Heterotrophic activity, bacterial types and abundance in different ecosystems of the Queen Maud Land

Abstract

Microbiological studies from the marine, limnetic, terrestrial and glacial ecosystems were carried out during the Ninth Indian Expedition (1989-90) to estimate the bacterial numbers, to characterise the generic types and also to estimate the uptake of sup(14)C glucose and glutamic acid by these heterotrophs. Bacterial communities in different habitats appeared to be having distinct ecosystem specialisation both in terms of number and activity. In the maritime Antarctic, their biomass was found to be substantially high. Vertical profiles of bacterial counts biomass decreased gradually and uniformly with increasing depth in the polynyas. A higher recovery of viable population from 100 m was seen in the pelagic waters within the Antarctic Convergence. Distribution of bacterial populations in freshwater, terrestrial and glacial habitats in the Schirmacher Oasis showed a remarkable ecological adaptation. They were more abundant in the habitats where there was accumulation of organic matter. Interestingly, marine bacterial populations were persistent and highly active in the materials of marine origin (eg. Flesh and bone remains of petrels) that were found far away in glacial and/or terrestrial regions. Production of extracellular enzymes in the freshwater bacterial strains was more pronounced than those of the marine origin and measurements of heterotrophic uptake of labelled substrates showed a distinctly different uptake pattern in the freshwater, polynyal and offshore natural microbial assemblages. Results of these studies are discussed with an emphasis on the role of microbial population in the oxidation and biotransformation of organic matter and in the trophodynamics of the Antarctic regimes