Indian Journal of Geo Marine Sciences Vol. 47 (01), January 2018, pp. 127-134

Studies on the vertical distribution pattern in associated molluscs along the coast,

Ziaullah1, Itrat Zehra2 & Muhammad Asif Gondal*3

1Department of Tourism and Hospitality, Abdul Wali Khan University, Mardan, Pakistan. 2Centre of Excellence in Marine Biology, University of Karachi, Karachi, Pakistan 3*Department of Biosciences, COMSATS Institute of Information Technology, Park Road, Islamabad, Pakistan

[Email: [email protected] ; [email protected]]

Received 13 October 2015 ; revised 17 November 2016

Present study consists the vertical distribution pattern in mangrove associated molluscs (gastropods and bivalves) in two mangal areas: Sandspit and Korangi along the Karachi coast, Pakistan. The vertical distribution pattern delineated that the number of decreased from high to low tide zone at two sites, however, marked differences were encountered with reference to the density distribution. At Sandspit, highest annual mean density was observed in the high tide zone followed by low and mid tide zones respectively, while, at Korangi the highest annual mean density was observed in the mid tide zone followed by high and low tide zones respectively. An important correlation was observed between the vertical distribution pattern of species and the sediments.

[Key Words: , molluscs, distribution, Karachi, Pakistan]

Introduction tolerance and desiccation rate are the primary Mangrove or Mangal forests cover about factors which limits the upper extent of zonation 617, 470 hectare in the Indus delta1. These of intertidal species within the supralittoral zone, wetlands provide both hatching as well as while the behavioral adoptions like restrictions nursery grounds for large number of to specific food resources or lack of upper shore commercially important fish and shell fish migratory behavior limited the distribution of species. Molluscs, especially the bivalves and species occurring in the lower intertidal. Several gastropods, form an important component of workers have their own observations regarding mangrove fauna2,3. However, the key ecological the distribution of molluscs in mangrove areas, factors that actually determine the fate of e.g. the factors that governs the vertical molluscs and govern their distribution pattern in distribution of gastropods and ranged out the mangrove habitat, is still a debatable question distribution zones for each species mainly based among the ecologist. The controversy exists upon the desiccation tolerance11. The intertidal about the totality of factors affecting the zonation seems maintained by the different distribution of these intertidal individuals. responses of organisms to change in physical Most studies on intertidal gastropods and biotic factors which vary from low to high suggest that the level of desiccation tolerated by tide zones12. The studies13-15 considered that a particular species generally increases with behavioral pattern, such as phototaxis, geotaxis, increasing height of the zone of occupation hydrotaxis and rheotaxis may be the main within the intertidal region4-10. Both desiccation determinants of vertical zonation in gastropods. 128 INDIAN J. MAR. SCI., VOL. 47, NO. 01, JANUARY 2018

Physiological characteristics of an may Korangi fish harbor. Geographically the site is govern its vertical distribution but movement located in the northern creek mangroves of the behavior is also important in leading a dislocated Indus delta. animal back to its preferred habitat13,14,16. It was For sampling each site was regularly observed while studying the ecology of molluscs visited, during low tide, at monthly intervals in mangroves the species abundance and from March 2001 to February 2002. The two distribution increase with salinity17. They also sites were thoroughly investigated for molluscan pointed out that vertical distribution of biomass diversity and their distribution pattern. At each remains highest in high tide zone and lowest in mangal area, a long transect of approximately low tide zone, however, density was calculated 180 meters of length was laid from the seaward highest in the mid tide zones. Various studies18 edge to landward. At each transect three recommend the importance of local habitat sampling stations were established with the first differences in species distribution and in the Low Tide Zone (LTZ) at the seaward edge mangrove associated gastropod fauna variation while the second (Mid Tide Zone: MTZ) and considerably between sites, both in terms of third (High Tide Zone: HTZ) stations were number of species and species composition. located at equal intervals within the mangroves Local habitat differences have major influences facing landward edge. At each station fifteen over species distribution both within and quadrates (each 1 m2) were randomly laid on between mangals. either side of the transect. At regional level the mangrove flora For sampling a fixed pattern was received due attention and is therefore well followed throughout the study period. The documented. On the contrary the mangrove samples were collected and observations were fauna, particularly the molluscan fauna, is not made from high (HTZ) to low (LTZ). The paid due attention and is therefore poorly collected samples were labeled and habitat notes known. The occurrence of some molluscs in the were made in the field. The epifaunal samples Indus mangroves is some decades old study were simply picked up by hand and collected in along the coast of Pakistan19. Occurrence of plastic bags while for the infaunal samples, molluscs in the mangrove area of Karachi coast sediment samples were obtained by sand corer. is also a significant study20-22. The The core samples were taken from a depth of 12 investigations23 on the benthic fauna of cms. Three replicates were made for each mangroves reported of five species of molluscs station. In laboratory, the sediment was passed e.g. Cerithidea cingulatus, Natica lamarckii, N. through a brass sieve (0.8 mm mesh size). didyma, Nodilittorina leucostica and N. picta Individuals collected were preserved in 70 % were regularly found in abundance. However, no alcohol. Molluscan friction was studied in detail detail work has been carried out on the and only live taken samples were used in distribution pattern and the various ecological subsequent analysis. factors that influence the occurrence and The preliminary investigations indicated distribution of molluscan fauna of the region. the predominance of epifaunal macromolluscs at the two sites. Telescopium telescopium, Materials and Methods Cerithidium cingulatus and Onchidium species Ecology and distribution of mangrove were observed as the permanent dwellers of the associated molluscs were investigated in two area and form an important component of the mangal areas: Sandspit (24 48'N, 66 59'E) and selected mangroves ecosystem. These species Korangi (24 48'N, 67 13'E) along the Karachi were selected for comprehensive studies, only coast, Pakistan. The study site at Sandspit was because of their abundance, to work with located within the mangrove habitat, quantitatively. representing backwaters of Karachi harbor. It The various physiochemical parameters forms the western most part of the Indus delta like salinity, pH, and temperature were recorded mangroves ecosystem, while, the study site at at each station. Impact of tidal effect was also Korangi was bounded on either side by channels investigated with reference to species of Korangi creek situated opposite to the distribution. Observations on behavioral responses of the individuals have also been ZIAULLAH et al.: VERTICAL DISTRIBUTION PATTERN IN MANGROVE ASSOCIATED MOLLUSCS 129 incorporated in the study. Whenever possible, tidal heights as the low, mid and high tide zones comparison was also made on population represent distinguished differences in the species dynamics of molluscan assemblages both before diversity as well as in abundance and and after low tide. distribution. Of the total 14 molluscan species recorded (Table-1), the number of species in Results general decreases from high to low tide zone. Vertical distribution of molluscan component varies significantly with reference to

Table 1- List of Molluscs found in the Mangrove areas of Sandspit and Korangi along the Karachi Coast Pakistan CLASSIFICATION IDENTIFIED FROM CLASS SUB CLASS: PROSOBRANCIA ORDER: ARCHAEOGASTROPODA Family: Turbinidae Turbo (Lunella) coronatus Zehra (1984)40 ORDER: MESOGASTROPODA Family: Potamididae Telescopium telescopium Zehra (1981)39 Cerithidea cingulatus Kira (1962)41 Family: Cerithidae Clypeomorus bifasciatum Dance (1974)38 Family: Littorinidae Littorina undulate Gray ORDER: Family: Thaididae Cymia carinifera Zehra (1981)39 SUBCLASS OPISTHOBRANCHIA Family: Haminoeidae Haminoe exarata *Gosliner (personal communication)44 SUBCLASS: ORDER: BASOMMATOPHORA Family: Ellobiidae Melampus taeniolatus (Hombron & Jacquinot) Habe (1964)42 Ellobium opportunatum (Gould) Habe (1964) 42 Melampus castaneus (Muhlfeld) Bosh et al. (1995)43 Family: fragilis (Lamarck) Bosh et al. (1995) 43 ORDER: SYSTELLOMMATOPHORA Family: Onchididae Onhidium sp. Gosliner (personal communication)44 CLASS: BIVALVIA Family: Ostreidae Crassostrea madrasensis (Preston) Siddiqui (1998)45 Crassostrea gryphoides (Schlotheim) Siddiqui (1998) 43

*Dr Terrace M. Gosliner, Department of Invertebrate Zoology and Geology, California Academy of Science, San Fancisco, California, USA

130 INDIAN J. MAR. SCI., VOL. 47, NO. 01, JANUARY 2018

At both sites, highest number of species (9) Telescopium telescopium and, Salinator fragilis observed in the mid and high tide zones and only inhabits only sheltered muddy habitats in the 5 species were recorded in the low tide zone at upper intertidal limits at both sites. Turbo Sandspit. However, the low tide zone at Korangi coronatus, Cymia carinifera, Crassostrea site appears comparatively richer where 8 gryphoides, and Crassostrea madrasensis were species were recorded. confined only to the seaward edge of the At Sandspit highest annual mean density Korangi mangals. Melampus taeniolatus, (264/m2) was observed in the high tide zone Ellobium opportunatumand Melampus followed by the low tide zone (259/m2), while, castaneus were only collected at both sites from the lowest density of 199/m2was found in the the back mangal areas. Littorina undulata, mid tide zone. At Korangi the highest annual Onhidium sp., Cerithidea cingulatus and mean density (197/m2) was observed in the mid Haminoe exarata exhibited a wide distribution tide zone followed by high tide zone (179/m2), from low to high tide zone. while, the lowest density of 65 An important correlation is also individuals/m2was observed in the low tide zone. observed between the vertical distribution of the The vertical distribution pattern of three species and the sediments. Cerithidea cingulatus dominant species: Cerithidea cingulatus, and Clypeomorus bifasciatum were in Telescopium telescopium and Onhidium sp. abundance in all the regions dominated by sand showed significant variations both within and particles. Telescopium telescopium and Salinator between the sites. Mean annual density of fragiliswere associated with silt particles. Cerithidea cingulatus at Sandspitwas highest Onhidium sp. was associated with clay. Elevated (219/m2) in the low tide zone followed by substrates, equally dominated by sand and clay, 115/m2 in the high tide zone, whereas the lower are the favorite habitats for Haminoe exarata. number of individuals (46/m2) were observed in However, Turbo coronatus, Cymia carinifera, the mid tide zone. At Korangi it was (116/m2) in Crassostrea gryphoides and Crassostrea the mid tide zone followed by 103 in the high madrasensis were found on hard stony tide zone, however, lowest number of substrates. individuals (32 m2) were observed in the low tide zone. Discussion Mean annual density of Telescopium The vertical distribution of molluscs telescopium at Korangi was 2.10 individuals/m2 defines their desiccation resistance and is closely in the high tide zone followed by 2.08/m2 in the related to the ebb and flood of the tide, which mid tide zone, not a single representative was submerges and exposes these regularly. found in the low tide zone. At Sandspit 1.77 Various studies 24, 25 have already reported the individuals/m2were recorded in the mid tide intertidal zonation in various mangroves zone followed by 1.59/m2 in the high and only associated molluscs. Inhabitants of high tide 0.416/m2 in the low tide zone. zone are comparatively more resistant to Significant differences were seen in the desiccation as compared to those of middle and vertical distribution of Onhidium sp. at both low tide zones. Present study delineate that low, sites. At Sandspit the mean annual density was mid, and high tide zones represent distinguished high (1.79/m2) in the mid tide zone followed by differences in the species diversity and 1.19/m2 in the high and only 0.26/m2 in the low abundance distribution. Range of vertical tide zone. At Korangi, although the species distribution varies with different species, which followed the similar distribution pattern as is the result of long time adaptation by shown at Sandspit, however, comparatively evolution, showing adoptive capability to the much higher density was found (16 environment as well as the rigidity in individuals/m2)in the mid tide zone followed by distribution18 however, the totality of factors 13/m2 in the high and 8 individuals in the low affecting the distribution of intertidal gastropods tide zone. is still undermined. The results of the Data on the vertical distribution pattern investigation presented herein agree with the in micro-habitats, however, delineated that above generalization. ZIAULLAH et al.: VERTICAL DISTRIBUTION PATTERN IN MANGROVE ASSOCIATED MOLLUSCS 131

Intertidal zonation is quite tangible in all Turbo coronatus, Cymia carinifera, the species at both sites. It is observed that Crassostrea gryphoides and Crassostrea Cerithidea cingulatus is widely distributed madrasensis are widely distributed in the within the mangrove and also cover the fore intertidal area of rocky shores but are also shore sand. At Sandspit, exposed low tide zone reported herein to occur at the seaward edge of harbors dense population of Cerithidea the Korangi creek mangals. The occurrence of cingulatus than the mid tide and high tide zone, these species at Korangi site can only be while at Korangi, the situation is reversed , explained by the presence of a small stony being thickly populated in the mid and high tide habitat at the low tide zone and open contact to zones. At this site the species is also observed on the seawater having comparatively low salinity. the mudflats without mangroves. Same An attribution of this type of distribution to the distribution pattern for this species has also been estuarine influence of the coast is evident18. As reported 26, 27. Observed pattern of distribution Korangi site is also subjected to the estuarine of this species indicates that desiccation influence, hence the distribution of these two resistance and temperature tolerance did not species i.e. Turbo coronatus and Cymia correlate well with their distribution. High carinifera are well justified. Crassostrea temperature tolerance of this species as observed gryphoides and Crassostrea madrasensis are at the exposed low tide station at Sandspit and also found attached to pneumetophores in the mudflats at Korangi might be considered as low tide zones at Korangi site only. The safety factor evolved as an adaptation to the presence of oyster species only at Korangi extreme temperature fluctuation associated with mangroves suggests that the site offers suitable the intertidal environment. The same habitat for spat settlement, probably because of observation has also been reported for several its more direct contact with seawater. Melampus other mangrove associated gastropods28-32,3,8. taeniolatus, Ellobium opportunatum, Melampus Restricted distribution of Telescopium castaneus collected only from back mangal telescopium and Salinator fragilis in upper areas at both sites and are therefore termed as intertidal limits in the sheltered muddy habitats back mangal species. These species are within mangals could be attributed either to their restricted to back mangals because of the lowered desiccation tolerance or preference to possession of free swimming suppressed muddy habitat which is more rich in food as veligers. A similar justification for the restricted compared to low tide open shore11. However, occurrence of Ellobids in back mangal areas has further studies with reference to desiccation been reported34. tolerance, and food preference are needed to Intertidal zonation in the population explain the distribution of these species along density is found to vary widely both within and mangroves. between the two investigated sites. At Sandspit, Several workers described the highest mean annual density (264/m2) is importance of movement behavior in the vertical observed in the high tide zone followed by low distribution of intertidal molluscs11,13, tide zone (259/m2) while the lowest density of 14,16,33.These studies also suggest that the 199 m2 is observed in the mid tide zone. At intertidal gastropods are able to determine their Korangi the highest density (197.9/m2) is relative position on the shore below or above the observed in the mid tide zone followed by high preferred habitat and display orientation tide zone (179/m2) while the lowest density of mechanism towards and in the direction of 65/m2 is observed in the low tide zone. These “home”. Fluctuation in hydrostatic pressure, differences in the population density might be wave direction and relative light values appear the result of hydrogeographical variations that to be instrumental in awakening these exists between the two sites. orientation mechanisms. The wider distribution The size distribution and types of settled of Littorina undulate, Onchidium sp. and particles in the mudflats of intertidal zone play Haminoe exarata as delineated in the present an important role in the composition, feeding study seems to agree with the observations put behavior, numerical development, and forth by these researchers. distribution of the molluscs in these habitats 17. 132 INDIAN J. MAR. SCI., VOL. 47, NO. 01, JANUARY 2018

Intertidal sediment at Sandspit comprises of fine Conclusion particles, mainly clay and silt in the mid tide It is concluded from the study that zone while both the upper and lower tide zones mangroves associated molluscs are variably are characterized by fine sand particles. distributed from low to high tide zone with Intertidal sediments at Korangi are respect to their own specific requirements. comparatively more complicated. It is composed However, the desiccation tolerance, adoptive of fine sand- clay silt in high tide zone and fine capabilities to the environment, competition, sand silt in the upper middle tide zone while the food preference, movement behavior, salinity low tide zone is characterized by clay-silt-coarse variations, habitat preference and finally, the sand with some stony portion. An interesting size and types of settled particles are identified correlation was observed between the species as major factors which govern the distribution of distribution and sediment type. Cerithidea molluscs in these habitats. cingulatus is found to inhabit a variety of habitats from well sheltered soft muddy to References deforested hard substrate and open mudflats 1. Vistro. N., Conservation and Rehabilitation of without mangrove vegetation. They also occur in Indus delta mangroves by Sindh Forest Department. on: Proceedings of the national great abundance in the regions dominated by seminar on Mangrove Ecosystem Dynamics of sand particles. Telescopium telescopium dwells the Indus Delta. Sindh Forest and only in the sheltered semi fluid muddy habitat Department, Government of Sindh Pakistan and dominated by silt particles. Onchidium sp. is the World Bank. (1999) 204 pp. found in close relation with soft substrate 2. Saenger, P., Specht, M. M., R. L. and Champan, V. J., Mangal and coastal salt marsh communities dominated by clay particles, a habitat can in Australia. In: Ecosystem of the World, Vol. I. reduces the chances of predation due to close Wet Coastal Ecosystem. (edited by V. J. resemblance to the background. Haminoea Chapman). Elsevier, Amsterdam, (1978) 293- exarata are mostly observed on hard elevated 346. 3. Hutchings, P. A. and H. F. Recher., The fauna of substrate dominated by sand and clay particles. Australian mangroves. in Proceedings of the Turbo coronatus, Cymia carinifera, Crassostrea Linnean Society of New South Wales 106 (1982) gryphoides and Crassostrea madrasensis are 83- 121. inhabitants of hard stony substrates collected 4. Broekhuysen, G. J., The Marine Flora and Fauna only from the low tide zone of Korangi. of Hong Kong and Southern China. A preliminary investigation of the importance of The arboreal nature for some mangrove desiccation, temperature, and salinity as factors associated molluscs that climb the trunk and controlling the vertical distribution of certain branches of the mangrove trees are there25,35 no intertidal gastropods from Hong Kong. (Hong such observations were recorded during the Kong University Press) 1940. 5. Davies, P. S., Environmental acclimation in the course of the study, however, Melampus limpet Patella vulgate L. Nature (1965)205: 924. taeniolatus, Ellobium opportunatum, Melampus 6. Davies, P. S., Physiological ecology of Patella. castaneus, Haminoea exarata and Onchidium III. Desiccation effect. J. Mar. Biol. Assoc. U. K sp. are often seen high on the pneumetophores. 49(1969) 291-304. It is also observed that these species make 7. Micallef, H., The Ecology and Behavior of Selected Intertidal gastropods. PhD. Thesis periodic excursion down the pneumetophores for (1966) University of London. feeding when water level recedes and exposes 8. Brown, A. C., Desiccation as a factor influencing the substratum and climb again before the the vertical distribution of some South African approach of high tide. An opinion that this gastropods from intertidal rocky shores. Port. 36 Acta Biol. 79B(1960) 11-23. behavior is followed to avoid predation . This 9. Wolcott, T. G., Physiological ecology and behavior also seems to safeguard these species intertidal zonation in limpets (Acmaea): A critical from dislocation due to high tide (personal look at limiting factors. Biol. Bull 145(1973) observation). Such behavior suggests that these 389-422. species are more nearly terrestrial in habits as 10. Branch, G. M., Ecology of the Patella species compared to their prosobranch allies37. from Cape Peninsula, South Africa. IV. Desiccation, temperature and salinity as factors controlling the vertical distribution of certain

ZIAULLAH et al.: VERTICAL DISTRIBUTION PATTERN IN MANGROVE ASSOCIATED MOLLUSCS 133

intertidal marine gastropods in False Bay, South 24. Mc Mahon, R. F. and J. D. Cleland., Thermal Africa. Trans. R. Soc. S. Afr. 28(1975) 255-91. tolerance, evaporative water loss and behavior 11. Cha, M. W., Factors affecting the vertical during prolonged emergence in the high tide distribution of four mangrove gastropods in Hong zoned mangrove gastropods Cerithidea ornate; Kong. Marine flora and fauna of Hong Kong and Evidence for atmospheric water uptake., South China III (ed. By Brian Morton). Hong Proceedings of the Second International Marine Kong University Press (1992) 373-382. Biological Workshop: The Marine Flora and 12. Sasekumar, A., Distribution of Macrofauna on a Fauna of Hong Kong and Southern China, Hong Malayan Mangrove shore. J. Anim. Ecol. Vol. Kong, (1986). Hong Kong University Press, 43(1974) 51-69. Hong Kong. 13. Gendron, R. P., Habitat selection and migratory 25. Yipp, M. W., The distribution of ground dwelling behavior of the intertidal gastropod Littorina gastropods in a small mangrove stand in Hong littorea. J. Anim. Ecol 46(1977) 79-92. Kong. In proceedings of the first International 14. Petraitis, P.S., Occurrence of random and Marine Biological Workshop: The Flora and directional movements in the Periwinkle, Fauna of Hong Kong and Southern China, Hong Littorina littorea (L). J Exp Mar Bio Ecol. Kong, 1980. (eds. B. Morton and C. K. Tsong). 59(1982) 207-17. Hong Kong University Press 295(1982) 705-720 15. Peckol, P., Guarnagia, S. and Fisher, M., 26. Wells F. E., An analysis of marine invertebrates Zonation and behavioral patterns of the intertidal distribution in a mangrove swamp in gastropods Nodilittorina antoni (Philippi, 1846) northwestern Australia. Bull. Mar. Sci 33(1983) and Nerita versicolor (gmelin 1791).In the 736-44. Bahamas. The Veliger 32 (1989) 8-15. 27. Gowanloch, J. N. and Hay., Contribution to the 16. Little, C., Factors governing pattern of forging study of marine gastropods II. Biological Station activity in Littoral marine herbivorus mollusc. ‎.J of Canada 3(1926) 135-165. dutS‎nacsulloM London 55(1989) 273-84. 28. Evans, R. G., The lethal temperature of some 17. Jiang, J. X. and R. G. Li., An ecological study on common British littoral molluscs. J Anim Ecol the in mangrove areas in the estuary of 17(1948) 165-73. the Jiulong River. Hydrobiologia 295(1995): 213- 29. Tirmizi, N. M. and S. Barkati., Studies on Wood 220. Borers from the mangroves of Karachi. in: 18. George, W., The distribution of mangrove Marine Biodeterioration (ed. Thompson, M. F.) associated gastropod snails in Hong Kong. (1988) 203- 213. Hydrobiologia 295(1995) 335-342. 30. Lewis, J. B., Environmental and tissues 19. Saifullah, S. M., Mangrove ecosystem of temperatures of some tropical intertidal marine Pakistan. in: The third Research Symposium on animals, Biol Bull 124(1963) 277-84. mangroves in the Middle East, Japanese 31. Frankel, G., The heat resistance of intertidal Corporation Center for Middle East, 137(1982) snails at ShirahamaWakayamaken, Japan. 69-80. Publications of the Seto Marine Biological 20. Tirmizi, N. M. and S. Barkati., Seasonal Laboratory 14(1966) 185-195. abundance and recruitment of the snail, 32. Mc Mahon, R. F. and W. D. Russel-Hunter., Potamides cingulatus from Karachi mangroves. Temperature relations of aerial and aquatic pp 23- 25. In: Mangrove fauna (invertebrate) of respiration in six littoral snails in relation to their Karachi, Sindh Coast. Report No. 2. (1983a) vertical zonation. Biol Bull 152(1977) 182-98. Pakistan Agricultural Council, Islamabad. 33. Fairweather, P. G., Movements of intertidal 21. Tirmizi, N. M. and S. Barkati., Molluscan fauna Whelks (Morula marginalaba &Thais orbita) in of mangroves of Karachi coast. in: Mangroves of relation to availability of prey and shelter. Mar Pakistan. Proceedings of National Workshop on Biol 100(1988) 63-68. Mangroves at Karchi. (1983 b ) 40-44. 34. Mac Nae, W., A general account of the fauna and 22. Barkati, S. and Rahman, S., Species composition flora of mangrove swamps and forests in the Indo and faunal diversity at three sites of Sindh West Pacific region. Adv. Mar. Biol 6(1968) 270- Mangroves. Pak J Zool. 37 (2005) 17-31. 73. 23. Britton, J. C. and R. F. Mc Mahon., The 35. Mc Guaness., The climbing behavior of relationship between vertical distribution, Cerithidea anticipate. North.Territ. Univ., Sch. evaporative water loss rate, behavior and some Bid. Sci., Casurina, N. T. (1994) 0811 Australia. morphometric parameters in four species of rocky 36. Mc Mahon, R. F., Interspecific relationships intertidal gastropods from Hong Kong. In: The between morphometric parameters and the marine flora and fauna of Hong Kong and vertical distribution patterns of seven species of Southern China II (ed. B. Morton) 1153-71. turbinate gastropods on mangrove trees in Hong Proceedings of the second International Marine Kong. In proceedings of the Second International Biological Workshop: The Marine Flora and Workshop on the Malacofauna of Hong Kong Fauna of Hong Kong and Southern China, Hong and Southern China (ed. B. Morton and D. Kong, 2-24 Apr. (Hong Kong University Press). Dudgeon) (1985) 199-215. Hong Kong (1986) University Press. 134 INDIAN J. MAR. SCI., VOL. 47, NO. 01, JANUARY 2018

37. Morton, B. and J. Morton., The Seashore Ecology 42. Habe, T., Shells of Western Pacific in color Vol. of Hong Kong. (1983) Hong Kong University II. (1964)Hoikusha Publishing Co., Ltd. Osaka, Press. Japan.td. Osaka, Japan. 38. Dance, S. P., The Encyclopedia of 43. Bosh, D. T., Dance, S. P., Moolenbeek, R. G. and Shells.Blandford Press, (1974)1-288. Oliver, P. G., Sea Shells of eastern Arabai (1995) 39. Zehra, I., Systematic study of some marine Emirates Printing Press, Dubai, UAE 1-296. molluscs of northern Arabia (Pakistan Coast) 44. Gosliner, T. California Academy of Sciences in PhD. Thesis University of Karachi (1981)1-237. San Francisco (personal communication) (2002). 40. Zehra, I., Marine : 2 Mollusca: 45. Siddiqui, G., Species of Pakistan Oysters and Gastropoda. (1984) University Grants some aspects of their Biology.PhD. Thesis, Commission Islamabad, Pakistan. (1998) University of Karachi. 41. Kira, T., Shells of the Western Pacific in color 46. Markel, R. P., Temperature relations in two Vol. I. (1962) Hoikusha Publishing Co., species of tropical West American littorines. Ecology 52(1971):126-30.