Is there a relationship between environmental variability and benthic diatom community composition?
Shelley McCabe & Hélène Cyr University of Toronto Theoretical models suggest that environmental fluctuations may influence the taxonomic composition of communities. These compositional changes have been observed in laboratory experiments with simplified phytoplankton communities that were grown with different regimes of magnitude and frequency of variability in light or nutrient availability. In this study, we test whether there is a difference in the structure of bottom-dwelling diatom communities growing on tile substrates under different regimes of environmental variability at upwind and downwind sites in a low-productivity lake. Six replicate tiles were placed at each of five upwind, and five downwind sites in Lake Opeongo, Ontario. Algal communities were grown for four weeks in midsummer, and temperature was recorded at eight minute intervals at each site. The algae grown at upwind sites were exposed to colder and more variable temperatures than those at downwind sites. These temp
