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