SS3.06 Large Scale Change in Prominent Ecosystems
Date: Wednesday, June 12, 2002
Time: 3:15:00 PM
Location: Lecture Theatre
 
VisC, Universite de Montreal, Montreal, Canada, chantal.vis@umontreal.ca
Carignan, R, , Universite de Montreal, Montreal, Canada, richard.carignan@umontreal.ca
Hudon, C, , St. Lawrence Centre, Environment Canada, Montreal, Canada, christiane.hudon@ec.gc.ca
 
IMPACTS OF CHANGING WATER LEVEL ON PHYTOPLANKTON AND EPIPHYTON PRODUCTIVITY IN A LARGE AND PHYSICALLY COMPLEX FLUVIAL LAKE
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Lake St. Pierre is a large (400 km2), shallow (4m mean depth) and physically complex widening of the St. Lawrence River. Recent fluctuations of water levels in the Great Lakes – St. Lawrence River system may have important consequences on the lake’s biological structure, in particular on the relative contribution of phytoplankton and epiphytic algae to total primary production. We estimated these effects by combining measured photosynthetic parameters with measured or remotely-sensed physical properties to produce a spatially explicit description of global productivity in the lake. During periods of high water level, phytoplankton productivity dominates over the majority of the growing season whereas under low water levels, epiphytic algae is the most important contributor to primary productivity.