A Structural Front Over the Continental Shelf of the Eastern Bering Sea

Schumacher, J. D.; Kinder, Thomas H.; Pashinski, David J.; Charnell, Robert L.

doi:10.1175/1520-0485(1979)009<0079:asfotc>2.0.co;2

Cited by 97 publications

(59 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1), which according to their origin and structure are similar to the inner front found over the depth range of 40-60 m of the inner shelf (Schumacher et al, 1979). In the late spring, summer and fall the coastal fronts separate the vertically mixed water of the coastal domains from the strictly stratified middle shelf water (Kinder et al, 1983;Schneider et al, 1990;Coyle and Cooney, 1993;Decker and Hunt, 1996;Flint et al, 1994Flint et al, , 1996Brodeur et al, 1997;Poyarkov and Emelianov, 2000;Poyarkov, 2001).…”

Section: Oceanographic Settingsupporting

confidence: 62%

“…We determined frontal zones as defined by Fedorov (1983) using the criteria of sharp horizontal gradients in the distribution of physical and chemical properties to compare with the mean distribution pattern of the properties. We also used the criteria established for specific types of structural fronts over the eastern Bering Sea shelf (Kinder and Coachman, 1978;Schumacher et al, 1979;Kinder and Schumacher, 1981;Coachman, 1986).…”

Section: Oceanographic Settingmentioning

confidence: 99%

“…Based on the known influence of oceanographic fronts on pelagic ecosystems (Fedorov, 1983;Le Fevre, 1986;Flint and Kolosova, 1990;Daly and Smith, 1993;Franks and Chen, 1996), we hypothesize that the productivity may be largely due to the existence of various types of fronts in a relatively small area around the islands. The map of frontal locations in the Pribilof area, based on a compilation of literary sources (Schumacher et al, 1979;Kinder and Schumacher, 1981;Kinder et al, 1983;Coachman, 1986;Schneider et al, 1990;Brodeur et al, 1997), as well as on our own data (Flint et al, 1994Poyarkov, 2000), is shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 96%

See 2 more Smart Citations

Plankton distribution associated with frontal zones in the vicinity of the Pribilof Islands

Флинт

Sukhanova

Копылов

et al. 2002

Deep Sea Research Part II: Topical Studies in Oceanography

View full text Add to dashboard Cite

We studied the effect of four types of fronts, the coastal front, the middle front, the shelf partition front and the shelf break front on the quantitative distribution and the composition of plankton communities in the Pribilof area of the eastern Bering Sea shelf in late spring and summer of 1993 and 1994. The coastal fronts near St. Paul and St. George Islands and the coastal domains encircled by the fronts featured specific taxonomic composition of planktonic algae, high abundance and production of phytoplankton, as well as large numbers of heterotrophic nanoplankton. The coastal fronts also were characterized by high values of total mesozooplankton biomass, high concentrations of Calanus marshallae, as well as relatively high abundances of Parasagitta setosa and Euphausiacea compared to surrounding shelf waters. We hypothesize that wind-induced erosion of a weak thermocline in the inner part of the coastal front as well as transfrontal water exchange in subthermocline layers result in nutrient enrichment of the euphotic layer in the coastal fronts and coastal domains in summer time. This leads to prolonged high primary production and high phytoplankton biomass. In this paper a new type of front-the shelf partition front located 45-55 km to the north-east off St. Paul Island-is described, which is assumed to be formed by the flux of oceanic domain waters onto the shelf. This front features a high abundance of phytoplankton and a high level of primary production compared to the adjacent middle shelf. Near the southwestern periphery of the front a mesozooplankton peak occurred, composed of C. marshallae, with biomass in the subthermocline layer, reaching values typical for the shelf break front and the highest for the area. High abundance of phyto-and zooplankton as well as heterotrophic nanoplankton and elevated primary production were most often observed in the area adjacent to the shelf break front at its oceanic side. The phyto-and mesozooplankton peaks here were formed by oceanic community species. The summer levels of phytoplankton numbers, biomass and primary production in the shelf break frontal area were similar to those reported for the outer and middle shelf during the spring bloom and the coastal domains and coastal fronts in summer. In the environment with a narrow shelf to the south of St. George Island, the mesozooplankton peak was observed at the inner side of the shelf break front as close as 20 km from the island shore and was comprised of a ''mixed'' community of shelf and oceanic species. The biomass in the peak reached the highest values for the Pribilof area at 2.5 g mean wet weight m À3 in the 0-100 m layer. Details of the taxonomic composition and the numbers and production of phytoplankton hint at the similarity of processes that affect the phytoplankton summer community in the coastal domains of the islands, at the coastal fronts, and at the oceanic side of the shelf break front. The middle front was the only one that had no effect on plankton composition or its quantitative c...

show abstract

Section: Oceanographic Settingsupporting

confidence: 62%

Section: Oceanographic Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

See 1 more Smart Citation

Plankton distribution associated with frontal zones in the vicinity of the Pribilof Islands

Флинт

Sukhanova

Копылов

et al. 2002

Deep Sea Research Part II: Topical Studies in Oceanography

View full text Add to dashboard Cite

show abstract

“…The middle transition and shelf-break front separate the middle shelf from the outer shelf, and outer shelf from the slope waters, respectively (Coachman, 1986;Schumacher and Stabeno, 1998;Stabeno et al, 1999). The inner or structural front, 5-30 km wide, separates the middle and coastal domains (Schumacher et al, 1979;Kachel et al, 2002). This feature is evident along the entire southeastern shelf and continues northward west of Nunivak Island.…”

Section: Study Areamentioning

confidence: 95%

Climate change and control of the southeastern Bering Sea pelagic ecosystem

Hunt

Stabeno

Walters

et al. 2002

Deep Sea Research Part II: Topical Studies in Oceanography

498

385

View full text Add to dashboard Cite

We propose a new hypothesis, the Oscillating Control Hypothesis (OCH), which predicts that pelagic ecosystem function in the southeastern Bering Sea will alternate between primarily bottom-up control in cold regimes and primarily top-down control in warm regimes. The timing of spring primary production is determined predominately by the timing of ice retreat. Late ice retreat (late March or later) leads to an early, ice-associated bloom in cold water (e.g., 1995, 1997, 1999), whereas no ice, or early ice retreat before mid-March, leads to an open-water bloom in May or June in warm water (e.g., 1996, 1998, 2000). Zooplankton populations are not closely coupled to the spring bloom, but are sensitive to water temperature. In years when the spring bloom occurs in cold water, low temperatures limit the production of zooplankton, the survival of larval/juvenile fish, and their recruitment into the populations of species of large piscivorous fish, such as walleye pollock (Theragra chalcogramma), Pacific cod (Gadus macrocephalus) and arrowtooth flounder (Atheresthes stomias). When continued over decadal scales, this will lead to bottom-up limitation and a decreased biomass of piscivorous fish. Alternatively, in periods when the bloom occurs in warm water, zooplankton populations should grow rapidly, providing plentiful prey for larval and juvenile fish. Abundant zooplankton will support strong recruitment of fish and will lead to abundant predatory fish that control forage fish, including, in the case of pollock, their own juveniles. Piscivorous marine birds and pinnipeds may achieve higher production of young and survival in cold regimes, when there is less competition from large piscivorous fish for coldwater forage fish such as capelin (Mallotus villosus). Piscivorous seabirds and pinnipeds also may be expected to have high productivity in periods of transition from cold regimes to warm regimes, when young of large predatory species of fish are numerous enough to provide forage. The OCH predicts that the ability of large predatory fish populations to sustain fishing pressure will vary between warm and cold regimes.The OCH points to the importance of the timing of ice retreat and water temperatures during the spring bloom for the productivity of zooplankton, and the degree and direction of coupling between zooplankton and forage fish. in the biomass of large piscivorous fish and a concurrent decline in the biomass of forage fish, including age-1 walleye pollock, particularly over the southern portion of the shelf. Populations of northern fur seals (Callorhinus ursinus) and seabirds such as kittiwakes (Rissa spp.) at the Pribilof Islands have declined, most probably in response to a diminished prey base. The available evidence suggests that these changes are unlikely the result of a decrease in total annual new primary production, though the possibility of reduced post-bloom production during summer remains. An ecosystem approach to management of the Bering Sea and its fisheries is of great importance if all o...

show abstract

“…A structural front, on average~30 km wide, separates the middle and coastal domains (Schumacher, Kinder, Pashinski & Charnell, 1979;Kachel et al, 2002). This feature, which is evident along the entire southeastern shelf, limits the horizontal flux of salt, nutrients and heat between the middle and coastal domains (Coachman, 1986;Kachel et al, 2002).…”

Section: The Eastern Bering Sea Regionmentioning

confidence: 99%

Climate change and the control of energy flow in the southeastern Bering Sea

Hunt

Stabeno

2002

Progress in Oceanography

143

View full text Add to dashboard Cite

We examine how coupling between physical and biological processes influences the production and transfer of energy to upper trophic-level species in the southeastern Bering Sea. We review time series that illustrate changes in the marine climate of the southeastern Bering Sea since the mid-1970s, particularly variability in the persistence of sea ice and the timing of its retreat. Time series (1995 -2001) from a biophysical mooring in the middle domain of the southeastern shelf support the hypothesis that retreat of the winter sea ice before mid-March (or the failure of ice to be advected into a region) results in an open water bloom in May or June in relatively warm water (Ն3°C). Conversely, when ice retreat is delayed until mid-March or later, an ice-associated bloom occurs in cold (Յ0°C) water in early spring. These variations are important because the growth and production of zooplankton and the growth and survival of larval and juvenile fish are sensitive to water temperature. The Oscillating Control Hypothesis (OCH) recently proposed by Hunt et al. (2002), predicts that control of the abundance of forage fish, and in the case of walleye pollock (Theragra chalcogramma), recruitment of large piscivorous fish, will switch from bottom-up limitation in extended periods with late ice retreat to top-down in warmer periods when ice retreat occurs before mid-March. In support of this hypothesis, we review recent data from the southeastern Bering Sea that show 2-to 13-fold changes in copepod abundance with changes in spring water temperatures of 3 to 5°C. We also provide indirect evidence that the abundance of adult pollock on the eastern Bering Sea shelf negatively affects the abundance forage fishes (including juvenile pollock) available to top predators. Although there is evidence that pollock year-class strength is positively related to temperature, we lack the time series of pollock populations in extended periods (8 -10 years) of cold-water blooms necessary to test the OCH. 

show abstract

A Structural Front Over the Continental Shelf of the Eastern Bering Sea

Cited by 97 publications

References 0 publications

Plankton distribution associated with frontal zones in the vicinity of the Pribilof Islands

Plankton distribution associated with frontal zones in the vicinity of the Pribilof Islands

Climate change and control of the southeastern Bering Sea pelagic ecosystem

Climate change and the control of energy flow in the southeastern Bering Sea

Contact Info

Product

Resources

About