SS3.09 Climate-Lake Interactions
Date: Wednesday, June 12, 2002
Time: 2:15:00 PM
Location: Colwood
DoranPT, University of Illinois at Chicago, Chicago, USA,
Fritsen, C, H, Desert Research Institute, Reno, USA,
Lyons, W, B, Ohio State University, Columbus, USA,
McKnight, D, M, Arctic and Alpine Institute, Boulder, USA,
Priscu, J, C, Montana State University, Bozeman, USA,
The McMurdo Dry Valleys comprise the largest ice-free area on the Antarctic Continent. A number of closed-basin perennially ice-covered lakes are located along the valley bottoms in this cold desert environment. We have established that a 14 year decrease in temperature has caused a rapid response in the aquatic ecosystem including: decreased stream flow, lowered lake levels, thickening ice cover, decreased under water light levels, and a decline in lake productivity. During this period we have been calibrating modern processes to sediment characteristics in order to interpret similar ecosystem fluctuations in the past from sediment cores. We have established a relationship between photosynthetic rates and fractionation of carbon isotopes that is likely to be our most useful tool for hindcasting lake conditions. Cooling in this environment leads to dessication of the lakes and/or cryoconcentration during extreme ice growth. The pathway the lake takes depends on the seasonality of the cooling. Records of both pathways may be preserved in the water column.