SS3.01 Landscape Control of High Latitude Lake and River Ecosystems
Date: Thursday, June 13, 2002
Time: 2:45:00 PM
Location: Carson A
O'BrienWJ, University of North Carolina-Greensboro, Greensboro, USA,
Hershey, A, E, University of North Carolina-Greensboro, Greensboro, USA,
barfield, M, , University of Florida, Gainesville, USA,
The geomorphic-trophic hypothesis has been useful in understanding foodweb interactions in arctic lakes in the Toolik Lake region of Alaska. The basic tenant is that landscape criteria control the distribution of fishes, and fish control lake trophic structure. To test and refine this idea we surveyed over 110 lakes over the summers of 1997-1999. The surveys were extensive but here we will focus on the presence and absence of fish and zooplankton species. Different landscape settings determined 6 unique fish communities. Lakes which lacked fish almost always had large-bodied zooplankton however, some lakes with fish also had these species. Likewise lakes with fish had small-bodied zooplankton, however, some lakes lacking fish also had these species. One species, Cyclops scutifer occurred in 94% of the lakes was little impacted by landscape setting. The fish species also had important effects. Heterocope septentrionalis and Daphnia middendorffiana were more likely with lake trout present but these species were much less likely with grayling present. Heterocope was also very less likely to be present in lake with arctic char while Daphnia longiremis was more likely to be present.