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Thursday, June 7, 2007 - 11:30 AM
393
Landscape control of biological attributes of connecting streams within a chain of Arctic lakes
Heidi M. Rantala1, Alexander D. Huryn1, and George W. Kling2. (1) Biological Sciences, University of Alabama, Box 870206, Tuscaloosa, AL 35487-0206, (2) Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109
Previous studies of a chain of lakes near Toolik Lake, Alaska, showed that landscape features control particulate nutrient concentration and water-column primary production, with values decreasing downstream. Little is known, however, about how the lakes affect the ecology of their connecting streams. We hypothesized that landscape position controls biological attributes of the connecting streams, paralleling the gradient in lake nutrient concentrations and biotic activity. Litter breakdown, benthic invertebrate biomass, and benthic chlorophyll-a were measured in 12 connecting streams. Contrary to our hypothesis, these attributes showed a trend of increasing values downstream. Each of these biological variables was analyzed using a multiple regression model using axis loadings from a Principle Components Analysis (PCA) of stream physical and biotic attributes as independent variables. Results indicate that location within the lake chain, ergosterol concentrations (an indicator of fungal biomass), invertebrate biomass, nutrients and temperature were important predictors of litter breakdown (r2=75.2%). Watershed area, stream gradient, and substrate movement were useful predictors of benthic chlorophyll-a (r2=69.6%). There was no significant relationship between PCA axes and total invertebrate biomass. These preliminary results suggest that the location of a connecting stream within a chain of lakes is a significant determinant of its ecological structure and process.