Bivalves constitute an important component of many benthic ecological habitats. They are adapted to

withstand the frequ e nt physical and chemical changes characteristic of the marine aquatic ecosystems

and as a resul they form an integral part of the benthic community structure. In estuaries, intertidal zones and

near shore coastal areas of Kerala, they are well distributed. Geological history records of Kerala havc

indicated several transgressions and reg ressions of the sea along the coast resu lting in many standstills

during the Pleistocene and Holocene periods

Kripa, V

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State Biodiversity S frategy and Actio" Plait fo r Kerala Ackll()lI'ledvemclI/s The author is thankfu l to Dr. D.M. Thampy, Former Dcan. College of Fisheries, Kcrala Agricultural Uni ve rsity for grant ing permission for attending all the workshops connected with NBSAP and SBSA P, which enabled me for the preparation of thi s paper. He is obli ged to Dr. J. K. Shanna, Director ofKFRI for giving the opportunity to prepare thi s paper. Thanks arc also due to Dr. P.S. Easa, Dr. E.A. Jayson, Dr. c.P. Shaji- sc ientists ofKFRI and to Mr. Raju Thomas, Sr. Research Fel low, College of Fisheries, KAU, for their suggestions. 3.3.5 Biodh'ersity ojbh'ulves (Invertebrata: Mol/lIse/I) --- V. KRJI'A MolIlI$COII Fisheric$ Divisioll. Cell/ra/ MarinI: Fishel"ielJ Reseorch /t1S/il ll le. CocM,. 682 014. Ken./a : [ntroduction " Bivalves constitute an important component of many benthic ecological habitats. They are adapted to withstand the frequent physical and chemical changes characteristic of the marine aquatic ecosystems ,nd as a resul t, they form an integral part of the benthic community structure. In estuaries, intertidal zones and ncar shore coastal areas of Kerala, they are well distributed. Geological history records of Kerala havc indicated severaitransgressions and reg ress ions of the sea along the coast resu lt ing in Illany standstill s during the Pleistocene and Holocene periods. The coastal plains of Kerala are probably of the late Pleistocene and alluvial origin. Recently, Pillai el a/. (1999) have collected 14 species of bivalves along with other mollusca and Scleractinian corals about 8 km from Coch in from a well cutting at a depth of 8 km. The fauna found in the collections arc also found in the extant fauna of the seas around India, indicating a somewhat stability in the marine Biodiversity. Literature perta ining to the occurrence, distribution and divers ity of bivalves are limited. B;JSCU on thc shell collections (both live and dead), Preston (1916) ilnd Cheriyan (\968) have described 36 species belonging to 24 gcncra in 15 fami lies of C lass Pelecypoda. In the 70's, research was ta rgeted at the habitat associations of bivalves (Ansell e/ af. , 1972; AppukuUan, 1973). A rev icw of tile litcra ture on the work done on bivalve resources of Kerala clearly indicates that this resource has been investigated by re sea rchers more fur unde rstanding thcir rol e as an indicator specics or pollution than the ir rol e in ecological communities. Based on thc obscrvations on the she lls landed by trawlers and those collected from the coastal areas, 7 I species of bivalves belonging to 48 gencra or 24 ramilies have alrcady been li sted as given in T;lblc 3.16. £Co/Qt';c"l diwrs;!Y Bivalves ill estuaries, intertidal zones and the subtid:1I continental shelf area have adaptive characters to suite the particular habitat. All the three groups of bival ves viz., clams, mussels and oysters, have well defined distribution pattern in the coastal regions of Kerala. E\'(uorille resource)" In Kernla, there arc about 4 1 wcst nowing rivers that di sc ha rge in to 30 estuaries, which open into the sea through perennial or seasonal outlets flcross bar mouths. In the cstua ries, the clams arc the dominant bivalves and they show zonation based on salini ty profile or the cstuary. The typical zona tion pattern of clams in so me of the lakes in Kcrala is presented here. For instance, in thc Vembanad Lake, there e;'(isls II hOlllogenic popu lation or SUllella scrip/(( ncar the bar mouth reg ion where the salinity is fai rly constant. Abollt 2 to 3 kill rrom thc bar mouth where the s;din it y docs not go below 15 ppt. ,I mixed (heterogenic) poplilutioll or Mcrilrix casta and Pllphi(/ mall/burica Ot.:curs. Similarl y. throughout thc estuarine regiun whcre fresh waler conditions prevail during the monsoo n period, a homogcnic population of J 'jI/orilll 144 SI(tle lJifl{[h'er,\'i~)' SII'fII('gy lIml Actio" /'hlll fo r KCl'lllll cypril/oides has been noticed (Kripa and Joseph, 1993), In addition to these dominant spec it.: s, there also occur other clams like Modio/lls sp. and MusclIllls spp, in regions where the salinity docs nol fall below 5 ppt. The Biva lve resources of Kcrala is given in Tab le 3.17. T,able 3.1 7 Bivalve resources of Kerala Family Genus Species Refercllcc 1 Nuculanidae N uclllalla mallrilial1(1 (Sowcrby) Chcriy,", P. V. 1968 2 Areidae Area laleralis Reeve Chcri y," P.v. 1968 3 , Arca illeqllivalvis Bruguiere Cheriya n, P. V. 1968 4 Arca tortl/osa Linlle Cberi ynn. P. V. 1968 5 Area indica Gmelin Chcri y. n, P. V. 1968 6 Mytilidae Madia/us stria tu/lls ( ilanley) Cheriyan, p,v. 1968 7 Modio/us ul/dulatlt.'i (Dunker) C heriyan, P. V. 1968 8 Madiollis IttlifJ(/ (Lamarck) Cheriyan, P. V. 1968 9 IJ /'llllchydoll/e,<; * 10 Sep/iier • 11 Muscllllls sellhallsia (De ll son) Shiny, S. 1991 12 Pernu virides Kuri:1kose. 1980 13 Pcr11a indica Kuriakose. 1980 14 Lithop/zaga lIigra (d Orbigny) APP"klU"n, 1973 15 Pteriidae Pla ia * 16 Pinclada (uca/a * Ach,ry, O. P.K 17 Pi llcrada ,wgilatn * i\ch,,,y. O.P.K IS Pillcfada olloJ1loiril's • 19 Pillctada l11argarilelera * Aelm!'y. G. P,K 20 Pill cfariu atl'opl!pllria • 21 Pinnidae Pinlla • 22 Pec tinidae Pectell trallqllc/}al'icfls Gmelin Chcri ya n. p, V. 1968 23 SPOII(/yIIIS • 24 Limidac Lima • 25 Anomiidae Placenta placcnta • 26 Ostrcidac CraSSOSfrea lIIa(/J'C1SCI1.\'is R,o. K.S. 1987 2? Sflccocll'l'(l ('{{{'III/Ia ( Born) Ran. K.S.19S7 28 C rass :1te llida c Crasslella * 29 Carditidae Cart/ita * 30 Beg llill(l * 3 1 Luci nid:1e Lllcilla ovum Reeve CheriY:1n, p, V. 1968 32 'Erycinidae Gu/coll1a * 33 Scilllelia • 34 C ham idac Chall/a • 35 Cal'dilllll • 36 VCllcridilc Dosillill /1I(J(lestll (Sowcrby) CltcriY;,\ Il , p, V I%R 37 nosillio c'/'('lcI(,('(/ (Rc(w ) ('heri),:!n , p,\" II)M': ~\ ~ /)(I ,\'IlIio 1I'I,I!.f!I/1/ ( Reeve) ( ' IIt.: r iyan. I I)(I~ ('1ahk 3,17 t'( lnltl.) 145 • , State Biodh!ersity Strategy and Action Plan for Kerala 39 Dosillia histrio (Gmclin ) Cheriyan, r.Y. 1968 40 Meretrix casta (Chemnitz) Cheriyan, r. V. 1963 41 Meretrix ovum Deshayr.:s Cheriyan, P. Y. 1968 42 Venus imbrica(a Sowerby Cheriyan, r.y. 1968 43 VCllcrllpis lIIacrophy//a Dcshayes Cheriyan, r.y. 1968 44 Papllia marlllorafa (Reeve) Cheriyan, r.y. 1968 45 Parhia malabarica (Chcmnitz) Cheriyan, P.y' 1968 46 Calelysia opima (Gmclin) Cheriyan, r .y. 1968 47 Circe scripla (Linne.) Cheriyan, r.y. 1968 48 Chiolle tiara (Dillwyn) Cheriyan, P. V, 1968 49 PitaI' * 51 Gafarariul/J * 52 SUI/etta scripta 53 Corbiculidac Vil/orita cyprinoidcs (Gray) Cheriyan, r.y. 1968 54 Geloilla bellgalcnsis * 55 Maetridae Standel/a pel/llcfda Cheri)",n, r.Y. 1968 56 Donacidae DOllax spiculum Reeve CheriYan. r.y. 1968 57 f)OI/(I'\: illC(ll"Iwflls Ansell cI 11/. 1')]2 58 DOllax scorlulIl * 59 DOl/ax (aba * 60 PS<l1111110bi ielae Cari psallllllobia ul/leythysfUS Chcriy-;m, P.Y. 1968 61 SClllclidac Theora opalil/a (Hinds) Cheriyan, r.v 1968 62 Tellinic!ae Tellina rhodol1 Hanley Cheriyall, P,Y. 1968 63 Tel/ilia {Jillgllis Hanley Chcriyan, P.Y. 1968 64 Solenidae Solell lamarckii Deshayes Cheriyal), r .y. 1968 65 aqllaedllicioris (Ghosh) Cheriyan, r.y. 1968 66 Gastrachacmidac Castracliaefl({ gigal1tea (Desha yes) Appllklillan, K.K. 1973 67 Pholadidac Pholas Chcriy;m, P.y' 1968 68 Marlesia striata (Linne.) Chcriyan, r.y. 1968 , 69 Pholas orienfalis Glllelin Cheriyatl, P.Y. 1968 70 JUII(lIIIl Clia cumingii (Sowcrby) AppukuHan, K.K. 1973 , 71 JOl{(Jllflelia globosa (Quoy and Gaimard ) Appukultan, K.K. 1973 • Pc" o", 1 obscr ... al iuo I Ob.~rv"l io " hy Df.K.K.l\I'I,,,klll l,,". llead. MFD. CMFRI . . , t~ In Ashtamudi Lake and Chcttuva estuarics also such zonation is cvident, but dense populat.i~ns '~ ~ Sill/etta scripata as observed in Vemanad Lakc· arc absent. Species diversity has been found fo be mare in ~ the Ashtamudi lake where in the estuarine beds other bivalves like Alladara granosa, JLrca·spp, .Marci¢ I' opillw arc seen along with oysters Crass(}s!!'ea lIIadraselisis and Saccos!!'ea clle/d/a!a and the mus~ . Perna virides. The density or clams and the area inhabited by each group is dctermined mainly by thf . tidal influx and the nature of thc estuarine substratum such as clayey, sandy or muddy. With regard If -: oysters, there arc two main species viz., C. rassos.'rea lIladrosel/sis and Succostrea clIclll/ala found in t'+ ~· ..upper intertidal C01ll1l1ul11ties. Thesc two species also show a clear distnbutionl zonation. Saccosfre4 . , cllelll/fa forms more than 80% in the m:1fllle regIon orlhc estual), whereas the dominance of this species .~'" to\v;1rds the intcrior decl incs slowly ;mu in the upper reachcs Cras.ws{l"ea /lJadra.H'l/sis forms homogcl1, l.,~ populations. (Kripa and S~llih, \(99). . .~ 1 j l Slale B;odiversity Strategy {lilt! Actio" PIau for Kerala The Illarine mussels had formed singh: species populations wi th g reen mussel in northern Kendi! allli brown mussel in sou thcm Kcrab. The d istri bution orbrowll 1l11ISScl, which was res tricted rrom south ern parts of Tamil Nadu uplo Kallam, has been found to extend uplo}\zhikodc nCaf Kochi (}\ppllkutt ~ 11 el (/1., 2001). Similarly mixed popu lati ons were observed in southern Kcrala ncar Vizhinjam where only the brown mussel was reported. Bivalve resources oUnler tidal shores Along the Keral a coast, rocky and sandy shores are common. In addition to this, in areas where sea . erosion is common during monsoon, granite boulders have been placed to prevent the destruction to the coastal arcas . The bivalve resources in these areas are typical representatives of the tropical intertidal region. In such arcas, the mussels Perna viridis. and P. indica are commonly found . In the northern and s.outhem regions of the Sta te, mussel beds are perennia l while in central Kerala, especially in locations having arti ficia! sea walls, the mussel beds usually ge t destroyed as the sea recedes after 111011S0011. Oysters arc also common in thcse regions but their contribution to the community is negligible. In Sou t~lern Kcrala, especially nearVizhinjam, a rich bivalve resource with several species ofPteridae like Pleria pCl/uin, Pillclada/ilcala . PSI/gil/ata have been observed. Such species diversity is not seen in the rocky shores or northern Kerala. Sim ilary, 0 11 the sandy bcaches DOlla.\" sp. is the main clam although other bivalves like Arca, SUI/efta, Gafraruilll are a lso COlll mOIl . Such species divers ity based a ll habitat structure is seen along the coastal region. ContiJlental shelf In the upper contincntal shelfwhere the substratum is hard. the mussels Pema virides or Perl/a indica are the dominant resource. In the sort bottom areas, other marine clams are known to occur (Table I). These are landed by the trawlers as by-catch and arc usually discarded as trash. Immediately after monsoon, huge quantities of dead shell s of these stenohali ne species accumulate near the sandy shores where they are fi shed and utilized as raw materia l for lime shell industry. inrormation on the bivalves occurring in the hard bank ncar Kollam, and in the coral patches ncar Vizh in ij am is scanty. Appukuttan (1973) has reported on the occurrence of four species of cora l boring bivalves of three ge nera from Kallam area . Targeted ra unal study about the resource o f Co ch in Harbour region lIas been donc hy C hcriyall ( J9GR). Dct:lilcd in rorl11ation oll lhe bivnlvc rcsource or shclfrcgioll or Kerala is not available. Mornh%~ical di versitv In order to withstand the adverse phys ical ! chem ical ! environlllcntal conditions, bival ves inhabi ti ng the estuaries as well as in sandy and rocky inter tidal zones have developed remarkable morphological fcatures. The common feature or bivalves is the two shells and a so ft body enclosed with in a mantle. To faci litate burrowing and fo r c ircukning water, species like Paphia malabarica have well deve loped siphon and foot. T he density of thi s species was round to be more than 1200 indi viduals per sq.m. indicating that they lay one above the other. In the same estuary, ce rtain other species like Merit"i.\" cosIO and Villorita cyprilloides have much lower density with less than 500 indiv iduals per sq. ll1. also occur. In these species, the si phon and root show reduc ti on. Such va ri<ltiOlls have been observed in the clams or estuarine region as well. In rocky areas also bivalves arc the dominant species because of their specia l adaptations for attac hment. In the sa ndy beaches of central Kc ral a where there is considerable erosion during 1110nsoon and the intertidal the beach area dimin ishes the zonation comprcsses during monsoon. In sll ch locations. DUllax illc((I"IIClles exhib it strong tidal migration. Anse l! et af. (1972) has observed that D. i llcamafes was able to keep pace with this e rosion ~ll1d formed a perma nellt c lclllcnl o/" the beal:h fauna. D. SI)iclI{lIll1 occ urred only sporadica lly in the same bcach. 147 · ' ' " Stute Biodiversity Strategy uJI(i Actio" Plait for Kuala Generic diversit)l Though different species ofbival vcs' co cxist, they rcmain as reproductively isolated populat ions'. Howcver, reccntly in addition to green and brown mussel, a third variety with light green colour pCI~Lostracum and shell characteristics similar to brown mussel has been observed in the heterogeneous mussel populations in Kollam area. 11 is presumed that this is a hybrid of tile green and brown mussel. COllclllSioliS In Kerala, faunistic studies related to the bivalve resources have been negligible. The Central M:trine Fisheries Research Ipstitute, Cochin has been conducting a detailed survey of the estuaries 'with special emphasis on resource utilization and biology of the major species. The other research Institutes and Fi sheries Colleges have given emphasis to pollution and bioaccumulation studies. A review of the literature on bivalve fauna has clearly indicated the need for quantitativc and qunlitativc assessmcnt of the resourccs. Recent studies have indicated that the cstuarine area ofKerala has reduced from 2426km2. to 652 km2• due to serious alterations during the past 150 yea rs through reclamation for agricultu re and human settlement. This habitat shrinkage also calls for the need to keep record of the richness of the bivalve fauna of the State-; 3.3.6 Sponge biodiJ1Ilfsity ill Kerala (111(1 its biotecllllOiogical potentials P.A. THOMAS and P. SUNIL KUMAR Vi:Jd/l}fll/I Cell/re. Ccn/ril l Marille Fisheries Ue.\·carc!z II/sti/l//e. Tlziruv(IIulIZ/lw[Ju ram • Introductioll Animals which exist today may bc classified under two categories; I) Protozoa or sil~glc ce lled animals 2) Metazoa or multi·ccllular animals. Metazoam in tum, l11;ly be divided into two groups: a) Diploblastic, with two gcrm laye rs (ectoderm and endoderm) and b) Triploblast ic, with three gcrm layers (eetodernl, mesoderm and endoderm). I n sponges thcre arc no layers as seen in diploblastic or triobl.astic or triploblastic groups, but the 'layers', in sponges, arc Ill,lde of loosely arranged cells which can cven change their location at will. So the ' layers' found in sponges arc not called 'ectoderm and endoderm', but 'cclosollle' and 'endosomc', and the cells never adhere to eaeh other firmly. The cells of sponges can be scpara ted individually using a bolting silk or fine cloth, but thi s is not possible with any triploblastic or diploblastic animal. Hence sponge cells provide ample scope for a cytologist to study the physiological propeltics of a cell which is more primiti ve than that in any adva nced animal. Out ofa total of360 dClllospongcan species (siliceous sponges) recorded from the Indi an seas, a few are known from Kerala coast. But no consolidated account 011 these spccies exists in literature, due to the following reasons; I. No paper has bccn published in the past dealing directly with the spongc fauna of Kerala, 2. Research organisations interested in biodiversity studies collected sponges from Kemla coast regularly, but when results are published, no details other than the name of species is g iven, and 3. Many students have studied sponges ofKerala COliSt for their M. Sc:, M. Phil;, or Ph.D programlTles. but these arc not published and the students al so do not take any responsibility to publish the results and the dnta rem;lin. 'inaccessible' to the lIser community. All the 'lbovc points indicnte that whatcver data available on tile sponges ofKcrala are scattcred and hence sOlne elTorts on a warrooting arc nceded in retrieving the data and to make them 'available' to the Planners and Policy·makcrs. III«JJ"ll/alioll gans 011 lite ,monge 1011110 or Kera/a Some information on the marine sponge [aulla of Southern Kcrala (Kovalam to Kollameodc) is avniJablc, but 110 infonn.lIiOIl of the kind is avnilable for the res t of the Kerala coast. Rcgnrding freshwater and br;lckish watcr!'pollgcs it Illay be st;lted tll ;11 a total of20 species has bccn recorded ill the P;lst rr91ll Ke rnla (ZS I Report). 148 

Biodiversity of bivalves (Invertebrata: Mollusca)

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Biodiversity of bivalves (Invertebrata: Mollusca)

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