SPATIAL HETEROGENEITY AND DIVERSITY OF MICROBIAL COMMUNITIES IN LAKE HURON SEDIMENTS: IMPLICATIONS FOR BIOGEOCHEMICAL CYCLING

Sediment microbial communities within freshwater ecosystems drive biogeochemical cycling, influencing the transformation and movement of nutrients and contaminants. However, there is a need to understand the coupling strengths of different biogeochemical cycles and how they vary across environmental gradients. As part of the Great Lakes Sediment Surveillance Program, we investigated spatial and temporal prokaryotic communities through surface sediment samples. We assessed the phylogenetic composition and functional traits of the potentially active community (RNA) compared to the total community (DNA) and identified contributing taxa to geochemical processes. Our results reveal microbial communities in Lake Huron are highly heterogeneous, suggesting local biogeochemistry is influenced by the variable land cover (e.g., forest types, cropland, urbanization) and environmental gradients. Distinctly, offshore sediment samples predominately harbor sulfur-transforming genera under the families Beggiatoaceae and Desulfosarcinaceae. Samples collected in the Georgian Bay, North Channel, and near river mouths showed distinct microbial communities and some overlap with sediments in Lake Superior. When compared to Lake Superior, Lake Huron has more diverse microbial communities with anaerobic and reductive metabolisms. Overall, local selective pressures shape microbial communities and their transformation of nutrients and contaminants. This approach is being applied to other Laurentian Great Lakes, which allows greater insight into the gradients found across the system.

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Primary Presenter: Britta Larson, Natural Resources Research Institute (lars5859@d.umn.edu)

Authors:

Britta Larson, Natural Resources Research Institute  (lars5859@d.umn.edu)

Chan Lan Chun, Natural Resources Research Institute  (chun0157@d.umn.edu)

Christopher Filstrup, Natural Resources Research Institute  (filstrup@d.umn.edu)

Molly Mikan, Natural Resources Research Institute  (mpmikan@gmail.com)