scholarly journals Absorption and fluorescence properties of chromophoric dissolved organic matter of the eastern Bering Sea in the summer with special reference to the influence of a cold pool

2014 ◽  
Vol 11 (12) ◽  
pp. 3225-3244 ◽  
Author(s):  
E. J. D'Sa ◽  
J. I. Goes ◽  
H. Gomes ◽  
C. Mouw
Keyword(s):  
Bering Sea ◽  
Fluorescence Properties ◽  
Chromophoric Dissolved Organic Matter ◽  
Cold Pool ◽  
Surface Mixed Layer ◽  
Spectral Slope ◽  
Inner Shelf ◽  
Eastern Bering Sea ◽  
Shelf Slope ◽  
The Bering Sea

Abstract. The absorption and fluorescence properties of chromophoric dissolved organic matter (CDOM) are reported for the inner shelf, slope waters and outer shelf regions of the eastern Bering Sea during the summer of 2008, when a warm, thermally stratified surface mixed layer lay over a cold pool (< 2 °C) that occupied the entire middle shelf. CDOM absorption at 355 nm (ag355) and its spectral slope (S) in conjunction with excitation–emission matrix (EEM) fluorescence and parallel factor analysis (PARAFAC) revealed large variability in the characteristics of CDOM in different regions of the Bering Sea. PARAFAC analysis aided in the identification of three humic-like (components one, two and five) and two protein-like (a tyrosine-like component three, and a tryptophan-like component four) components. In the extensive shelf region, average absorption coefficients at 355 nm (ag355, m−1) and DOC concentrations (μM) were highest in the inner shelf (0.342 ± 0.11 m−1, 92.67 ± 14.60 μM) and lower in the middle (0.226 ± 0.05 m−1, 78.38 ± 10.64 μM) and outer (0.185 ± 0.05 m−1, 79.24 ± 18.01 μM) shelves, respectively. DOC concentrations, however were not significantly different, suggesting CDOM sources and sinks to be uncoupled from DOC. Mean spectral slopes S were elevated in the middle shelf (24.38 ± 2.25 μm−1) especially in the surface waters (26.87 ± 2.39 μm−1) indicating high rates of photodegradation in the highly stratified surface mixed layer, which intensified northwards in the northern middle shelf likely contributing to greater light penetration and to phytoplankton blooms at deeper depths. The fluorescent humic-like components one, two, and five were most elevated in the inner shelf most likely from riverine inputs. Along the productive "green belt" in the outer shelf/slope region, absorption and fluorescence properties indicated the presence of fresh and degraded autochthonous DOM. Near the Unimak Pass region of the Aleutian Islands, low DOC and ag355 (mean 66.99 ± 7.94 μM; 0.182 ± 0.05 m−1) and a high S (mean 25.95 ± 1.58 μm−1) suggested substantial photobleaching of the Alaska Coastal Water, but high intensities of humic-like and protein-like fluorescence suggested sources of fluorescent DOM from coastal runoff and glacier meltwaters during the summer. The spectral slope S vs. ag355 relationship revealed terrestrial and oceanic end members along with intermediate water masses that were modeled using nonlinear regression equations that could allow water mass differentiation based on CDOM optical properties. Spectral slope S was negatively correlated (r2 = 0.79) with apparent oxygen utilization (AOU) for waters extending from the middle shelf into the deep Bering Sea indicating increasing microbial alteration of CDOM with depth. Although our data show that the CDOM photochemical environment of the Bering Sea is complex, our current information on its optical properties will aid in better understanding of the biogeochemical role of CDOM in carbon budgets in relation to the annual sea ice and phytoplankton dynamics, and to improved algorithms of ocean color remote sensing for this region.

scholarly journals Absorption and fluorescence properties of the eastern Bering Sea in the summer with special reference to the influence of a Cold Pool

2013 ◽  
Vol 10 (12) ◽  
pp. 19109-19154
Author(s):  
E. J. D'Sa ◽  
J. I. Goes ◽  
H. Gomes ◽  
C. Mouw
Keyword(s):  
Mixed Layer ◽  
Bering Sea ◽  
Outer Shelf ◽  
Fluorescence Properties ◽  
Cold Pool ◽  
Surface Mixed Layer ◽  
Inner Shelf ◽  
Eastern Bering Sea ◽  
Shelf Slope ◽  
The Bering Sea

Abstract. The absorption and fluorescence properties of chromophoric dissolved organic matter (CDOM) are reported for the inner shelf, slope waters and outer shelf regions of the eastern Bering Sea during the summer of 2008, when a warm, thermally stratified surface mixed layer lay over a Cold Pool (< 2 °C) that occupied the entire middle shelf. CDOM absorption at 355 nm (ag355) and its spectral slope (S) in conjunction with excitation emission matrix (EEM) fluorescence and parallel factor analysis (PARAFAC) revealed large variability in the characteristics of CDOM in different regions of the Bering Sea. PARAFAC analysis aided in the identification of three humic-like (components 1, 2 and 5) and two protein-like (a tyrosine-like component 3, and a tryptophan-like component 4) components. In the extensive shelf region, average absorption coefficients at 355 nm (ag355 m–1) and DOC concentrations (μM) were highest in the inner shelf (0.342 ± 0.11 m–1, 92.67 ± 14.60 μM) and lower in the middle (0.226 ± 0.05 m–1, 78.38 ± 10.64 μM) and outer (0.176 ± 0.05 m–1, 80.73 ± 18.11 μM) shelves, respectively. Mean spectral slopes S were elevated in the middle shelf (24.38 ± 2.25 μm–1) especially in the surface waters (26.87 ± 2.39 μm–1) indicating high rates of photodegradation in the highly stratified surface mixed layer, which intensified northwards in the northern middle shelf likely contributing to greater light penetration and to phytoplankton blooms at deeper depths. The fluorescent humic-like components 1, 2, and 5 were most elevated in the inner shelf most likely from riverine inputs. Measurements at depth in slope waters (> 250 m) revealed low values of ag355 (0.155 ± 0.03 m–1) and S (15.45 ± 1.78 μm–1) indicative of microbial degradation of CDOM in deep waters. DOC concentrations, however were not significantly different suggesting CDOM sources and sinks to be uncoupled from DOC. Along the productive "green belt" in the outer shelf/slope region, absorption and fluorescence properties indicated the presence of fresh and degraded autochthonous DOM. Near the Unimak Pass region of the Aleutian Islands, low DOC and ag355 (mean 66.99 ± 7.94 μM; 0.182 ± 0.05 m–1) and a high S (mean 25.95 ± 1.58 μm–1) suggested substantial photobleaching of the Alaska Coastal Waters, but high intensities of humic-like and protein-like fluorescence suggested sources of fluorescent DOM from coastal runoff and glacier melt waters during the summer. Although our data show that the CDOM photochemical environment of the Bering Sea is complex, our current information on its optical properties will aid in better understanding of the biogeochemical role of CDOM in carbon budgets in relation to the annual sea ice and phytoplankton dynamics, and to improved algorithms of ocean color remote sensing for this region.

Lycodapus (Pisces: Zoarcidae) of eastern Bering Sea and nearby Pacific Ocean, with three new species and a revised key to the species

1981 ◽  
Vol 59 (4) ◽  
pp. 667-678 ◽  
Author(s):  
Alex E. Peden ◽  
M. Eric Anderson
Keyword(s):  
New Species ◽  
Pacific Ocean ◽  
Bering Sea ◽  
Sea Of Okhotsk ◽  
Range Limit ◽  
The Sea Of Okhotsk ◽  
Eastern Bering Sea ◽  
Northern Range Limit ◽  
Three New Species ◽  
The Bering Sea

Lycodapus leptus n.sp., L. poecilus n.sp., and L. psarostomatus n.sp. are described from the eastern Bering Sea. A new key to all known species of Lycodapus is presented. In addition, L. fierasfer Gilbert, L. parviceps Gilbert, and L. derjugini Andriashev are recognized from the Bering Sea and L. microdon Schmidt is recognized from the Sea of Okhotsk. The northern range limit of Lycodapus dermatinus Gilbert is established from a sea mount off southeastern Alaska. A specimen of Lycodapus that cannot be identified to species represents the most southern record for the genus in Asiatic waters.

Application of a sequential regime shift detection method to the Bering Sea ecosystem

2005 ◽  
Vol 62 (3) ◽  
pp. 328-332 ◽  
Author(s):  
Sergei Rodionov ◽  
James E. Overland
Keyword(s):  
Bering Sea ◽  
Regime Shift ◽  
Poor Performance ◽  
Regime Shifts ◽  
Test Analysis ◽  
Eastern Bering Sea ◽  
Time Signals ◽  
Shift Detection ◽  
Changes Over Time ◽  
The Bering Sea

Abstract A common problem of existing methods for regime shift detection is their poor performance at the ends of time-series. Consequently, shifts in environmental and biological indices are usually detected long after their actual appearance. A recently introduced method based on sequential t-test analysis of regime shifts (STARS) treats all incoming data in real time, signals the possibility of a regime shift as soon as possible, then monitors how perception of the magnitude of the shift changes over time. Results of a STARS application to the eastern Bering Sea ecosystem show how the 1989 and 1998 regime shifts manifest themselves in biotic and abiotic indices in comparison with the 1977 shift.

scholarly journals Age, growth, and maturity of the whitebrow skate, Bathyraja minispinosa, from the eastern Bering Sea

2011 ◽  
Vol 68 (7) ◽  
pp. 1426-1434 ◽  
Author(s):  
Shaara M. Ainsley ◽  
David A. Ebert ◽  
Gregor M. Cailliet
Keyword(s):  
Bering Sea ◽  
Growth Models ◽  
Gompertz Model ◽  
Parameter Estimates ◽  
Population Declines ◽  
Age At Maturity ◽  
Von Bertalanffy Model ◽  
Eastern Bering Sea ◽  
Best Fit ◽  
The Bering Sea

Abstract Ainsley, S. M., Ebert, D. A., and Cailliet, G. M. 2011. Age, growth, and maturity of the whitebrow skate, Bathyraja minispinosa, from the eastern Bering Sea. – ICES Journal of Marine Science, 68: 1426–1434. Skates are a common bycatch in groundfish fisheries in the Bering Sea; however, their life-history characteristics are not well known. The study is the first to investigate the age, growth, and age at maturity of Bathyraja minispinosa. Ages were estimated using sectioned vertebrae and several growth models were compared. The Gompertz model was the best fit and no significant differences were detected between sexes for any model. The maximum age estimated was 37 years, and parameter estimates generated from the three-parameter von Bertalanffy model were k = 0.02 year−1 and L∞ = 146.9 cm total length (TL). Males reached their size at 50% maturity larger than females (70.1 and 67.4 cm, respectively), but no significant differences in the estimated size or age at maturity were found. Whereas B. minispinosa is smaller than many skate species in the eastern Bering Sea, it has a considerably longer estimated lifespan, indicating that size may not be a reliable method of estimating the vulnerability of a rajid species to population declines in the eastern North Pacific.

scholarly journals Seasonal distribution of dissolved inorganic carbon and net community production on the Bering Sea shelf

2010 ◽  
Vol 7 (1) ◽  
pp. 251-300 ◽  
Author(s):  
J. T. Mathis ◽  
J. N. Cross ◽  
N. R. Bates ◽  
S. B. Moran ◽  
M. W. Lomas ◽  
...  
Keyword(s):  
Primary Production ◽  
Bering Sea ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Inner Shelf ◽  
Net Community Production ◽  
Important Indicator ◽  
Bering Sea Shelf ◽  
Community Production ◽  
The Bering Sea

Abstract. The southeastern shelf of the Bering Sea is one of the ocean's most productive ecosystems and sustains more than half of the total US fish landings annually. However, the character of the Bering Sea shelf ecosystem has undergone a dramatic shift over the last several decades, causing notable increases in the dominance of temperate features coupled to the decline of arctic species and decreases in the abundance of commercially important organisms. In order to assess the current state of primary production in the southeastern Bering Sea, we measured the spatio-temporal distribution and controls on dissolved inorganic carbon (DIC) concentrations in spring and summer of 2008 across six shelf domains defined by differing biogeochemical characteristics. DIC concentrations were tightly coupled to salinity in spring and ranged from ~1900 μmol kg−1 over the inner shelf to ~2400 μmol kg−1 in the deeper waters of the Bering Sea. In summer, DIC concentrations were lower due to dilution from sea ice melt and primary production. Concentrations were found to be as low ~1800 μmol kg−1 over the inner shelf. We found that DIC concentrations were drawn down 30–150 μmol kg−1 in the upper 30 m of the water column due to primary production between the spring and summer occupations. Using the seasonal drawdown of DIC, estimated rates of net community production (NCP) on the inner, middle, and outer shelf averaged 28±10 mmol C m−2 d−1. However, higher rates of NCP (40–47 mmol C m−2 d−1) were observed in the ''Green Belt'' where the greatest confluence of nutrient-rich basin water and iron-rich shelf water occurs. We estimated that in 2008, total productivity across the shelf was on the order of ~105 Tg C yr−1. Due to the paucity of consistent, comparable productivity data, it is impossible at this time to quantify whether the system is becoming more or less productive. However, as changing climate continues to modify the character of the Bering Sea, we have shown that NCP can be an important indicator of how the ecosystem is functioning.

scholarly journals Role of physical processes in formation of spring phytoplankton bloom in the Bering Sea

Trudy VNIRO ◽  
2020 ◽  
Vol 181 ◽  
pp. 206-222
Author(s):  
K.K. Kivva ◽  
◽  
J.V. Selivanova ◽  
M.N. Pisareva ◽  
A.A. Sumkina ◽  
...  
Keyword(s):  
Bering Sea ◽  
Phytoplankton Bloom ◽  
Physical Processes ◽  
Spring Phytoplankton Bloom ◽  
Eastern Bering Sea ◽  
Ice Retreat ◽  
Shelf Region ◽  
Sea Ice Retreat ◽  
Bering Sea Shelf ◽  
The Bering Sea

The main part of the annual primary production in the Arctic and Subarctic zones of the World Ocean is formed during the spring phytoplankton bloom. The timing of the bloom depends on combination of physical factors. Oscillating control hypothesis, proposed in [Hunt et al., 2002] for the Eastern Bering Sea, describes annual peculiarities of ecosystem development related to conditions of the spring phytoplankton bloom. We review propositions of this hypothesis on the reasons of phytoplankton bloom and its connection with physical processes for four local regions of the Bering Sea shelf. The regions include western, northern and south-eastern parts of the shelf. The analysis is based on ocean color and microwave remotely sensed data as well as on atmospheric reanalysis. The results allow for hypothesis improvement. An early phytoplankton bloom may be present in the surface layer in April or May along the eastern Bering Sea shelf even in situations of early sea ice retreat (e. g. February-March) or absence of ice during winter. However, such combinations were not observed in the western Bering Sea shelf region. In 1998–2018, early ice retreat in the western shelf region was always accompanied by relatively late phytoplankton bloom. The temporal lag between sea ice retreat and phytoplankton bloom may be substantial in some years along the southernmost position of the ice edge. On the other hand, the spring bloom in the northern part of the shelf usually follows the ice retreat. In case of early ice retreat, the timing of the bloom is determined not only by wind conditions, but also by heat balance at the surface of the sea. The results are proposed to be used in further analysis of ecosystem dynamics of the western Bering Sea shelf.

scholarly journals Seasonal distribution of dissolved inorganic carbon and net community production on the Bering Sea shelf

2010 ◽  
Vol 7 (5) ◽  
pp. 1769-1787 ◽  
Author(s):  
J. T. Mathis ◽  
J. N. Cross ◽  
N. R. Bates ◽  
S. Bradley Moran ◽  
M. W. Lomas ◽  
...  
Keyword(s):  
Primary Production ◽  
Bering Sea ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Inner Shelf ◽  
Net Community Production ◽  
Important Indicator ◽  
Carbonate Formation ◽  
Community Production ◽  
The Bering Sea

Abstract. In order to assess the current state of net community production (NCP) in the southeastern Bering Sea, we measured the spatio-temporal distribution and controls on dissolved inorganic carbon (DIC) concentrations in spring and summer of 2008 across six shelf domains defined by differing biogeochemical characteristics. DIC concentrations were tightly coupled to salinity in spring and ranged from ~1900 μmoles kg−1 over the inner shelf to ~2400 μmoles kg−1 in the deeper waters of the Bering Sea. In summer, DIC concentrations were lower due to dilution from sea ice melt, terrestrial inputs, and primary production. Concentrations were found to be as low ~1800 μmoles kg−1 over the inner shelf. We found that DIC concentrations were drawn down 30–150 μmoles kg−1 in the upper 30 m of the water column due to primary production and calcium carbonate formation between the spring and summer occupations. Using the seasonal drawdown of DIC, estimated rates of NCP on the inner, middle, and outer shelf averaged 28 ± 9 mmoles C m−2 d−1. However, higher rates of NCP (40–47 mmoles C m−2 d−1) were observed in the "Green Belt" where the greatest confluence of nutrient-rich basin water and iron-rich shelf water occurs. We estimated that in 2008, total NCP across the shelf was on the order of ~96 Tg C yr−1. Due to the paucity of consistent, comparable productivity data, it is impossible at this time to quantify whether the system is becoming more or less productive. However, as changing climate continues to modify the character of the Bering Sea, we have shown that NCP can be an important indicator of how the ecosystem is functioning.

Contrasting the variability in spatial distribution of two juvenile flatfishes in relation to thermal stanzas in the eastern Bering Sea

2019 ◽  
Vol 77 (3) ◽  
pp. 953-963
Author(s):  
Cynthia Yeung ◽  
Daniel W Cooper
Keyword(s):  
Spatial Distribution ◽  
Bering Sea ◽  
Thermal Environment ◽  
Bottom Temperature ◽  
Eastern Bering Sea ◽  
Northward Expansion ◽  
Yellowfin Sole ◽  
Temperature Indices ◽  
Limanda Aspera ◽  
The Bering Sea

Abstract Groundfish species in the Bering Sea are undergoing pronounced changes in spatial distribution and abundance due to warming ocean temperatures. The main drivers of interannual variability in this ecosystem are the alternating warm and cold thermal stanzas. Yellowfin sole (Limanda aspera; YFS) and northern rock sole (Lepidopsetta polyxystra; NRS) are commercially-valuable flatfishes in the Bering Sea and are among the most dominant groundfish species there in numbers and biomass. We examined the variability in the spatial distribution and abundance of juvenile NRS and YFS in relation to the ice and temperature conditions associated with warm-cold thermal shifts from 1982 to 2017. The goal was to assess the implications of the fluctuating thermal environment for Bering Sea flatfish production. We found ice cover and bottom temperature indices in the preceding 1 to 3 years to be the best predictors of NRS juvenile distribution. In contrast, these indices were not significantly correlated with YFS juvenile distribution, which could be an artifact of their relatively low availability to sampling. A warm stanza, as the Bering Sea is currently in, is expected to favor high numbers of NRS juveniles and the northward expansion of their distribution.

Middle Pleistocene Mollusks from St. Lawrence Island and their Significance for the Paleo-Oceanography of the Bering Sea

1972 ◽  
Vol 2 (02) ◽  
pp. 119-134 ◽  
Author(s):  
David M. Hopkins ◽  
Robert W. Rowland ◽  
William W. Patton
Keyword(s):  
Bering Sea ◽  
Middle Pleistocene ◽  
Pacific Water ◽  
Arctic Water ◽  
Ice Cap ◽  
Northern Bering Sea ◽  
Eastern Bering Sea ◽  
Flow Through ◽  
The Bering Sea ◽  
Arctic Fauna

Drift, evidently of Illinoian age, was deposited on St. Lawrence Island at the margin of an ice cap that covered the highlands of the Chukotka Peninsula of Siberia and spread far eastward on the continental shelf of northern Bering Sea. Underlying the drift on the northwestward part of the island are mollusk-bearing beds deposited during the Kotzebuan Transgression. A comparison of mollusk faunas from St. Lawrence Island, Chukotka Peninsula, and Kotzebue Sound suggests that the present northward flow through Bering and Anadyr Straits was reversed during the Kotzebuan Transgression. Cold arctic water penetrated southward and southwestward bringing an arctic fauna to the Gulf of Anadyr. Warmer Pacific water probably entered eastern Bering Sea, passed eastward and northeastward around eastern and northern St. Lawrence Island, and then became entrained in the southward currents that passed through Anadyr Strait.

scholarly journals Distributional patterns of 0-group Pacific cod (Gadus macrocephalus) in the eastern Bering Sea under variable recruitment and thermal conditions

2012 ◽  
Vol 69 (2) ◽  
pp. 163-174 ◽  
Author(s):  
Thomas P. Hurst ◽  
Jamal H. Moss ◽  
Jessica A. Miller
Keyword(s):  
Bering Sea ◽  
Thermal Conditions ◽  
Pacific Cod ◽  
Eastern Bering Sea ◽  
Pacific Cod Gadus Macrocephalus ◽  
Gadus Macrocephalus ◽  
Basin Scale ◽  
Distributional Patterns ◽  
Variable Recruitment ◽  
The Bering Sea

Abstract Hurst, T. P., Moss, J. H., and Miller, J. A. 2012. Distributional patterns of 0-group Pacific cod (Gadus macrocephalus) in the eastern Bering Sea under variable recruitment and thermal conditions. – ICES Journal of Marine Science, 69: 163–174. Despite the importance of Pacific cod in Bering Sea fisheries and foodwebs, little is known about the habitat use and the distribution of early life stages. We analysed 6 years of catch data for 0-group Pacific cod in fishery-independent surveys of the Bering Sea shelf. Juvenile cod were most commonly captured on the middle shelf over depths of 50–80 m and were rarely captured north of 58°N. Consistently high catches were observed east of the Pribilof Islands and north of Port Moller along the Alaska Peninsula. There was evidence of density-dependent habitat selection at the local scale as the frequency of occurrence increased with regional catch per unit effort. At the basin scale, the southerly distribution of the weak 2009 cohort suggested the possibility of a range contraction for small cohorts. There was no consistent shift in the distribution of juvenile Pacific cod in response to interannual climate variability. These results for Pacific cod contrast with those observed for walleye pollock, which appears to exhibit greater variance in distribution, but are similar to patterns observed for juvenile Atlantic cod. Future work should focus on distribution in nearshore habitats and examine the patterns of dispersal and the connectivity of the Bering Sea and Gulf of Alaska populations.

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