Biological processes of the northern Indian Ocean

Abstract

Physical processes such as wind-driven coastal run-off during the monsoons and convective overturning of surface waters due to winter cooling bring in nutrients into the euphotic zone and enhance primary productivity of the northern Indian Ocean. Nitrogen import, on decay of extensive blooms of Trichodesmium, appears to be another mechanism through which production increases in the eastern Arabian Sea. Zooplankton abundances usually match trends in phytoplankton production. However, at times, increases in the abundances of microzooplankton may lead to higher standing stocks of mesozooplankton. Blooms of phytoplankton and swarms of zooplankton are common in the northern Indian Ocean and influence rates of particle fluxes into the ocean interiors. High primary production, microbial activity and zooplankton abundances are characteristic of atoll lagoon waters. Microbial community appears to have a key role in food-chains and biogeochemical processes. Available data show that at least in the Arabian Sea, the high production modifies the ocean physics and chemistry of surface/subsurface waters