Mathieu Ardyna

French National Centre for Scientific Research | CNRS · TAKUVIK

The Arctic Ocean (AO) is a key component of Earth’s climate, acting as a coolant by contributing ~10% to the global oceanic carbon pump. Its capacity to remove carbon dioxide (CO2) from the atmosphere comes from its cold waters that favour CO2 dissolution and its highly productive continental shelves that help sequester this carbon. Yet, the AO is warming at an unprecedented rate and the local and global consequences of its rapid evolution remain uncertain. The Last Ice Area (LIA), north of Canada and Greenland, is the last sanctuary of multiyear sea ice in the AO. The LIA includes the Lincoln Sea, which hosts unique endemic sea ice-dependent ecosystems. However, the physical, chemical, and biological properties of the Lincoln Sea remain nearly undocumented. RED-AO aims at improving understanding of how global change influences ecosystem functioning and biogeochemical cycling in northern Baffin Bay and the Lincoln Sea – an emblematic refuge of climate change. This project proposes a pioneer oceanographic expedition during which, 4 for the first time, sea ice, hydrography, biogeochemical cycling of nutrients and contaminants, and marine ecosystems will be observed simultaneously. It will provide a comprehensive baseline for conservation efforts and allow us to study key processes related to past, present, and future climate-induced changes. This project will strengthen both the conservation and sustainable resource harvesting of this fragile region by helping to i) create and manage permanent marine protected areas supported by indigenous governments, and ii) support ecosystem-based management of commercial fisheries led by indigenous groups in the eastern Canadian Arctic.

Climate change is altering the Arctic atmosphere, cryosphere, and ocean and is having a significant impact on marine primary production. Satellite observations of phytoplankton primary production over the past 20 years show a steady increase due to increased light availability and nutrient input to Arctic surface waters. Although there is consensus that climate change is having profound impacts on the Arctic marine ecosystem, controversy still exists regarding the future of Arctic primary production: will it continue to increase as the sea ice melts further, or will nutrient availability limit further production? One component of Arctic marine primary production that has received little attention is benthic primary production. Located on the seabed surface, benthic primary producers such as diatoms and macroalgae receive a steady supply of nutrients from underlying sediments. When sufficient sunlight is available, benthic producers can dominate marine primary production in shallow Arctic waters. Given that shallow shelves occupy about half of the Arctic Ocean, benthic production may be a particularly important for the Arctic marine ecosystem, but this remains poorly understood. With an expanding ice-free Arctic in summer, these new and potentially increasing nutritious carbon sources could have a significant impact on marine ecosystems and fisheries resources of Northern communities. By bringing together research groups in Canada and Denmark, a unique set of scientific capabilities and datasets (field/satellite) will provide the first comprehensive picture of Arctic marine primary production, informing contemporary and future scenarios of a changing Arctic Ocean.

The general objective of this research project is to understand the dynamics of the phytoplankton spring bloom and determine its role in the Arctic Ocean of tomorrow, including for human populations. http://www.greenedgeproject.info/ PI: Marcel Babin