Influence of hydrography and microbial processes on the cycling of sea ice-associated material in the Arctic

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The Arctic Ocean is experiencing rapid changes including sea ice decline, increase in temperature and stratification, and redistribution of water masses. These changes fundamentally impact ecological processes that, in turn, influence the biogeochemical cycling of carbon and materials. Of significance, changes in microbial community structure and increases in bacterial respiration influence export fluxes and the CO2 uptake capacity of the Arctic Ocean. The rapid decrease in multi-year ice, with a new record minimum in 2012, also reaffirms the urgency to better understand the role of multi-year versus first-year sea ice in the cycling of carbon and materials in the Arctic. Increased microbial activity is anticipated in a warmer Arctic and concomittantly, a shift from multi-year to first-year ice is expected to modify the distribution and composition of organic material available for microbial communities. This study is interested in better understanding the factors that influence the productivity and composition of sea ice-associated communities and thereby impact carbon and elemental cycling in the Arctic Ocean. The general objectives of this study are to: 1) evaluate the influence of hydrographic conditions on the regional abundance, composition, and activity of Arctic sea ice and underice microbial communities; 2) determine the role of microbial processes and community structure on sea ice-associated elemental cycling and export. This research will contribute to better understanding changes in microbial communities in response to Arctic changes, which is essential to further our predictive understanding of the global carbon cycle.