CS06 Benthos
Date: Friday, June 14, 2002
Time: 10:15:00 AM
Location: Colwood
 
FureyPC, NSERC-Industry Research Chair Prog., Env. Managment of Drinking Water, Biol. Dept., Univ. Victoria, Victoria, Canada, pcfurey@hotmail.com
Mazumder, A, , NSERC-Industry Research Chair Prog., Env. Managment of Drinking Water, Biol. Dept., Univ. Victoria, Victoria, Canada, mazumder@uvic.ca
Nordin, R, N, Ministry of Water, Land, and Air Protection, Victoria, Canada, Rick.Nordin@gems2.gov.bc.ca
 
SEDIMENT CHARACTERISTICS AND BENTHIC COMMUNITIES UNDER RESERVOIR DRAWDOWN
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Seasonal drawdown of water level is a major physical process distinguishing reservoirs from lakes. Drawdown induced changes in thermal structure, light quality and intensity, water column mixing, and sediment exposure may affect the structure or function of benthic communities, potentially degrading water quality. To determine the influence of reservoir drawdown on benthic communities, we examined sediment characteristics and the temporal and spatial changes in periphyton and macroinvertebrates in a drinking water reservoir which experiences large drawdown (greater than 6m) compared to a lake which experiences natural fluctuations in water level. Samples were collected with the aide of SCUBA diving equipment from littoral-pelagic transects in two adjacent, morphometrically similar coastal water-bodies (Sooke Reservoir and Shawnigan Lake, Victoria, BC, Canada) at regular drawdown intervals from May through October 2000. Seasonal drawdown influenced the chemical and physical characteristics of the sediment. We discuss this data in relation to periphyton biomass estimates and benthic invertebrate composition and biomass results. Understanding the resulting biological, chemical, and physical changes associated with drawdown and how benthic communities respond to these changes may provide information for making decisions regarding optimal management strategies for drinking water reservoirs.