SS3.01 Landscape Control of High Latitude Lake and River Ecosystems
Date: Thursday, June 13, 2002
Location: Poster Session - VCC
 
VanMatreEC, Institute of Arctic and Alpine Research/ University of Colorado, Boulder, USA, keeleye@colorado.edu
McKnight, D, M, Institute of Arctic and Alpine Research, Boulder, USA, Diane.McKnight@colorado.edu
Priscu, J, C, Montana State University, Department of Biology, Bozeman, USA, 
Lyons, W, B, Byrd Polar Institute, Ohio State University, Columbus, USA, 
 
LINKAGES BETWEEN PHYTOPLANKTON SPECIES DYNAMICS AND CLIMATE IN TWO ICE-COVERED ANTARCTIC LAKES
image
The lakes in the Dry Valleys have permanent ice covers, causing depthwise zonation of algal populations in the stable water columns. We examined 12 years of record for phytoplankton species distribution in two lakes of contrasting characteristics. Lake Fryxell is wide and shallow (18 m) with a saline anoxic zone below 9 m. Whereas, Lake Hoare is oxic, more dilute and deeper (27 m). During the study, inflow streams had low flows except during 1990-1993. The phytoplankton species in the two lakes were similar, reflecting adaptation to low light, water column stability and nitrogen limitation. In low flow summers, Chroomonas lacustris and Chlamydomonas intermedia were dominant species in both lakes, and Chlorella vulgaris was another dominant in Lake Hoare. In Lake Fryxell, Cryptomonas sp., Chlamydomonas subcaudata, and Pyramimonas sp. displaced these smaller species during high flow summers. In both lakes, cyanobacteria species have steadily increased in abundance. These results illustrate that the phytoplankton species distribution of dry valley lakes is coupled to climate, probably through competitive interactions, potentially providing a tool for interpreting the sediment record of accessory pigments.