Thursday, June 7, 2007 - 11:00 AM
398

The Effect of Hydroelectric Reservoir Draw-down on Benthic Macroinvertebrate Communities of Stony Littoral Habitats: an Application of the Reference Condition Approach

Michael S. White, M.Sc.1, M. A. Xenopoulos, Ph.D.1, R. A. Metcalfe, Ph.D.2, and K. Somers, Ph.D3. (1) Watershed Ecosystems Graduate Department, Trent University, 1600 West Bank Drive, Peterborough, ON K9J7B8, Canada, (2) Renewable Energy Section, Ministry of Natural Resources, 1600 West Bank Drive, Peterborough, ON K9J7B8, Canada, (3) Dorset Environmental Science Centre, Ontario Ministry of the Environment, 1026 Bellwood Acres Road, Dorset, ON P0A1E0, Canada

Due to increasing power demands and the general desire to pursue renewable energy opportunities, future hydroelectric power generation is expected to increase: resulting in the creation of more hydroelectric reservoirs across the globe.  To assess the impact of waterpower generation on aquatic communities twenty-one reference lakes having similar influences relative to a set of hydroelectric reservoirs were instrumented with water level data loggers in 2005, each recording water level and temperature at hourly intervals 365 days a year.  In August 2006, nearshore stony littoral benthic macroinvertebrate communities were sampled using the kick and sweep method at each of the twenty-one reference lakes and thirty-two hydroelectric reservoirs; all having a characteristic WLF depending on the reservoirs operating management plan (i.e. peaking, run of the river, winter draw-down, exaggerated natural).  A modified reference condition approach (RCA) was used to determine differences in community structure between the reference lakes and each of the reservoirs.  The results demonstrate that the stony littoral benthic macroinvertebrate communities of hydroelectric reservoirs differed significantly from reference-lake communities.  The difference in community structure is primarily a function of the WLF regime used in the different reservoirs resulting in decreased biodiversity: specifically extirpation of the Sphaeriidae, Elmidae and Trichoptera taxons.

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