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Current state and trends in Canadian Arctic marine ecosystems: I. Primary production |
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| Authors: | Jean-éric Tremblay Dominique Robert Diana E Varela Connie Lovejoy Gérald Darnis R John Nelson Akash R Sastri |
| Institution: | 1. Qu??bec-Oc??an, D??partement de biologie, Universit?? Laval, 1045 avenue de la M??decine, Qu??bec, QC, G1V 0A6, Canada 2. Department of Biology & School of Earth and Ocean Sciences, University of Victoria, P.O. Box 3020, Stn CSC, Victoria, BC, V8W 3N5, Canada 3. Institute of Ocean Sciences, Fisheries and Oceans Canada, 9860 West Saanich Road, P.O. Box 6000, Sidney, BC, V8L 4B2, Canada 4. D??partement des sciences biologiques, Universit?? du Qu??bec ?? Montr??al, Montr??al, QC, H3C 3P8, Canada |
| Abstract: | During the International Polar Year (IPY), large international research programs provided a unique opportunity for assessing the current state and trends in major components of arctic marine ecosystems at an exceptionally wide spatio-temporal scale: sampling covered most regions of the Canadian Arctic (IPY-Canada??s Three Oceans project), and the coastal and offshore areas of the southeastern Beaufort Sea were monitored over almost a full year (IPY-Circumpolar Flaw Lead project). The general goal of these projects was to improve our understanding of how the response of arctic marine ecosystems to climate warming will alter the productivity and structure of the food web and the ecosystem services it provides to Northerners. The present paper summarizes and discusses six key findings related to primary production (PP), which determines the amount of food available to consumers. (1) Offshore, the warming and freshening of the surface layer is leading to the displacement of large nanophytoplankton species by small picophytoplankton cells, with potentially profound bottom-up effects within the marine food web. (2) In coastal areas, PP increases as favourable winds and the deeper seaward retreat of ice promote upwelling. (3) Multiple upwelling events repeatedly provide food to herbivores throughout the growth season. (4) A substantial amount of pelagic PP occurs under thinning ice and cannot be detected by orbiting sensors. (5) Early PP in the spring does not imply a trophic mismatch with key herbivores. (6) The epipelagic ecosystem is very efficient at retaining carbon in surface waters and preventing its sedimentation to the benthos. While enhanced PP could result in increased fish and marine mammal harvests for Northerners, it will most likely be insufficient for sustainable large-scale commercial fisheries in the Canadian Arctic. |
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