and
parameters recorded in the study area from April 2000 to diversity of macrofauna on Digha Beach is rich, due to the
Penaeusindicus Acetesindicus
60
2001
O2004
Month
Month
Macrobrachiumrosenbergii
Penaeusmonodon
20
40 1
18 i
35
j 16
|
30 14
,
?
25
j 2001
2001
20 2004
D2004
2 8
15
10 imnill
nun
nlll
Jan Feb Mar Apr May Jun Jul Aug Sep Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Month
Fig. 2: Comparativechart showing monthlyabundanceoffourprawn species recordedfromthe studyarea during2001 and2004
J. Bombay Nat. Hist. Soc., 104 (3), Sep-Dec 2007 313
FAUNAL DIVERSITY IN PRAWNSAND CRABS IN DIGHAAND ADJACENT COAST
relatively sheltered sand flat rich in organic detritus. Due to Due tofluctuations in the biotic and abiotic factors of
the fine nature ofthe substratum, the majority ofthe species the environment, seasonal changes in population density of
colonising the beach are deposit and filter feeders macrofauna are known to occur from season to season and
(Chandrasekhara Rao and Misra 1986). The abundant fromyeartoyear. Interestingly,themaximumcountsofUca
occurrence ofDonax-Odostomia populations in the middle lactea in the present study were obtained during summer
ofthe beach is probably related to the abundant supply of probably related with highertemperatures and salinity. Uca
detritusonthebeach. Fineintertidaldepositsarealsoknown lactea counts were also higher from October to December
tosupportrichpopulationsofmicroorganismsformingfood due to an undisturbed substratum. Scylla serrata, one ofthe
for bivalves. The patchy distribution ofmacrofauna on the important commercial species, has the maximum count in
beach seems tobedue tothe environmental preferences and thesummer.Thespeciesisknowntopreferlowsalinity,hence
tolerances of the component species (McIntyre 1969). The furtherstudiesareneededtounderstanditsabundanceduring
macrofauna shows some submergence in the beach towards the periods ofhigh salinity in summermonths. It was found
higher tidal levels, apparently seeking optimum conditions to occur in burrows during the daytime. The depth of the
ofwatersaturation in the habitat. burrows varied from 1.0 to 1.5 m from the surface and the
Matulaplanipes Ucalactea
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Month
Ocypodemacrocera Scyllaserrata
Fig. 3: Comparativechartshowing monthlyabundanceoffourcrabspecies recordedfromthe studyarea during 2001 and 2004
314 J. Bombay Nat. Hist. Soc., 104 (3), Sep-Dec 2007
:
FAUNAL DIVERSITY IN PRAWNSAND CRABS IN DIGHAANDADJACENTCOAST
diameterat the mouth from 8 to 16 cm. During low tide the Penaeus monodon. From November to February, netting of
burrowsarefloodedwithseawater. DevRoyandDas(2000) prawn seeds is done intensively. This wild harvest
reported that the species also inhabits the muddy banks of undoubtedly destroys seeds of other species of prawn and
creeks,channelsandmangroves.Anothercrabspecies, Vanina various finfishes.
litterata,hadthe maximumcount during monsoon.The Red Theresultsofthepresentstudyagreewiththefindings
Crab Ocypodemacrocera is found throughout the yearwith ofBrady (1943), who showed that the distribution offauna
the peak in December-March, and the Two-spined Crab variedwithseasons,occurringindifferenttidal levelsduring
Matuta planipes is found in the postmonsoon period. The different seasons. The seasonal dynamics exhibited by the
crab Chatybdis rostrata occurs in this area throughout the Donax-Odostomia populations on Digha Beach apparently
yearand dominates all the otherspecies in number, with the follow a similarpattern.
peakin the late monsoon period.
Asstatedtwenty-fourspeciesofprawnsandtwospecies ACKNOWLEDGEMENTS
oflobsterswererecordedfromtheDighacoast.Thesespecies
occur in abundance from June to August, with the peak in The authors are grateful to Dr. J.R.B. Alfred, former
July. Formeeting the increasing demand ofprawn seeds for Director, Zoological Survey of India (ZSI), Kolkata,
prawnculturefarms,thecoastalpopulationisgreatlyinvolved Dr. Ramakrishna, Director-in-Charge, ZSI for facilities and
in wild harvesting of prawn seeds, in particular seeds of toDr.R.A.Khan,AdditionalDirector,ZSIforencouragement.
REFERENCES
DevRoy,M.K&A.K.Das(2000):Taxonomy,ecologyanddistribution macrofaunaofDighaBeach.Rec. zool. Surv. India83(3-4): 31-49.
patternoftheBrachyurancrabsofmangroveecosysteminAndaman FAO (1984): FAO species identification sheets for fishery purposes.
islands. Rec. zool. Surv. Ind. Occ. Pap. 185 1-209. Western Indian Ocean (Fishing area 51). 5 (Ed: Fischer W. &
Brady,F.(1943):Thedistributionofthefaunaofsomeintertidalsands G. Bianchi.). 131 pp.
andmudsontheNorthumberlandcoast.J. anim. Ecol12: 27-41. McIntyre,A.D.(1969):Ecologyofmarinemeiobenthos.Biol. Rev44:
Chandrasekhara Rao, G. & A. Misra (1986): The meiofauna and 245-290.
J. Bombay Nat. Hist. Soc., 104 (3), Sep-Dec 2007 315