What we do...

We try to understand how bacteria and dissolved organic matter affect biogeochemical processes in aquatic systems. Microbes are incredibly important to ecosystem processes because of the great magnitude of their biomass and their diverse modes of metabolism (aerobic, anaerobic, sulfate reduction, methanogenesis, iron reduction, sulfide oxidation, metal oxidation, photosynthesis). Because of this diversity of function, bacteria and archaea have significant impacts on the geochemistry of lakes, rivers and oceans. We are particularly interested in how variation in microbial metabolism can affect ecosystem dynamics. Heterotrophic bacteria represent a greater proportion of pelagic biomass and production in oligotrophic than eutrophic systems and their biomass stoichiometry can be incredibly plastic. What does this mean for ecosystem structure and function? Recent work is focused on bacterial and archaeal production and degradation of greenhouse gases (CO2, CH4 and N2O) and release to the atmosphere.

We have examined microbial processes in pelagic and benthic habitats, freshwater and marine, lotic and lentic and natural and human-dominated systems.

One of our favorite places is pictured below: Lake Itasca at sunset!