Journal of the Indian· Fisheries Association 93 28, 2001, 93-100

VERTICAL DISTRffiUTION OF MOLLUSCS IN THE INTERTIDAL AREA IN AND AROUND , .

A. K. JAISWAR AND B. G. KULKARNI* Central Institute of Fisheries Education (Deemed University) Seven Bungalows, Mumbai- 400 061. India.

ABSTRACT Vertical distribution of intertidal molluscs in and around Mumbai had been studied. Each species has an upper and lower limit of distribution along the vertical intertidal gradient and are concentrated at particular levels or zones where they find optimum living conditions. Zonation of the intertidal area with reference to molluscs at rocky shores of TIFR, Bandstand and NCPA have similarities. However, there is no similarity in zonation among rocky, sandy and muddy shores. Rocky intertidal zones are more diverse and dense in terms of molluscs. The mid and lower littoral zones have rich molluscan diversity. The upper littoral zone at some sites, especially chowpatty is totally devoid of molluscs due to anthropogenic activities. Gafrarium divaricatum, Nerita oryzarum, N. polita and Neritina crepidularia have established themselves in all three marked zones, indicating their power to adjust with the wide fluctuations in surrounding environmental conditions. Keywords : Interidal, molluscs, zonation, pollution, dominance.

INTRODUCTION 1933). Species at high shore levels have appropriate morphology, physiology and The intertidal region, a zone of behaviour to allow them to survive for longer interaction between sea, land and periods without being submerged in sea atmosphere, is one of the most interesting water, whereas species of lower level are divisions of marine ecosystem, as it is daily essentially marine and can cope only for covered and uncovered by flooding and brief period of exposure. Each species has ebbing tides. The width of intertidal belt an upper and lower limit of distribution exposed depends on the level of high and along the vertical intertidal gradient of low tides and gradient of the shore. The shore and are concentrated at particular inhabitants of this zone are known to be levels or zones where they find optimum hardy and highly diverse as the result of living conditions. These zones are usually diel changes in exposure, dessication and named after their dominance. The most submergence. This area ranks next only to outstanding contribution in the field of the sub-tidal region in terms of richness zonation is that of Prof. and Mrs. and variety of the life it supports (Colman, Stephenson, who, after 30 years of research

* The Institute of Science, 15 Madam Cama Road, Mumbai - 400 032. India. 94 JAISWAR AND KULKARNI

in the field, put forward an universal system near TIFR (Tata Institute of Fundamental of interidal zonation in 1949 (Stephenson Research) at represents, the and Stephenson, 1949). Zonation of species southern most end ofMumbai Island. The in intertidal area has been studied by many shore is an open type and hence subjected workers in different countries (Evans, 1948- to direct wave action throughout the year. Great Britain; Stephenson and Stephenson, In order to protect the shore line from 1949-Australia; Chapman and Traverthen, erosion due to wave action cement boulders 1953-New Zealand; Southward and Oston, are arranged along the upper most zone of 1954-Australia; Arudpragasum, 1970- the shore. Remaining intertidal area is Srilanka; Lubchenco, 1980. England and formed of rocks and boulders of varying Rakocinski et al., 1993-USA) dimensions. Maximum width of intertidal belt recorded during spring low tides Though India is surrounded by sea (0.03m) is 315m and shore exhibits very from three sides, with a long coast line of uneven profile. This shore is protected and 8129 km, very limited studies have been prohibited therefore, it is free from human done on intertidal zonation, such as those activities. As a result, it is cleaner than of Bhatt (1959), Parulekar (1973), Balani other stretches ofMumbai shore. (1975) and Sriramamurthy (1980). ii) NCPA shore : NCPA (National One of the most dominant group of Center for Performing Art) sea shore is a occupying the intertidal zone are semi-sheltered shore. Big cement boulders molluscs. The molluscs are not only rich and stones are arranged in the high water protein source for the people, but also play zone in order to avoid erosion of the shore. a very important role in small scale The remaining part of the shore is comprised industries as molluscan shells are used in of stones and debries like bricks and preparation of washing soda, cement, lime, concrete structures. Initially, it was a sandy jewelleries, decorative items and various shore but today it is neither a rocky nor a medicines. The economic importance of the sandy shore. However, it is much similar molluscs compelled us for recording the to rocky shore. The shore has a very steep vertical distribution of mollscan species slope, therefore, shore are exposed during inhabiting in the intertidal zone in and spring low tide (0.06m) is limited to 31m around Mumbai. only.

iii) Girgaon shore : This shore is MATERIAL AND METHODS located in and popularly known as . It is a sandy TOPOGRAPHY OF SELECTED SITES: shore and one of the most famous Mter a preliminary survey of entire recreational points for people living in coastline around Mumbai, the following Mumbai. Thus thousands of people visit sites (Fig. 1) were selected for the present the shore every day, as a result of which study. the ecological conditions of the shore are deteriorated. It is a very gently sloping i) TIFR Shore : The coastal stretch shore and therefore, a large width (58 1m) VERTICAL DISTRIBUTION OF MOLLUSCS IN THE INTERTIDAL AREA 95 IN AND AROUND MUMBAI, INDIA

7t30'

BASSEIN ~ A C~EEK R A 19d 8 15' l v A N

s E • A IV .. 19- 19 N ili ii

.. 65

Fig. 1: Map showing sites ofinvestigation i) TIFR shore ii) NCPA shore iii) Girgaon shore iv) Bandstand shore v) Gorai creek 96 JAISWAR AND KULKARNI

of shore is exposed during spring low tide The distribution pattern of molluscs in (0.06m). these zones at each station was studied on fortnightly basis between September 1996 iv) Bandstand shore : It is situated and August 1998. Molluscs were identified at , the mid point of western coast following Hormell (1949); Subrarnanium et line ofMumbai. It is an open type of natural al., (1949, 1951, 1952); Bhatt (1959); Rao rocky shore composed of rock beds and (1982) andApte (1996). Identities of some of stones of various dimension. It is also the specimen were confirmed by ZSI, subjected to direct wave action throughout Kolkata. the year. Maximum exposure was recorded 198m during spring low tide (0.03m). Shore profile is very uneven. RESuLTS AND DISCUSSION v) Gorai Creelt : Gorai creek is Zonation of molluscan species at situated at the northern end of Mumbai, NCPAshore: · which has a narrow link with Arabian Sea. Many narrow and wide drainage channels The upper littoral zone measurmg discharge their effluents into it. The creek 11.5m, was dominated by Littorina encloses a large area of mud flat infested intermedia, L. ventricosa and Tectarius with dense mangrove on both sides, which malaccanus, hence this zone is known as gets competely exposed during low tide the littorinid zone. Of the three littorinids measuring 96m in width (0.03m). T. malaccanus was most dominant species found crawling up to 1m above the mark of Total width oftidal belt exposed during spring high tide (splash zone). L. ventricosa spring low tide, and shore profile at the was not found in certain months of the selected sites were measured following Bhatt year. In the lower level of upper littoral (1959) and Holme and Mcintyre (1971). zone sporadic distribution of gastropods Following Bhatt, (1959) and Parulekar Drupa contracta, D. subnodulosa, Thais (1973) three tidal zones were adapted for tissoti, Nerita oryzarum andN polita were regular study. recorded. 1. Upper littoral zone (High water Although the narrowest (9.0m) of the zone - HWZ) - area between highest high three zones, the mid littoral zone ofNCPA water (spring tide) mark and lowest high shore had a rich molluscan diversity. water (neap high tide) mark. Gastropod species Nerita oryzarum, N. 2. Mid littoral zone (Mid water zone­ polita, Drupa contracta, D. subnodulosa, MWZ) - area between lowest high water D. konkanensia, Planaxis sulcatus, Bursa mark and highest low water (neap low tide) tuberculata, B. granularis, Thais mark. carinifera, T. tissoti, Pyrene terpsichore , Cypraea arabica, Hemifusus pugilinus, 3. Lower littoral zone (Low water zone Cellana radiata and bivalve species Area - L WZ) - area between highest low water symmetrica, Gafrarium divaricatum, mark and lowest low water (spring low Anomia achaeus, Crassostrea gryphoides tide) mark. VERTICAL DISTRIBUTION OF MOLLUSCS IN THE INTERTIDAL AREA 97 IN AND AROUND MUMBAI, INDIA and C. lugubris were found in this zone. A. Gastropods Nerita polita, N.oryzarum, acheus and Crassostrea gryphoides were N.albicilla, Planaxis sulcatus, P. simils, very common, but C. lugabris was recorded Cerithium morus, Ergaea walshi, Thais only twice. Gastropods Cypraea arabica, blanfordi, T. tissoti, T. carinifera, Cypraea and Drupa kokanensis were recorded only arabica, Bursa tuberculata, Drupa twice during the study. H. pugilinus was contracta, D. tuberculata and D. recorded occasionally, however, P. sulcatus knokanensis were collected in the mid and Drupa contracta were most dominant. littoral zone at both shores, However Conus textile, C. piperatus, Murex adustus, Aplsia Lower littoral zone covers a width of benedicti were noticed at TIFR and T. 12.5m of the shore thereby representing rudolphi. T. hippocastanum, Pyrene the widest part of this shore. The trochids terpsichore, P. atrata were found Euchelus indicus, E.asper, Trochus exclusively at Bandstand shore. Highest radiatus, Clanculus depictus, C. ceylanicus density of P. sulcatus and P. atrata were and C. scombinatum were dominating in recorded throughout the mid littoral at this zone, therfore, this zone is named as TIFR shore. Murex adustus, Nerita trochid zone. The lower part of this zone is chamaeleon were rare in this zone at TIFR. completely dominated by E. indicus; At Bandstand P. sulcatus and C. morus sometimes, entire rocks were found covered were abundant in upper part of mid littoral by this species. Drilla atkinsonii, Clavatula zone while, N. oryzarum was abundant in virginia, Diodora bombayana, Scutus lower part. Bivalves Gafrarium unquis and N. oryzarum were also recorded divaricatum, G. pectinatum and Semele in the area. N. oryzarum was present cordiformis and a continuous bed of throughout the shore having maximum Saccostrea cucullata were recorded at both density in mid littoral zone. The bivalves shores. G. divaricatum and Cardium latum also occurred with the former being dominant. Gastropods Nerita oryzarum, N. albicilla, Turbo brunneus, Trochus Zonation at TIFR and Bandstand radiatus, Cellana radiata, Euchelus Shore :A tidal belt of 315m and 198m indicus, E. asper, Clanculus ceylanicus, were recorded at TIFR and Bandstand sea Bursa tuberculata and bivalve G. shores during low tide. The upper littoral pectinatum, Modiolus emarginatus, zone at both shores was limited in the tidal Gastrana polygona and Oyster Crassostrea height of 1.3m. The upper most part of the lugubris were detected only at Bandstand upper littoral zone at both shores was shore. littorinid zone, where, Littorina intermedia and Tectarius malaccanus were detected The results, specially pertaining to abundantly. These littorinids were also occurrence ofAplysia benedicti along with present in splash zone up to 2m height at the colony of corals in the mid littoral zone TIFR. L. undulata was rare at Bandstand ofTIFR contradicts the common belief that shore. these species occur in pollution free oceanic . waters. The rich coral ground recorded in 98 JAISWAR AND KULKARNI the intertidal zone at TIFR indicates that antiquata, Placenta placenta, Mactra this r-egion is still free from adverse effects cornea, Paphia textile, P. malabarica and of environmental pollution. Gafrarium Area granosa were recorded in this zone. divaricatum was distributed at all levels at An overlapping of B. spirata and H. NCPA, TIFR and Bandstand shores which pugilinus were observed in mid and lower indicates its tolerance to wide fluctuations littoral zone, which is the Cardita zone. C. in the surrounding environment. Some antiquata was found overlapping in mid variations recorded in distribution and and lower littoral zone; however, their zonation of molluscs between TIFR and population was found to decrease from upper Bandstand would be attributed to the to lower level of lower littoral zone. The variations in the ecological conditions of lower level of this zone had a thin population the two shores. of . The gastropod curta and bivalve Chione imbricata recorded by Bhatt Zonation at Girgaon chowpatty : (1959) were found to be absent from this The upper littoral zone, measuring 18m in area due to many fold increase in pollution. width, is devoid of molluscan fauna, as an impact of anthropogenic activities. Plenty Zonation at Gorai creek: The upper of garbage including plastic bags, flowers, and mid littoral zones of the creek is densely waste papers and many other waste covered by mangroves on both the sides. materials are dumped on the shore every Gastropods Littorina scabra, Neritina day leading to increased stress on the crepidularia, Potamides cingulatus and intertidal biota. Despite such a condition, Telescopium telescopium were distributed the lower part of the shore possesses a among these mangroves. In the lower variety of fauna. littoral zone only Katelysia opima was recorded. Normally the intertidal estuarine In the mid littoral zone, which areas are characterized by fine sediments measures 75.5m in width, Gastropods inhabited by relatively few species in Nassarius ornatus, Babylonia spirata and comparision with marine intertidal areas. H. pugilinus were found plentiful along These few species may however be very with considerable number of bivalves abundant and the overall biomass may be Donax scortum and Cardita antiquata high in comparision with other aquatic which occur superficially or fully buried in system. (Me Lusky et al., 1993) the sediment. GastropodErgaea walshi and bivalve Solen truncatus reported by Bhatt At all the sites, the mid littoral zone (1959) in this area were not detected during was found to harbour maximum number of present investigation. The loss is due to species and individuals owing to the increased pollution in the surrounding area. presence of optimum living conditions. Presence of very few molluscan species in Lower littoral zone is broader (487.5m the upper littoral zone indicates unsuitability width) among all the three zones. of environment due to maximum percent Gastropods Babylonia spirata, Hemifusus exposure, minimum submergence and high pugilinus and bivalves Donax scortum, D. degree of dessication (Parulekar, 1973). incarnatus, Cardium asiaticum, Cardita VERTICAL DISTRIBUTION OF MOLLUSCS IN THE INTERTIDAL AREA 99 IN AND AROUND MUMBAI, INDIA

More number of species recorded at Mumbai for the sanction of study leave rocky shore of NCPA, TIFR, Bandstand with financial benefits. Authors are also followed by sandy shore of Girgaon thankful to Dr. S. C. Mitra of Zoological chawpatty and muddy shore of Gorai creek Survey oflndia, Kolkatta, and Dr. Deepak is an confirmation with findings of Apte of Bombay Natural History Society Parulekar (1981) from Konkan shore. for their help rendered for identification of Pattern of zonation at rocky (TIFR, Band molluscan species collected during the stand and NCPA), sandy (Girgaon study. chowpatty) and muddy shore (Gorai creek) was also found to differ due to fundamental differences in the physical environment of REFERENCES different types of substrata. Any common Apte, D. 1998. The Book ofIndian Shells, universal system can not be employed to Published by BNHS Oxford University explain the zonation of intertidal organisms Press India: 115p. by adopting a common system for rocky, sandy and muddy shores (Chapman and Arudpragasum, K.D. 1970. Zonation of Traverthen, 1953). two shores of the west coast of Ceylon. J.mar. biol. Ass. India. 12 (1&2): 1-14. Occurrence of larger number of molluscs at low tide levels may be due to Balani, M.C. 1975. Intertidal ecology of greater environmental stability, lesser the seashore near Tarapure Atomic dessication, lower temperature range and Power Station. J.Mar. biol. Ass. India. increased time for feeding (McLachlan, 17(1): 101-106. 1990). Such distribution pattern has been Bhatt, Y.M. 1959. A study of intertidal discribed as a typical pattern by Eltringham organims of Bombay, M.Sc. thesis, (1971). Univ. Bombay. Overlapping of molluscs like Nerita Chapman, V.J. and 'l'raverthen, C.B. oryzarum, N. polita and G. divaricatum 1953. General schemes of classification was noticed in all the zones of rocky shores. in relation to marine coastal zonation. Neritina crepidularia from Gorai creek was Jour. Ecol. 41: 198-204. also present in upper and mid littoral zones. The ability these molluscs to survive in Colman, J. 1933. The nature of intertidal wide range of environmental conditions is zonation of plants and animals. J.Mar. certainly due to the euryhaline and Biol. Ass. U.K. 18: 435-476. eurythermal characteristics of these Eltringham, S.K. 1971. Life in mud and animals. sand, English University Press, London. 218 p.

ACKNOWLEDGEMENTS Evans, R.G. 1948. The intertidal ecology of selected localities in Plymouth First author is grateful to late Dr. neighbourhood. J. Mar. Biol. Ass. UK. N.K.Thakur, former Director, CIFE, 7:173-218. 100 JAISWAR AND KULKARNI

Honell, J. 1949. The study of Indian zonation of the sandy shore macrofauna mollusca. J. Bombay nat. his. Soc. 48 at Perdido key, Florida USA. Estuarine (2): 34pp. coastal and shelf science. 36: 81.104.

Holme, N.A. and Mcintyre, A.D. 1971. Rao, Satyanarayan K. 1982. Methods for the Study of Marine ofindian oysters Bull. Cent. Mar. Fish. Benthos, IBP Handbook No.16 Res. Inst. 38: 1-6. (Blackwell Scientific Publication, Southward, A.J. and Oston, J.J. 1954. Oxford and Edinburgh): 181p. The effects of wave action on the Lubchenco, J. 1980. Algal zonation in the distribution of number of common new England rocky intertidal plants and animals living on the community, an experimental analysis. Plymouth backwater. J. mar. biol. Ass. Ecology. 61: 333-3434. U.K. 33: 1-9.

McLachlan, A. 1990. Dissipative beaches Stephenson, T. A. And Stephenson, and macrofauna communities of Anne. 1949. The universal feature of exposed intertidal sands. J. Coast. Res. zonation between the tidal marks on 6 (1): 57-71. rocky coasts, Ecology. 37: 289-305.

McLusky, D.S., Hull, S.C. and Elliott, Subramanyam, T.V., K.R. Karandikar M. 1993. Variations in the intertidal and N.N. Murthi, 1949. The marine and subtidal macrofauna and sediments pelecypods ofBombay. J. Univ. Bombay along a salinity gradient in the upper 17:50-81. Forth estuary. Marine and Estuarine Subrahmanyam, T.V., Karandikar, gradients. 27 (204): 101-109. K.R., and Murthi, N.N. 1951. Marine Parulekar, A.H. 1973. Studies on of Bombay. J. Univ. intertidal ecology of Anjidiv Island Bombay 20 (1): 21-34. Proc. Indian National Science Subramanyam, T.V., Karandikar, K.R. Academy. 39 (B): 611-631. and Murthi, N.N. 1952. The marine Parelekar, A.H. 1981. Marine fauna of gastroponds of Bombay J. Univ. Malvan central west coast of India, Bombay. 21 (3): 26-73. Mahasagar. 14 (1): 33-44. Sreeramamurthy, K.B. 1980. Ecology Rakocinski, C.F., Heard, R.W., of Intertidal Macrofauna at Versova LeCroy, S.E., McLelland, J.A. and and Seven Bunglow Beaches, Bombay. Simon, T. 1993. Seaward change and M.Sc. Thesis,. Univ. Bombay : 239p.