Species diversity and distribution of Ostracoda from the surface sediments off Vetharanyam, Tamil Nadu, southeast coast of India

A study on ostracod diversity, distribution, and their relation with the environment was taken up from the sediment samples of the shelf area off Vetharanyam, Nagapattinam district, Tamil Nadu. Twenty-eight surface sediment samples along 4 transects within a water depth ranging from 4 m to 14.8 m were retrieved. The work was carried out to infer the ostracod species diversity and distribution implying the depositional environment. The sediment characteristics such as calcium carbonate, organic matter, and sand-silt-clay ratio have been determined and correlated for the observed Ostracoda population. The predominant and widely spread sediment types in the area are sandy silt and silty sand. Micropaleontological studies were carried out using standard techniques and thirty Ostracoda taxa were separated. About 5955 Ostracod specimens were recovered with 6 abundant species (Xestolebris variegata, Paijenborchella keij, Loxoconcha gruendeli, Keijella reticulata, Keijella karwarensis). The ostracod assemblage recorded herein is indicative of a tropical, shallow, and inner shelf environment.