Oceanography of the Canadian Shelf of the Beaufort Sea: A Setting for Marine Life

Abstract

Conservation of marine biodiversity in the Beaufort Sea demands that we understand what individual organisms require of their physical and geochemical environments in order to survive. Specifically, how do the extraordinary spatial and seasonal variations in ice cover, temperature, light, freshwater, turbidity, and currents of the Beaufort Sea define unique places or times critical to marine life? We start with the traditional "bottom-up" approach, which is to review the strongly seasonal physical forcing of the system, and from it to infer the resultant oceanographic regimes and seasons. This approach, while valuable, remains incomplete: this is due partly to limitations of the data and partly to our limited understanding of this complex system. The oceanographic features (e.g., upwelling regions, recurrent polynyas, coastal currents, sediment types and distributions) define the backdrop that animals "know and understand" in the sense of interacting with one another and finding food and habitat. We therefore seek clues to the underlying oceanographic processes in the behavioural patterns of fish, marine mammals, and birds. This "top-down" approach also has limitations, but it offers the opportunity to seek those connections in the system where climate change is likely to have its greatest impact on biological populations.

Vertical stability and the annual dynamics of nutrients and chlorophyll fluorescence in the coastal, southeast Beaufort Sea

“…Their influence must vanish during winter when freshwater from the Mackenzie River is contained in a neritic lake by the stamukhi [Carmack and MacDonald, 2002] and the Horton River is frozen to the bottom. There was no evidence of a spring upper euphotic zone and drove the modest autumn bloom, must have been halted with the consolidation of fast ice in December ( Figure 5).…”

The fate of mercury in Arctic terrestrial and aquatic ecosystems, a review

“…The shelves tend to be the location of active biogeochemical cycling because they have higher primary production and are the locations of recurrent flaw leads in winter. [14] Flaw leads form when winds or currents open the ice pack and expose ocean water. The leads provide important oases for the production of food and are the immediate recipients of the enormous dissolved and particulate terrigenous inputs.…”

“…[36] Seawater in the upper Arctic Ocean has residence times varying from one to 3 years on the shelves, ,10 years in the polar mixed layer, and ,30 years in halocline waters beneath the mixed layer. [39,40] Deeper in the ocean, the residence times are up to several centuries based on 14 C and other tracers. [41,42] Again, these ocean circulation rates set the time scale over which deposited Hg can be held in the various ocean reservoirs within the Arctic.…”

Ocean currents shape the microbiome of Arctic marine sediments

“…Atlantic water enters the Arctic through the Fram Strait, and moves counter-clockwise along the ABS break. During summer, as ice melts and vertical mixing is reduced, water on the ABS is density stratified, resulting in a layer of Pacific origin water sandwiched between an Arctic surface layer, and a deep, cold and saline layer of Atlantic origin water (Carmack and Macdonald, 2002;McLaughlin et al, 2004;Shimada et al, 2005). The halocline (40-100 m) between surface and Pacific water and pycnocline (200 m) between Pacific and Atlantic water physically separates these masses (McLaughlin et al, 2004;Pickart, 2004).…”