Short-term dynamics of physico-chemical and biological features in a shallow, evaporative antarctic lake

Lakes are among the most productive and biodiverse ecosystems in Antarctica, and they behave as important indicators of local climatic and environmental changes. However, few studies have focused on the local drivers of short-term temporal variability in lacustrine biogeochemical variables. In the present study, measurements of physical, chemical, biological and optical characteristics of the shallow endorheic Lake 14 at Edmonson Point (74.33° S, 165.13° E) were made over the ice-free period in December 2006. A significant variation in most variables was observed. Possible drivers for these changes were the loss of the ice cover, an increase in solar irradiance, a change in photosynthetic activity and the evaporative loss of water. By removing relative changes due to evaporative losses, new insights were gained into the driving factors controlling the biogeochemistry and primary productivity in the shallow Antarctic lake. In particular, a decrease in phytoplankton biomass was observed and was probably linked to photoinhibition as revealed by an increase in photoprotective pigments. The absorbance by dissolved organic matter, when weighted with respect to evaporative loss, shows an overall reduction in humic-like absorption, most likely linked to photodegradation.