ECOBIOLOGICAL ASSESSMENT OF A FRESH-WATER LAKE AT SCHIRMACHER OASIS, EAST ANTARCTICA, WITH REFERENCE TO HUMAN ACTIVITIES

The scale and magnitude of probable impact of human activities over a decade (1983-1994) on the freshwater lake Priyadarshini, at Schirmache r Oasis, East Antarctica, was assessed through an ecological study con ducted over an annual cycle during January 1993 to January 1994. Air t emperature ranged from -34.5 degrees C to +8.2 degrees C, water temper ature (below frozen layer) from -1.5 degrees to +4.7 degrees C, and pH from 8.10 to 8.77. Dissolved oxygen varied from 8.4 to 12.1 mg l(-1) with higher values during winter months (June-July). The biological pa rameters - phytoplankton, chlorophyll-alpha and microbenthos - showed a bi-modal pattern of fluctuations with one maxima in austral summer a nd another in spring (late winter). Fluctuations in the hydrobiologica l parameters were closely related to meteorological conditions over th e area, Biological productivity of the lake was dependent on the avail ability of ice-free water and increase in atmospheric temperature. An in-depth analysis and comparison of certain lake environmental aspects over a decadal period indicate that the lake environment is in a heal thy condition. However, intensive human activities in the catchment ar ea may deteriorate the ecosystem and hence regular monitoring and stri ngent regulations are needed to maintain its quality.