Reconstructing Paleoenvironmental Change in Lake Scugog (Ontario, Canada) Using Subfossil Diatoms Preserved in Lake Sediments

Lake Scugog is a shallow impoundment in Ontario that is facing multiple stressors, especially eutrophication and climate change. This thesis used paleolimnological approaches to reconstruct diatom assemblage responses to climate change and anthropogenic stressors in the east and west basins of Lake Scugog over the last ~150 years, and in the west basin over the Holocene. The east basin experienced a diatom assemblage transition from the heavy, tychoplanktonic Aulacoisera to the small, buoyant Cyclotella likely indicating increased thermal stratification due to climate change, and an increase in small, benthic Fragilaria potentially corresponding to reduced ice cover. In Port Perry Bay, where urban development is most concentrated, small, benthic Fragilaria became dominant following the construction of the Lindsay Dam, and no other diatom assemblage changes occurred over the last ~150 years. The Holocene paleoenvironmental history of Port Perry Bay was similar to other records of Holocene climate from southern Ontario.