Physical and biological controls of primary production in the ice-covered Canadian Arctic marine system

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The Arctic ice-covered marine environment is undergoing unprecedented changes with recent accelerated declines in sea ice cover and changes to water mass characteristics and distribution. Understanding the timing and controls of ice-covered primary production, a critical component of the polar marine ecosystem, is therefore critically important. For example, an earlier termination of the ice algal bloom could favor a switch from high-energy Arctic specialist species to less energy-rich generalists from the south, due, in part, to lower ice algal production, but also to enhanced phytoplankton production associated with a longer ice-free period. The long-term goal of my research program is to obtain a comprehensive understanding of processes controlling Arctic marine primary production in the ice-covered ecosystem to better predict how the system will respond to its changing environment. My specific research objectives over the next 5 years are to: (1) examine the spectral dependence of sub-ice transmitted irradiance on ice algal photophysiology, biomass, and taxonomic composition to further develop under-ice remote sensing techniques; (2) investigate physical and biological processes that control spatial and temporal variability of ice algal production, accumulation and loss; (3) determine photoprotective strategies of ice melt water algae to high ultraviolet (UV) and visible light levels; and (4) investigate the mechanisms that control the timing and magnitude of under-ice phytoplankton production. The objectives will be met through an interactive approach of field studies, experiments, and algal growth modeling. By meeting these objectives, my team and I (including 5 B.Sc., 2 M.Sc. and 3 Ph.D. students over the grant's tenure) will increase our knowledge on physical and biological controls of primary production in the ice-covered ecosystem, develop new observational techniques, fuel novel ideas, fill knowledge gaps, and improve our capability to model the ecosystem. A declining ice cover, expectation of increased shipping traffic, and political pressure for an increased understanding of our North highlight the importance of the work described above.