Effects of Thermal Effluent on the Diversity and Distribution of Benthic Invertebrates in the St. Lawrence River PDF Download

Author: Kayla Hamelin
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Languages : en
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Book Description
"Temperature is a primary physical constraint on the distribution and abundance of aquatic organisms. Increasingly, human activities modify natural thermal regimes of aquatic systems, thereby altering the composition and structure of the organismal community. For decades, the Gentilly-2 Nuclear Power Plant (G2NPP) in Bécancour, QC, has discharged coolant water into the St. Lawrence River at temperatures more than 10oC above ambient. My study aimed to quantify how the diversity, composition, and abundance of the St. Lawrence benthic macroinvertebrate community has been altered by G2NPP thermal effluent. Benthic samples were collected at sites along the thermal gradient downstream of G2NPP in May and September 2012. Environmental predictors varying with distance downstream of G2NPP (e.g., temperature, depth, flow rate) were recorded at each station. Macroinvertebrate diversity and abundance were measured for each site and analyzed in relation to local environmental variables. Taxonomic richness and abundance (density and biomass) were elevated close to the power plant, but these patterns were best explained by environmental variables such as depth and sediment type. Taxonomic evenness was reduced in the warmest sites, and this pattern was driven by a few highly tolerant taxa, including thermophilic invasive species like the Asian clam, Corbicula fluminea, which was amongst the most dominant species in terms of abundance and biomass. Despite the strong thermal gradient at G2NPP, diversity indices and characteristics of community composition primarily reflected abiotic habitat characteristics other than temperature, whereas temperature was an important predictor only for a minority of taxa, like C. fluminea. With the closure of G2NPP in December 2012, and the subsequent eradication of cold-sensitive C. fluminea, these results provide a baseline for monitoring the succession of the benthic community in future years." --