Takacs, C. D. Montana State University, takacs@montana.edu
Priscu, J. C. Montana State University, ubijp@montana.edu

The Taylor Valley lakes of the McMurdo Dry Valleys are chemically stratified, hydrologically closed systems. The lakes are permanently covered by 4 to 5 m of ice and stream input occurs only 4 to 8 weeks each year. Dissolved organic carbon (DOC) is supplied to the trophogenic zone of the lakes primarily by phytoplankton excretion, streams, and upward diffusion across the chemocline. DOC supply and bacterial DOC demand were computed in Lakes Fryxell, Hoare, and Bonney (east and west lobes) to determine potential bacterioplankton carbon limitation during the Austral summers of 1994 to 1997. Bacterial carbon demand exceeded total DOC supply to the trophogenic zone and entire water column of both Lakes Fryxell and Hoare, but not in either lobe of Lake Bonney. Although our carbon budget indicates that carbon deficiency may play a role in regulating summer bacterial growth in Taylor Valley lakes, an inverse relationship between phytoplankton supplied DOC and bacterial carbon demand suggests that other factors, such as competition for inorganic nutrients, may also be important. Bacterioplankton DOC demand will be discussed in the context of the relative contribution by bacteria to microplankton biomass, POC, and respiration.
Day: Tuesday, Feb. 2
Time: 02:30 - 02:45pm
Location: Sweeney Center
Code: SS27TU0230S