A comparative study on intertidal faunal biodiversity of selected beaches of Mumbai coast.

Comparative study has been done to examine the biodiversity and ecological status of the intertidal region of Tata Institute of Fundamental Research (TIFR), Bandstand and National Centre for Performing Arts (NCPA) rocky beaches in Mumbai, West coast of India. A total of 50 species of intertidal organisms were recorded from these shores. Shannon and Simpson’s diversity index, Margalef’s richness index and Pielou’s evenness index indicated different level of ecological state of the shore in different months. Dendrograms and 2-D non metric MDS ordination from Bray-Curtis similarity matrix of occurrence of intertidal organisms from these sites showed highest similarity and combination pattern of occurrence between Nerita oryzarum and Planaxis sulcatus in TIFR and Bandstand shore. Nerita oryzarum and Tactarius malaccanus at NCPA shore. Abundance/ biomass comparison (ABC) method of determining level of disturbance also pointed towards the polluted status of these shores. Study concludes that though these beaches are highly disturbed due to anthropogenic activities, they still support a rich intertidal biodiversity which need immediate attention for protection and conservation.

Assessment of coastal pollution through bioassay and transplantation of intertidal clams.

In the present study, a survey of Mahim creek and Bay area was undertaken that indicated absence of fauna, particularly molluscs from the area, which was a repository in the past. During bioassay experiments of Mahim creek water, the clams G. divaricatum and C. antiquata could not open their valves in 100% creek water and died within 12 hrs of exposure. The 96 hrs LC50 values of Mahim creek water for G. divaricatum and C. antiquata were found to be 20% and 40% respectively during summer and 38% and 57% respectively during rainy season. When two sets of the clams were transplanted at Mahim creek, they died within 12 hrs. These experiments suggest the extreme level of pollution in the area. This level of pollution is responsible for transforming the area into barren locality in terms of fauna, specially the rich molluscan diversity. However, Gorai creek was found to be comparatively very less polluted and it still serves as breeding and nursery ground for various fishes and prawn species. Hence it must be protected and conserved.