Distribution of recent Ostracoda from the sediments of Gulf of Mannar, Tamil Nadu, southeast coast of India

Emphasizing the distribution of Ostracoda in the shallow marine environment, fifteen surface sediment samples were retrieved along 5 vertical transects from the Gulf of Mannar, southeast coast of India. Forty-one ostracod species belonging to thirty-seven genera have been identified, out of these Xestoleberis variegata, Tanella gracilis and Semicytherura contraria were the dominant species present in the study area. Sand and silty-sand are the congenial sediment substrate for the ostracod's growth. Calcium carbonate has a sheer control over the ostracod population. Ostracod population decreases as the depth increases in the present study. The inferences made on the external morphology of carapaces indicate that they lie in a moderately agitated and turbulent environment. Ostracod assemblages obtained indicate that the deposition of sediments is under normal oxygenated, tropical, shallow marine, and inner shelf environment. The ratio between the carapaces and open valves of ostracoda is studied to understand the relative rate of sedimentation; the result indicates a relatively faster rate of sedimentation prevails in the study area.