Seminar: Emily Zakem – USC Department of Marine and Environmental Biology

UNC-CH’s Department of Marine Sciences is proud to host a seminar by Emily Zakem. This event is scheduled for Wednesday, September 25th, at 12:30 pm in room G201 on the ground floor of Murray/Venable Hall at the University of North Carolina at Chapel Hill. This seminar will also be broadcast live to seminar room 222 at the Institute of Marine Sciences (IMS) in Morehead City, NC and online via Zoom (Meeting ID: 840-640-874).

Presenter Affiliation: Simons Foundation Postdoctoral Fellow; Levine Laboratory, University of Southern California

Title: Opening up the black box of remineralization in marine ecosystem models: Systematic variation in dissolved organic matter stoichiometry and remineralization ratios as a function of lability

Abstract: Primary production converts inorganic carbon, nitrogen, and other nutrients into biomass via photosynthesis. The return reaction — the remineralization of organic matter back into its inorganic constituents by heterotrophic organisms — fuels this production by resupplying inorganic nutrients. Both processes regulate the biological sequestration of carbon and thus atmospheric CO2. However, non-photosynthetic microbial activity is typically not resolved dynamically or mechanistically in global earth system models, inhibiting predictive capability. I will present progress towards such mechanistic description, focusing specifically on the dynamics of dissolved organic matter (DOM) remineralization and its stoichiometry in a marine microbial ecosystem model. The model captures observed patterns in the stoichiometry of phytoplankton vs. heterotrophic biomass, DOM and its remineralization ratios, and the preferential remineralization of DON with respect to DOC. Results emphasize the importance of understanding the physiology of both phytoplankton and heterotrophs for anticipating changes in biologically driven ocean carbon storage.