Effect of river discharge on the morphology of benthic foraminiferal test

Abstract

Twenty one surface sediment samples collected from the inner shelf region off Karwar at 22-52 m water depth range have been studied for foraminiferal content. Based on the external test morphology the entire foraminiferal population (148 species) can be placed into two broad morpho-groups namely angular-asymmetrical and rounded-symmetrical morpho-groups. The surficial distribution of these groups revealed that angular-asymmetrical morpho-group gets adversely affected by high turbulence associated with increased fresh water river discharge, whereas, rounded-symmetrical morpho-group responded in a reverse manner. Since areal extent of river induced turbulence depends upon fresh water discharge due to monsoonal rains, the results show high potential in generating proxy data for the reconstruction of paleomonsoonal history through the study of morpho-groups in sub surface sediments of coastal regions