Using Field and Remote-Sensing Data to Investigate the Interplay Between Eutrophication, Algal Blooms, and Greenhouse Gas Emissions in Freshwater Lakes and Reservoirs

Abstract Submission: Lakes and reservoirs, integral to the carbon cycle, experience significant shifts in nutrient dynamics due to the inundation of terrestrial organic matter. Algal blooms, which can impact greenhouse gas (GHG) emissions—particularly methane (CH4) and carbon dioxide (CO2)—are not well understood, especially in freshwater systems prone to eutrophication. This research aims to deepen our understanding of the intricate relationships between eutrophication, algal blooms, and GHG emissions in these aquatic environments. We explored these interactions by analyzing recent field data on water quality, GHG emissions, and chlorophyll a from Douglas Reservoir (Tennessee, USA). Recently collected field observations have revealed increased temperatures and extended thermal stratification, which can drive increased algal productivity. As increased algal production may increase CH4 emissions, we expect elevated CH4 emissions in response to a warmer climate. However, these types of observational data are rare given the high costs and time demands of fieldwork; therefore, we also explored remote sensing options to broaden temporal and spatial understanding of algal dynamics in this reservoir. We have identified suitable indices for monitoring algal blooms using remote sensing data. Our findings highlight high chlorophyll-a concentrations in late spring and summer, especially in coves and slow-moving water areas. This integrated approach and additional context enhances our understanding of the environmental impacts of algal blooms in reservoirs. Ultimately this research can contribute to improved management practices to mitigate freshwater ecosystem degradation.

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