This proposal will improve understanding of present carbon cycling in polynyas, major features of the flaw lead system in the Arctic, by applying a unique combination of analyses to the same samples: radionuclide approaches for measuring carbon fluxes, sources and attenuation and molecular and enzymatic approaches for evaluating microbial diversity and hydrolytic activity. Previous work in two major polynyas (not influenced by rivers) showed that the flux of organic matter from the photic zone is high, yet strongly attenuated in the "twilight zone." Separate microbial work showed that sinking particles are colonized by an abundance of active bacteria, with hydrolytic activities as high in subzero waters as in warmer seas. Little information exists on specific bacteria associated with particles in the twilight zone of Arctic (or other marine) waters, with virtually none on how microbial diversity may relate to carbon flux in the ocean's interior or to differing inputs of marine and terrestrial carbon. This comparative research in several of the major polynyas of the Arctic system (two river-influenced, one not), in the same season over successive years, will help to develop a broader perspective on the possible changes in carbon cycling likely to result from a seasonally ice-free Arctic Ocean. The proposed research plan will characterize by modern molecular (or any) techniques the microbial communities that play a role in attenuating carbon flux. The success of this combined approach may prove valuable to evaluating aspects of carbon cycling elsewhere in the world oceans. Both principal investigators are dedicated educators, as well as researchers. In addition to providing graduate and undergraduate students with unique cross-disciplinary training, they will also be engaged in innovative shipboard programs, as part of a multi-national cooperative venture (NABOS), and the Canadian ArcticNet "Schools on Board" program dedicated to engaging indigenous communities in research by bringing in high school students to participate directly in research.
