SS3.01 Landscape Control of High Latitude Lake and River Ecosystems
Date: Thursday, June 13, 2002
Time: 10:15:00 AM
Location: Carson A
 
PriscuJC, Montana State University, Bozeman, USA, jpriscu@montana.edu
Wolf, C, F, Montana State University, Bozeman, USA, cwolf@montana.edu
Doran, P, T, University of Illinois at Chicago, Chicag, USA, pdoran@uic.edu
Lyons, W, B, Ohio State University, Columbus, USA, lyons142@osu.edu
 
RESPONSE OF PHYTOPLANKTON PRODUCTIVITY TO RECENT CLIMATE COOLING IN MCMURDO DRY VALLEY LAKES (ANTARCTICA)
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Continuous automated meteorological measurements have shown that the air temperature in the McMurdo Dry Valleys has cooled by 0.7 degrees centigrade per decade from 1986 to 1999. This cooling trend has led to an increase in the thickness of the permanent ice covers of these lakes by about 1 m. The climate induced increase in lake ice thickness has reduced under-ice irradiance during summer (November-December) by about 0.06 mol photons per meter squared per day during this period. Because phytoplankton production in these lakes is light limited, the reduced PAR has led to a significant reduction in phytoplankton primary production since 1990. For example, depth integrated primary production in the east and west lobes of Lake Bonney has decreased by 6% and 9% per year, respectively. Recent data on the carbon biogeochemistry of the lakes has shown that the photosynthesis:respiration ratios are less than unity. The climate-induced reduction in primary production in these lakes may produce a system that is eventually depleted in organic carbon.