She is an aquatic microbiologist and biogeochemist who specializes in the abundance, diversity, and activity of aquatic microbes in the oceans, lakes, rivers, wetland ecosystems, and extreme environments.  She studies the role of microorganisms as agents of biogeochemical transformations and how microbes adapt to different environments/respond to stress.  She is interested in the effects of climate, nutrient and energy availability on the distribution, growth, and productivity of microplankton and the potential of life to adapt to extreme environments and the implications for astrobiology.