Marine mollusc (Mollusca: Gastropoda and Bivalvia) diversity of the Saya de Malha and Nazareth Banks, Mascarene Plateau

Marine molluscs are among the largest assemblages of the animal kingdom and inhabit the marine environment from the intertidal zone to the deep sea. This study reports the diversity of marine molluscs (Gastropoda and Bivalvia) collected from sediments at 19 stations (SS) at the Saya de Malha and Nazareth Banks during the EAFNansen expedition in May 2018. Sampling was carried out using the five hydraulic Van Veen grabs mounted on a Video-Assisted Multi-Sampler (VAMS). The mollusc shells were morphologically identified using established procedures and published guides. Shannon-Wiener diversity (H’) and Pielou’s evenness (J) indices were used to assess the diversity of the molluscs at each station. A total of 56 genera of marine gastropods belonging to 34 families, and 40 genera of bivalves from 16 families were recorded. The SS8 station at the Saya de Malha Bank had the highest diversity at a depth of 79 m for Gastropoda and Bivalvia, while SS1 harbored the highest overall molluscan diversity. At the Nazareth Bank, highest gastropod diversity was recorded at SS44, while SS43 had the highest bivalve and overall molluscan diversity. This study provides new information on the molluscan diversity at the Saya de Malha and Nazareth Banks.