Evaluation of the Beaufort Sea Shelf Structure and Function in Support of the Tarium Niryutait Marine Protected Area

Arctic ecosystems are at risk to climate impacts, challenging existing conservation measures such as protected areas. This study aims to describe the ecological dynamics of the Canadian Beaufort Sea Shelf (BSS) ecosystem and the Tarium Niryutait Marine Protected Area (TNMPA) under historical changes in sea surface temperature and sea ice extent. Using Ecopath with Ecosim, we compared the status of the BSS between two time periods, 1970-1974 and 2008-2012, and against four ecosystem models (Eastern Chukchi Sea, Barents Sea, Eastern Bering Sea, Gulf of Alaska) to inform the relative long-term health and status of Arctic marine ecosystems. We find that relative to the comparable ecosystems, the BSS had a greater proportion of biomass from pelagic primary and secondary producers, and limited production from higher trophic levels. Estimates of trophic structure indices for the BSS indicate temporal ecosystem stability, and no loss in diversity. While beluga whales are a focus of the TNMPA management plan, they are not considered a key component of the modeled food web. Rather, Arctic and polar cods (main beluga prey group), arthropods, large copepods, micro-zooplankton, and herring and smelt, were identified as keystone species and warrant attention as proxies for both beluga whales and ecosystem health.