SS1.05 How Will Aquatic Ecosystems Respond to Climate Change?
Date: Tuesday, June 11, 2002
Location: Poster Session - VCC
 
DonahueWF, Department of Biological Sciences, University of Alberta, Edmonton, Canada, wfdonahue@powersurfr.com
Turner, M, A, Department of Fisheries and Oceans, Central and Arctic Region, Freshwater Institute, Winnipeg, Canada, TurnerMi@DFO-MPO.GC.CA
Findlay, D, L, Department of Fisheries and Oceans, Central and Arctic Region, Freshwater Institute, Winnipeg, Canada, FindlayD@DFO-MPO.GC.CA
Leavitt, P, R, Department of Biology, University of Regina, Regina, Canada, leavitt@leroy.cc.uregina.ca
Stainton, M, P, Department of Fisheries and Oceans, Central and Arctic Region, Freshwater Institute, Winnipeg, Canada, 
Page, S, J, Department of Fisheries and Oceans, Central and Arctic Region, Freshwater Institute, Winnipeg, Canada, 
 
The role of ultraviolet radiation in structuring the shallow benthic communities of boreal forest lakes
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We attempted to quantify the roles of physical, chemical, and biological interactions in structuring epilithon in boreal lakes. A suite of 8 lakes with a range of dissolved organic carbon (DOC) concentrations (3-9 mg/L) at the Experimental Lakes Area were sampled for epilithon (0.1 - 1.5 m depths) and basic physical and chemical parameters. Using multivariate analyses, algal community structure appears to be most determined by photosynthetically active and ultraviolet radiation (UVR). Littoral biofilm communities on rock surfaces exposed to high solar fluxes had very high concentrations of the photoprotective pigment scytonemin and were dominated by filamentous green algae. Deeper, more shielded communities were dominated by diatoms and had low concentrations of scytonemin. This suggests that previous paleolimnological evidence of UVR increases within lakes are a result of changes in littoral attached algal communities rather than planktonic ones. Littoral epilithic invertebrate communities appear to be affected most by a combination of exposure to solar radiation and food quality and quantity. With climate warming, we predict a deepening dominance of UVR-resistant epilithic algae in littoral zones, and coincident reductions in densities of many invertebrate taxa in algal mats increasingly exposed to high solar fluxes.