ECIMMEE Project: The role of uncultured microbes in the Arctic marine sediment carbon cycle
The Arctic is experiencing disproportionately large effects of global climate change and melting glaciers will likely deposit large amounts of organic carbon into Arctic coastal marine zones. Once this organic carbon is deposited on the seafloor, microbes quickly use up all the available oxygen, leaving the rest of the carbon cycle to anaerobic microbes. Little is known about the responses of the sedimentary microbial populations to this increasing organic carbon deposition. If anaerobic microorganisms living in the upper meter of Arctic marine sediments adapt quickly to the increase in organic matter, much of this organic matter will be remineralized back to CO2, driving a positive feedback on warming. On the other hand, if these populations cannot keep up with the influx of organic matter, organic matter burial rates will increase, driving a negative feedback on warming. Much of the microbial communities in Arctic sediments are unrelated to cultured microbes, so their potential role in organic matter remineralization is unknown. These types of organisms have been termed Microbial Dark Matter (MDM) since they are ubiquitous, enigmatic, and comprise some of the deepest evolutionary branches of life. I propose to use novel genetic, metabolic, and quantitative techniques to incorporate these MDM communities into models of carbon degradation in Arctic marine sediments in Svalbard, Norway.
Karen Lloyd is from Beaufort, North Carolina, and graduated from Swarthmore College with a degree in Biochemistry. She completed an MS and PhD in Marine Sciences at the University of North Carolina, and a postdoc at the Center for Geomicrobiology at Aarhus University, Denmark. She is currently an Assistant Professor at the University of Tennessee, where her research group studies the vast majority of marine subseafloor microorganisms that have never been grown in a laboratory, and are therefore mostly uncharacterized. Lloyd was awarded the Holger Hannasch Award from the Woods Hole Oceanographic Institution (2012), and the Alfred P. Sloan Fellowship (2015), and is an editor at mSystems.