Diversity and Distribution of Intertidal Molluscan Fauna of Great Nicobar Biosphere Reserve

Abstract

The present study aimed to assess the diversity and distribution of molluscan fauna in the intertidal regions of Great Nicobar Biosphere Reserve. The island intertidal habitat of the study areas is mainly composed of rocky flats, rock cliffs and sandy. In this study, we collected both live and dead shells from all study sites and recorded 185 species of molluscs belonging to 97 genera, 46 families, 15 orders and 4 classes from the 12 study sites of the Great Nicobar. Among the 15 orders, Neogastropoda contributed 67 species, and among 46 families, Cypraeidae represented 25 species from Great Nicobar Island. Gastropods commonly occur in various substrates such as beneath rocks, mud and sandy areas, whereas most of the bivalves are found on the soft substratum and as burrowers on coral and rocks. Among 12 study sites, the species richness was highest in the B. quarry region (132 species), followed by Shastri Nagar Bay (124 species). A high similarity was observed between B. quarry and Shastri Nagar (83%) and the lowest between Laxman Beach and Galathea Bay (0.6%). We also provided a checklist of 258 mollusc species belonging to 61 families, 22 orders and 4 classes from the Great Nicobar Island.