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Description: The threat of multiple anthropogenic stressors on global freshwater systems impacts ecological structure and function necessary to maintain the welfare of freshwater ecosystems. In order to properly manage freshwater ecosystems, we must have a better understanding of the ecological response to human-induced stressors, and in multiple stressor environments. Where long-term observational records are scarce or non-existent, paleolimnology provides a means to understanding ecological response to long-term stress. Lake Gusinoye is a large, deep lake in continental southeast Siberia, and has been subject to multiple human-induced stressors since the 19th century. In the present study, changes in diatom assemblages since the late-17th century were reconstructed from a Lake Gusinoye sediment core, to increase our understanding of the response of primary producer communities to centuries of environmental change. Records of anthropogenic contamination of Lake Gusinoye (including spheroidal carbonaceous particle, trace metal and element records) indicate early increases in regional and local development c. 1920. Early diatom assemblages were dominated by Aulacoseira granulata, which declined beginning in the 18th century, likely as a response to hydrological change in the Gusinoye basin due to regional climate warming following the termination of the Little Ice Age. Lake Gusinoye diatom assemblages changed more profoundly since the early-20th century, as a result of multiple anthropogenic stressors, including nutrient influx, aquaculture, and wastewater discharge from the Gusinoozersk State Regional Power Plant. Current diatom assemblages are dominated by nutrient-rich species, including Fragilaria crotonensis and Asterionella formosa, and Lindavia ocellata. Significant diatom compositional turnover was observed at Lake Gusinoye since the 19th century. Evidence of continued enrichment at Lake Gusinoye is likely due to continued aquaculture in the lake, and suggests potential interactive effects of warming regional temperatures and increasing nutrients (eutrophication) at Lake Gusinoye.