Benthic Foraminifera in Recognising Siltation: A Case Study from the Palk Strait, East Coast of India

In order to use foraminifera as a tool for siltation studies, benthic foraminiferal studies of both living and dead have been undertaken in the Palk Strait, East coast of India. Forty Two offshore sediment samples upto 10 m water depth in eight transects have been collected using Lafond-Dietz snapper. The study has yielded a total of 102 benthic foraminiferal species. It has been observed that benthic foraminifera are abundant at Mandaparn and Devipattinam transects with high diversity in living species while the Manalmelkudi transect has displayed less abundance with the low diversity. The living/dead ratio is 6.6 % in Manalmelkudi and 24.57 % in Devipattinam. Based on the living/dead ratio, the raté of sedimentation has been estimated to be more in the south of Manalmelkudi than in the north. Unlike in the adjacent Gulf of Mannar and Bay of Bengal, an abrupt reduction in the diversity of benthic foraminifera, abnormality in the shape and size of the tests of species of Lagena, Asterorotalia, Quinqueloculina, Spiroloculina, Pararotalia, etc., and the presence of agglutinated foraminifera in the Palk Strait, in fact, suggests the prevailing high turbidity and in turn siltation, leading to an unfavourable environment in the present study area.