My research focuses on how microorganisms, such as algae and bacteria, modulate key ecosystem functions. Ecosystems are connected via the flow of nutrients and organic matter and I study the mechanisms by which this material is transported, transformed and assimilated into food webs. As an example, terrestrial dissolved organic matter often comprises a majority of the material exported into streams via the hydrologic cycle. In streams, microorganisms can assimilate, change the chemical composition and/or release the nutrients and organic matter for downstream transport. Invertebrates consume these microorganisms and, in turn, feed fish and other secondary consumers. Assimilation, chemical transformation, and nutrient release are ubiquitous across ecosystems and can largely dictate the magnitude of CO2 efflux to the atmosphere, organic matter production and the structure of food webs, watershed material export, and many other ecosystem services. My research elucidates the mechanisms and complex feedbacks within ecosystems, with special focus on the microbiota, and aids predictions on the response of the biosphere to changing conditions, such as climate change and land development.
My Ph.D. research is also the first to demonstrate that leachates from terrestrial detritus contain polymer dissolved organic matter (DOM), dissolved material that can abiotically combine into larger particles. In oceans, polymer DOM and subsequent flocculation have revolutionized the understanding of carbon fluxes in these ecosystems by providing a mechanism for algal and bacterial contribution to long-term storage of organic material in the deep ocean. My research is exciting because it introduces this same polymer DOM to new environments with very different capabilities to influence ecosystem function. Aspects of watershed science, global carbon predictions, and ecosystem functions depend on estimates of organic matter export and my research is the first to show that a large fraction of this DOM may be less mobile. My research also provides practical applications within the water treatment arena. Polymer DOM and flocculates can quickly clog filtration membranes and are a huge financial burden on water treatment plants. I am currently developing a post-doctoral research program focused on clarifying the prevalence and function of polymer DOM in a variety of terrestrial and aquatic ecosystems.