ECIMMEE Project: Growth Efficiency in the Mesopelagic at Station ALOHA
Organic carbon sinking from the ocean’s surface can meet three fates in the dark waters below: it can be assimilated into biomass, respired back to carbon dioxide, or continue sinking to the seafloor. Quantifying these fates—the ocean’s biological pump—is essential to constructing a carbon and energy budget for the ocean’s interior, and predicting changes in this budget into the future. The growth efficiency of microorganisms, that is, what fraction of the carbon they consume becomes cellular biomass, is an essential parameter to developing balanced budgets of carbon storage in the ocean’s interior. I will use novel cultivation techniques to establish bacterial and archaeal culture systems for understanding carbon, nitrogen, and energy flow in the mesopelagic at Station ALOHA. Efforts will be directed at determining quantitative physiological parameters such as growth efficiencies, substrate affinities, and temperature optima that can feed directly into predictive models of microbial ecosystem structure and function. By combining laboratory experiments, in situ experimentation, and time-series measurements of material export and microbial standing stocks, the SCOPE initiative provides a unique opportunity to undertake a systematic and integrated study of microbial growth efficiency in the mesopelagic at unprecedented resolution. The ultimate goal of this work is to construct an energy budget for the mesopelagic to understand and predict the efficiency of the biological pump.
Alyson Santoro is an assistant professor in the Department of Ecology, Evolution, and Marine Biology at the University of California, Santa Barbara. She received a B.A. from Dartmouth College in Ecology and Evolutionary Biology and an M.S. and Ph.D. from Stanford University in Environmental Engineering and Science. She was the recipient of the Woods Hole Oceanographic Institution Postdoctoral Scholar Fellowship for her research in nitrogen isotope geochemistry. Her research combines sea-going and laboratory investigations of marine microbes, with an emphasis on marine archaea and their role in the nitrogen cycle. She is the recipient of a Sloan Foundation Early Career Fellowship in Ocean Sciences.