The transition zones between the North Pacific Subtropical Gyre (NPSG) and neighboring ecosystems, notably the subpolar gyre, exhibit steep changes in environmental conditions (gradients) associated with dramatic changes in the microbial ecosystem. These zones provide suitable venues to understand mechanisms that structure microbial communities and to test ecological theory of how resource supply ratios drive productivity, export, particle size distributions, and elemental stoichiometry. A multidisciplinary team led by Ginger Armbrust is testing three interconnected hypotheses via interrogation of model simulations and direct observations of the transition zone between marine ecosystems.
Project: Phytoplankton-based networks in the North Pacific Ocean
Marine ecosystems consist of interconnected networks of microbial species, most of which have not yet been cultured in the laboratory. Our focus is on the photosynthetic marine phytoplankton and their interactions with other microbes. Open ocean phytoplankton communities consist largely of cyanobacteria and eukaryotic picoplankton, with aperiodic blooms of eukaryotic diatoms that often possess symbiotic nitrogen-fixing cyanobacteria. This project will combine laboratory-based studies of model species with field-based genomics and flow cytometric approaches to determine how microbial synergisms and non-equilibrium environmental conditions impact the growth and loss of different members of the phytoplankton community. The goal is to develop a mechanistic understanding of the role of biotic and abiotic factors in shaping the flow of carbon via the photosynthetic base of marine food webs.
E. Virginia Armbrust is the Director of and a Professor in the School of Oceanography at the University of Washington. She received her A.B. from Stanford University in 1980 and her PhD from Massachusetts Institute of Technology and Woods Hole Oceanographic Institution in 1990. She carried out postdoctoral research training at Washington University before joining the faculty at the University of Washington in 1996.
Dr. Armbrust’s research focuses on marine phytoplankton, particularly marine diatoms, which are responsible for about 20% of global photosynthesis. She has pioneered the use of environmental genomics and transcriptomics, combined with metabolomics, to understand how natural diatom communities are shaped by the environment and by their interactions with other microbes. Most recently, she has identified chemical signals that form the basis of cross-kingdom communication. Her group developed ship-board instrumentation that now permits the fine-scale continuous mapping of distributions, growth rates and loss rates of different groups of phytoplankton. Armbrust is a Fellow of the American Academy of Microbiology, the American Association for the Association for the Advancement of Science, and a member of the Washington State Academy of Science.