Summary
Antarctica remains one of the last bastions of exploratory limnology. Lakes in many regions remain completely unknown, in part because of their often cryptic nature. Of particular interest is whether the biological communities present in these isolated lakes consist of recent (postglacial) immigrants, or species that have survived on the continent for extended periods. Here I describe the chemistry, physics and biology of a series of deep epiglacial lakes in the Framnes Mountains, approximately 30 km inland from Australia’s Mawson Station. The lakes were permanently covered by up to 5 m of ice, and had no contact with the atmosphere. They were cold (<0.2 °C), slightly brackish, well mixed (except in one case) and oxygenated throughout. The pHs were surprisingly high at 10.5 – 11.0, reflecting extremely low carbonate buffering and the nature of the local rock. The chlorophyll content of the water columns indicated low-to-moderate biomass. Even though many of the lakes were in quite close proximity to each other, the biota of each lake was distinctive. An under-ice cyanobacterial mat with an associated metazoan community consisting of nematodes, tardigrades and possibly copepods was observed in one lake, while in the others rotifers were the dominant grazers. This poorly studied lake type is perhaps the most common in Antarctica, and the observations made in this study have important implications for biodiversity throughout the continent.