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Current state and trends in Canadian Arctic marine ecosystems: II. Heterotrophic food web, pelagic-benthic coupling, and biodiversity |
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| Authors: | Gérald Darnis Dominique Robert Corinne Pomerleau Heike Link Philippe Archambault R John Nelson Maxime Geoffroy Jean-éric Tremblay Connie Lovejoy Steve H Ferguson Brian P V Hunt Louis Fortier |
| Institution: | 1. Qu??bec-Oc??an, D??partement de biologie, Universit?? Laval, 1045 avenue de la M??decine, Qu??bec, QC, Canada, G1V 0A6 2. Institut des sciences de la mer de Rimouski, Universit?? du Qu??bec ?? Rimouski, 310 all??e des Ursulines, Rimouski, QC, Canada, G5L 3A1 3. Institute of Ocean Sciences, Fisheries and Oceans Canada, 9860 West Saanich Road, P.O. Box 6000, Sidney, BC, Canada, V8L 4B2 4. Freshwater Institute, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, MB, Canada, R3T 2N6 5. Department of Earth and Oceans Sciences, University of British Columbia, 6339 Stores Road, Vancouver, BC, Canada, V6T 1Z4 |
| Abstract: | As part of the Canadian contribution to the International Polar Year (IPY), several major international research programs have focused on offshore arctic marine ecosystems. The general goal of these projects was to improve our understanding of how the response of arctic marine ecosystems to climate warming will alter food web structure and ecosystem services provided to Northerners. At least four key findings from these projects relating to arctic heterotrophic food web, pelagic-benthic coupling and biodiversity have emerged: (1) Contrary to a long-standing paradigm of dormant ecosystems during the long arctic winter, major food web components showed relatively high level of winter activity, well before the spring release of ice algae and subsequent phytoplankton bloom. Such phenological plasticity among key secondary producers like zooplankton may thus narrow the risks of extreme mismatch between primary production and secondary production in an increasingly variable arctic environment. (2) Tight pelagic-benthic coupling and consequent recycling of nutrients at the seafloor characterize specific regions of the Canadian Arctic, such as the North Water polynya and Lancaster Sound. The latter constitute hot spots of benthic ecosystem functioning compared to regions where zooplankton-mediated processes weaken the pelagic-benthic coupling. (3) In contrast with another widely shared assumption of lower biodiversity, arctic marine biodiversity is comparable to that reported off Atlantic and Pacific coasts of Canada, albeit threatened by the potential colonization of subarctic species. (4) The rapid decrease of summer sea-ice cover allows increasing numbers of killer whales to use the Canadian High Arctic as a hunting ground. The stronger presence of this species, bound to become a new apex predator of arctic seas, will likely affect populations of endemic arctic marine mammals such as the narwhal, bowhead, and beluga whales. |
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