Ecosystem characterization in Indian Ocean sector, Antarctica

Abstract

High Chl a) values characterized the surface water (0.445-2.085 mg m sup(-3)) and column (14.63-105.46 mg m sup(-2)). The rate and magnitude pattern of production varied under pack ice influence and also in offshore region. The divergence zone is most pronounced, which makes Indian Ocean sector an upwelled area marked by high nutrients, appreciable growth rate of phytoplankton and rich organic matter in the water column. The fractionation studies revealed the importance of picoautotrophs and picoheterotrophs in food chain. The bacterioplankton equals the zooplankton biomass, at second trophic level. The zooplankton biomass recorded was 100 g/1000 m sup(3) , 50 g/1000 m sup(3) being krill. The 50% of zooplankton were copepods alone. Its relation to fronts, blooming nature of plankton and other components of ecosystem is assessed and discussed, for delineating ecosystems in Antarctic marine environment