Meromictic Antarctic lakes as recorders of climate change: the structures of Ace and Organic Lakes, Vestfold Hills, Antarctica

The meromictic lakes that occur in closed, rocky basins of the Vestfold Hills provide records of local climate change. From a consideration of the physical structure of these stratified lakes it is apparent that maximum winter under-ice water salinity (associated with minimum water temperatures) is a function of the water level for a particular lake. The structure of the lakes will also be affected by changes in water balance. An increase in water level will result in a lens of fresher water and warmer winter temperatures at the surface of the lake, whereas a decrease will result in increased salinity, colder temperatures and deeper epilimnetic mixing. Evidence of periods oflow water level is retained by the lakes as intervals of near isopycnal water within the water column, which can be used to calculate minimum palaeolevels. Changes in the structures of Organic Lake and Ace Lake between 1975 and 1995 are used in this article to illustrate these points