SS3.15 Physical Forcing and Pelagic-Benthic Interactions in Aquatic Systems
Date: Thursday, June 13, 2002
Time: 10:15:00 AM
Location: Oak Bay
 
CyrH, University of Toronto, Toronto, Canada, helene@zoo.utoronto.ca
Rider, P, A, University of Toronto, Toronto, Canada, rider@scar.utoronto.ca
Lozon, J, D, University of Toronto, Toronto, Canada, lozonj@zoo.utoronto.ca
 
DISTRIBUTION OF SOFT SEDIMENT HABITATS IN THE LITTORAL ZONE OF CANADIAN SHIELD LAKES
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The littoral zone of lakes is notoriously patchy and dynamic. Sediment resuspension models provide clear predictions of the physical and chemical composition of soft sediments around lake basins, which should affect the development of biological communities. We tested these relationships in 2 stratified and 2 unstratified lakes on the Canadian Shield. Sediment composition at a 2-3 m depth was closely related to sediment porewater content, but not to fetch, a common measure of site exposure. Total nitrogen (TN) was positively related to organic content, but not total phosphorus (TP), resulting in a clear increase in TN:TP ratio with increasing organic and porewater content of the sediments. Benthic algal biomass was positively related to sediment porewater content in unstratified basins, but negatively related in stratified basins. Preliminary pigment data suggest a systematic change in the taxonomic composition of algal communities, with relatively more bluegreen algae on sediments with low porewater content. Our results suggest that sediment porewater content is a powerful predictor of the chemical and biological composition of soft sediments in the shallow littoral zone of lakes.