Sea-ice and polynya productivity in relation to climate-induced environmental changes along the Baffin and Labrador Currents during the Holocene

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The objective of this research program is to provide detailed qualitative and quantitative information on the long-term evolution of sea ice, primary production and hydrographic parameters in key recurrent polynyas (i.e. areas of open-water surrounded by sea-ice) located along the Labrador coast and in Baffin Bay. A series of microfossil and geochemical analyses will be performed on well-dated marine sediment cores spanning the middle to late Holocene (0-8000 years), during which several transitions between colder and warmer climate intervals have occurred. In particular, the program foresees extensive analysis of diatom and dinoflagellate cyst assemblages and geochemical tracers by two MSc students and two PhD students, complemented by my own downcore diatom analysis. This will be done in close collaboration with colleagues from the Geological Survey of Canada, the Geological Survey of Denmark and Greenland, and Université du Québec.Marine primary producers - photosynthetic organisms at the basis of marine food webs such as cyanobacteria, diatoms and dinoflagellates - play a crucial role in the biochemistry and functioning of ecosystems. Their ecology is governed by the ocean's physical and chemical properties (e.g. sea-surface temperature and salinity, sea ice cover, ocean circulation, etc.), making primary producers highly sensitive to, and indicative of, climatic changes. In order to make reliable predictions about the magnitude and consequences of current and future Arctic warming on the productive capacity of the Baffin/Labrador coastal waters and their recurrent polynyas, a complete understanding of the response of the system to climate fluctuations is required. Such an understanding can be obtained through the study of comparable system responses to climatic changes in the past.The proposed program will help to understand the contribution of polynyas to the Arctic productivity budget and their role as carbon sinks. The research activities will contribute to the training of highly-qualified-personnel along different steps of paleo-environmental studies. The data that will be produced will increase our capacity to gauge the impact of present and future climate changes on the ecosystem services that these polynyas have historically maintained and will help local northern communities to anticipate and prepare for the potential economic and social consequences of these changes. Finally, the proposed project fits within the larger framework of ongoing efforts to better understand the climate system, and validate regional climate models in which sea ice and primary production constitute key components.