Radiolarian Occurrences in Surface Sediments of the Indian Ocean in Relation to Bottom Water Circulation

Occurrences of radiolaria in the surface sediments collected at 22 stations in the Indian Ocean are noted. While some samples contain abundant radiolaria, others show extremely poor concentration, or, are practically devoid of them. A distinct relationship is found between radiolarian abundance and deep water current systems. It is suggested that the occurrence of radiolaria is largely controlled by currents which are responsible for dissolving radiolarian skeletons. The assemblage is dominated by warm-water species and also contains a few cold-water forms. The cold-water species are believed to be transported by the Antarctic Bottom Waters (AABW) to the present area.