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Temporal variation of periphyton communities: a 3-year study from northwest Lake Simcoe, Ontario, Canada

Abstract Periphyton composition, density, and diversity (Shannon-Wiener index), as well as thickness of periphyton communities developed on glass coupons, were studied from nearshore areas of northwest Lake Simcoe, Canada, during 2009, 2010, and 2011. The objective of this study was to quantify the temporal (yearly) changes in periphyton occurring in the littoral zone of Lake Simcoe and identify water quality variables that may be driving periphyton community dynamics. Clean glass slides were suspended at 0.5 m below the surface waters and retrieved on multiple days after suspension. The retrieved glass slides were immediately analyzed under a microscope to observe periphyton genera composition, density, diversity, and biofilm thickness. While the number of genera, diversity, and biofilm thickness showed significant variation among years of observation, the density did not. In all 3 years, Bacillariophyta were the dominant group, while Chlorophyta, cyanobacteria, and Chrysophyta were routinely represented in the periphyton community. A periphyton community dominated by Navicula and Gomphonema in 2009 changed to Achnanthidium and Cocconeis in 2010, which subsequently changed to Achnanthidium and Navicula (all belonging to Bacillariophyta) in 2011. The density of periphyton was significantly related to biofilm thickness across all 3 years. Principal component analysis on periphyton genera composition and abundance showed variation among years. Regression analysis suggested the shift in the number of genera was related to the variation in total phosphorus and dissolved oxygen concentrations in the water. Long-term data on periphyton community dynamics will prove useful to devise a periphyton-based water quality index for northwest Lake Simcoe.