Project: Models of Marine Microbial Biogeography and Biogeochemistry
Microbial communities in the sea mediate the global cycles of elements including climatically significant carbon, sulfur and nitrogen. Photosynthetic microbes in the surface ocean fix carbon and other elements into organic molecules, fueling food webs that sustain fisheries and most other life in the ocean. Sinking and subducted organic matter is remineralized and respired in the dark, sub-surface ocean maintaining a store of carbon about three times the size of the atmospheric inventory of CO2. The communities of microbes that sustain these global-scale cycles are functionally and genetically extremely diverse, non-uniformly distributed and sparsely sampled. Their biogeography reflects selection according to the relative fitness of myriad combinations of traits that govern interactions with the environment and other organisms. Trait-based theory and simulations provide tools with which to interpret biogeography and microbial mediation of biogeochemical cycles. Several outstanding challenges remain: observations to constrain the biogeography of marine microbes are still sparse and based on eclectic sampling methods, theories of the organization of the system have not been quantitatively tested, and the models used to simulate the system still lack sufficiently mechanistic biological foundations that will enable meaningful, dynamic simulations and state estimation.
We propose: to integrate key new data sets in real time as they are collected at sea to facilitate direct tests of theoretical predictions; to synthesize an atlas of marine microbial biogeography suitable for testing some specific ecological theories and quantifying the skill of numerical simulations; to develop new trait-based models and simulations of regional and global microbial communities bringing to bear the power of metabolic constraints and knowledge of macro-molecular composition; to analyze these data and models using statistical tools to interpolate and extrapolate the sparse data sets, formally quantify the skill of numerical simulations, and employ data assimilation technologies to identify and optimize compatible model frameworks. Together, the results of these efforts will advance new theoretical approaches and lead to improved global ocean-scale predictions and regional state-estimates, constrained by observed biogeography. They will provide a quantification of the associated biogeochemical fluxes.
Dr Stephanie Dutkiewicz is a principal research scientist at the Massachusetts Institute of Technology. She received a B.Sc. (physics) from University of Miami and a Ph.D. (oceanography) from the University of Rhode Island. Her research interests lie at the intersection of the marine ecosystem and the physical and biogeochemical environment. She is involved in developing and using complex computer models of the physical, chemical and ecosystems of the ocean. These models synthesis the knowledge gained from satellite, field and laboratory observations. Much of Dr. Dutkiewicz’s recent work has been in understanding the patterns of, and controls on the diversity of phytoplankton. This has led model development to include the representation of diverse phytoplankton communities. She uses theoretical frameworks along with the model output to gain understanding of the controls on phytoplankton biogeography and coexistence between competing species. Additionally she is interested in understanding how phytoplankton communities might change in a warming world, as part of her affiliation with the MIT Center for Global Change Science.