| Abstract | Deep Lake is one of a number of hypersaline lakes in the Vestfold Hills, near Davis Station in the Australian Antarctic Territory. The lake water which originated as seawater when the lake basin was isolated from the sea following isostatic uplift of this part of the Antarctic continent, now has a salinity of ten times that of sea water. Due to its extremely high salinity, the lake does not freeze over winter. The lack of insulating ice cover results in winter water temperatures as low as - 19 !C. As a result of the extremely harsh aquatic conditions, the lake biota consists of only one species of algae (Dunaliella sp.) and one species of bacteria (Lacusprofundi sp.). Deep Lake is a closed lake system in which blowing and falling snow, along with summer meltstream flow, account for the total inputs and evaporation is the only output. Throughout 1989 the lake level, water temperature, salinity and abundance of algae cells were regularly monitored. Meteorological records from an automatic weather station located at the north - west corner of the lake, enabled daily evaporation rates to be calculated, using the Bulk-Aerodynamic Method. Estimates of evaporation, meltwater inputs and lake levels were used to construct a water budget for 1989. In contrast to the long-term trend of a decreasing water level, the results of this study indicate a rising lake level with a corresponding decrease in salinity and an increase in the abundance of algae cells. The rising lake level may be indicative of a regional climatic change causing an increase in low pressure systems and an increase in precipitation rates, which in turn increases the input to Deep Lake. |