Aquatic Sciences Meeting, Albuquerque 2001

SS40 Long-Term Research Programs in the Twenty-first Century (Spatial and Temporal Connections)

Date: Thursday, February 15, 2001, Time: 11:15:00 AM

Location: Ruidoso/Pecos

McKnight, D, M, University of Colorado, Boulder, USA, mcknight@snobear.colorado.edu

Priscu, J, C, Montana State University, Bozeman, USA, ubijp@gemini.oscs.montana.edu

VanMatre, E, C, University of Colorado, Boulder, USA, Keeleye@Colorado.EDU

Lyons, W, B, Ohio State University, Columbus, USA, lyons.142@osu.edu

RESPONSE OF AN ANTARCTIC LAKE ECOSYSTEM TO CLIMATE VARIATION: LINKAGES BETWEEN PHYTOPLANKTON SPECIES DYNAMICS AND STREAMFLOW

Lake Fryxell has a permanent ice cover, causing a stable water column and depthwise zonation of algal populations. We examined a 12 year record of streamflow, water chemistry, and phytoplankton species. In high flow summers (1989 -1991) the upper water column became more dilute and during low flow summers (93-99) major ions have increased. In low flow summers, stream cyanobacterial mats increased, recovering from scour during high flow. Because these mats assimilate nutrients, stream nutrient flux was lowered by recovery of the mats. Associated with these changes were changes in phytoplankton species. In low flow summers, Chroomonas lacustris was dominant and in high flow summers Cryptomonas sp. was dominant. Chlamydomonas intermedia followed the same pattern as Chromonas lacustris, whereas Chlamydomonas subcaudata was most abundant in high flow years. Interannual variation in cyanobacteria species did not match variations in flow, however, cyanobacteria had maximum abundance at higher depths during low flow summers. The results illustrate that interannual variation in the lake is coupled to climate as moderated by processes in the streams, and may aid in interpreting the sediment record.

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Aquatic Sciences Meeting, Albuquerque 2001

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