FISH AND SHELL FISH FAUNA OF THE RETTING AND NONRETT1NG ZONES OF THE KADINAMKULAM KAYAL, KERALA AI$STRACT

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1 Journal of the Indian Fisheries Associank at , 1993, FISH AND SHELL FISH FAUNA OF THE RETTING AND NONRETT1NG ZONES OF THE KADINAMKULAM KAYAL, KERALA S. BUOY NANDAN* AND P.K. ABDUL AZIS Department of Aquatic Biology & Fisheries, University of Kerala, Trivandrum AI$STRACT Retting of coconut husk is one of the major problems of pollution hi the estuaries (kayals) of Kerala. Retting activity has resulted in the mass destruction of the flora and fauna and has converted sizeable sections of the kayal into virtual cesspools of foul smelling stagnant waters. Levels of hydrogen sulphide, phosphate and BOD, increased while dissi lived oxygen and fish and shellfish fauna decreased in the ambient waters. In the Kadinamkulam kayal a total of 37 species of fishes belonging to 26 families, 5 species of prawn and 2 species each of crabs and molluscs were recorded from the nonretting zone, whereas only 20 species of fish in dead condition were collected from the rating zone. Prawns, crabs and molluscs were absent at the vetting zone. IVIajority of the fish fauna in the kayal were marine forms. INTRODUCTION The rating of coconut husk has led to extensive pollution of the clean and highly productive estuaries of Kerala, The process of retting involves the immersion of raw coconut husks in shallow waters for a period of 6-10 inontlasresulting in the microbial decomposition of the husks. Retting is brought about by the pectinolytic activity of microorganisms like bacteria, fungi and yeast releasing large amounts of organic matter like pectin, ployphenol, tannin etc. into the medium. The mat or bacterial groups associated with retting are Aerobacter, 13seuclomonas, Bacillus, Paracolobactruin, Escherichia and Micrococcus (Ghat and Nambudiri, 1971). Fungi like Rhodowrulaflava and Saccromyces fructum were also reported (Bliat and Nainbudiri, 1971) from the vetting zones. A proper knowledge of the available fish fauna in the coastal ecosystems is a pre-requisite for the successful fishery development, culture practice and conservation. Preliminary survey of the fish fauna was carried out at the Kayamkulam lake by John (1958); &lava- Nadayara estuary (Abdul Azis and Nair, 1978) and Aslitamudi estuary (Nair and Abdul Azis, 1987). This is the first report on the effect of rotting of coconut husk on the fish and shell fish fauna of the Kadinamkulam kayal. MATERIAL AND METHODS Two stations were selected in the Kadinamkulam. kayal (lat.8 35'-8 40'N and long '-76 52'E), the largest among the estuaries in Thiruvammthapuram district, Kerala, India (Fig.1). Station 1 (Kotrakiri) represented a polluted zone, which is an interior bay of the kayal used entirely for the rotting of coconut husk. Station TI (Peruinathura) is an area free from rotting activity and is exposed to fresh water influx and estuarine in nature. The Vamanapuram river empties into the estuary at its northern extensity at Perurnathura. The study was conducted from October 1987 to September Surface and bottom water from both stations were collected at fortnightly interval for estimation of temperature, salinity, dissolved oxygen, hydrogen sulphide, BOD5, nitrate and ammonia following standard procedures (Strickland and Parsons, 1972). Fish and shell fish were collected at random from the local fishermen for one year, Amongst the cast nets and seine nets used commonly, the latter accounts for the major share of the catch. Identifications were carried out following Day ( ), Munro (1967), Whitehead (1972) and Ihingraii (1975). Present At.:clress : Central InlAnd Fisherie Research Centre (ICAR), Alappuzha , Kerala

2 36 NANDAN AND AZIS 744 5' 40' ANCNUMENGU- AKA THUMURI KAYAL 51.1 EDANAPIOOLA 51.1 PERumAINURA 1ff WING ZONES ALONG lit KAUNAmKULAM KAYAL Fig. 1 Location of Stations

3 FISH AND SHELL FISH FAUNA OF KADINAMKULAM KAYAL 37 SULTS AND DISCUSSION Water quality : The temperature of the surface and bottom water at the retting zone (St.I) varied from 26 to 34 C whereas that at the nonretting zones (St.II) varied from 25 to 32.5 C. The salinity values in the surface and bottom water ranged from 2.55 to 30.19%0 at the retting zone and that from 8.15 to 31.70%0 at the nonretting zone. Depletion of dissolved oxygen leading to anoxic condition coupled with the production of large amount of hydrogen sulphide was the characteristic feature of the retting zone. The dissolved oxygen concentration ranged from zero to 0.72 mg/1 at the retting zone whereas that at the nonretting zone ranged from 2.28 to 6.21 mg/1 in the surface and bottom waters (Fig.2). The hydrogen 7.6 to 40.2 mg/1 and that at the nonretting zones ranged from zero to 3 mg/1, in the surface and bottom waters (Fig.3). Very high BOD5 values ranging from 4.96 to mg/1 in the surface and bottom waters were another notable aspect of the water quality in the retting zone and that it ranged from 0 to 3.74 mg/1 at the nonretting zones (Fig.4). Generally the nitrate content was found to be lower whereas the nitrite and ammonia contents were higher in the retting zone. The NO 3-N values at St.' varied from') 0 to 2.48 pg at /1 and that at St.II from 0 to 4 tg at/1. The nitrite and ammonia concentrations ranged from 0 to 1.78µg at/1 and 6.40 to fig at/1 respectively at the retting zone and from 0 to 1.66 pg at/1 and 0 to tg at/1 at the nonretting zone. Fauna : A total of 37 species of fishes belonging to 26 families, 5 species of prawns, 2 species of crabs and 2 species of molluscs were collected from the nonretting zone. (Table I) There was considerable reduction in the fauna at the retting zone and only 20 species of fish in dead condition were collected. Of the 37 species of fishes recorded from the nonretting zone, 13 were typically marine while others are transient forms inhabiting different habitats viz., marine, estuarine (11 species), Estuarine/riverine (4 species) and marine/estuarine/riverine (4 species), (Munro, 1955). Megalops cyprinoides and Gerreomoipha setifer were the true estuarine forms occurring in the kayal. It is thus apparent that nearly 50% of the fish fauna in the Kadinamkulam kayal are marine forms which migrate into the kayal when hydrobiological conditions are favourable as observed in other kayals of India (Jhingran and Gopalakrishnan, 1973). Of the 5 species of prawns recorded trom the nonretting zones, Penaeus indicus showed the highest numerical density followed by Metapenaeus dobsoni. Scylla serrata showed higher abundance when compared to Neptumus pelagicus. Among the shellfish fauna, the bivalve Villorita cyprinoides showed the highest numerical density. (Table II) Salinity and temperature were the most significant factors which determined the distribution of fishes in the Kadinamkulam kayal also as found in other estuaries (De Silva and Silva, 1979). Since this kayal is not permanently connected to the sea, condition of the barmouth has a significant role in the recruitment of marine species. Retting activities at station I led to an anoxic condition concomittant with the production of large quantities of hydrogen sulphide and ammonia which in turn had a fatal effect on all the 20 species of fish fauna collected from the retting zone during the present study. Of the 36 species of fishes recorded from the nonretting zone, 28 were economically important (Thingran, 1975) and most of the marine species were occasional visitors. Mugilids, tachysurids, cichlids and centropomids were the most common groups contributing substantially to the fisheries. Among the mullets recorded, Liza parsia and L. macrolepis and from cichlids, Etroplus surratensis and E. maculatus were most common and caught round the year. Earlier studies conducted by Nair et al. (1983) from the Kadinamkulam kayal recorded 67 species of fishes belonging to 34 families. A sharp depletion of fauna was observed from the

4 38 NANDAN AND AZIS SIATION I. $01114(1 VAIII.--- YAW, E 0 I D I / lti 21,0N STATION II 3(45(1 15A1111 VAPIl r e-f- -I, - I t I I I I V..8 I I % I i I I 0 I t, I; w 021 (21221 A A 01 Is el 21014I/IS Fig. 2 Fortnightly variation of dissolved oxygen in the Kadinainkulain estuary

5 FISH AND SHELL FISH FAUNA OF KADINAMKULAM KAYAL STATION I /IMO VIII PAM find 61 HAM) /AS 110NTIIS SIAHON 155tH! PIUS VAN /3 U. a t S r H A HONTHS Fig. 3 Fortnightly variation of hydrogen sulphide in the Kadinamkulam estuwy

6 40 NANDAN AND AZIS B OT TOH MAT ER S T.0 S U:=. FACE MA TE7'. OTTOM MA TE R 1/61u ) 'a. o a S T. I SUR FA CE MA TE? Fig. 4 Fortnightly variation of BOD, in the Kadinainlailain estuary.

7 FISH AND SHELL FISH FAUNA OF KAD1NAMKULAM KAYAL 41 Table 1. List offishes of the retting and nonretting zones in the Kadinamkulam kayal Family Species Local Name Habitat (Munro 1967) 3 4 No. Collected Non-retting retting Megalopidae Iviegalops eyprinoides Nunna Chankanni 10 6 Clupeidae Sardinella sp. Chaala 7 2 Engraulidae Stolephorus indicus Netholi M 9 7 Chanidae Chanos chanos* Poomeen M 15 2 Tachysuridae Tachysurus maelf idtlis *41 Koori Thedu E 3 1 Heiniramp4idae Hyporhamphus limbatus Koralan M, E 9 Hemiramphus cantori M, E 12 4 Rynehoramphus georgi 7 2 Sphyraenidae Sphyraena jells * Cheelavu M 16 7 Mugilidae cephalus * Kanambu 22 Liza macrolepis M, E 1. 2 L. parsia M, E 17 8 Valaniugil scheli * M 7 Atherinidae Pranesus doudecimalis * Kayal netholi M, E 12 Centropomidae Chanda commersonii ** Nulli Nandal E, R 1. 6 Serranidae Epinephelus tauvina Azhutha M 9 Theraponidae Therapon jarbua * Keeli M,E 13 4 Sillaginidae SA -Igo sihama * Ocl i M, E 13 Carangidae Carom sexfasiatus * Paara M 10 Lutjanidae Lutfanus,ffilvillamma * Chemballi M, E, 9 Gerridae Pertica filamentosa * Praachi M 8 Genres ovena * M 7 2 Gerreonumpha.setifer * E 3 1 Leiognathidae Leiognathus equulus Kaaral M, E, R 8 L. splendens * M 1 Mullidae tipeneta sulphureus Navara S catoph a gi dae Scatophagus an Marappi M,E 3 Cichlidae Tilapia mossambiea Tilapi 16 Etroplus suratensis Karimeen E, R E. maculatus. ** Pallathi E,R 20 4 Eleotridae Eleo iris jusea * Karimpoonthi E,R 12 Gobiidae Glossogobius giuris * Poonthi M, E, R 6 2 P.seudogobiu.s javanicus M, E 8 Platycephalidae ThysanOpThys indieus *- Oratha 8 Soleidae Brachirus orientalis M 8 Cynoglossidae Cynoglossus lida M 1 1 Tetrodontidae' Chelondon patoca Oothaampetti M, E 2 * - Commercially important species (Jhingran, 1975) - Species substantially contributing to fisheries M - Marine, E - Estuarine, R Riverine.

8 42 NANDAN AND AZIS Table 2. Shell fish fauna of the retting (SU) and nonretting (St.I1) zones in the Kadinamkulam kayal Species St.I St.II Local name No. Collected (nonretting zone) Penaeus indices Penaeus monodon Metapenaeus dobsoni Metapenaeus monoceros Macrobrachium idilla Scylla serrata Neptunus pelagicus. Villorita cyprinoides Crassostrea madrasensis - Absent, + Present Naran Kara Poovalan or Thelly Choodan Koona present study in the kayal, due to the large scale retting activity. Retting activity in the Kadinamkulam kayal had a serious effect on the fauna particularly during the premonsoon period when the temperature was relatively high with practically no rainfall and river discharge. High temperature accelerates the process of disintegration of coconut husk producing hydrogen sulphide causing depletion of oxygen in the aquatic environment. However, a recovery period was observed during the monsoon due to flushing by rain water, river discharge and land washings. Depletion of fish catch in the retting area could be attributed to the fact that fishes avoid the oxygen depleted area loaded with suspended particles, such as fibres and pith which have detrimental effect on the penetration of sunlight and distribution of fishes. The gills of fish and shell fishes get clogged by the pith and their movements are adversely affected by the fibre particles suspended in water. Reduction in swimming endurance has a discouraging effect on the normal activities of the fish thereby reducing the chances of survival in the polluted waters. Under such conditions the fishes would tend to avoid an oxygen deficient zone. Hynes (1966) have also reported such a repellent reaction of fishes due to low oxygen concentrations. Commensurate with the establishment of retting yards in the kayals, the once continuous stock of biota should have been separated by the pollution block created. Hydrogen sulphide is very toxic to fishes. According to Metelev et al., (1983) when the fishes are exposed to hydorgen sulphide (1 mg/ 1) the rate of respiration dropped, respiratory movements became arhythmic and depth of breathing became highly variable. The sulphides impede cellular respiration by suppressing the capacity of the tissues to utilise oxygen. The fishes- in the retting zone of the present study were exposed to very high concentrations of hydrogen sulphide ( mg/1). The poisoned fish at the retting zone of the Kadinamkulam kayal exhibited sluggish movement'and paralysis was observed with the body covered with an opalescent mucus, ACKNOWLEDGEMENTS The first author is thankful to the University of Kerala for the award of a Junior Research Fellowship and the second author to the Kerala State Committee on Science, Technology and Environment, Government of Kerala, for their financial support under the S.R.F. scheme. Both authors are indebted to the Head, Department of Aquatic Biology and Fisheries, University of Kerala, for the facilities provided.

9 FISH AND SHELL FISH FAUNA OF KADINAMKULAM KAYAL 43 REFERENCES Abdul Azis, P. K. and Nair, N. B The nature of pollution in the retting zones of the backwaters of Kerala, Aquatic Biol., 3 : Bhat, J.V. and Nambudiri, A.M.D The uniquity of coir retting.,ls'ci.indus. Res., 30 : 12. Day, F The Fishes of India, Bernard Quaritch, London. De Silva, S.S. and Silva, E.I.L Fish fauna of a coastal lagoon in Sri Lanka : Distribution and seasonal variation, Bull. Fish. Res. Station Sri Lanka, 29 : 1-9. Hynes, H.B.N The Biology of Polluted Waters,.L iverpool University Press : 202 pp. Thingran, V.G Fish and Fisheries of India. Hindustan Publishing Corporation (India), New Delhi, : 954 pp. Jhingran, V.G. and Gopalakrishnan, V Estuarine fisheries resources of India in relation to adjacent seas. J. Mara Biol. Ass. India, John, C.M Preliminary survey of the Kayamkulam lake. Bulletin of Central Research Institute, University of Kerala, Series C, Natural Science, 6 : Metelev, V.V., Kenav, A.I. and Ozasakhova, N.G Water Toxicology, Amerind Publishing Co. Pvt. Ltd., New Delhi. Munro, I.S.R The Fishes ofnew Cuinea, Department of Aquaculture, Stock and Fisheries, Port Moresby, New Guinea: 651pp. Nair, N.B. and Abdul Azis, P.K Hydrobiology of the Ashtamuch estuary - a tropical backwater system in Kerala. Proc. Natn. Sem. Estuar. Management, Nair, N.B., Krishnakumar, K., Rajasekharan Nair, J, Abdul Azis, P.K., Dharmara,j, K. and Arunachalam, M Ecology of Indian Estuaries - XII. A preliminary account on the fish fauna of the Kadin amkularn backwater, Mahasagar, Bull num. bast. Oceanogr, 16.(4) : 473,-477. Strickland, J.D.H. and Parsons, T.R A Practical Handbook of Seawater Analysis, Fish. Res. Bd. Canada, Bulletin, Second ed., 167: 310pp, Whitehead, P.J.P A Synopsis of the clupeoid fishes of India, J. Mar, Biol. Ass. India, 14 :