Ecology of
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            rctic Shelf and Deep Ocean Benthos

Kędra, Monika; Grebmeier, Jacqueline M.

doi:10.1002/9781118846582.ch12

Cited by 5 publications

(9 citation statements)

References 80 publications

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“…Conversely, the distribution of gray whales in the northern Bering Sea was extensive, with a dense cluster of sightings extending north from St. Lawrence Island through Bering Strait. This dense summertime distribution of gray whales in the DBO 2 area continued at least through the mid-1980s [42,43], but by the early 2000s gray whale sightings were comparatively sparse and shifted northward following a shrinking pattern of amphipod distribution [44,45]. In the northeastern Chukchi Sea, focal areas for gray whale distribution in the 1980s included coastal waters between Icy Cape and Pt.…”

Section: Plos Onementioning

confidence: 99%

“…This decline has been ongoing since the late 1980s [42,43] leaving a reduced area of the northern Bering sea suitable for gray whale foraging. This change is concomitant with a shift in sediment quality due to faster currents, with the finer sediments required for tube building by A. macrocephala found only where current speed is reduced by land mass constriction south of Bering Strait [45]. Of note, the decline of infaunal crustaceans in DBO 2 is also coincident with an increase in polychaetes and bivalves [32,33].…”

Section: Gray Whale Infaunal Prey Abundance Community Composition And...mentioning

confidence: 99%

“…Clearly other environmental factors, such as sea ice thinning [10], increase in ocean heat and freshwater in the Chukchi Sea [5,6], and changing sediment grain size associated with variability in current speed [32,33,45] are also influencing benthic macrofauna community structure. Specifically, increased water temperatures in DBO regions 2-4 is likely affecting the distribution of benthic species, as has been reported for the northeastern Atlantic where Ampelisca spp.…”

Section: Environmental Factors and Pelagic-benthic Couplingmentioning

confidence: 99%

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Changes in gray whale phenology and distribution related to prey variability and ocean biophysics in the northern Bering and eastern Chukchi seas

et al. 2022

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Changes in gray whale (Eschrichtius robustus) phenology and distribution are related to observed and hypothesized prey availability, bottom water temperature, salinity, sea ice persistence, integrated water column and sediment chlorophyll a, and patterns of wind-driven biophysical forcing in the northern Bering and eastern Chukchi seas. This portion of the Pacific Arctic includes four Distributed Biological Observatory (DBO) sampling regions. In the Bering Strait area, passive acoustic data showed marked declines in gray whale calling activity coincident with unprecedented wintertime sea ice loss there in 2017–2019, although some whales were seen there during DBO cruises in those years. In the northern Bering Sea, sightings during DBO cruises show changes in gray whale distribution coincident with a shrinking field of infaunal amphipods, with a significant decrease in prey abundance (r = -0.314, p<0.05) observed in the DBO 2 region over the 2010–2019 period. In the eastern Chukchi Sea, sightings during broad scale aerial surveys show that gray whale distribution is associated with localized areas of high infaunal crustacean abundance. Although infaunal crustacean prey abundance was unchanged in DBO regions 3, 4 and 5, a mid-decade shift in gray whale distribution corresponded to both: (i) a localized increase in infaunal prey abundance in DBO regions 4 and 5, and (ii) a correlation of whale relative abundance with wind patterns that can influence epi-benthic and pelagic prey availability. Specifically, in the northeastern Chukchi Sea, increased sighting rates (whales/km) associated with an ~110 km (60 nm) offshore shift in distribution was positively correlated with large scale and local wind patterns conducive to increased availability of krill. In the southern Chukchi Sea, gray whale distribution clustered in all years near an amphipod-krill ‘hotspot’ associated with a 50-60m deep trough. We discuss potential impacts of observed and inferred prey shifts on gray whale nutrition in the context of an ongoing unusual gray whale mortality event. To conclude, we use the conceptual Arctic Marine Pulses (AMP) model to frame hypotheses that may guide future research on whales in the Pacific Arctic marine ecosystem.

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Section: Plos Onementioning

confidence: 99%

Section: Gray Whale Infaunal Prey Abundance Community Composition And...mentioning

confidence: 99%

Section: Environmental Factors and Pelagic-benthic Couplingmentioning

confidence: 99%

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Changes in gray whale phenology and distribution related to prey variability and ocean biophysics in the northern Bering and eastern Chukchi seas

et al. 2022

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“…Much less is known about the propagation of such changes from the surface to the seafloor via pelagic-benthic coupling (e.g. Wassmann et al, 2004;Carmack and Wassmann, 2006;Grebmeier et al, 2006;Wassmann and Reigstad, 2011;Boetius et al, 2013;Rapp et al, 2018;Kedra and Grebmeier, 2021). However, the availability of organic matter at the seafloor is known to be a major driver for the structure and function of benthic communities, including fauna (Smith et al, 2008) and microbes (Boetius and Damm, 1998;.…”

Section: Introductionmentioning

confidence: 99%

Effects of sea ice retreat and ocean warming on the Laptev Sea continental slope ecosystem (1993 vs 2012)

et al. 2022

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The central Arctic Ocean is rapidly changing due to amplified warming and sea ice retreat. Nonetheless, it remains challenging to document and decipher impacts on key ecosystem processes such as primary production and pelagic-benthic coupling, due to limited observations in this remote area. Here we investigated environmental changes at the Laptev Sea continental slope (60-3400 m water depth) from the surface to the seafloor, by replicating sample transects two decades apart. Mean break-up of sea ice occurred earlier and mean freeze-up occurred later in 2012 compared to 1993, extending the ice-free period by more than 30 days. On average, observations and model results showed an annual increase in primary production of 30% and more in the study area in 2012. In contrast, calculated and modelled fluxes of particulate organic carbon (POC) to the seafloor were only slightly higher in 2012 and did not extend as far into the deep Laptev Sea as the increase in primary production, possibly due to a more developed retention system. Nevertheless, benthic surveys revealed a substantial increase in phytodetritus availability at the seafloor along the entire transect from the shelf edge to the deep sea. This calls for carbon input by lateral advection from the shelves, additional input from sea ice, and/or a late summer bloom. We also investigated the composition and activity of bacterial communities at the seafloor and potential linkages to the observed environmental changes. While bacterial abundance, biomass and overall community structure showed no systematic differences between the two contrasting years at all depths, extracellular enzymatic activities had increased as a result of higher food availability. This was partly reflected in higher benthic oxygen uptake, indicating a moderate impact on benthic remineralization rates at the time of sampling. Our results show considerable effects of ocean warming and sea ice loss on the ecosystem from the surface ocean to the seafloor in the Laptev Sea, which are likely to continue in the coming decades.

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“…Previously published food web models of the BS and Norwegian Sea have been fish-centered with relatively few lower trophic level groups and benthic invertebrate groups (Blanchard et al, 2002;Dommasnes et al, 2002;Hansen et al, 2016;Skaret and Pitcher, 2016;Bentley et al, 2017). Arctic and sub-Arctic ecosystems, however, are well-known for the strong role of seafloor communities in regulating carbon cycling pathways (Kędra and Grebmeier, 2021). Based on a dynamic mass-balance model (Ecopath with Ecosim-EwE) and future warming scenarios for the Norwegian and the BS, Bentley et al (2017) suggested that the biomasses of widely migrating pelagic species, such as mackerel and blue whiting, are expected to increase with future rising ocean temperature.…”

Section: Introductionmentioning

confidence: 99%

Overexploitation, Recovery, and Warming of the Barents Sea Ecosystem During 1950–2013

et al. 2021

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The Barents Sea (BS) is a high-latitude shelf ecosystem with important fisheries, high and historically variable harvesting pressure, and ongoing high variability in climatic conditions. To quantify carbon flow pathways and assess if changes in harvesting intensity and climate variability have affected the BS ecosystem, we modeled the ecosystem for the period 1950–2013 using a highly trophically resolved mass-balanced food web model (Ecopath with Ecosim). Ecosim models were fitted to time series of biomasses and catches, and were forced by environmental variables and fisheries mortality. The effects on ecosystem dynamics by the drivers fishing mortality, primary production proxies related to open-water area and capelin-larvae mortality proxy, were evaluated. During the period 1970–1990, the ecosystem was in a phase of overexploitation with low top-predators’ biomasses and some trophic cascade effects and increases in prey stocks. Despite heavy exploitation of some groups, the basic ecosystem structure seems to have been preserved. After 1990, when the harvesting pressure was relaxed, most exploited boreal groups recovered with increased biomass, well-captured by the fitted Ecosim model. These biomass increases were likely driven by an increase in primary production resulting from warming and a decrease in ice-coverage. During the warm period that started about 1995, some unexploited Arctic groups decreased whereas krill and jellyfish groups increased. Only the latter trend was successfully predicted by the Ecosim model. The krill flow pathway was identified as especially important as it supplied both medium and high trophic level compartments, and this pathway became even more important after ca. 2000. The modeling results revealed complex interplay between fishery and variability of lower trophic level groups that differs between the boreal and arctic functional groups and has importance for ecosystem management.

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Ecology of A rctic Shelf and Deep Ocean Benthos

Cited by 5 publications

References 80 publications

Changes in gray whale phenology and distribution related to prey variability and ocean biophysics in the northern Bering and eastern Chukchi seas

Changes in gray whale phenology and distribution related to prey variability and ocean biophysics in the northern Bering and eastern Chukchi seas

Effects of sea ice retreat and ocean warming on the Laptev Sea continental slope ecosystem (1993 vs 2012)

Overexploitation, Recovery, and Warming of the Barents Sea Ecosystem During 1950–2013

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