Dynamics and functions of pelagic copepod communities in a changing Arctic Ocean.

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The long-term goal of the proposed research is to develop the predictive capabilities of numerical models of Arctic marine ecosystems. The acquisition of new knowledge in marine ecology is currently outpaced by the acceleration of changes faced by marine ecosystems, particularly in the Arctic where the impacts of climate warming are the strongest on our planet. Yet, modern approaches using powerful computers can provide the means for effective forecasting of the impacts of these environmental changes on marine ecosystems. This research will focus on zooplankton. Zooplankton is an essential interface between the microbes and animals, between the phytoplankton (unicellular plants) and the predators from the higher trophic levels (fishes, whales, birds…), between the thin surface layer receiving the sun’s energy and the dark and cold ocean’s depths. Copepods are a group of zooplankton that incarnates this critical role. These small crustaceans are so successful that they actually are the most numerous animals on Earth. In the Arctic, a handful of keystone copepod species form communities that are essential hubs of energy and matter transfer. Copepods transform the intense but short spring phytoplankton bloom into an energy-dense biomass (lipids) available for higher trophic levels during a much longer period of time. As a result copepods play a key role in both trophic networks and biogeochemical cycles of important elements such as carbon or nitrogen. The proposed five-year research plan aims at exploring the mechanisms underpinning the Arctic copepod communities’ organization, operation and response to environmental forcing. Students under my supervision and myself will follow four specific objectives in order to better understand: (1) how the fitness of copepods from species found in Arctic marine ecosystems should respond to various environmental conditions when isolated from other species (2) how inter-specific interactions in a community alter species-specific responses studied in point (1) (3) how the individual and population-level processes studied in points (1) and (2) scale-up to shape stable copepod communities (4) how changes in copepod communities influence trophic transfers in Arctic marine ecosystems In order to achieve these objectives, we will use a combination of theoretical modelling approaches and applied bio-physical regional 3D models of the Canadian seas. The models will be supported by numerous observations collected during several tens of years of Canadian research efforts in the Arctic and acquired in upcoming sampling missions, as well as from international collaborators. Major changes in Arctic marine ecosystems are already observed and more are expected to come. Numerical modelling is one powerful avenue of research that can help enhancing our mechanistic understanding of these highly specialized ecosystems. Efficient mechanistic models of zooplankton communities are currently very rare and none exist for the Arctic. The innovative numerical methods that will be developed during this research will keep Canadian research at the forefront of marine ecology. It will also help addressing pressing management issues such as the development of new fisheries in the Arctic, the implementation of marine reserves according to Canada’s commitments or legal obligations, or the impacts of new kinds of anthropic hazards (oil spills among others) on Arctic marine ecosystems.