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This paper compares and contrasts the ecosystems of the Barents and Chukchi Seas. Despite their similarity in a number of features, the Barents Sea supports a vast biomass of commercially important fish, but the Chukchi does not. Here we examine a number of aspects of these two seas to ascertain how they are similar and how they differ. We then indentify processes and mechanisms that may be responsible for their similarities and differences.Both the Barents and Chukchi Seas are high latitude, seasonally ice covered, Arctic shelf-seas. Both have strongly advective regimes, and receive water from the south. Water entering the Barents comes from the deep, ice-free and "warm" Norwegian Sea, and contains not only heat, but also a rich supply of zooplankton that supports larval fish in spring. In contrast, Bering Sea water entering the Chukchi in spring and early summer is cold. In spring, this Bering Sea water is depleted of large, lipid-rich zooplankton, thus likely resulting in a relatively low availability of zooplankton for fish. Although primary production on average is similar in the two seas, fish biomass density is an order of magnitude greater in the Barents than in the Chukchi Sea. The Barents Sea supports immense fisheries, whereas the Chukchi Sea does not. The density of cetaceans in the Barents Sea is about double that in the Chukchi Sea, as is the density of nesting seabirds, whereas, the density of pinnipeds in the Chukchi is about double that in the Barents Sea. In the Chukchi Sea, export of carbon to the benthos and benthic biomass may be greater. We hypothesize that the difference in fish abundance in the two seas is driven by differences in the heat and plankton advected into them, and the amount of primary production consumed in the upper water column. However, we suggest that the critical difference between the Chukchi and Barents Seas is the pre-cooled water entering the Chukchi Sea from the south. This cold water, and the winter mixing of the Chukchi Sea as it becomes ice covered, result in water temperatures below the physiological limits of the commercially valuable fish that thrive in the southeastern Bering Sea. If climate change warms the Barents Sea, thereby increasing the open water area via reducing ice cover, productivity at most trophic levels is likely to increase. In the Chukchi, warming should also reduce sea ice cover, permitting a longer production season. However, the shallow northern Bering and Chukchi Seas are expected to continue to be ice-covered in winter, so water there will continue to be cold in winter and spring, and is likely to continue to be a barrier to the movement of temperate fish into the Chukchi Sea. Thus, it is unlikely that large populations of boreal fish species will become established in this Arctic marginal sea. © 2012 Elsevier B.V.

Data from two moorings deployed at 166°W on the northern Chukchi shelf and slope from summer 2002 to fall 2004, as part of the Western Arctic Shelf‐Basin Interactions program, are analyzed to investigate the characteristics and variability of the flow in this region. The depth‐mean velocity at the outer‐shelf mooring is northeastward and bottom‐intensified, while that at the upper‐slope mooring is northwestward and surface‐intensified. This, together with results from a high resolution ocean and sea ice reanalysis, indicates that the outer‐shelf mooring sampled the seaward edge of the Chukchi Shelfbreak Jet, while the upper‐slope mooring sampled the shoreward edge of the Chukchi Slope Current. The coupled variability in velocity at both sites is related to the wind stress curl over the Chukchi Sea shelf, likely via Ekman dynamics and geostrophic set up, analogous to the dynamics of both currents closer to Barrow Canyon near 157°W. Hydrographic signals are analyzed to elucidate the origin of the water masses present at this location. It is argued that the annual appearance of Pacific‐origin warm water at the outer‐shelf (upper‐slope) mooring in late‐fall and winter originates from Herald (Barrow) Canyon some months earlier. Our results constitute the first robust evidence that the westward‐flowing Chukchi Slope Current persists this far west of Barrow Canyon. Plain Language Summary: The boundary currents along the shelfbreak and slope of the Chukchi Sea play a key role in the regional ecosystem via advection and shelf‐basin exchange of water and properties. Two‐years of observational data obtained at two fixed locations on the Chukchi Shelfbreak and slope at 166°W revealed that the mean current in this region was northeastward on the outer shelf and northwestward at the upper slope. This is the signature of the Chukchi Shelfbreak Jet and Chukchi Slope Current, respectively, further verified using output from a high resolution ocean model over the same time period. The velocity at the two locations co‐varies, driven predominantly by the changing rotation of the wind over the Chukchi shelf. Warm water was found annually in the fall/winter at the two locations. Using additional mooring data, it is argued that the warm water in the Chukchi Shelfbreak Jet stems from Herald Canyon in the west, while the warm water in the Chukchi Slope Current stems from Barrow Canyon in the east. Our results demonstrate for the first time that the Chukchi Slope Current persists far west of Barrow Canyon. Key Points: Mooring data reveal the presence of the Chukchi Shelfbreak Jet and Chukchi Slope Current at 166°WThe dominant variability of both currents is driven by the wind stress curl on the Chukchi shelf via geostrophic setupThe warm water present in fall/winter in the Chukchi Shelfbreak Jet and Slope Current originates from Herald Canyon and Barrow Canyon [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.dsr.2005.01.007 Byline: Kelly Kenison Falkner (a), Michael Steele (b), Rebecca A. Woodgate (b), James H. Swift (c), Knut Aagaard (b), James Morison (b) Abstract: Dissolved oxygen (O.sub.2) profiling by new generation sensors was conducted in the Arctic Ocean via aircraft during May 2003 as part of the North Pole Environmental Observatory (NPEO) and Freshwater Switchyard (SWYD) projects. At stations extending from the North Pole to the shelf off Ellesmere Island, such profiles display what appear to be various O.sub.2 maxima (with concentrations 70% of saturation or less) over depths of 70-110m in the halocline, corresponding to salinity and temperature ranges of 33.3-33.9 and -1.7 to -1.5[degrees]C. The features appear to be widely distributed: Similar features based on bottle data were recently reported for a subset of the 1997-1998 SHEBA stations in the southern Canada Basin and in recent Beaufort Sea sensor profiles. Oxygen sensor data from August 2002 Chukchi Borderlands (CBL) and 1994 Arctic Ocean Section (AOS) projects suggest that such features arise from interleaving of shelf-derived, O.sub.2-depleted waters. This generates apparent oxygen maxima in Arctic Basin profiles that would otherwise trend more smoothly from near-saturation at the surface to lower concentrations at depth. For example, in the Eurasian Basin, relatively low O.sub.2 concentrations are observed at salinities of about 34.2 and 34.7. The less saline variant is identified as part of the lower halocline, a layer originally identified by a Eurasian Basin minimum in 'NO,' which, in the Canadian Basin, is reinforced by additional inputs. The more saline and thus denser variant appears to arise from transformations of Atlantic source waters over the Barents and/or Kara shelves. Additional low-oxygen waters are generated in the vicinity of the Chukchi Borderlands, from Pacific shelf water outflows that interleave with Eurasian waters that flow over the Lomonosov Ridge into the Makarov Basin and then into the Canada Basin. One such input is associated with the well-known silicate maximum that historically has been associated with a salinity of [approximately equal to]33.1. Above that (32 Author Affiliation: (a) College of Oceanic & Atmospheric Sciences, 104 Ocean Admin Bldg., Oregon State University, Corvallis, OR 97331-5503, USA (b) Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA 98105-6698, USA (c) UCSD Scripps Institution of Oceanography, 9500 Gilman Dr., La Jolla, CA 92093-0214, USA

Research from three slope moorings along the Eurasian slope of the Arctic Ocean is presented, drawn from data taken between 1995 and 1996. In general, the mean flow was found to be weak, cyclonic, possessing an equivalent barotropic formation in the vertical, and is for the most part aligned along isobaths.

Research on the movement of episodic ocean bottom currents, or benthic storms, is presented. The influence of surface currents, wind speed, and sediment-driven plumes on benthic storms are examined.