Macrobenthos off Mahim (Bombay), west coast of India in relation to coastal pollution and aquaculture

Abstract

Deterioration of water quality clearly indicated a moderate to severe coastal pollution around Mahim whereas a relatively healthy marine environment towards offshore was noticed. Foraminiferans, polychaetes, crustaceans and pelecypods were the dominant macrofaunal groups encountered in the area. The occasional inhabitants like pennatularians, nemertines, sipunculids, ophiuroids and fish larvae were mostly restricted to offshore regions. Biomass and population density of macrofauna were moderate and showed fluctuating trend. Similarity coefficients of foraminifera (0.89) and polychaetes (0.81) were high for high for offshore unpolluted stations (3 and 4) as compared to nearshore coastal stations (1 and 2). Faunal diversity was relatively more in unpolluted zone. The diversity Index (H) was more at station 3 for polychaetes (1.39) and at station 4 for foraminiferans (0.54). In general, biomass was high during postmonsoon excepting station 1 which was invariably under severe pollution stress throughout the study period. Foraminiferans were abundant at sandy bottom while polychaetes preferred muddy (clayey-silt) bottom. A noticeable ecological modification associated with faunal abundance and diversity were related to deteriorating marine water quality due to anthropogenic waste disposals. The prevailing water quality around Mahim is unsuitable for any kind of culture practices and also for harvesting economically important marine species.