WorldWideScience

Sample records for bering sea elevated

  1. New Coccolithophore Bloom in Bering Sea

    Science.gov (United States)

    2002-01-01

    For the fourth year in a row it appears as if there is a bloom of coccolithophores-marine single-celled plants with calcite scales-in the Bering Sea off the coast of Alaska. Similar blooms were rare before 1997, but they have appeared every year since then. Scientists believe the coccolithophore blooms are the result of changing wind patterns in the region. Weaker than normal winds fail to mix the water of the Bering Sea, resulting in the growth of coccolithophores instead of other types of phytoplankton. Seabird populations have also been changing as a result of this climate change. The Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), flying aboard the OrbView-2 satellite, saw the coccolith-brightened waters of the Bering Sea in 1997, 1998, and 1999. The waters have looked fairly bright again this winter and spring, as seen in this SeaWiFS image acquired April 29, 2000. But scientists are unsure whether this year's phenomenon is caused by living coccolithophorids, re-suspended coccoliths, or something else. Like all phytoplankton, coccolithophores contain chlorophyll and have the tendency to multiply rapidly near the surface. Yet, in large numbers, coccolithophores periodically shed their tiny scales, called 'coccoliths,' by the bucketful into the surrounding waters. The calcium-rich coccoliths turn the normally dark water a bright, milky aquamarine, making coccolithophore blooms easy to spot in satellite imagery. The edge of the whitish cloud in the water seen in this image is roughly 50 kilometers off the West Coast of Alaska. For more information see: SeaWiFS home page Changing Currents Color the Bering Sea a New Shade of Blue Image courtesy SeaWiFS project

  2. Pollen evidence for late pleistocene bering land bridge environments from Norton Sound, Northeastern Bering Sea, Alaska

    Science.gov (United States)

    Ager, T.A.; Phillips, R.L.

    2008-01-01

    After more than half a century of paleoenvironmental investigations, disagreements persist as to the nature of vegetation type and climate of the Bering land bridge (BLB) during the late Wisconsin (Sartan) glacial interval. Few data exist from sites on the former land bridge, now submerged under the Bering and Chukchi Seas. Two hypotheses have emerged during the past decade. The first, based on pollen data from Bering Sea islands and adjacent mainlands of western Alaska and Northeast Siberia, represents the likely predominant vegetation on the Bering land bridge during full-glacial conditions: graminoid-herb-willow tundra vegetation associated with cold, dry winters and cool, dry summer climate. The second hypothesis suggests that dwarf birch-shrub-herb tundra formed a broad belt across the BLB, and that mesic vegetation was associated with cold, snowier winters and moist, cool summers. As a step towards resolving this controversy, a sediment core from Norton Sound, northeastern Bering Sea was radiocarbon dated and analyzed for pollen content. Two pollen zones were identified. The older, bracketed by radiocarbon ages of 29,500 and 11,515 14C yr BP, contains pollen assemblages composed of grass, sedge, wormwood, willow, and a variety of herb (forb) taxa. These assemblages are interpreted to represent graminoid-herb-willow tundra vegetation that developed under an arid, cool climate regime. The younger pollen zone sediments were deposited about 11,515 14C yr BP, when rising sea level had begun to flood the BLB. This younger pollen zone contains pollen of birch, willow, heaths, aquatic plants, and spores of sphagnum moss. This is interpreted to represent a Lateglacial dwarf birch-heath-willow-herb tundra vegetation, likely associated with a wetter climate with deeper winter snows, and moist, cool summers. This record supports the first hypothesis, that graminoid-herb-willow tundra vegetation extended into the lowlands of the BLB during full glacial conditions of the

  3. Neogene sedimentation on the outer continental margin, southern Bering Sea

    Science.gov (United States)

    Vallier, T.L.; Underwood, M.B.; Gardner, J.V.; Barron, J.A.

    1980-01-01

    Neogene sedimentary rocks and sediments from sites on the outer continental margin in the southern Bering Sea and on the Alaska Peninsula are dominated by volcanic components that probably were eroded from an emergent Aleutian Ridge. A mainland continental source is subordinate. Most sediment in the marine environment was transported to the depositional sites by longshore currents, debris flows, and turbidity currents during times when sea level was near the outermost continental shelf. Fluctuations of sea level are ascribed both to worldwide glacio-eustatic effects and to regional vertical tectonics. Large drainage systems, such as the Yukon and Kuskokwim Rivers, had little direct influence on sedimentation along the continental slope and Unmak Plateau in the southern Bering Sea. Sediments from those drainage systems probably were transported to the floor of the Aleutian Basin, to the numerous shelf basins that underlie the outer continental shelf, and to the Arctic Ocean after passing through the Bering Strait. Environments of deposition at the sites along the outer continental margin have not changed significantly since the middle Miocene. The site on the Alaska Peninsula, however, is now emergent following shallow-marine and transitional sedimentation during the Neogene. ?? 1980.

  4. AFSC/NMML with NPRB: Whale broad-scale distribution in southeastern Bering Sea, 2008 and 2010

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — As part of the Bering Sea Integrated Ecosystem Research Program (BSIERP) funded by the North Pacific Research Board (http://www.nprb.org/bering-sea-project),...

  5. 76 FR 45219 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Science.gov (United States)

    2011-07-28

    ...-BA18 Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management... management plan amendment; request for comments. SUMMARY: Amendment 93 to the Fishery Management Plan for Groundfish of the Bering Sea and Aleutian Islands Management Area (FMP) would amend the Bering Sea and...

  6. Microfaunal analysis of late Quaternary deposits of the northern Bering Sea.

    Science.gov (United States)

    McDougall, K.

    1982-01-01

    Holocene microfaunal associations and distribution patterns define three inner-shelf (1-20m) biofacies in Norton Sound, northern Bering Sea. The Holocene facies relations are the basis for interpreting early Holocene and late Pleistocene environmental conditions in the NE Bering Sea area. Norton Sound cores provide evidence of two marine transgressions and a varying river input.-from Author

  7. Environmental predictors of ice seal presence in the Bering Sea.

    Science.gov (United States)

    Miksis-Olds, Jennifer L; Madden, Laura E

    2014-01-01

    Ice seals overwintering in the Bering Sea are challenged with foraging, finding mates, and maintaining breathing holes in a dark and ice covered environment. Due to the difficulty of studying these species in their natural environment, very little is known about how the seals navigate under ice. Here we identify specific environmental parameters, including components of the ambient background sound, that are predictive of ice seal presence in the Bering Sea. Multi-year mooring deployments provided synoptic time series of acoustic and oceanographic parameters from which environmental parameters predictive of species presence were identified through a series of mixed models. Ice cover and 10 kHz sound level were significant predictors of seal presence, with 40 kHz sound and prey presence (combined with ice cover) as potential predictors as well. Ice seal presence showed a strong positive correlation with ice cover and a negative association with 10 kHz environmental sound. On average, there was a 20-30 dB difference between sound levels during solid ice conditions compared to open water or melting conditions, providing a salient acoustic gradient between open water and solid ice conditions by which ice seals could orient. By constantly assessing the acoustic environment associated with the seasonal ice movement in the Bering Sea, it is possible that ice seals could utilize aspects of the soundscape to gauge their safe distance to open water or the ice edge by orienting in the direction of higher sound levels indicative of open water, especially in the frequency range above 1 kHz. In rapidly changing Arctic and sub-Arctic environments, the seasonal ice conditions and soundscapes are likely to change which may impact the ability of animals using ice presence and cues to successfully function during the winter breeding season.

  8. Environmental predictors of ice seal presence in the Bering Sea.

    Directory of Open Access Journals (Sweden)

    Jennifer L Miksis-Olds

    Full Text Available Ice seals overwintering in the Bering Sea are challenged with foraging, finding mates, and maintaining breathing holes in a dark and ice covered environment. Due to the difficulty of studying these species in their natural environment, very little is known about how the seals navigate under ice. Here we identify specific environmental parameters, including components of the ambient background sound, that are predictive of ice seal presence in the Bering Sea. Multi-year mooring deployments provided synoptic time series of acoustic and oceanographic parameters from which environmental parameters predictive of species presence were identified through a series of mixed models. Ice cover and 10 kHz sound level were significant predictors of seal presence, with 40 kHz sound and prey presence (combined with ice cover as potential predictors as well. Ice seal presence showed a strong positive correlation with ice cover and a negative association with 10 kHz environmental sound. On average, there was a 20-30 dB difference between sound levels during solid ice conditions compared to open water or melting conditions, providing a salient acoustic gradient between open water and solid ice conditions by which ice seals could orient. By constantly assessing the acoustic environment associated with the seasonal ice movement in the Bering Sea, it is possible that ice seals could utilize aspects of the soundscape to gauge their safe distance to open water or the ice edge by orienting in the direction of higher sound levels indicative of open water, especially in the frequency range above 1 kHz. In rapidly changing Arctic and sub-Arctic environments, the seasonal ice conditions and soundscapes are likely to change which may impact the ability of animals using ice presence and cues to successfully function during the winter breeding season.

  9. Did the Bering Sea Form as a Cenozoic Backarc Basin?

    Science.gov (United States)

    Stern, R. J.; Barth, G. A.; Scheirer, D. S.; Scholl, D. W.

    2012-12-01

    Understanding the origins of Bering Sea marginal basins (Aleutian, Bowers, and Komandorsky basins; AB, BB, KB) is key for reconstructing N. Pacific tectonic and magmatic evolution. New acquisitions and recompilations of MCS, OBS, and potential field data (Barth et al. poster. this session) for USGS Extended Continental Shelf project and selection of Aleutians as GeoPrisms Subduction Cycles and Deformation focus site stimulate reconsideration of BB, KB, and especially AB origins. AB has long been regarded as N. Pacific crust trapped when the Aleutian subduction began ~45-50 Ma. BB and KB probably formed together as Miocene backarc basins. Presence of Oligo-Miocene arc volcanics on Bowers and Shirshov ridges suggests that these are remnant arcs, orphaned by AB and KB opening. Seven lines of evidence suggest that AB formed as a Paleogene backarc basin: 1) AB heatflow suggests an age of about 44 Ma (Langseth et al 1980 JGR). 2) Formation of NNW-trending rift basins on Bering shelf (Navarin, Pribilof, and St. George basins) in Paleogene time indicate extension at this time. 3) The early Paleogene "red unconformity" of the Beringian margin could indicate uplift, erosion, and subsidence associated with AB opening. 4) ~N-S magnetic anomalies in AB contrasts with E-W Kula anomalies on N. Pacific, indicating that the two tracts of oceanic crust formed at different spreading ridges. 5) Thicker sediment in AB (2-4 km) vs. BB and KB (oceanic crust.ectonic scenario for formation of Aleutian Arc and Bering Sea basins. Green = present land; yellow = shelf; AB = Aleutian Basin; KB = Komandorsky Basin; BB = Bowers Basin; SR = Shirshov Ridge, BR = Bowers Ridge; Red = active volcanism and spreading ; Blue = extinct volcanism and spreading

  10. Sand waves on an epicontinental shelf: Northern Bering Sea

    Science.gov (United States)

    Field, M.E.; Nelson, C.H.; Cacchione, D.A.; Drake, D.E.

    1981-01-01

    Sand waves and current ripples occupy the crests and flanks of a series of large linear sand ridges (20 km ?? 5 km ?? 10 m high) lying in an open-marine setting in the northern Bering Sea. The sand wave area, which lies west of Seward Peninsula and southeast of Bering Strait, is exposed to the strong continuous flow of coastal water northward toward Bering Strait. A hierarchy of three sizes of superimposed bedforms, all facing northward, was observed in successive cruises in 1976 and 1977. Large sand waves (height 2 m; spacing 200 m) have smaller sand waves (height 1 m; spacing 20 m) lying at a small oblique angle on their stoss slopes. The smaller sand waves in turn have linguoid ripples on their stoss slopes. Repeated studies of the sand wave fields were made both years with high-resolution seismic-reflection profiles, side-scan sonographs, underwater photographs, current-meter stations, vibracores, and suspended-sediment samplers. Comparison of seismic and side-scan data collected along profile lines run both years showed changes in sand wave shape that indicate significant bedload transport within the year. Gouge marks made in sediment by keels of floating ice also showed significantly different patterns each year, further documenting modification to the bottom by sediment transport. During calm sea conditions in 1977, underwater video and camera observations showed formation and active migration of linguoid and straight-crested current ripples. Current speeds 1 m above the bottom were between 20 and 30 cm/s. Maximum current velocities and sand wave migration apparently occur when strong southwesterly winds enhance the steady northerly flow of coastal water. Many cross-stratified sand bodies in the geologic record are interpreted as having formed in a tidal- or storm-dominated setting. This study provides an example of formation and migration of large bedforms by the interaction of storms with strong uniform coastal currents in an open-marine setting. ?? 1981.

  11. Sea ice dynamics across the Mid-Pleistocene transition in the Bering Sea.

    Science.gov (United States)

    Detlef, H; Belt, S T; Sosdian, S M; Smik, L; Lear, C H; Hall, I R; Cabedo-Sanz, P; Husum, K; Kender, S

    2018-03-05

    Sea ice and associated feedback mechanisms play an important role for both long- and short-term climate change. Our ability to predict future sea ice extent, however, hinges on a greater understanding of past sea ice dynamics. Here we investigate sea ice changes in the eastern Bering Sea prior to, across, and after the Mid-Pleistocene transition (MPT). The sea ice record, based on the Arctic sea ice biomarker IP 25 and related open water proxies from the International Ocean Discovery Program Site U1343, shows a substantial increase in sea ice extent across the MPT. The occurrence of late-glacial/deglacial sea ice maxima are consistent with sea ice/land ice hysteresis and land-glacier retreat via the temperature-precipitation feedback. We also identify interactions of sea ice with phytoplankton growth and ocean circulation patterns, which have important implications for glacial North Pacific Intermediate Water formation and potentially North Pacific abyssal carbon storage.

  12. Skate Bathyraja spp. egg predation in the eastern Bering Sea.

    Science.gov (United States)

    Hoff, G R

    2009-01-01

    Predation on skate eggs by snails was examined for three skate species at seven nursery sites in three regions (north, middle and south) of the eastern Bering Sea. Mean predation levels were 6.46% for the Alaska skate Bathyraja parmifera, 2.65% for the Aleutian skate Bathyraja aleutica and 22.25% for the Bering skate Bathyraja interrupta. Predation levels were significantly higher at the middle and north sites than the south sites for all species combined. Predation levels decreased with increasing egg-case densities at all nursery sites, and the highest predation levels occurred where egg-case densities were very low. Predated egg-case density increased with increasing snail densities across all nursery sites examined. The Oregon triton Fusitriton oregonensis was the most abundant snail species at all nursery sites and displayed ability to drill holes in the egg case of B. parmifera. Holes left by predatory snails in egg cases of B. parmifera were significantly larger, and of different shape at the middle site compared to the south site. Holes in B. parmifera were also significantly larger than those in egg cases of B. interrupta across all sites examined. Egg cases of B. aleutica possess surface spines that cover the egg case and may inhibit predation by snails at a greater rate than that of the B. parmifera and B. interrupta, which have a smoother egg-case surface.

  13. Impact of climate warming on upper layer of the Bering Sea

    Science.gov (United States)

    Lee, Hyun-Chul; Delworth, Thomas L.; Rosati, Anthony; Zhang, Rong; Anderson, Whit G.; Zeng, Fanrong; Stock, Charles A.; Gnanadesikan, Anand; Dixon, Keith W.; Griffies, Stephen M.

    2013-01-01

    The impact of climate warming on the upper layer of the Bering Sea is investigated by using a high-resolution coupled global climate model. The model is forced by increasing atmospheric CO2 at a rate of 1% per year until CO2 reaches double its initial value (after 70 years), after which it is held constant. In response to this forcing, the upper layer of the Bering Sea warms by about 2°C in the southeastern shelf and by a little more than 1°C in the western basin. The wintertime ventilation to the permanent thermocline weakens in the western Bering Sea. After CO2 doubling, the southeastern shelf of the Bering Sea becomes almost ice-free in March, and the stratification of the upper layer strengthens in May and June. Changes of physical condition due to the climate warming would impact the pre-condition of spring bio-productivity in the southeastern shelf.

  14. AFSC FIT Pacific cod tagging data from the Bering Sea, 2002-2006

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data from opportunistic tagging studies in the southest Bering Sea 2002-2003. Individually numbered loop spaghetti tags released during research cruises; all...

  15. AFSC/ABL: Chum salmon bycatch genetic stock identification 1994-1995 Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In some years, the Bering Sea trawl fishery incidentally harvests (bycatch) large numbers of chum salmon. Because chum salmon were declining in some western Alaska...

  16. AFSC/ABL: Eastern Bering Sea (BASIS) Coastal Research on Juvenile Salmon (Oceanography data)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Pacific salmon (Oncorhynchus spp.) runs in rivers that flow into the eastern Bering Sea have been inconsistent and at times very weak. Low returns of chinook (O....

  17. AFSC/ABL: Eastern Bering Sea (BASIS) Coastal Research on Juvenile Salmon (TSG-thermosalinigraph data)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Pacific salmon (Oncorhynchus spp.) runs in rivers that flow into the eastern Bering Sea have been inconsistent and at times very weak. Low returns of chinook (O....

  18. AFSC/RACE/MACE: Results of 2007 Pollock Acoustic-Trawl Survey Bering Sea- DY0707

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Eastern Bering Sea shelf walleye pollock (Theragra chalcogramma) abundance and distribution in midwater were assessed between 2 June and 30 July 2007 using echo...

  19. AFSC/RACE/MACE: Results of 2014 Pollock Acoustic-Trawl Survey Bering Sea- DY1407

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Eastern Bering Sea shelf walleye pollock (Gadus chalcogrammus) midwater abundance and distribution were assessed from Bristol Bay in the United States, to Cape...

  20. AFSC/ABL: 2008 Chum Salmon Bycatch Sample Analysis Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2008 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was...

  1. AFSC/ABL: Eastern Bering Sea (BASIS) Coastal Research on Juvenile Salmon

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Pacific salmon (Oncorhynchus spp.) runs in rivers that flow into the eastern Bering Sea have been inconsistent and at times very weak. Low returns of chinook (O....

  2. AFSC/ABL: Eastern Bering Sea (EMA-BASIS) Zooplankton data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Pacific salmon (Oncorhynchus spp.) runs in rivers that flow into the eastern Bering Sea have been inconsistent and at times very weak. Low returns of chinook (O....

  3. AFSC/RACE/EcoFOCI: 2010 Eastern Bering Sea Juvenile Survey - 1MF10

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data collected on this cruise included the following: We conducted a juvenile fish and benthic fish prey survery in the eastern Bering Sea (61 3-meter beam trawls,...

  4. AFSC/RACE/MACE: Results of 2009 Pollock Acoustic-Trawl Survey Bering Sea- DY0909

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Eastern Bering Sea shelf walleye pollock (Theragra chalcogramma) abundance and distribution in midwater were assessed between 9 June and 7 August 2009 using...

  5. Obsolete - AFSC/RACE/Eco-FOCI: 2010 Eastern Bering Sea Juvenile Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data collected on this cruise included the following: We conducted a juvenile fish and benthic fish prey survery in the eastern Bering Sea (61 3-meter beam trawls,...

  6. AFSC/ABL: 2007 Chum Salmon Bycatch Sample Analysis Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2007 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was...

  7. AFSC/ABL: 2012 Chum Salmon Bycatch Sample Analysis Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch from the 2012 Bering Sea walleye pollock (Gadus chalcogrammus) trawl fishery was...

  8. AFSC/ABL: 2009 Chum Salmon Bycatch Sample Analysis Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2009 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was...

  9. AFSC/ABL: 2010 Chum Salmon Bycatch Sample Analysis Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2010 Bering Sea groundfish trawl fishery was undertaken to determine the...

  10. AFSC/ABL: 2011 Chum Salmon Bycatch Sample Analysis Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch from the 2011 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was...

  11. Particle sizes of Pliocene and Pleistocene core sediments from IODP Expedition 323 in the Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data compilation includes the results of grain size analyses of core sediment collected by IODP during Expedition 323 in the Bering Sea. One dataset is included...

  12. AFSC/ABL: 2005 Chum Salmon Bycatch Sample Analysis Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2005 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was...

  13. AFSC/ABL: 2006 Chum Salmon Bycatch Sample Analysis Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A genetic analysis of samples from the chum salmon (Oncorhynchus keta) bycatch of the 2006 Bering Sea walleye pollock (Theragra chalcogramma) trawl fishery was...

  14. AFSC/RACE/MACE: Results of 2012 Pollock Acoustic-Trawl Survey Bering Sea- DY1207

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Eastern Bering Sea shelf walleye pollock (Theragra chalcogramma) midwater abundance and distribution were assessed from Bristol Bay in the United States, to Cape...

  15. AFSC/RACE/MACE: Results of 2010 Pollock Acoustic-Trawl Survey Bering Sea- DY1006

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Eastern Bering Sea shelf walleye pollock (Theragra chalcogramma) abundance and distribution in midwater were assessed between 5 June and 7 August 2010 using...

  16. An Interdecadal Increase in the Spring Bering Sea Ice Cover in 2007

    Directory of Open Access Journals (Sweden)

    Renguang eWu

    2016-03-01

    Full Text Available The sea ice coverage of the Northern Hemisphere as a whole has been declining since 1979. On contrary, the March-April sea ice concentration in the Bering Sea experienced a prominent increase in year 2007. The present study documents the changes in surface air temperature, surface heat fluxes, sea surface temperature, and atmospheric circulation accompanying the above interdecadal change in the Bering Sea ice concentration. It is shown that an obvious decrease in surface air temperature, sea surface temperature, and surface net shortwave radiation occurred in concurrent with the sea ice increase. The surface air temperature decrease is associated with a large-scale circulation change, featuring a decrease in sea level pressure extending from the Pacific coast of Alaska to northwestern Europe and an increase in sea level pressure over the high-latitude Asia and the high-latitude North Atlantic Ocean. The enhancement of northwesterly winds over the Bering Sea led to a large decrease in surface air temperature there. The associated increase in upward turbulent heat flux cooled the sea surface temperature in the waters south of the ice covered region, favoring the southward expansion of ice extent. This, together with a positive ice-albedo feedback, amplified the sea ice anomalies after they were initiated, leading to the interdecadal increase in sea ice in the Bering Sea.

  17. Biogeochemical Cycling and Sea Ice Dynamics in the Bering Sea across the Mid-Pleistocene Transition

    Science.gov (United States)

    Detlef, H.; Sosdian, S. M.; Belt, S. T.; Smik, L.; Lear, C. H.; Hall, I. R.; Kender, S.; Leng, M. J.; Husum, K.; Cabedo-Sanz, P.

    2017-12-01

    Today the Bering Sea is characterized by high primary productivity (PP) along the eastern shelf, maintained by CO2 and nutrient rich upwelled deep waters and nutrient release during spring sea ice melting. As such, low oxygen concentrations are pervasive in mid-depth waters. Changes in ventilation and export productivity in the past have been shown to impact this oxygen minimum zone. On glacial/interglacial (G/IG) timescales sea ice formation plays a pivotal role on intermediate water ventilation with evidence pointing to the formation of North Pacific Intermediate Water (NPIW) in the Bering Sea during Pleistocene glacial intervals. In addition, sea ice plays a significant role in both long- and short-term climate change via associated feedback mechanisms. Thus, records of sea ice dynamics and biogeochemical cycling in the Bering Sea are necessary to fully understand the interaction between PP, circulation patterns, and past G/IG climates with potential implications for the North Pacific carbon cycle. Here we use a multi-proxy approach to study sea ice dynamics and bottom water oxygenation, across three intervals prior to, across, and after the Mid-Pleistocene Transition (MPT, 1.2-0.7 Ma) from International Ocean Discovery Program Site U1343. The MPT, most likely driven by internal climate mechanisms, is ideal to study changes in sea ice dynamics and sedimentary redox conditions on orbital timescales and to investigate the implications for associated feedback mechanisms. The sea ice record, based on various biomarkers, including IP25, shows substantial increase in sea ice extent across the MPT and the occurrence of a late-glacial/deglacial sea ice spike, with consequences for glacial NPIW formation and land glacier retreat via the temperature-precipitation feedback. U/Mn of foraminiferal authigenic coatings, a novel proxy for bottom water oxygenation, also shows distinct variability on G/IG timescales across the MPT, most likely a result of PP and water mass

  18. Environmental controls on spatial variability of summer phytoplankton structure and biomass in the Bering Sea

    Science.gov (United States)

    Wang, Yu; Xiang, Peng; Kang, Jian-hua; Ye, You-yin; Lin, Geng-ming; Yang, Qing-liang; Lin, Mao

    2018-01-01

    The subarctic Bering Sea, one of the most productive regions of the world's oceans, is undergoing significant ecological shifts possibly linked to global climate change. During the Fourth Chinese National Arctic Research Expedition (CHINARE) from July 10 to 20 of 2010, phytoplankton community structure, species diversity, spatial distribution, community types, abundance and biomass variations were investigated in a large scale study extending from the Bering Strait into the open waters down to the subarctic Pacific. These patterns were linked to potential environmental drivers, including effects of water masses and seasonal sea ice retreat. Results showed a marked spatial zonation in the taxonomic composition, abundance and biomass. A total of 149 phytoplankton taxa distributed among 57 genera of 5 phyla were identified, characterized into three ecological groups, namely Arctic, Boreal-temperate and cosmopolitan species. Phytoplankton included 101 species of diatoms, 44 species of dinoflagellates, 2 species of Chrysophyta, 1 species of each Chlorophyta and Euglenophyta. Both abundance and biomass were highest in the Bering Shelf, moderate on the Bering Slope, and lowest on the Bering Basin. Chlorophyll a was found highest in the subsurface chlorophyll maxima (SCM) close to the thermocline and halocline layers but its depth varied regionally. Multi-dimensional scaling (MDS) revealed two types of assemblages, one a deep-sea assemblage associated with the Bering Basin and a neritic assemblage found in the Bering Slope and Shelf. Average abundance (10.22 × 103 cells/L), biomass (0.43 mg/m3), species diversity (2.60) and species richness (1.66) were established for deep-sea assemblage with the dominant species ranked as Neodenticula seminae, Chaetoceros atlanticus, Pseudonitzschia delicatissima, and Thalassionema nitzschioides. Neritic assemblage had higher values with 12.73 × 103 cells/L, 2.41 mg/m3, and 2.55 species richness but lower (2.41) species diversity, and

  19. Oxygen isotopic composition and its application to the study of tracing oceanographical process in Bering Sea and Chukchi Sea

    Institute of Scientific and Technical Information of China (English)

    尹明端; 曾宪章; 曾文义; 吴世炎; 施纯坦

    2002-01-01

    In this paper, the 18O distribution of surface water from the central sea areas of the Bering Sea and the Chukchi Sea was studied. The δ18O value of surface water from the Bering Sea is averagely -0.5‰; the δ18O contents of the Chukchi Sea are distributionally lower in northeast and higher in southwest; the δ18O value at the margin of Canadian Basin is -2.8‰, and averagely -0.8‰ in the southern area of the Chukchi Sea. The δ18O vertical distribution in some deep water stations from the Chukchi Sea and the Bering Sea is also studied. In the southern margin of Canadian Basin, the δ18O value is -2‰ -3‰ for surface layer and rises to 0 at 100 m depth layer. In the Bering Sea, the δ18O is about -0.5‰ for surface layer and increases to 0 at the depth of 300 m. The NO tracer can reflect obviously three water masses vertically distributed in the central Bering Sea: the upper Bering water mass, the middle Bering water mass and the deep Pacific water mass. The distributive ranges of NO and temperature for the various water masses are T780 μmol/dm3 and T≥7℃, NO>650 μmol/dm3 for upper Bering water mass, T<4℃, 550Bering water mass, and T<4℃, 330sea bottom. Its isotopic characteristics are the same as the Atlantic water, showing that the sea water comes from the north Atlantic. The freshwater end-member of the Chukchi Sea in the survey period is also explored.

  20. 50 CFR Figure 20 to Part 679 - Steller sea lion conservation area (SCA) of the Bering Sea

    Science.gov (United States)

    2010-10-01

    ... 50 Wildlife and Fisheries 9 2010-10-01 2010-10-01 false Steller sea lion conservation area (SCA) of the Bering Sea 20 Figure 20 to Part 679 Wildlife and Fisheries FISHERY CONSERVATION AND MANAGEMENT... EXCLUSIVE ECONOMIC ZONE OFF ALASKA Pt. 679, Fig. 20 Figure 20 to Part 679—Steller sea lion conservation area...

  1. Corals, Canyons, and Conservation: Science Based Fisheries Management Decisions in the Eastern Bering Sea

    Directory of Open Access Journals (Sweden)

    Steve A. MacLean

    2017-05-01

    Full Text Available When making science matter for conservation, marine conservation practitioners, and managers must be prepared to make the appropriate decision based on the results of the best available science used to inform it. For nearly a decade, many stakeholders encouraged the North Pacific Fishery Management Council to enact protections for deep-sea corals in several canyons in the Eastern Bering Sea slope. In 2014, at the request of the Council, the National Marine Fisheries Service, Alaska Fisheries Science Center conducted a strip-transect survey along the Eastern Bering Sea slope to validate the results of a model predicting the occurrence of deep-sea coral habitat. More than 250,000 photos were analyzed to estimate coral, sponge, and sea whip abundance, distribution, height, and vulnerability to anthropogenic damage. The results of the survey confirmed that coral habitat and occurrence was concentrated around Pribilof Canyon and the adjacent slope. The results also confirmed that the densities of corals in the Eastern Bering Sea were low, even where they occurred. After reviewing the best available scientific information, the Council concluded that there is no scientific evidence to suggest that deep-sea corals in the Eastern Bering Sea slope or canyons are at risk from commercial fisheries under the current management structure, and that special protections for deep-sea corals were not warranted.

  2. 76 FR 49417 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Science.gov (United States)

    2011-08-10

    .... 100819383-0386-01] RIN 0648-BA18 Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management Area; Limited Access Privilege Program AGENCY: National Marine Fisheries... Management Plan for Groundfish of the Bering Sea and Aleutian Islands Management Area (FMP). This proposed...

  3. 76 FR 47155 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2011-08-04

    ... the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab Rationalization Program... program for the Bering Sea/Aleutian Islands crab fisheries managed under the BSAI Crab Rationalization... Center Web site at http://www.afsc.noaa.gov/ . For further information on the Crab Rationalization...

  4. Improved Chlorophyll-a Algorithm for the Satellite Ocean Color Data in the Northern Bering Sea and Southern Chukchi Sea

    Science.gov (United States)

    Lee, Sang Heon; Ryu, Jongseong; Park, Jung-woo; Lee, Dabin; Kwon, Jae-Il; Zhao, Jingping; Son, SeungHyun

    2018-03-01

    The Bering and Chukchi seas are an important conduit to the Arctic Ocean and are reported to be one of the most productive regions in the world's oceans in terms of high primary productivity that sustains large numbers of fishes, marine mammals, and sea birds as well as benthic animals. Climate-induced changes in primary production and production at higher trophic levels also have been observed in the northern Bering and Chukchi seas. Satellite ocean color observations could enable the monitoring of relatively long term patterns in chlorophyll-a (Chl-a) concentrations that would serve as an indicator of phytoplankton biomass. The performance of existing global and regional Chl-a algorithms for satellite ocean color data was investigated in the northeastern Bering Sea and southern Chukchi Sea using in situ optical measurements from the Healy 2007 cruise. The model-derived Chl-a data using the previous Chl-a algorithms present striking uncertainties regarding Chl-a concentrations-for example, overestimation in lower Chl-a concentrations or systematic overestimation in the northeastern Bering Sea and southern Chukchi Sea. Accordingly, a simple two band ratio (R rs(443)/R rs(555)) algorithm of Chl-a for the satellite ocean color data was devised for the northeastern Bering Sea and southern Chukchi Sea. The MODIS-derived Chl-a data from July 2002 to December 2014 were produced using the new Chl-a algorithm to investigate the seasonal and interannual variations of Chl-a in the northern Bering Sea and the southern Chukchi Sea. The seasonal distribution of Chl-a shows that the highest (spring bloom) Chl-a concentrations are in May and the lowest are in July in the overall area. Chl-a concentrations relatively decreased in June, particularly in the open ocean waters of the Bering Sea. The Chl-a concentrations start to increase again in August and become quite high in September. In October, Chl-a concentrations decreased in the western area of the Study area and the Alaskan

  5. The First Saildrone Scientific Mission: The Bering Sea

    Science.gov (United States)

    Cokelet, E. D.; Meinig, C.; Jenkins, R.; Lawrence-Slavas, N.; Mordy, C. W.; Tabisola, H. M.; Stabeno, P. J.; Cross, J. N.

    2016-02-01

    Unmanned surface vehicles (USV) are a rapidly advancing technology that has the potential to meet the requirement for long duration and economical scientific data collection with the ability for real-time data and adaptive sampling. In 2015, NOAA's Pacific Marine Environmental Laboratory, the University of Washington and Saildrone Inc. explored the use of a novel USV technology in the Bering Sea. Two Saildrones, wind- and solar-powered autonomous surface vehicles that can be used for extended research missions in challenging environments, were equipped with a suite of meteorological and oceanographic sensors. Each Saildrone measured position, vehicle attitude, atmospheric pressure, wind speed and direction, PAR, air temperature, relative humidity, magnetic field strength, ocean skin temperature, water temperature, salinity, dissolved oxygen concentration, chlorophyll and CDOM fluorescence. Diagnostic data were transmitted ashore every 10 minutes via Iridium satellite and updated on a web site. Command and control information was sent to the Saildrones for setting waypoints, etc. One-minute data were transmitted ashore four times per day allowing measurements to be analyzed and plotted for scientific insight and mission guidance. During this first-ever scientific mission, lasting 97 days and covering over 7600 km each, the Saildrones successfully completed several scientific survey assignments. They encountered below-freezing temperatures and winds in excess of 20 kn several times with gusts of over 46 kn. Measurements were validated against shipboard and mooring observations. Saildrone sampling strategies were modified on the fly, first to measure the effects of sea-ice melt on surface cooling and freshening, and then to study the Yukon River plume. This mission demonstrated the capability of the Saildrone vehicle to be launched from a dock to conduct autonomous and adaptive oceanographic research in a harsh, high-latitude environment.

  6. Processes driving sea ice variability in the Bering Sea in an eddying ocean/sea ice model: Mean seasonal cycle

    Science.gov (United States)

    Li, Linghan; McClean, Julie L.; Miller, Arthur J.; Eisenman, Ian; Hendershott, Myrl C.; Papadopoulos, Caroline A.

    2014-12-01

    The seasonal cycle of sea ice variability in the Bering Sea, together with the thermodynamic and dynamic processes that control it, are examined in a fine resolution (1/10°) global coupled ocean/sea-ice model configured in the Community Earth System Model (CESM) framework. The ocean/sea-ice model consists of the Los Alamos National Laboratory Parallel Ocean Program (POP) and the Los Alamos Sea Ice Model (CICE). The model was forced with time-varying reanalysis atmospheric forcing for the time period 1970-1989. This study focuses on the time period 1980-1989. The simulated seasonal-mean fields of sea ice concentration strongly resemble satellite-derived observations, as quantified by root-mean-square errors and pattern correlation coefficients. The sea ice energy budget reveals that the seasonal thermodynamic ice volume changes are dominated by the surface energy flux between the atmosphere and the ice in the northern region and by heat flux from the ocean to the ice along the southern ice edge, especially on the western side. The sea ice force balance analysis shows that sea ice motion is largely associated with wind stress. The force due to divergence of the internal ice stress tensor is large near the land boundaries in the north, and it is small in the central and southern ice-covered region. During winter, which dominates the annual mean, it is found that the simulated sea ice was mainly formed in the northern Bering Sea, with the maximum ice growth rate occurring along the coast due to cold air from northerly winds and ice motion away from the coast. South of St Lawrence Island, winds drive the model sea ice southwestward from the north to the southwestern part of the ice-covered region. Along the ice edge in the western Bering Sea, model sea ice is melted by warm ocean water, which is carried by the simulated Bering Slope Current flowing to the northwest, resulting in the S-shaped asymmetric ice edge. In spring and fall, similar thermodynamic and dynamic

  7. Optical properties and molecular diversity of dissolved organic matter in the Bering Strait and Chukchi Sea

    Science.gov (United States)

    Gonsior, Michael; Luek, Jenna; Schmitt-Kopplin, Philippe; Grebmeier, Jacqueline M.; Cooper, Lee W.

    2017-10-01

    Changes in the molecular composition of dissolved organic matter (DOM) and its light absorbing chromophoric component (CDOM) are of particular interest in the Arctic region because of climate change effects that lead to warmer sea surface temperatures and longer exposure to sunlight. We used continuous UV-vis (UV-vis) spectroscopy, excitation emission matrix fluorescence and ultrahigh resolution mass spectrometry during a transect from the Aleutian Islands in the Bering Sea to the Chukchi Sea ice edge through Bering Strait to determine the variability of DOM and CDOM. These data were combined with discrete sampling for stable oxygen isotopes of seawater, in order to evaluate the contributions of melted sea ice versus runoff to the DOM and CDOM components. This study demonstrated that high geographical resolution of optical properties in conjunction with stable oxygen ratios and non-targeted ultrahigh resolution mass spectrometry was able to distinguish between different DOM sources in the Arctic, including identification of labile DOM sources in Bering Strait associated with high algal blooms and sampling locations influenced by terrestrially-derived DOM, such as the terrestrial DOM signal originating from Arctic rivers and dirty/anchor sea ice. Results of this study also revealed the overall variability and chemodiversity of Arctic DOM present in the Bering and Chukchi Seas.

  8. Arctic sea ice decline: Projected changes in timing and extent of sea ice in the Bering and Chukchi Seas

    Science.gov (United States)

    Douglas, David C.

    2010-01-01

    The Arctic region is warming faster than most regions of the world due in part to increasing greenhouse gases and positive feedbacks associated with the loss of snow and ice cover. One consequence has been a rapid decline in Arctic sea ice over the past 3 decades?a decline that is projected to continue by state-of-the-art models. Many stakeholders are therefore interested in how global warming may change the timing and extent of sea ice Arctic-wide, and for specific regions. To inform the public and decision makers of anticipated environmental changes, scientists are striving to better understand how sea ice influences ecosystem structure, local weather, and global climate. Here, projected changes in the Bering and Chukchi Seas are examined because sea ice influences the presence of, or accessibility to, a variety of local resources of commercial and cultural value. In this study, 21st century sea ice conditions in the Bering and Chukchi Seas are based on projections by 18 general circulation models (GCMs) prepared for the fourth reporting period by the Intergovernmental Panel on Climate Change (IPCC) in 2007. Sea ice projections are analyzed for each of two IPCC greenhouse gas forcing scenarios: the A1B `business as usual? scenario and the A2 scenario that is somewhat more aggressive in its CO2 emissions during the second half of the century. A large spread of uncertainty among projections by all 18 models was constrained by creating model subsets that excluded GCMs that poorly simulated the 1979-2008 satellite record of ice extent and seasonality. At the end of the 21st century (2090-2099), median sea ice projections among all combinations of model ensemble and forcing scenario were qualitatively similar. June is projected to experience the least amount of sea ice loss among all months. For the Chukchi Sea, projections show extensive ice melt during July and ice-free conditions during August, September, and October by the end of the century, with high agreement

  9. 76 FR 17360 - Fisheries of the Exclusive Economic Zone Off Alaska; Octopus in the Bering Sea and Aleutian...

    Science.gov (United States)

    2011-03-29

    .... 101126521-0640-02] RIN 0648-XA322 Fisheries of the Exclusive Economic Zone Off Alaska; Octopus in the Bering... allowable catch of octopus in the Bering Sea and Aleutian Islands (BSAI). This action is necessary to allow... subpart H of 50 CFR part 600 and 50 CFR part 679. The 2011 initial total allowable catch (ITAC) of octopus...

  10. 76 FR 55276 - Fisheries of the Exclusive Economic Zone Off Alaska; Octopus in the Bering Sea and Aleutian Islands

    Science.gov (United States)

    2011-09-07

    .... 101126521-0640-02] RIN 0648-XA683 Fisheries of the Exclusive Economic Zone Off Alaska; Octopus in the Bering... retention of octopus in the Bering Sea and Aleutian Islands (BSAI). This action is necessary because the 2011 total allowable catch of octopus in the BSAI has been reached. DATES: Effective 1200 hrs, Alaska...

  11. 76 FR 59924 - Fisheries of the Exclusive Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian...

    Science.gov (United States)

    2011-09-28

    .... 101126521-0640-2] RIN 0648-XA733 Fisheries of the Exclusive Economic Zone Off Alaska; Sharks in the Bering... prohibiting retention of sharks in the Bering Sea and Aleutian Islands management area (BSAI). This action is necessary because the 2011 total allowable catch (TAC) of sharks in the BSAI has been reached. DATES...

  12. 78 FR 57097 - Fisheries of the Exclusive Economic Zone Off Alaska; Sharks in the Bering Sea and Aleutian...

    Science.gov (United States)

    2013-09-17

    .... 121018563-3418-02] RIN 0648-XC872 Fisheries of the Exclusive Economic Zone Off Alaska; Sharks in the Bering... prohibiting retention of sharks in the Bering Sea and Aleutian Islands management area (BSAI). This action is necessary because the 2013 total allowable catch (TAC) of sharks in the BSAI has been reached. DATES...

  13. Front affecting the distribution of seabirds in the northern Bering Sea

    OpenAIRE

    Harrison, Nancy M.; L Hunt Jr., George; Cooney, Robert T.

    1990-01-01

    We observed seabirds aggregated at a front marking the boundary between two water masses in the Bering Sea. Least Auklets (Aethia pusilla) were most abundant at the front; surface-feeding species including Northern Fulmars (Fulmarus glacialis), Black-legged Kittiwakes (Rissa tridactyla) and Red Phalaropes (Phalaropusfuscus) were also present.

  14. Pliocene cooling enhanced by flow of low-salinity Bering Sea water to the Arctic Ocean.

    Science.gov (United States)

    Horikawa, Keiji; Martin, Ellen E; Basak, Chandranath; Onodera, Jonaotaro; Seki, Osamu; Sakamoto, Tatsuhiko; Ikehara, Minoru; Sakai, Saburo; Kawamura, Kimitaka

    2015-06-29

    Warming of high northern latitudes in the Pliocene (5.33-2.58 Myr ago) has been linked to the closure of the Central American Seaway and intensification of North Atlantic Deep Water. Subsequent cooling in the late Pliocene may be related to the effects of freshwater input from the Arctic Ocean via the Bering Strait, disrupting North Atlantic Deep Water formation and enhancing sea ice formation. However, the timing of Arctic freshening has not been defined. Here we present neodymium and lead isotope records of detrital sediment from the Bering Sea for the past 4.3 million years. Isotopic data suggest the presence of Alaskan glaciers as far back as 4.2 Myr ago, while diatom and C37:4 alkenone records show a long-term trend towards colder and fresher water in the Bering Sea beginning with the M2 glaciation (3.3 Myr ago). We argue that the introduction of low-salinity Bering Sea water to the Arctic Ocean by 3.3 Myr ago preconditioned the climate system for global cooling.

  15. 75 FR 59687 - Proposed Information Collection; Comment Request; Alaska Region Bering Sea & Aleutian Islands...

    Science.gov (United States)

    2010-09-28

    ... among harvesters, processors, and coastal communities and monitors the ``economic stability for... Collection; Comment Request; Alaska Region Bering Sea & Aleutian Islands (BSAI) Crab Economic Data Reports... CR Program's mandatory economic data collection report (EDR) used to assess the efficacy of the CR...

  16. Potential impact of increased temperature and CO2 on particulate dimethylsulfoniopropionate in the Southeastern Bering Sea

    Directory of Open Access Journals (Sweden)

    Peter A. Lee

    2011-06-01

    Full Text Available The potential impact of elevated sea surface temperature (SST and pCO2 on algal community structure and particulate dimethylsulfoniopropionate (DMSPp concentrations in the southeastern Bering Sea was examined using a shipboard “Ecostat” continuous culture system. The ecostat system was used to mimic the conditions projected to exist in the world's oceans by the end of this century (i.e. elevated pCO2 (750 ppm and elevated SST (ambient + 4°C. Two experiments were conducted using natural phytoplankton assemblages from the high-nutrient low-chlorophyll (HNLC central basin and from the middle domain of the southeastern continental shelf. At the HNLC site, the relative abundances of haptophytes and pelagophytes were higher and the relative abundance of diatoms lower under “greenhouse” conditions (i.e. combined 750 ppm CO2 and elevated temperature than control conditions (380 ppm CO2 and ambient temperature. This shift in algal community structure was accompanied by increases in DMSPp (2–3 fold, DMSPp:Chl a (2–3 fold and DMSP:PON (2 fold. At the continental shelf site, the changes in the relative abundances of haptophytes, pelagophytes and diatoms under “greenhouse” conditions were similar to those observed at the HNLC site, with 2.5 fold increases in DMSPp, 50–100% increases in DMSPp:Chl a and 1.8 fold increases in DMSP:PON. At both locations, changes in community structure and the DMSPp parameters were largely driven by increasing temperature. The observed changes were also consistent with the phytoplankton-DMS-albedo climate feedback mechanism proposed in the Charlson-Lovelock-Andreae-Warren (CLAW hypothesis.

  17. Growth Rate Potential of Juvenile Sockeye Salmon in Warmer and Cooler Years on the Eastern Bering Sea Shelf

    Directory of Open Access Journals (Sweden)

    Edward V. Farley

    2009-01-01

    Full Text Available A spatially explicit bioenergetics model was used to predict juvenile sockeye salmon Oncorhynchus nerka growth rate potential (GRP on the eastern Bering Sea shelf during years with cooler and warmer spring sea surface temperatures (SSTs. Annual averages of juvenile sockeye salmon GRP were generally lower among years with cooler SSTs and generally higher in offshore than nearshore regions of the eastern Bering Sea shelf during years with warmer SSTs. Juvenile sockeye salmon distribution was significantly (P<.05 related to GRP and their prey densities were positively related to spring SST (P<.05. Juvenile sockeye salmon GRP was more sensitive to changes in prey density and observed SSTs during years when spring SSTs were warmer (2002, 2003, and 2005. Our results suggest that the pelagic productivity on the eastern Bering Sea shelf was higher during years with warmer spring SSTs and highlight the importance of bottom-up control on the eastern Bering Sea ecosystem.

  18. The physiological adaptations and toxin profiles of the toxic Alexandrium fundyense on the eastern Bering Sea and Chukchi Sea shelves.

    Science.gov (United States)

    Natsuike, Masafumi; Oikawa, Hiroshi; Matsuno, Kohei; Yamaguchi, Atsushi; Imai, Ichiro

    2017-03-01

    Abundant cyst distributions of the toxic dinoflagellate Alexandrium fundyense (previous A. tamarense north American clade) were recently observed on the north Chukchi Sea shelf and on the eastern Bering Sea shelf, suggesting that A. fundyense is both highly adapted to the local environments in the high latitude areas and might cause toxin contamination of plankton feeders. However, little is known about the physiological characteristics and toxin profiles of A. fundyense in these areas, which are characterized by low water temperatures, weak sunlight, and more or less permanent ice cover during winter. To clarify the physiological characteristics of A. fundyense, the effects of water temperature and light intensity on the vegetative growth and toxin profiles of this species were examined using A. fundyense strains isolated from one sediment sample collected from each area. Using the same sediments samples, seasonal changes of the cyst germination in different water temperatures were investigated. Vegetative cells grew at temperatures as low as 5°C and survived at 1°C under relatively low light intensity. They also grew at moderate water temperatures (10-15°C). Their cysts could germinate at low temperatures (1°C) and have an endogenous dormancy period from late summer to early spring, and warmer water temperatures (5-15°C) increased germination success. These physiological characteristics suggest that A. fundyense in the Chukchi Sea and eastern Bering Sea is adapted to the environments of high latitude areas. In addition, the results suggest that in the study areas A. fundyense has the potential to germinate and grow when water temperatures increase. Cellular toxin amounts of A. fundyense strains from the eastern Bering Sea and Chukchi Sea were ranged from 7.2 to 38.2 fmol cell -1 . These toxin amounts are comparable with A. fundyense strains isolated from other areas where PSP toxin contamination of bivalves occurs. The dominant toxin of the strains isolated

  19. AFSC/NMML: Cetacean line-transect survey in the eastern Bering Sea shelf; 1999, 2000, 2002, and 2004

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Visual surveys for cetaceans were conducted on the eastern Bering Sea shelf along transect lines, in association with the AFSC.s echo integration trawl surveys for...

  20. BAROMETRIC PRESSURE and Other Data from ALPHA HELIX From Bering Sea from 19940503 to 19940608 (NODC Accession 9500029)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in Bering Sea as part of Inner SHelf Transfer and recycling (ISHTAR) and "St. Lawrence...

  1. AFSC/REFM: Movement of Alaska skates (Bathyraja parmifera) in the Bering Sea , determined through conventional tagging

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains the results of a tagging study being conducted on the Alaska skate (Bathyraja parmifera) in the eastern Bering Sea. The purpose of the study is...

  2. AFSC/NMML: Passive acoustic sonobuoy recordings from Bering, Chukchi, and Beaufort Seas in Alaska, 2007-2014

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The National Marine Mammal Laboratory (NMML) has conducted passive acoustic monitoring in the Bering, Chukchi, and Western Beaufort Seas to determine spatio-temporal...

  3. Acoustic-Trawl Survey of Walleye Pollock on the Eastern Bering Sea Shelf (DY1407, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — National Marine Fisheries Service (NMFS), Alaska Fisheries Science Center (AFSC) conducted an acoustic-trawl (AT) stock assessment survey on the eastern Bering Sea...

  4. NPRB711 Quantification of unobserved injury and mortality of Bering Sea crabs due to encounters with trawls on the seafloor

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The potential for unobserved mortality of crabs encountering bottom trawls, but not captured, has long been a concern in the management of Bering Sea fisheries. We...

  5. AFSC/RACE/FBEP/Hurst: Contrasting coastal and shelf nursery habitats of Pacific cod in the southeastern Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is from a study examining the use of demersal and pelagic habitats in the southeast Bering Sea by age-0 Pacific cod, based on 4 years of demersal trawl...

  6. Pacific walrus (Odobenus rosmarus divergens resource selection in the Northern Bering Sea.

    Directory of Open Access Journals (Sweden)

    Chadwick V Jay

    Full Text Available The Pacific walrus is a large benthivore with an annual range extending across the continental shelves of the Bering and Chukchi Seas. We used a discrete choice model to estimate site selection by adult radio-tagged walruses relative to the availability of the caloric biomass of benthic infauna and sea ice concentration in a prominent walrus wintering area in the northern Bering Sea (St. Lawrence Island polynya in 2006, 2008, and 2009. At least 60% of the total caloric biomass of dominant macroinfauna in the study area was composed of members of the bivalve families Nuculidae, Tellinidae, and Nuculanidae. Model estimates indicated walrus site selection was related most strongly to tellinid bivalve caloric biomass distribution and that walruses selected lower ice concentrations from the mostly high ice concentrations that were available to them (quartiles: 76%, 93%, and 99%. Areas with high average predicted walrus site selection generally coincided with areas of high organic carbon input identified in other studies. Projected decreases in sea ice in the St. Lawrence Island polynya and the potential for a concomitant decline of bivalves in the region could result in a northward shift in the wintering grounds of walruses in the northern Bering Sea.

  7. Occurrence and Turnover of Biogenic Sulfur in the Bering Sea During Summer

    Science.gov (United States)

    Li, Cheng-Xuan; Wang, Bao-Dong; Yang, Gui-Peng; Wang, Zi-Cheng; Chen, Jian-Fang; Lyu, Yang

    2017-11-01

    The horizontal/geographical variations in dissolved dimethylsulfide (DMS), its precursor dimethylsulfoniopropionate (DMSPd and DMSPp), and chlorophyll a (Chl a), as well as the oceanographic parameters influencing the concentrations of dimethylated sulfur compounds, were investigated in the Bering Sea from July to August 2012. Similar to Chl a, the surface DMS and DMSPp levels, as well as DMS(P) production and consumption rates, exhibited a declining gradient from the central basin to the continental shelf, with high-value areas appearing in the central basin, the slope regions, and Anadyr Strait but a low-value area occurring on the outer-middle continental shelf. Considerably high values of DMS and DMSP were measured in the saline Bering Sea Basin Deep Water (>2,000 m) located at the southwest of the Bering Basin because of the release of resuspension in 2,000 m depth and the DMSP production from endogenous benthic bacteria and cyanobacteria population. Chl a was positively correlated with DMSPp and DMS in the surface waters and the upper water of the basin, whereas significant negative correlations were found between DMS and nutrients (dissolved inorganic nitrogen [DIN], phosphorus, and silicate) in the inner shelf of the Bering Sea. DMS microbial consumption was approximately 6.26 times faster than the DMS sea-air exchange, demonstrating that the major loss of DMS in the surface water occurred through biological consumption relative to evasion into the atmosphere. Average sea-to-air DMS fluxes were estimated to be 4.66 μmol/(m2·d), and consequently oceanic biogenic DMS emission had a dominant contribution to the sulfur budget over the observational area.

  8. The Paleoceanography of the Bering Sea During the Last Glacial Cycle

    Science.gov (United States)

    2006-02-01

    pachyderma (s.). This suggests that the P180 reflects transient warmings, but sustained freshening of surface water. 3.1 Introduction The heat...centennial and millenial time scales during the deglaciation, even though the climate system was undergoing a major transition. 60 Chapter 4 Marine Isotope...and transient warming, and a sudden and sustained freshening of surface water in the Bering Sea. I made one simple test of whether the faunal record

  9. Distribution and sources of polycyclic aromatic hydrocarbons in surface sediments from the Bering Sea and western Arctic Ocean.

    Science.gov (United States)

    Zhao, Mengwei; Wang, Weiguo; Liu, Yanguang; Dong, Linsen; Jiao, Liping; Hu, Limin; Fan, Dejiang

    2016-03-15

    To analyze the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) and evaluate their potential ecological risks, the concentrations of 16 PAHs were measured in 43 surface sediment samples from the Bering Sea and western Arctic Ocean. Total PAH (tPAH) concentrations ranged from 36.95 to 150.21 ng/g (dry weight). In descending order, the surface sediment tPAH concentrations were as follows: Canada Basin>northern Chukchi Sea>Chukchi Basin>southern Chukchi Sea>Aleutian Basin>Makarov Basin>Bering Sea shelf. The Bering Sea and western Arctic Ocean mainly received PAHs of pyrogenic origin due to pollution caused by the incomplete combustion of fossil fuels. The concentrations of PAHs in the sediments of the study areas did not exceed effects range low (ERL) values. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Evidence of increased toxic Alexandrium tamarense dinoflagellate blooms in the eastern Bering Sea in the summers of 2004 and 2005.

    Science.gov (United States)

    Natsuike, Masafumi; Saito, Rui; Fujiwara, Amane; Matsuno, Kohei; Yamaguchi, Atsushi; Shiga, Naonobu; Hirawake, Toru; Kikuchi, Takashi; Nishino, Shigeto; Imai, Ichiro

    2017-01-01

    The eastern Bering Sea has a vast continental shelf, which contains various endangered marine mammals and large fishery resources. Recently, high numbers of toxic A. tamarense resting cysts were found in the bottom sediment surface of the eastern Bering Sea shelf, suggesting that the blooms have recently occurred. However, little is known about the presence of A. tamarense vegetative cells in the eastern Bering Sea. This study's goals were to detect the occurrence of A. tamarense vegetative cells on the eastern Bering Sea shelf and to find a relationship between environmental factors and their presence. Inter-annual field surveys were conducted to detect A. tamarense cells and environmental factors, such as nutrients, salinity, chlorophyll a, and water temperature, along a transect line on the eastern Bering Sea shelf during the summers of 2004, 2005, 2006, 2009, 2012, and 2013. A. tamarense vegetative cells were detected during every sampling year, and their quantities varied greatly from year to year. The maximum cell densities of A. tamarense observed during the summers of 2004 and 2005 were much higher than the Paralytic shellfish poisoning warning levels, which are greater than 100-1,000 cells L-1, in other subarctic areas. Lower quantities of the species occurred during the summers of 2009, 2012, and 2013. A significant positive correlation between A. tamarense quantity and water temperature and significant negative correlations between A. tamarense quantity and nutrient concentrations (of phosphate, silicate, and nitrite and nitrate) were detected in every sampling period. The surface- and bottom-water temperatures varied significantly from year to year, suggesting that water temperatures, which have been known to affect the cell growth and cyst germination of A. tamarense, might have affected the cells' quantities in the eastern Bering Sea each summer. Thus, an increase in the Bering Sea shelf's water temperature during the summer will increase the

  11. Bioindicators of Organochlorine Pesticides in the Sea of Okhotsk and the Western Bering Sea.

    Science.gov (United States)

    Tsygankov, Vasiliy Yu; Boyarova, Margarita D; Lukyanova, Olga N; Khristoforova, Nadezhda K

    2017-08-01

    Organochlorine pesticides (OCPs), such as HCHs and DDTs, are still used as pesticides in the Southern Hemisphere and can reach the North Pacific due to long range atmospheric transfer. Marine mammals (Pacific walrus Odobenus rosmarus divergens, gray whale Eschrichtius robustus), the seabirds (Pacific gull Larus schistisagus, crested auklet Aethia cristatella, auklet crumb Aethia pusilla, northern fulmar Fulmarus glacialis, and grey petrel Oceanodroma furcata) and Pacific salmon (pink Oncorhynchus gorbuscha, chum O. keta, chinook O. tshawytscha, and sockeye O. nerka) were collected near the Kuril Islands (the northern-western part of the Pacific Ocean), in the Sea of Okhotsk and the Bering Sea. The total OCPs concentration (HCHs + DDTs) was found in each organism, including the Pacific walrus (70-90,263 ng/g lipid), the seabirds (29-16,095 ng/g lipid), and the Pacific salmon (41-7103 ng/g lipid). The concentrations and possible sources of OCPs in marine organisms as biological indicators are discussed.

  12. Foraging ecology as related to the distribution of planktivorous auklets in the Bering Sea

    Science.gov (United States)

    Hunt, George L.; Harrison, Nancy M.; Piatt, John F.

    1993-01-01

    We review recent accounts of the foraging ecologies of  five species of small auklets found in the Bering Sea. These birds eat a wide variety of zooplankton and micronekton. Least Auklets Aethia pusilla and Whiskered Auklets A. pygmaea, as far as is known, primarily eat copepods, whereas Created Auklets A. cristatella appear to specialize on euphausiids, at least during the breeding season. The diet of Parakeet Auklets Cyclorrhynchus psittacula is much broader than that of most other Aethia species, and includes many gelatinous species and their commensals. Little is known of the diet of Cassin's Auklet Ptychoramphus aleuticus in the Bering Sea, although elsewhere they take large copepods, euphausiids, and larval fish.There are considerable differences in the at-sea distributions and foraging behaviors of these five species of auklet. Least Auklets in the norhtern Bering Sea concentrate their foraging activities over strongly stratified water and near fronts where pycnoclines may approach the surface. In the Aleutian Islands, Least Auklets forage where oceanic and tidal currents strike the shelf between the islands and rise toward the surface carrying plankton. Least Auklets and Crested Auklets are often found in large flocks, whereas Parakeet Auklets are rarely found in groups of more than three birds and are usually widely dispersed. The few at-sea observations of Whiskered Auklets have been of small flocks in turbulent waters of island passes. We relate prey types taken, foraging dispersion, and the use of hydrographic features by these auklet species.

  13. Habitat selection and seasonal movements of young bearded seals (Erignathus barbatus in the Bering Sea.

    Directory of Open Access Journals (Sweden)

    Michael F Cameron

    Full Text Available The first year of life is typically the most critical to a pinniped's survival, especially for Arctic phocids which are weaned at only a few weeks of age and left to locate and capture prey on their own. Their seasonal movements and habitat selection are therefore important factors in their survival. During a cooperative effort between scientists and subsistence hunters in October 2004, 2005, and 2006, 13 female and 13 male young (i.e., age <2 bearded seals (Erignathus barbatus were tagged with satellite-linked dive recorders (SDRs in Kotzebue Sound, Alaska. Shortly after being released, most seals moved south with the advancing sea-ice through the Bering Strait and into the Bering Sea where they spent the winter and early spring. The SDRs of 17 (8 female and 9 male seals provided frequent high-quality positions in the Bering Sea; their data were used in our analysis. To investigate habitat selection, we simulated 20 tracks per seal by randomly selecting from the pooled distributions of the absolute bearings and swim speeds of the tagged seals. For each point in the observed and simulated tracks, we obtained the depth, sea-ice concentration, and the distances to sea-ice, open water, the shelf break and coastline. Using logistic regression with a stepwise model selection procedure, we compared the simulated tracks to those of the tagged seals and obtained a model for describing habitat selection. The regression coefficients indicated that the bearded seals in our study selected locations near the ice edge. In contrast, aerial surveys of the bearded seal population, predominantly composed of adults, indicated higher abundances in areas farther north and in heavier pack ice. We hypothesize that this discrepancy is the result of behavioral differences related to age. Ice concentration was also shown to be a statistically significant variable in our model. All else being equal, areas of higher ice concentration are selected for up to about 80%. The

  14. Abrupt changes of intermediate water properties on the northeastern slope of the Bering Sea during the last glacial and deglacial period

    Science.gov (United States)

    Rella, Stephan F.; Tada, Ryuji; Nagashima, Kana; Ikehara, Minoru; Itaki, Takuya; Ohkushi, Ken'ichi; Sakamoto, Tatsuhiko; Harada, Naomi; Uchida, Masao

    2012-09-01

    Millennial-scale variability in the behavior of North Pacific Intermediate Water during the last glacial and deglacial period, and its association with Dansgaard-Oeschger (D-O) cycles and Heinrich events, are examined based on benthic foraminiferal oxygen and carbon isotopes (δ18Obf and δ13Cbf) and %CaCO3 using a sediment core recovered from the northeastern slope of the Bering Sea. A suite of positive δ18Obf excursions at intermediate depths of the Bering Sea, which seem at least in part associated with increases in the δ18Obf gradients between the Bering and Okhotsk Seas, suggest the Bering Sea as a proximate source of intermediate water during several severe stadial episodes in the last glacial and deglacial period. Absence of such δ18Obf gradients during periods of high surface productivity in the Bering and Okhotsk Seas, which we correlate to D-O interstadials, suggests a reduction in intermediate water production in the Bering Sea and subsequent introduction of nutrient-rich deep waters from the North Pacific into intermediate depths of the Bering Sea. We argue that a reorganization of atmospheric circulation in the high-latitude North Pacific during severe cold episodes in the last glacial and deglacial period created favorable conditions for brine rejection in the northeastern Bering Sea. The resulting salinity increase in the cold surface waters could have initiated intermediate (and deep) water formation that spread out to the North Pacific.

  15. On the relationship between atmospheric circulation and the fluctuations in the sea ice extents of the Bering and Okhotsk Seas

    Science.gov (United States)

    Cavalieri, D. J.; Parkinson, C. L.

    1987-01-01

    The influence of the hemispheric atmospheric circulation on the sea ice covers of the Bering Sea and the Sea of Okhotsk is examined using data obtained with the Nimbus 5 electrically scanning microwave radiometer for the four winters of the 1973-1976 period. The 3-day averaged sea ice extent data were used to establish periods for which there is an out-of-phase relationship between fluctuations of the two ice covers. A comparison of the sea-level atmospheric pressure field with the seasonal, interannual, and short-term sea ice fluctuations reveal an association between changes in the phase and the amplitude of the long waves in the atmosphere and advance and retreat of Arctic ice covers.

  16. Export of Nitrogen From the Yukon River Basin to the Bering Sea

    Science.gov (United States)

    Dornblaser, M. M.; Striegl, R. G.

    2005-12-01

    The US Geological Survey measured nitrogen export from the 831,400 km2 Yukon River basin during 2001-04 as part of a five year water quality study of the Yukon River and its major tributaries. Concentrations of NO2+NO3, NH4+DON, and particulate N were measured ~6 times annually during open water and once under ice cover at three locations on the Yukon River, and on the Porcupine and Tanana Rivers. Concentration and continuous flow data were used to generate daily and annual loads of N species. NH4 concentration was generally negligible when compared to DON concentration, allowing for comparison of the relative importance of DIN vs. DON export at various watershed scales. NO2 concentration was also small compared to NO3. At Pilot Station, the last site on the Yukon before it flows into the Yukon Delta and the Bering Sea, DIN, DON, and particulate N loads averaged 19.3 × 106 kg/yr, 52.6 × 106 kg/yr, and 39.1 × 106 kg/yr, respectively. Normalized for the watershed area at Pilot Station, corresponding N yields were 1.65, 4.52, and 3.35 mmol/m2/yr. DIN yield for the Yukon at Pilot Station is substantially less than the NO3 flux reported for tropical/temperate rivers such as the Amazon, the Yangtze, and the Mississippi. DIN yield in the upper Yukon River basin is similar to that of the Mackenzie and other arctic rivers, but increases substantially downstream. This is likely due to development around Fairbanks in the Tanana River basin. When compared to other headwater basins in the upper Yukon, the Tanana basin yields about four times more DIN and two times more particulate N, while DON yields are only slightly elevated.

  17. Cloud amount/frequency, ANIMALS - INDIVIDUAL and other data from AIRCRAFT in the Bering Sea from 1987-09-02 to 1988-10-20 (NODC Accession 9100026)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The aerial surveys of Whales data in this accession were collected from aircraft by Steve Tracey over the Bering Sea between September 1987 and October 1988 by Sea...

  18. Deep-Water Acoustic Anomalies from Methane Hydrate in the Bering Sea

    Science.gov (United States)

    Wood, Warren T.; Barth, Ginger A.; Scholl, David W.; Lebedeva-Ivanova, Nina

    2015-01-01

    A recent expedition to the central Bering Sea, one of the most remote locations in the world, has yielded observations confirming gas and gas hydrates in this deep ocean basin. Significant sound speed anomalies found using inversion of pre-stack seismic data are observed in association with variable seismic amplitude anomalies in the thick sediment column. The anomalously low sound speeds below the inferred base of methane hydrate stability indicate the presence of potentially large quantities of gas-phase methane associated with each velocity-amplitude anomaly (VAMP). The data acquired are of such high quality that quantitative estimates of the concentrations of gas hydrates in the upper few hundred meters of sediment are also possible, and analyses are under way to make these estimates. Several VAMPs were specifically targeted in this survey; others were crossed incidentally. Indications of many dozens or hundreds of these features exist throughout the portion of the Bering Sea relevant to the U.S. extended continental shelf (ECS) consistent with the United Nations Convention on the Law of the Sea

  19. The Sea of Okhotsk and the Bering Sea as the region of natural aquaculture: Organochlorine pesticides in Pacific salmon

    International Nuclear Information System (INIS)

    Tsygankov, Vasiliy Yu.; Lukyanova, Olga N.; Khristoforova, Nadezhda K.

    2016-01-01

    Kuril Islands of the Sea of Okhotsk and the western part of the Bering Sea are an area of natural feeding of Pacific salmon, and the catch area of ones for food market. Food safety of products is an important task of aquaculture. Сoncentrations of HCHs (α-, β-, γ-) and DDT and its metabolites (DDD and DDE) were determined in organs of the pink (Oncorhynchus gorbuscha), chum (O. keta), chinook (O. tshawytscha), and sockeye (O. nerka), which caught from the natural aquaculture region of Russia (near the Kuril Islands (the northern-western part of the Pacific Ocean), the Sea of Okhotsk and the Bering Sea). The average total concentration of OCPs in organs of salmon from Western Pacific is lower than that in salmon from the North Pacific American coast and the Atlantic Ocean. The region can be used to grow smolts, which will be later released into the ocean. - Highlights: • The study area is area of natural feeding of Pacific salmon, and the catch area of ones for food market. • ΣOCPs in salmon muscle increases in the following: chum ≤ pink < chinook < sockeye. • ΣOCPs in salmon from study area is lower than that in ones from the Atlantic Ocean. • The salmon, which feeding in the study area, did not accumulate higher OCPs content.

  20. Hindcast storm events in the Bering Sea for the St. Lawrence Island and Unalakleet Regions, Alaska

    Science.gov (United States)

    Erikson, Li H.; McCall, Robert T.; van Rooijen, Arnold; Norris, Benjamin

    2015-01-01

    This study provides viable estimates of historical storm-induced water levels in the coastal communities of Gambell and Savoonga situated on St. Lawrence Island in the Bering Sea, as well as Unalakleet located at the head of Norton Sound on the western coast of Alaska. Gambell, Savoonga, and Unalakleet are small Native Villages that are regularly impacted by coastal storms but where little quantitative information about these storms exists. The closest continuous water-level gauge is at Nome, located more than 200 kilometers from both St. Lawrence Island and Unalakleet. In this study, storms are identified and quantified using historical atmospheric and sea-ice data and then used as boundary conditions for a suite of numerical models. The work includes storm-surge (temporary rise in water levels due to persistent strong winds and low atmospheric pressures) modeling in the Bering Strait region, as well as modeling of wave runup along specified sections of the coast in Gambell and Unalakleet. Modeled historical water levels are used to develop return periods of storm surge and storm surge plus wave runup at key locations in each community. It is anticipated that the results will fill some of the data void regarding coastal flood data in western Alaska and be used for production of coastal vulnerability maps and community planning efforts.

  1. Submarine canyons as coral and sponge habitat on the eastern Bering Sea slope

    Directory of Open Access Journals (Sweden)

    Robert J. Miller

    2015-07-01

    Full Text Available Submarine canyons have been shown to positively influence pelagic and benthic biodiversity and ecosystem function. In the eastern Bering Sea, several immense canyons lie under the highly productive “green belt” along the continental slope. Two of these, Pribilof and Zhemchug canyons, are the focus of current conservation interest. We used a maximum entropy modeling approach to evaluate the importance of these two canyons, as well as canyons in general, as habitat for gorgonian (alcyonacean corals, pennatulacean corals, and sponges, in an area comprising most of the eastern Bering Sea slope and outer shelf. These invertebrates create physical structure that is a preferred habitat for many mobile species, including commercially important fish and invertebrates. We show that Pribilof canyon is a hotspot of structure-forming invertebrate habitat, containing over 50% of estimated high-quality gorgonian habitat and 45% of sponge habitat, despite making up only 1.7% of the total study area. The amount of quality habitat for gorgonians and sponges varied in other canyons, but canyons overall contained more high-quality habitat for structure-forming invertebrates compared to other slope areas. Bottom trawling effort was not well correlated with habitat quality for structure-forming invertebrates, and bottom-contact fishing effort in general, including longlining and trawling, was not particularly concentrated in the canyons examined. These results suggest that if conserving gorgonian coral habitat is a management goal, canyons, particularly Pribilof Canyon, may be a prime location to do this without excessive impact on fisheries.

  2. Flatfish recruitment response to decadal climatic variability and ocean conditions in the eastern Bering Sea

    Science.gov (United States)

    Wilderbuer, T. K.; Hollowed, A. B.; Ingraham, W. J.; Spencer, P. D.; Conners, M. E.; Bond, N. A.; Walters, G. E.

    2002-10-01

    This paper provides a retrospective analysis of the relationship of physical oceanography and biology and recruitment of three Eastern Bering Sea flatfish stocks: flathead sole ( Hippoglossoides elassodon), northern rock sole ( Lepidopsetta polyxystra), and arrowtooth flounder ( Atheresthes stomias) for the period 1978-1996. Temporal trends in flatfish production in the Eastern Bering Sea are consistent with the hypothesis that decadal scale climate variability influences marine survival during the early life history period. Density-dependence (spawning stock size) is statistically significant in a Ricker model of flatfish recruitment, which includes environmental terms. Wind-driven advection of flatfish larvae to favorable nursery grounds was also found to coincide with years of above-average recruitment through the use of an ocean surface current simulation model (OSCURS). Ocean forcing of Bristol Bay surface waters during springtime was mostly shoreward (eastward) during the 1980s and seaward (westerly) during the 1990s, corresponding with periods of good and poor recruitment. Distance from shore and water depth at the endpoint of 90-day drift periods (estimated time of settlement) were also found to correspond with flatfish productivity.

  3. Tephrochronology as a tool to constrain radiocarbon reservoir age in the deglacial Bering Sea

    Science.gov (United States)

    Chapman, A. U.; White-Nockleby, C.; de Konkoly Thege, P. A.; Rubel, J. N.; Cook, M. S.; Mix, A. C.; Addison, J. A.

    2015-12-01

    In order to accurately calendar date marine carbon, it is necessary to constrain surface reservoir age, the apparent 14C age difference between the atmosphere and surface ocean that results from incomplete equilibration of 14C across the air-sea interface. Surface reservoir age is generally assumed to be constant at the preindustrial value, but evidence suggests it has varied through time by up to 1000 years. In this study we use tephrochronology, a method of correlating tephras across different environments, to identify equivalent strata, as a tool to quantify reservoir age in the Bering Sea during the transition between the Oldest Dryas and Bolling-Allerod (14.7 kcal BP). With frequent volcanic eruptions that allow for possibility of high-resolution reservoir age reconstructions, the Bering Sea/Aleutian Islands region is uniquely positioned to provide insight into the hypothesis that dense water formed in the North Pacific during the last deglaciation. We compare a massive tephra found in three deep-sea sediment cores from Umnak Plateau in the southeast Bering Sea (HLY02-02-55JPC, HLY-02-02-51JPC, and IODP Site U1339) to a tephra dated to 14.8 kcal BP from Deep Lake, Sanak Island in the Eastern Aleutians. For both the Umnak and Sanak tephras, volcanic glass shards are geochemically matched using major and trace elements from electron microprobe and laser-ablation inductively-coupled-plasma mass spectrometry. We compare 14C ages of foraminiferal species Uvigerina peregrina and Neogloboquadrina pachyderma (sinistral) from just above the tephra in HLY-02-02-51JPC (1467 m) to 14C age of the corresponding tephra at Sanak Island from terrestrial plant macrofossils. The surface reservoir age found (930 ± 160 14C y) is similar to the average preindustrial value in the region (790 ± 130 14C y). Benthic-atmosphere age difference (1860 ± 200 14C y) is also comparable to the preindustrial value (2030 ± 60 14C y). These results and future work on additional tephras from

  4. 77 FR 59852 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Science.gov (United States)

    2012-10-01

    ... made by this final rule to the management of the Amendment 80 fleet and an explanation of any... Aleutian Islands Management Area; Amendment 97 ACTION: Final rule. SUMMARY: NMFS publishes regulations to implement Amendment 97 to the Fishery Management Plan for Groundfish of the Bering Sea and Aleutian Islands...

  5. 77 FR 62482 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Science.gov (United States)

    2012-10-15

    ... Aleutian Islands Management Area; Groundfish Retention Standard AGENCY: National Marine Fisheries Service... standard (GRS) program in the Bering Sea and Aleutian Islands (BSAI) management area by removing certain... the Amendment 80 fleet. This action is intended to promote the goals and objectives of the Magnuson...

  6. 78 FR 12627 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Science.gov (United States)

    2013-02-25

    ... Aleutian Islands Management Area; Groundfish Retention Standard AGENCY: National Marine Fisheries Service... Bering Sea and Aleutian Islands Management Area (BSAI). This final rule removes certain regulatory... monitoring requirements for the Amendment 80 fleet and establishes a new requirement for Amendment 80...

  7. 78 FR 68390 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Science.gov (United States)

    2013-11-14

    .... 130306200-3200-01] RIN 0648-BD03 Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management Area; Amendment 102 AGENCY: National Marine Fisheries Service (NMFS) National.... SUMMARY: NMFS proposes regulations to implement Amendment 102 to the Fishery Management Plan for...

  8. 78 FR 65602 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Science.gov (United States)

    2013-11-01

    ...-BD03 Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management... Administration (NOAA), Commerce. ACTION: Notice of availability of fishery management plan amendment; request for comments. SUMMARY: NMFS announces that the North Pacific Fishery Management Council (Council) has submitted...

  9. 76 FR 68354 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Science.gov (United States)

    2011-11-04

    .... 100819383-1652-02] RIN 0648-BA18 Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management Area; Limited Access Privilege Program AGENCY: National Marine Fisheries.... SUMMARY: NMFS issues regulations implementing Amendment 93 to the Fishery Management Plan for Groundfish...

  10. 76 FR 35772 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2011-06-20

    ... Aleutian Islands Crab Rationalization Program AGENCY: National Marine Fisheries Service (NMFS), National... Tanner Crabs. Amendment 34 amends the Bering Sea and Aleutian Islands Crab Rationalization Program to... for the Crab Rationalization Program are available from the NMFS Alaska Region Web site at http...

  11. 76 FR 35781 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2011-06-20

    ... Aleutian Islands Crab Rationalization Program; Amendment 37 AGENCY: National Marine Fisheries Service (NMFS... Tanner Crabs (FMP). This action amends the Bering Sea/Aleutian Islands Crab Rationalization Program by... Assessment prepared for the Crab Rationalization Program are available from the NMFS Alaska Region Web site...

  12. 78 FR 28523 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2013-05-15

    ...; Bering Sea and Aleutian Islands Crab Rationalization Program AGENCY: National Marine Fisheries Service... Rationalization Program (CR Program) by establishing a process whereby holders of regionally designated individual... scope of this action. Comment 9: One comment generally supported the Crab Rationalization Program...

  13. 78 FR 49200 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Pollock in the Bering Sea...

    Science.gov (United States)

    2013-08-13

    ... most recent fisheries data in a timely fashion and would delay the reallocation of Aleutian Islands... industry as to the final Bering Sea subarea pollock allocations. Immediate notification is necessary to allow for the orderly conduct and efficient operation of this fishery; allow the industry to plan for...

  14. 78 FR 5143 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Pollock in the Bering Sea...

    Science.gov (United States)

    2013-01-24

    ... a timely fashion and would delay the reallocation of AI pollock. Since the pollock fishery opens January 20, 2013, it is important to immediately inform the industry as to the final Bering Sea subarea... operation of this fishery; allow the industry to plan for the fishing season and avoid potential disruption...

  15. 75 FR 43147 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2010-07-23

    ... of a 2.67-percent fee for cost recovery under the Bering Sea and Aleutian Islands Crab... for the 2010/2011 crab fishing year so they can calculate the required payment for cost recovery fees...-Stevens Act). The Program includes a cost recovery provision to collect fees to recover the actual costs...

  16. 78 FR 46577 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2013-08-01

    ... of a 0.69-percent fee for cost recovery under the Bering Sea and Aleutian Islands Crab... for the 2013/2014 crab fishing year so they can calculate the required payment for cost recovery fees... Program includes a cost recovery provision to collect fees to recover the actual costs directly related to...

  17. 76 FR 43658 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2011-07-21

    ... of a 1.23-percent fee for cost recovery under the Bering Sea and Aleutian Islands Crab... for the 2011/2012 crab fishing year so they can calculate the required payment for cost recovery fees...-Stevens Act). The Program includes a cost recovery provision to collect fees to recover the actual costs...

  18. 77 FR 44216 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2012-07-27

    ... of a zero (0) percent fee for cost recovery under the Bering Sea and Aleutian Islands Crab... Program includes a cost recovery provision to collect fees to recover the actual costs directly related to... processing sectors to each pay half the cost recovery fees. Catcher/processor quota share holders are...

  19. 76 FR 80782 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; Proposed...

    Science.gov (United States)

    2011-12-27

    ... Initial Regulatory Flexibility Analysis (IRFA), and the Supplemental IRFA prepared for this action may be... OFLs, ABCs and TACs for the Bering Sea subarea and the Aleutian Island districts. This split is... levels (OFL), acceptable biological catches (ABC), and total allowable catches (TAC) for Pacific cod on...

  20. 76 FR 66655 - Fisheries of the Exclusive Economic Zone Off Alaska; Pacific Cod and Octopus in the Bering Sea...

    Science.gov (United States)

    2011-10-27

    ... Octopus in the Bering Sea and Aleutian Islands Management Area AGENCY: National Marine Fisheries Service... catch of octopus by vessels using pot gear to fish for Pacific cod the BSAI. DATES: Effective 1200 hrs... and management measures prevent overfishing. The 2011 octopus overfishing level in the BSAI is 528...

  1. 78 FR 36122 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2013-06-17

    ... the harvesting and processing sectors'' and to monitor the ``economic stability for harvesters.... 120806311-3530-02] RIN 0648-BC25 Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and... Tanner Crabs (FMP). These regulations revise the annual economic data reports (EDRs) currently required...

  2. 75 FR 51185 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Rock Sole in the Bering Sea...

    Science.gov (United States)

    2010-08-19

    ... 600 and 50 CFR part 679. The 2010 rock sole TAC specified for the Bering Sea and Aleutian Islands ICA... Amendment 80 Allocations of The Aleutian Islands Pacific Ocean Perch, And BSAI Flathead Sole, Rock Sole, And.... 0910131363-0087-02] RIN 0648-XY29 Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Rock...

  3. Evidence of increased toxic Alexandrium tamarense dinoflagellate blooms in the eastern Bering Sea in the summers of 2004 and 2005.

    Directory of Open Access Journals (Sweden)

    Masafumi Natsuike

    Full Text Available The eastern Bering Sea has a vast continental shelf, which contains various endangered marine mammals and large fishery resources. Recently, high numbers of toxic A. tamarense resting cysts were found in the bottom sediment surface of the eastern Bering Sea shelf, suggesting that the blooms have recently occurred. However, little is known about the presence of A. tamarense vegetative cells in the eastern Bering Sea. This study's goals were to detect the occurrence of A. tamarense vegetative cells on the eastern Bering Sea shelf and to find a relationship between environmental factors and their presence. Inter-annual field surveys were conducted to detect A. tamarense cells and environmental factors, such as nutrients, salinity, chlorophyll a, and water temperature, along a transect line on the eastern Bering Sea shelf during the summers of 2004, 2005, 2006, 2009, 2012, and 2013. A. tamarense vegetative cells were detected during every sampling year, and their quantities varied greatly from year to year. The maximum cell densities of A. tamarense observed during the summers of 2004 and 2005 were much higher than the Paralytic shellfish poisoning warning levels, which are greater than 100-1,000 cells L-1, in other subarctic areas. Lower quantities of the species occurred during the summers of 2009, 2012, and 2013. A significant positive correlation between A. tamarense quantity and water temperature and significant negative correlations between A. tamarense quantity and nutrient concentrations (of phosphate, silicate, and nitrite and nitrate were detected in every sampling period. The surface- and bottom-water temperatures varied significantly from year to year, suggesting that water temperatures, which have been known to affect the cell growth and cyst germination of A. tamarense, might have affected the cells' quantities in the eastern Bering Sea each summer. Thus, an increase in the Bering Sea shelf's water temperature during the summer will

  4. Seasonal distribution of dissolved inorganic carbon and net community production on the Bering Sea shelf

    Directory of Open Access Journals (Sweden)

    J. T. Mathis

    2010-05-01

    Full Text Available 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.

  5. Sea-ice habitat preference of the Pacific walrus (Odobenus rosmarus divergens) in the Bering Sea: A multiscaled approach

    Science.gov (United States)

    Sacco, Alexander Edward

    The goal of this thesis is to define specific parameters of mesoscale sea-ice seascapes for which walruses show preference during important periods of their natural history. This research thesis incorporates sea-ice geophysics, marine-mammal ecology, remote sensing, computer vision techniques, and traditional ecological knowledge of indigenous subsistence hunters in order to quantitatively study walrus preference of sea ice during the spring migration in the Bering Sea. Using an approach that applies seascape ecology, or landscape ecology to the marine environment, our goal is to define specific parameters of ice patch descriptors, or mesoscale seascapes in order to evaluate and describe potential walrus preference for such ice and the ecological services it provides during an important period of their life-cycle. The importance of specific sea-ice properties to walrus occupation motivates an investigation into how walruses use sea ice at multiple spatial scales when previous research suggests that walruses do not show preference for particular floes. Analysis of aerial imagery, using image processing techniques and digital geomorphometric measurements (floe size, shape, and arrangement), demonstrated that while a particular floe may not be preferred, at larger scales a collection of floes, specifically an ice patch (cross-cultural sea-ice observations, knowledge and science to determine sea ice importance to marine mammals in a changing Arctic.

  6. The radon-222 transfer coefficients across air-sea interface determined in the Bering Sea, the Okhotsk Sea and the North Pacific Ocean

    International Nuclear Information System (INIS)

    Kholujskij, S.N.; Anikiev, V.V.; Popov, N.I.

    1995-01-01

    Determination of velocity coefficient for gas flow transfer across the natural sea surface into the atmosphere (K v ) was attempted by means of radon method on board the SRS Academician Alexander Nesmeyanov (July-August 1992). The measurements were conducted in the Bering Sea, the Okhotsk Sea and in the North Pacific Ocean. It is shown that the total range of the K v observed values equaled from 1.8 up to 5.4 m.day, which is within the known limits for other regions of the world ocean. 9 refs., 1 fig

  7. Links between Iron Fertilization and Biological Pump Efficiency in the Bering Sea Over the Last 3.5 Myrs

    Science.gov (United States)

    Bartoli, G. L.; Studer, A. S.; Martinez Garcia, A.; Haug, G. H.

    2011-12-01

    The Bering Sea is one of the major sink of atmospheric CO2 today, due to the efficiency of its biological pump, despite a limitation by iron. Here we present records of iron fertilization by aeolian dust deposition (n-alkane concentration) and phytoplankton nutrient consumption (diatom-bound δ15N record) over the last 3.5 Myrs in the southwestern Bering Sea at Site U1341 drilled during IODP Expedition 323. During the Pliocene Epoch, when sea surface temperatures were 3-4°C warmer than today and sea-ice cover was reduced, the biological pump efficiency during glacial and interglacial stages was minimal, similar to Quaternary interglacials. Low iron deposition and weaker surface water stratification resulting in higher nutrient inputs contributed to reduce the biological pump efficiency until 1.5 Ma. After the intensification of glacial conditions in the Bering Sea and the increase in sea-ice cover and iron inputs, the biological pump efficiency progressively increased, reaching values similar to Quaternary glacials after the mid-Pleistocene transition.

  8. Carbon sources and trophic relationships of ice seals during recent environmental shifts in the Bering Sea.

    Science.gov (United States)

    Wang, Shiway W; Springer, Alan M; Budge, Suzanne M; Horstmann, Lara; Quakenbush, Lori T; Wooller, Matthew J

    2016-04-01

    Dramatic multiyear fluctuations in water temperature and seasonal sea ice extent and duration across the Bering-Chukchi continental shelf have occurred in this century, raising a pressing ecological question: Do such environmental changes alter marine production processes linking primary producers to upper trophic-level predators? We examined this question by comparing the blubber fatty acid (FA) composition and stable carbon isotope ratios of individual FA (δ¹³CFA) of adult ringed seals (Pusa hispida), bearded seals (Erignathus barbatus), spotted seals (Phoca largha), and ribbon seals (Histriophoca fasciata), collectively known as "ice seals," sampled during an anomalously warm, low sea ice period in 2002-2005 in the Bering Sea and a subsequent cold, high sea ice period in 2007-2010. δ¹³C(FA) values, used to estimate the contribution to seals of carbon derived from sea ice algae (sympagic production) relative to that derived from water column phytoplankton (pelagic production), indicated that during the cold period, sympagic production accounted for 62-80% of the FA in the blubber of bearded seals, 51-62% in spotted seals, and 21-60% in ringed seals. Moreover, the δ¹³CFA values of bearded seals indicated a greater incorporation of sympagic FAs during the cold period than the warm period. This result provides the first empirical evidence of an ecosystem-scale effect of a putative change in sympagic production in the Western Arctic. The FA composition of ice seals showed clear evidence of resource partitioning among ringed, bearded, and spotted seals, and little niche separation between spotted and ribbon seals, which is consistent with previous studies. Despite interannual variability, the FA composition of ringed and bearded seals showed little evidence of differences in diet between the warm and cold periods. The findings that sympagic production contributes significantly to food webs supporting ice seals, and that the contribution apparently is less in

  9. Cloud amount/frequency, NITRATE and other data from ALPHA HELIX in the Bering Sea and Chukchi Sea from 1993-09-09 to 1993-10-10 (NODC Accession 9400036)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in Bering Sea and Chukchi Sea. Data was collected from Ship ALPHA HELIX. The data was...

  10. Temperature profile data collected using BT and XBT casts from NOAA Ship RESEARCHER and other platforms in the Bering Sea and other Sea areas from 1987-02-25 to 1987-07-27 (NODC Accession 8700280)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profile data were collected using XBT and BT casts from NOAA Ship RESEARCHER and other platforms in the Bering Sea and other Sea areas from 25 February...

  11. Individual animals and other data collected using visual observations and other instruments from AIRCRAFT in the Bering Sea and other seas from 02 September 1990 to 07 November 1991 (NODC Accession 9200080)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Individual Animal and other data were collected using visual observation and other instruments from AIRCRAFT in the Bering Sea, Chukchi Sea, and Arctic Ocean. Data...

  12. Bering Sea Inner Front zooplankton data sets collected with CalVet net on four cruises from 6/3/1997 - 9/1/1998 (NODC Accession 0000103)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton and other data were collected using CalVet net in Bering sea from ALPHA HELIX. Data were collected from 01 June 1997 to 01 September 1998 by University...

  13. AFSC/RACE/FBEP/Hurst: Distributional patterns of 0-group Pacific cod (Gadus macrocephalus) in the eastern Bering Sea under variable recruitment and thermal conditions

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is from a study that analyzed the late summer distribution of juvenile Pacific cod in the eastern Bering Sea for 6 cohorts (2004-2009), based on catches...

  14. AFSC/RACE/SAP/Pathobiology: 2015 Bitter crab disease prevalence in immature Chionoecetes spp. at 6 index sites in eastern Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains crab data from a field survey of Chionoecetes bairdi and C. opilio collected at six designated index sites in the Bering Sea during the 2015...

  15. AFSC/RACE/SAP/Pathobiology: 2016 Bitter crab disease prevalence in immature Chionoecetes spp. at 6 index sites in eastern Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains crab data from a field survey of Chionoecetes bairdi and C. opilio collected at six designated index sites in the Bering Sea during the 2016...

  16. Cloud amount/frequency, NITRATE and other data from ALPHA HELIX in the Bering Sea from 1993-06-12 to 1993-07-01 (NODC Accession 9400026)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in Bering Sea. Data was collected from Ship ALPHA HELIX cruise HX 171. The data was...

  17. AFSC/RACE/SAP/Pathobiology: 2014 Bitter crab disease prevalence in immature Chionoecetes spp. at 6 index sites in eastern Bering Sea

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains crab data from a field survey of Chionoecetes bairdi and C. opilio collected at six designated index sites in the Bering Sea during the 2014...

  18. AFSC/NMML: Killer whale surveys in the Aleutian Islands, Bering Sea, and western and central Gulf of Alaska, 2001 - 2010

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is a compilation of line-transect data collected on surveys in the Aleutian Islands, Bering Sea, and western and central Gulf of Alaska, 2001 - 2010....

  19. BAROMETRIC PRESSURE and Other Data from ALPHA HELIX and Other Platforms From Bering Sea and Others from 19940627 to 19950106 (NODC Accession 9500031)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in Gulf of Alaska and Bering Sea as part of Inner SHelf Transfer and recycling (ISHTAR)...

  20. BAROMETRIC PRESSURE and Other Data from ALPHA HELIX and Other Platforms From Bering Sea from 19850101 to 19950106 (NODC Accession 9500145)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The accession contains Conductivity, Temperature and Depth (CTD); Chlorophyll; and Nutrient data collected in Bering Sea as part of Inner Shelf Transfer and...

  1. Survey Data of Community-Based Environmental and Species Observations from the Bering Sea Sub-Network, 2008-2009, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Bering Sea Sub-Network (BSSN) is comprised of a set of coastal communities representing six indigenous cultures: three in the Russian Federation and three in the...

  2. Summary Report of Community-Based Environmental and Species Observations from the Bering Sea Sub-Network, 2008-2009, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Bering Sea Sub-Network (BSSN) is comprised of a set of coastal communities representing six indigenous cultures: three in the Russian Federation and three in the...

  3. AFSC/RACE/SAP: Detailed Crab Data From NOAA Fisheries Service Annual Eastern Bering Sea Summer Bottom Trawl Surveys 1975 - 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains detailed crab data collected from the annual NOAA/NMFS/AFSC/RACE crab-groundfish bottom trawl survey of the eastern Bering Sea continental...

  4. Pelagic tar and plastic in the Gulf of Alaska and Bering Sea: 1975

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, D G

    1977-07-01

    Seventy-one tows of 740 m/sup 2/ each were made in search of pelagic tar and plastics in the Gulf of Alaska and Bering Sea during the period October 1974 to October 1975. Tar was observed on nine occasions while plastics were found six times. The arithmetic mean value of tar abundance, 3.3 x 10/sup -3/ mg/m/sup 2/, is considerably lower than most other oceanic areas for which values have been reported. Gas chromatographic analysis of this tar indicates that it is more extensively weathered than tar from the north Atlantic. An estimate of the abundance of tar lumps too small to be sampled by net tows is made based on the assumption that there are equal weights of particles in logarithmetically equal size intervals. The abundance of pelagic plastics is also low.

  5. Tritium and plutonium in waters from the Bering and Chukchi Seas

    Science.gov (United States)

    Landa, E.R.; Beals, D.M.; Halverson, J.E.; Michel, R.L.; Cefus, G.R.

    1999-01-01

    During the summer of 1993, seawater in the Bering and Chukchi Seas was sampled on a joint Russian-American cruise [BERPAC] of the RV Okean to determine concentrations of tritium, 239Pu and 240Pu. Concentrations of tritium were determined by electrolytic enrichment and liquid scintilation counting. Tritium levels ranged up to 420 mBq L-1 showed no evidence of inputs other than those attribute atmospheric nuclear weapons testing. Plutonium was recovered from water samples by ferric hydroxide precipitation, and concentrations were determined by thermal ionization mass spectrometry. 239+240Pu concentrations ranged from nuclear facilities in the United States. This study and others sponsored by the International Atomic Energy Agency and the Office of Naval Research's Arctic Nuclear Waste Assessment Program are providing data for the assessment of potential radiological impacts in the Arctic regions associated with nuclear waste disposal by the former Soviet Union.

  6. Marine Emissions and Atmospheric Processing Influence Aerosol Mixing States in the Bering Strait and Chukchi Sea

    Science.gov (United States)

    Kirpes, R.; Rodriguez, B.; Kim, S.; Park, K.; China, S.; Laskin, A.; Pratt, K.

    2017-12-01

    The Arctic region is rapidly changing due to sea ice loss and increasing oil/gas development and shipping activity. These changes influence aerosol sources and composition, resulting in complex aerosol-cloud-climate feedbacks. Atmospheric particles were collected aboard the R/V Araon in July-August 2016 in the Alaskan Arctic along the Bering Strait and Chukchi Sea. Offline analysis of individual particles by microscopic and spectroscopic techniques provided information on particle size, morphology, and chemical composition. Sea spray aerosol (SSA) and organic aerosol (OA) particles were the most commonly observed particle types, and sulfate was internally mixed with both SSA and OA. Evidence of multiphase sea spray aerosol reactions was observed, with varying degrees of chlorine depletion observed along the cruise. Notably, atmospherically processed SSA, completely depleted in chlorine, and internally mixed organic and sulfate particles, were observed in samples influenced by the central Arctic Ocean. Changes in particle composition due to fog processing were also investigated. Due to the changing aerosol sources and atmospheric processes in the Arctic region, it is crucial to understand aerosol composition in order to predict climate impacts.

  7. Climate program "stone soup": Assessing climate change vulnerabilities in the Aleutian and Bering Sea Islands of Alaska

    Science.gov (United States)

    Littell, J. S.; Poe, A.; van Pelt, T.

    2015-12-01

    Climate change is already affecting the Bering Sea and Aleutian Island region of Alaska. Past and present marine research across a broad spectrum of disciplines is shedding light on what sectors of the ecosystem and the human dimension will be most impacted. In a grassroots approach to extend existing research efforts, leveraging recently completed downscaled climate projections for the Bering Sea and Aleutian Islands region, we convened a team of 30 researchers-- with expertise ranging from anthropology to zooplankton to marine mammals-- to assess climate projections in the context of their expertise. This Aleutian-Bering Climate Vulnerability Assessment (ABCVA) began with researchers working in five teams to evaluate the vulnerabilities of key species and ecosystem services relative to projected changes in climate. Each team identified initial vulnerabilities for their focal species or services, and made recommendations for further research and information needs that would help managers and communities better understand the implications of the changing climate in this region. Those draft recommendations were shared during two focused, public sessions held within two hub communities for the Bering and Aleutian region: Unalaska and St. Paul. Qualitative insights about local concerns and observations relative to climate change were collected during these sessions, to be compared to the recommendations being made by the ABCVA team of researchers. Finally, we used a Structured Decision Making process to prioritize the recommendations of participating scientists, and integrate the insights shared during our community sessions. This work brought together residents, stakeholders, scientists, and natural resource managers to collaboratively identify priorities for addressing current and expected future impacts of climate change. Recommendations from this project will be incorporated into future research efforts of the Aleutian and Bering Sea Islands Landscape Conservation

  8. Do microzooplankton grazers control biomass of large-phytoplankton in the northern Bering and Chukchi Seas?

    Science.gov (United States)

    Krause, J. W.; Lomas, M. W.

    2017-12-01

    In high-latitude environments like the northern Bering and Chukchi Seas, microzooplankton and phytoplankton biomass can be tightly coupled. Microzooplankton consumption of primary production decreases the efficiency of transfer to higher trophic levels by increasing the number of food web steps and compounding losses from respiration. Thus, the balance of phytoplankton growth and microzooplankton grazing directly affects the availability of primary production to support higher-trophic processes (e.g. fisheries productivity). Despite compelling qualitative observations, there are no quantitative data demonstrating that larger phytoplankton (e.g. diatoms) growth is balanced by microzooplankton grazing in the northern Bering and Chukchi Seas. We report the first size-fractionated data for phytoplankton growth and grazing loss rates from microzooplankton in these regions during late spring 2017. Within the small size fraction (5 µm), which was presumably dominated by diatoms, less than 33% of experiments showed a potential control of growth by grazing and among these even fewer showed grazing rates statistically different from zero. In the few cases where there was a significant grazing rate, a negative correlation was observed between the microzooplankton grazing rate on large phytoplankton and chlorophyll in that size fraction; a similar negative trend was observed for these same grazing rates on large cells versus biogenic silica concentration (an independent metric of diatom biomass). These data show that the growth of large phytoplankton (e.g. diatoms) was typically decoupled from microzooplankton grazing losses, suggesting that at most stations a high proportion of this phytoplankton productivity escapes microzooplankton grazing and is available for consumption by higher trophic organisms.

  9. Brucella Infection in Asian Sea Otters (Enhydra lutris lutris) on Bering Island, Russia.

    Science.gov (United States)

    Burgess, Tristan L; Johnson, Christine Kreuder; Burdin, Alexander; Gill, Verena A; Doroff, Angela M; Tuomi, Pamela; Smith, Woutrina A; Goldstein, Tracey

    2017-10-01

    Infection with Brucella spp., long known as a cause of abortion, infertility, and reproductive loss in domestic livestock, has increasingly been documented in marine mammals over the past two decades. We report molecular evidence of Brucella infection in Asian sea otters (Enhydra lutris lutris). Brucella DNA was detected in 3 of 78 (4%) rectal swab samples collected between 2004 and 2006 on Bering Island, Russia. These 78 animals had previously been documented to have a Brucella seroprevalence of 28%, markedly higher than the prevalence documented in sea otters (Enhydra lutris) in North America. All of the DNA sequences amplified were identical to one or more previously isolated Brucella spp. including strains from both terrestrial and marine hosts. Phylogenetic analysis of this sequence suggested that one animal was shedding Brucella spp. DNA with a sequence matching a Brucella abortus strain, whereas two animals yielded a sequence matching a group of strains including isolates classified as Brucella pinnipedialis and Brucella melitensis. Our results highlight the diversity of Brucella spp. within a single sea otter population.

  10. High incorporation of carbon into proteins by the phytoplankton of the Bering Strait and Chukchi Sea

    Science.gov (United States)

    Lee, Sang H.; Kim, Hak-Jun; Whitledge, Terry E.

    2009-07-01

    High incorporation of carbon into proteins and low incorporation into lipids were a characteristic pattern of the photosynthetic allocations of phytoplankton throughout the euphotic zone in the Bering Strait and Chukchi Sea in 2004. According to earlier studies, this indicates that phytoplankton had no nitrogen limitation and a physiologically healthy condition, at least during the cruise period from mid-August to early September in 2004. This is an interesting result, especially for the phytoplankton in the Alaskan coastal water mass-dominated region in the Chukchi Sea which has been thought to be potentially nitrogen limited. The relatively high ammonium concentration is believed to have supported the nitrogen demand of the phytoplankton in the region where small cells (stress than large phytoplankton. If the high carbon incorporation into proteins by the phytoplankton in 2004 is a general pattern of the photosynthetic allocations in the Chukchi Sea, they could provide nitrogen-sufficient food for the highest benthic faunal biomass in the Arctic Ocean, sustaining large populations of benthic-feeding marine mammals and seabirds.

  11. Coupled organic and inorganic carbon cycling in the deep subseafloor sediment of the northeastern Bering Sea Slope (IODP Exp. 323)

    DEFF Research Database (Denmark)

    Wehrmann, Laura M.; Risgaard-Petersen, Nils; Schrum, Heather

    2011-01-01

    We studied microbially mediated diagenetic processes driven by carbon mineralization in subseafloor sediment of the northeastern Bering Sea Slope to a depth of 745 meters below seafloor (mbsf). Sites U1343, U1344 and U1345 were drilled during Integrated Ocean Drilling Program (IODP) Expedition 323......) and between 300 and 400 mbsf. The SMTZ at the three sites is located between 6 and 9 mbsf. The upward methane fluxes into the SMTZ are similar to fluxes in SMTZs underlying high-productivity surface waters off Chile and Namibia. Our Bering Sea results show that intense organic carbon mineralization drives...... microbially mediated carbon mineralization leaves DIC isotope composition unaffected. Ongoing carbonate formation between 300 and 400 mbsf strongly influences pore-water DIC and magnesium concentration profiles. The linked succession of organic carbon mineralization and carbonate dissolution and precipitation...

  12. Sedimentology and geochemistry of surface sediments, outer continental shelf, southern Bering Sea

    Science.gov (United States)

    Gardner, J.V.; Dean, W.E.; Vallier, T.L.

    1980-01-01

    Present-day sediment dynamics, combined with lowerings of sea level during the Pleistocene, have created a mixture of sediments on the outer continental shelf of the southern Bering Sea that was derived from the Alaskan Mainland, the Aleutian Islands, and the Pribilof ridge. Concentrations of finer-grained, higher-organic sediments in the region of the St. George basin have further modified regional distribution patterns of sediment composition. Q-mode factor analysis of 58 variables related to sediment size and composition - including content of major, minor, and trace elements, heavy and light minerals, and clay minerals - reveals three dominant associations of sediment: 1. (1) The most significant contribution, forming a coarse-grained sediment scattered over most of the shelf consists of felsic sediment derived from the generally quartz-rich rocks of the Alaskan mainland. This sediment contains relatively high concentrations of Si, Ba, Rb, quartz, garnet, epidote, metamorphic rock fragments, potassium feldspar, and illite. 2. (2) The next most important group, superimposed on the felsic group consists of andesitic sediment derived from the Aleutian Islands. This more mafic sediment contains relatively high concentrations of Na, Ca, Ti, Sr, V, Mn, Cu, Fe, Al, Co, Zn, Y, Yb, Ga, volcanic rock fragments, glass, clinopyroxene, smectite, and vermiculite. 3. (3) A local group of basaltic sediment, derived from rocks of the Pribilof Islands, is a subgroup of the Aleutian andesite group. Accumulation of fine-grained sediment in St. George basin has created a sediment group containing relatively high concentrations of C, S, U, Li, B, Zr, Ga, Hg, silt, and clay. Sediment of the Aleutian andesite group exhibits a strong gradient, or "plume", with concentrations decreasing away from Unimak Pass and toward St. George basin. The absence of present-day currents sufficient to move even clay-size material as well as the presence of Bering submarine canyon between the Aleutian

  13. Oryong 501 sinking incident in the Bering Sea-International DVI cooperation in the Asia Pacific.

    Science.gov (United States)

    Chung, Nak-Eun; Castilani, Anton; Tierra, Wilfredo E; Beh, Philip; Mahmood, Mohd Shah

    2017-09-01

    On December 1st, 2014, the sinking of Oryong 501 occurred in the Bering Sea off the east coast of Russia. A total of 60 crew members, including 35 Indonesians, 13 Filipinos, 11 South Koreans and 1 Russian inspector were on board out of which only seven survived. Through an international rescue operation, the dead bodies of 27 were found and the remaining 26 crew are still missing. After transferring the dead bodies to the Busan Harbor in South Korea, the operation to identify the deceased began involving DVI teams from three countries: Korea, Indonesia and the Philippines. When a deep sea fishing boat sinks, it is very difficult to obtain antemortem data of the crew who had been on board for a long time. This is especially so if the crews are multinational. Further, the accuracy of the antemortem data provided by the families may be questionable, and the provided data is often not standardized. Despite the fact that the antemortem data were received in different formats, the identification process for the bodies of the 27 crew from the Oryong sinking was quickly completed through the cooperation among the three DVI teams. This case is an excellent example of how efficiently a DVI operation can be conducted in the Asia Pacific region. Issues raised during this operation should enable even better preparation for similar events in the future. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Climate change and control of the southeastern Bering Sea pelagic ecosystem

    Science.gov (United States)

    Hunt, George L., Jr.; Stabeno, Phyllis; Walters, Gary; Sinclair, Elizabeth; Brodeur, Richard D.; Napp, Jeffery M.; Bond, Nicholas A.

    2002-12-01

    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 cold-water 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

  15. Diatom Surface Sediment Assemblages from the Bering Sea Shelf: a Tossed Salad or Faithful Recorder of 50 Years of Environmental Change?

    Science.gov (United States)

    Caissie, B.; Brigham-Grette, J.; Kanamaru-Shinn, K.

    2010-12-01

    Recent environmental change in the Bering Sea includes a shift from the negative to positive phase of the Pacific Decadal Oscillation in 1976/77, a secondary shift in sea level pressure and sea surface temperatures in 1998, increasing sea surface temperatures, an earlier spring, an increase in the number of days that sea ice is present along the shelf-slope break, and a decrease in the number of days that sea ice is present in the Chukchi Sea and Arctic Ocean. These physical changes have manifest biological changes such as a northward migration of invertebrates and fish from the southern Bering Sea and shifts in the timing and duration of sea-ice related primary productivity and the spring bloom. We aim to see if diatom sediment assemblages are faithful recorders of these ecological changes in the Bering Sea or if bioturbation has essentially mixed today’s rapid change down core such that the signal is either muted or no longer apparent. Six continental shelf areas were examined in the Bering Sea ranging from northeast of St. Lawrence Island to the shelf-slope break in the south-central Bering Sea. Diatom assemblages from core tops collected as part of the PROBES program in the 1960s were compared to core tops taken nearby (7 m) multi-year ice so their decline may be related to the decrease in multi-year ice over the past 30 years. Additionally, in most cases, species diversity has declined over the past 50 years with Fragilariopsis oceanica and Fragilariopsis cylindrus accounting for a greater percentage of the sediment assemblages today. These two species are collectively considered indicators of seasonal sea ice; their relative abundance peaks when ice is present for 5 months per year. Ongoing down core analyses in these six areas will further reveal the nature of these assemblage changes.

  16. CDOM Optical Properties and Connectivity in the Western Gulf of Alaska, the Unimak Pass and the Southeastern Bering Sea in the Spring During a Cold Year

    Science.gov (United States)

    D'Sa, E. J.; Goes, J. I.; Mouw, C. B.

    2016-02-01

    Flow through the Aleutian Passes connects the North Pacific to the Bering Sea with the Unimak Pass forming an important conduit for the flow of Gulf of Alaska water to the southeastern Bering shelf. While the biophysical properties have been studied for this region, little is known about the dissolved organic matter (DOM) and its optically active chromophoric component (CDOM) which play key roles in ocean color and several biogeochemical and photochemical processes. Dissolved organic carbon (DOC), and CDOM absorption and fluorescence properties were measured at locations in the western Gulf of Alaska, Unimak Pass and the southeastern Bering Sea in spring 2012, a relatively cold year as indicated by hydrographic field and satellite sea surface temperature data. DOC concentrations were on average higher in the western Gulf of Alaska (112.21 ± 20.05 µM) and Unimak Pass (106.14 ± 16.10 µM), than the southeastern Bering Sea shelf (73.28 ± 11.71 µM) suggesting Gulf of Alaska shelf water to be an important source of DOM to the eastern Bering Sea. Overall, CDOM absorption was relatively low while parallel factor (PARAFAC) analysis of DOM fluorescence identified two humic-like (terrestrial and marine) and one protein-like (tryptophan-like) component in the DOM pool. Relationships between the DOM optical properties and the physical regime will be further examined in this study.

  17. Continuity and change in subsistence harvests in five Bering Sea communities: Akutan, Emmonak, Savoonga, St. Paul, and Togiak

    Science.gov (United States)

    Fall, James A.; Braem, Nicole S.; Brown, Caroline L.; Hutchinson-Scarbrough, Lisa B.; Koster, David S.; Krieg, Theodore M.

    2013-10-01

    To document and quantify subsistence harvests of fish and wildlife resources, and provide topics for subsequent key respondent interviews to collect local and traditional knowledge (LTK) about the Bering Sea ecosystem, comprehensive household harvest surveys were conducted in four Bering Sea Alaska Native communities: Akutan, Emmonak, Savoonga, and Togiak. In a fifth community, St. Paul, annual programs to document two key subsistence resources, fur seals and sea lions, continued. Surveys documented relatively high and diverse subsistence harvests, consistent with earlier research that demonstrated the continuing economic, social, and cultural importance of subsistence uses of wild resources. The research also found differences in subsistence use patterns compared to previous years' studies, such as harvest levels, harvest composition, and diversity of resources used, although differences between study years were not uniform across communities. Survey respondents, as well as key respondents in subsequent interviews, identified a complex range of personal, economic, and environmental factors when comparing subsistence uses in the study year with other years, such as increasing costs of fuel and purchased food, commercial fisheries harvests and bycatch, more persistent storms and less predictable winds, and reduced sea ice. Such conditions affect resource abundance and locations as well as access to fish and wildlife populations, and may shape long-term trends. So far, as in the past, families and communities have adapted to changing economic, social, and environmental conditions, but the future is less clear if such changes intensify or accelerate. Local community residents should be essential partners in future efforts to understand these complex processes that affect the natural resources of the Bering Sea.

  18. Quantifying the Bering Strait Oceanic Fluxes and their Impacts on Sea-Ice and Water Properties in the Chukchi and Beaufort Seas and Western Arctic Ocean for 2013-2014

    Science.gov (United States)

    2016-07-27

    impacts on sea-ice and water properties in the Chukchi and Beaufort Seas and western Arctic Ocean for 2013-2014 Rebecca Woodgate Polar Science...and G. R. Bigg (2002), Impact of flow through the Canadian Archipelago and Bering Strait on the North Atlantic and Arctic circulation: an ocean ...Technical 3. DATES COVERED (From - To) Feb 2013 - April 2016 4. TITLE AND SUBTITLE Quantifying the Bering Strait oceanic fluxes and their impacts

  19. Radon-222 and radium-226 in southeastern Bering Sea shelf waters and sediment

    International Nuclear Information System (INIS)

    Glover, D.M.; Reeburgh, W.S.

    1987-01-01

    Radon-222 and 226 Ra activities were measured in the waters and sediment of the southeastern Bering Sea shelf to evaluate the use of radon as a tracer of gas exchange, water column mixing and sediment-water exchange. Cross-shelf distributions of 222 Rn and 226 Ra are presented. Gas transfer coefficients were estimated using near-surface 222 Rn deficiency measurements. A statistically significant linear relationship between averaged wind speed and transfer coefficient was found. Vertical eddy diffusivities were evaluated by applying a one-dimensional model to near-bottom excess 222 Rn distributions; these diffusivities were compared to independently determined values. The one-dimensional model applied to the near-bottom 222 Rn data was found to be inadequate and a two-dimensional model was applied to improve the fit between model and data. Exchange across the sediment-water interface was computed from the deficiency of 222 Rn measured in sediment cores, standing crop estimates of excess 222 Rn in the water column and 222 Rn production rates of sediment surface grab samples. Biological irrigation of the sediments appeared to be the primary exchange mechanism between the sediment and water columns. Distributions in the water column showed finestructure reported previously and suggested biological removal of 226 Ra. (author)

  20. Nutrient regeneration and oxygen demand in Bering Sea continental shelf sediments

    Science.gov (United States)

    Rowe, Gilbert T.; Phoel, William C.

    1992-04-01

    Measurements of seabed oxygen demand and nutrient regeneration were made on continental shelf sediments in the southeast Bering Sea from 1 to 15 June 1981. The mean seabed oxygen demand was relatively modest (267 μM O 2 m -2 h -1), equivalent to a utilization of 60 mg organic carbon m -2 day -1. The seasonal build up of ammonium over the mid-shelf domain was generated at least in part by the bottom biota, as previously suggested ( WHITLEDGEet al., 1986 , Continental Shelf Research, 5, 109-132), but on the outer shelf nitrate replaced ammonium as the dominant inorganic nitrogen compound that was regenerated from the sediments. Comparison of oxygen consumption with the organic matter in sedimenting particulate matter (sampled with sediment traps) could imply that benthic processes were not accounting for the fate of considerable quantities of organic matter. Benthic oxygen demand rates, however, probably lag behind the input of the spring bloom to the bottom, thus extending the remineralization process out over time. Consumption by small microheterotrophs in the water column was also a likely sink, although shelf export and advective transport north were possible as well. Estimated nitrification rates in surface sediments could account for only a small fraction of the abrupt increase in nitrate observed in the water column over the shelf just prior to the spring bloom.

  1. 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

    Science.gov (United States)

    D'Sa, E. J.; Goes, J. I.; Gomes, H.; Mouw, C.

    2014-06-01

    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 (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

  2. A comparison of ship and Coastal Zone Color Scanner mapped distribution of phytoplankton in the southeastern Bering Sea

    Science.gov (United States)

    Mcclain, C. R.; Sambrotto, R. N.; Ray, G. C.; Muller-Karger, F. E.

    1990-01-01

    Twenty-one Coastal Zone Color Scanner (CZCS) images of the southeastern Bering Sea are examined in order to map the near-surface distribution of phytoplankton during 1979 and 1980. The information is compared with the mesoscale (100-1000 km) distribution of phytoplankton inferred from pooled ship sampling obtained during the Processes and Resources of the Bering Shelf (PROBES) intensive field study during the late 1970s and early 1980s. The imagery indicates that open-water phytoplankton blooms occur first in late April in coastal waters, peak in early May over the middle shelf, and decay rapidly afterwards, reaching concentration minima in June in both regions. These patterns show that the earlier ship observations are valid for most of the eastern Bering shelf. A very tight correlation is found between the PROBES surface chlorophyll a concentrations and mean mixed-layer chlorophyll concentrations. The significant discrepancies between CZCS and ship-based chlorophyll estimates may be due to aliasing in time by the CZCS. It is concluded that neither satellite nor ship alone can do an adequate job of characterizing the physics or biological dynamics of the ocean.

  3. Distribution and sources of dissolved black carbon in surface waters of the Chukchi Sea, Bering Sea, and the North Pacific Ocean

    Science.gov (United States)

    Nakane, Motohiro; Ajioka, Taku; Yamashita, Youhei

    2017-05-01

    Pyrogenic carbon, also called black carbon (BC), is an important component in the global carbon cycle. BC produced by biomass burning or fossil fuel combustion is transported to oceans by the atmosphere or rivers. However, environmental dynamics (i.e., major sources and sinks) of BC in marine environments have not been well documented. In this study, dissolved BC (DBC) collected from surface waters of the Chukchi Sea, the Bering Sea, and the subarctic and subtropical North Pacific were analyzed using the benzene polycarboxylic acid (BPCA) method. The DBC concentration and the ratio of B5CA and B6CA to all BPCAs (an index of the DBC condensation degree) ranged from 4.8 to 15.5 µg-C L-1 and from 0.20 to 0.43, respectively, in surface waters of the Chukchi/Bering Seas and the North Pacific Ocean. The concentration and condensation degree of DBC in the Chukchi/Bering Seas were higher and more variable than those in the subarctic and subtropical North Pacific, which implies that the major factors controlling DBC distribution were different in these marine provinces. In the Chukchi/Bering Seas, the DBC concentration was negatively correlated to salinity but positively correlated to chromophoric dissolved organic matter (CDOM) quantity and total dissolved lignin phenol concentration estimated by CDOM parameters. These correlations indicated that the possible major source of DBC in the Chukchi/Bering Seas was Arctic rivers. However, in the North Pacific, where riverine inputs are negligible for most sampling sites, DBC was possibly derived from the atmosphere. Although spectral slopes of CDOM at 275-295 nm (an index of the photodegradation degree of CDOM) differed widely between the subarctic and subtropical North Pacific, the concentration and condensation degrees of DBC were similar between the subarctic and subtropical North Pacific, which suggests that photodegradation was not the only major factor controlling DBC distribution. Therefore, DBC distributions of the

  4. Millennial-scale variability of marine productivity and terrigenous matter supply in the western Bering Sea over the past 180 kyr

    Directory of Open Access Journals (Sweden)

    J.-R. Riethdorf

    2013-06-01

    Full Text Available We used piston cores recovered in the western Bering Sea to reconstruct millennial-scale changes in marine productivity and terrigenous matter supply over the past ~180 kyr. Based on a geochemical multi-proxy approach, our results indicate closely interacting processes controlling marine productivity and terrigenous matter supply comparable to the situation in the Okhotsk Sea. Overall, terrigenous inputs were high, whereas export production was low. Minor increases in marine productivity occurred during intervals of Marine Isotope Stage 5 and interstadials, but pronounced maxima were recorded during interglacials and Termination I. The terrigenous material is suggested to be derived from continental sources on the eastern Bering Sea shelf and to be subsequently transported via sea ice, which is likely to drive changes in surface productivity, terrigenous inputs, and upper-ocean stratification. From our results we propose glacial, deglacial, and interglacial scenarios for environmental change in the Bering Sea. These changes seem to be primarily controlled by insolation and sea-level forcing which affect the strength of atmospheric pressure systems and sea-ice growth. The opening history of the Bering Strait is considered to have had an additional impact. High-resolution core logging data (color b*, XRF scans strongly correspond to the Dansgaard–Oeschger climate variability registered in the NGRIP ice core and support an atmospheric coupling mechanism of Northern Hemisphere climates.

  5. Cloud amount/frequency, TRANSMISSIVITY and other data from NOAA Ship MILLER FREEMAN in the Bering Sea, NW Pacific and other waters from 1992-04-04 to 1992-09-25 (NODC Accession 9300022)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in NW Pacific (limit-180), NE Pacific (limit-180), Greenland Sea and Bering Sea as part...

  6. Testing the fidelity of laminations as a proxy for oxygen concentration in the Bering Sea over millennial to orbital timescales

    Science.gov (United States)

    Black, A. E.; Baranow, N.; Amdur, S.; Cook, M. S.

    2017-12-01

    Ocean circulation and biological productivity play an important role in the climate system through their contribution to global heat transport and air-sea exchange of CO­2. Oceanic oxygen concentration provides insight to ocean circulation and biological productivity. Sediment laminations provide a valuable proxy for local oceanic oxygen concentration. Many sediment cores from the Pacific Ocean are laminated from the last deglaciation, but previous studies have not provided an in-depth examination of laminations over many glacial and interglacial (G/IG) cycles. Typically, studies to date that consider bioturbation as a proxy for oxygen concentration have only considered one sediment core from a site, leaving ambiguity as to whether laminations faithfully record local oxygen levels. With sediment cores from three different holes (A, C, D) on the northern Bering Slope from IODP site U1345 (1008m), we investigate how faithfully laminations record oxygen concentration. We assign a bioturbation index from 1 to 4 for 1-cm intervals for the cores from each of the three holes and align the holes based on physical properties data. We find that the bioturbation is relatively consistent (within one bioturbation unit) between holes, suggesting that laminations may be a faithful, if not perfect, proxy for local oxygen concentration. After examining laminations from a complete hole, representing over 500,000 years, there seems to be no consistent pattern of laminations during the past five glacial cycles, suggesting there is no consistent pattern to oxygen concentration during glacial periods in the northern Bering Slope. Thus, hypotheses on ocean circulation and productivity in the northern Bering Sea from the last deglaciation may not apply to previous G/IG cycles.

  7. Determination of iridium in the Bering Sea and Arctic Ocean seawaters by anion exchange preconcentration-neutron activation analysis

    International Nuclear Information System (INIS)

    Li Shihong; Mao Xueying; Chai Zhifang

    2004-01-01

    Anion exchange method is investigated to separate and enrich iridium in seawater by radiotracer 192 Ir. The adsorption of Ir in the resin increases with the decreasing acidity in the 0.05-1.2 mol/L HCl media, The recovery of iridium in pH=1.5 seawater reaches 89% by a single anion-exchange column. The polyethylene container of acidity of pH=1.5 are suitable for storing trace Ir in seawater. An anion exchange preconcentration-neutron activation analysis procedure is developed to determine iridium in seawaters sampled from the Bering Sea and Arctic Ocean at different depth. The reagent blank value of the whole procedures is (0.18-0.20) x 10 -12 g Ir. The iridium concentrations in the Bering Sea and Arctic Ocean seawater samples are (0.85-3.58) x 10 -12 g/L (0-3504 m) and (1.26-1.97) x 10 -12 g/L (25-1900 m), respectively

  8. Petrology and isotopic composition of Quaternary basanites dredged from the Bering Sea continental margin near Navarin Basin

    Science.gov (United States)

    Davis, A.S.; Gunn, S.H.; Gray, L.-B.; Marlow, M. S.; Wong, F.L.

    1993-01-01

    Quaternary basanites were recovered from the continental margin of the Bering Sea near Navarin Basin. The basanites are highly vesicular flow rock and hyaloclastites similar to other alkalic volcanic rocks erupted repeatedly during the last Cenozoic on islands in the Bering Sea region and in mainland Alaska. K-Ar ages for the basanites indicate at least two episodes of volcanism at about 1.1 and 0.4 Ma. Trace-element data indicate these alkalic lavas have been generated by small, but variable, amounts of partial melting of a metasomatized lherzolite source. The relativley primitive compositions (MgO >9%), presence of mantle-derived xenoliths in some alkalic lavas, and presence of forsteritic olivine with low CaO and high NiO suggest that magma rose rapidly from great depth without spending time in large, long-lived magma chambers. Alkalic volcanism apparently resulted from upwelling and decompressional melting of small isolated mantle diapirs in response to local lithospheric attenuation associated with jostling of blocks during adjustment to regional stresses. -from Authors

  9. Dissolved inorganic carbon, temperature, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer and other instruments from unknown platforms in the Arabian Sea, Bering Sea and others from 1955-01-01 to 1974-12-31 (NCEI Accession 0157456)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0157456 includes Surface underway, chemical and physical data collected from unknown platforms in the Arabian Sea, Bering Sea, Caribbean Sea, Coastal...

  10. Effects of lead structure in Bering Sea pack ice on the flight costs of wintering spectacled eiders

    Science.gov (United States)

    Bump, Joseph K.; Lovvorn, James R.

    2004-10-01

    In polar regions, sea ice is critical habitat for many marine birds and mammals. The quality of pack ice habitat depends on the duration and spacing of leads (openings in the ice), which determine access to water and air for diving endotherms, and how often and how far they must move as leads open and close. Recent warming trends have caused major changes in the extent and nature of sea ice at large scales used in climate models. However, no studies have analyzed lead structure in terms of habitat for ice-dependent endotherms, or effects of climate on ice habitat at scales relevant to their daily movements. Based on observations from an icebreaker and synthetic aperture radar (SAR) images, we developed methods to describe the dynamics and thermodynamics of lead structure relative to use by spectacled eiders ( Somateria fischeri) wintering in pack ice of the Bering Sea. By correlating lead structure with weather variables, we then used these methods to estimate changes in lead dynamics from 1945 to 2002, and effects of such changes on flight costs of the eiders. For 1991-1992, when images were available about every 3 days throughout winter, SAR images were divided among five weather regimes defined by wind speed, wind direction, and air temperature. Based on 12.5-m pixels, lead shape, compass orientation, and fetch across leads did not differ among the weather regimes. However, the five regimes differed in total area of open water, leads per unit area, and distance between leads. Lead duration was modeled based on air temperature, wind, and fetch. Estimates of mean daily flight time for eiders, based on lead duration and distance between neighboring leads, differed among regimes by 0 to 15 min. Resulting flight costs varied from 0 to 158 kJ day -1, or from 0% to 11% of estimated field metabolic rate. Over 57 winters (1945-2002), variation among years in mean daily flight time was most influenced by the north-south wind component, which determined pack divergence

  11. Anthropogenic {sup 129}I in the North Pacific, Bering and Chukchi Seas, and Arctic Ocean in 2012–2013

    Energy Technology Data Exchange (ETDEWEB)

    Nagai, H., E-mail: hnagai@chs.nihon-u.ac.jp [Department of Chemistry, College of Humanities and Sciences, Nihon University, Tokyo 156-8550 (Japan); Hasegawa, A. [Graduate School of Integrated Basic Sciences, Nihon University, Tokyo 156-8550 (Japan); Yamagata, T. [Department of Chemistry, College of Humanities and Sciences, Nihon University, Tokyo 156-8550 (Japan); Kumamoto, Y.; Nishino, S. [Japan Agency for Marine-Earth Science and Technology, Kanagawa 237-0061 (Japan); Matsuzaki, H. [Department of Nuclear Engineering and Management, The University of Tokyo, Tokyo 113-0032 (Japan)

    2015-10-15

    Most of anthropogenic {sup 129}I in marine environment are due to discharge from the nuclear fuel reprocessing facilities at Sellafield (U.K.) and La Hague (France) for past few decades. The discharge raised {sup 129}I concentration in seawaters in the North Atlantic and Arctic Oceans to more than 10{sup 9} atoms L{sup −1}, which is two orders of magnitude higher than that in other region. Recently, in March 2011, a large quantity of {sup 129}I was released into the western North Pacific due to the Fukushima Daiichi Nuclear Power Plant (F1NPP) accident. To evaluate the influence of these events, we have measured {sup 129}I concentration in seawaters in the northern North Pacific Ocean, Bering and Chukchi Seas, and Arctic Ocean in 2012–2013. The {sup 129}I concentrations were 1.0–1.8 × 10{sup 7} atoms L{sup −1} in the surface waters in the vicinity of 47°N 150°E–130°W North Pacific Ocean, Bering Sea, and Chukchi Sea (<74°N), which are equal to or lower than the {sup 129}I concentration level in surface water in the North Pacific Ocean before the F1NPP accident. The vertical profiles in the North Pacific were almost same as that observed in the western North Pacific before the F1NPP accident. The {sup 129}I distribution in seawater in the North Pacific to the Chukchi Sea revealed no significant increase of {sup 129}I concentration caused by the F1NPP accident. The {sup 129}I concentrations were 13–14 × 10{sup 7} atoms L{sup −1} in surface waters and 80 × 10{sup 7} atoms L{sup −1} at depths of 300 and 800 m in the Arctic Ocean.

  12. Linkages between sea-ice coverage, pelagic-benthic coupling, and the distribution of spectacled eiders: observations in March 2008, 2009 and 2010, northern Bering Sea

    Science.gov (United States)

    Cooper, L.W.; Sexson, M.G.; Grebmeier, J.M.; Gradinger, R.; Mordy, C.W.; Lovvorn, J.R.

    2013-01-01

    Icebreaker-based sampling in the northern Bering Sea south of St. Lawrence Island in March of 2008, 2009, and 2010 has provided new data on overall ecosystem function early in the annual productive cycle. While water-column chlorophyll concentrations (−2 integrated over the whole water column) are two orders of magnitude lower than observed during the spring bloom in May, sea-ice algal inventories of chlorophyll are high (up to 1 g m−3 in the bottom 2-cm of sea-ice). Vertical fluxes of chlorophyll as measured in sediment traps were between 0.3 to 3.7 mg m−2 d−1 and were consistent with the recent deposition (days to weeks time scale) of chlorophyll to the surface sediments (0–25 mg m−2 present at 0–1 cm). Sediment oxygen respiration rates were lower than previous measurements that followed the spring bloom, but were highest in areas of known high benthic biomass. Early spring release of sedimentary ammonium occurs, particularly southeast of St. Lawrence Island, leading to bottom-water ammonium concentrations of >5 µM. These data, together with other physical, biological, and nutrient data are presented here in conjunction with observed sea-ice dynamics and the distribution of an apex predator, the Spectacled Eider (Somateria fischeri). Sea-ice dynamics in addition to benthic food availability, as determined by sedimentation processes, play a role in the distribution of spectacled eiders, which cannot always access the greatest biomass of their preferred bivalve prey. Overall, the data and observations indicate that the northern Bering Sea is biologically active in late winter, but with strong atmospheric and hydrographic controls. These controls pre-determine nutrient and chlorophyll distributions, water-column mixing, as well as pelagic-benthic coupling.

  13. Moored current meter data collected from the Bering Sea, Gulf of Alaska, and North Pacific Ocean in support of the Fisheries Oceanography Cooperative Investigations (FOCI) project, from 16 February 1994 to 25 May 2002 (NODC Accession 0001014)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Moored current meter data were collected from the Bering Sea, Gulf of Alaska, and North Pacific Ocean from February 16, 1994 to May 25, 2002. Data were collected by...

  14. Observations of carbon dioxide in the surface waters of the Eastern North Pacific Ocean and the Bering Sea from 21 July 1968 to 03 September 1968 (NODC Accession 7100114)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Measurements of the equilibrium concentration of carbon dioxide in the air and surface waters of the North Pacific Ocean and the Bering Sea are presented....

  15. Turbidity, cloud amount/frequency and other data from ALPHA HELIX in the Gulf of Alaska and Bering Sea from 1989-10-04 to 1990-06-26 (NODC Accession 9100032)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and Benthic data were collected from Gulf of Alaska and Bering Sea using NOAA Ship Alpha Helix. The data was collected...

  16. Cetacean line-transect survey conducted in the eastern Bering Sea shelf by Alaska Fisheries Science Center, National Marine Mammal Laboratory from NOAA Ship Miller Freeman from 1999-07-07 to 2004-06-30 (NCEI Accession 0131862)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Visual surveys for cetaceans were conducted on the eastern Bering Sea shelf along transect lines, in association with the AFSC’s echo integration trawl surveys for...

  17. CHLOROPHYLL A - INTEGRATED, CARBON ASSIMILATION - INTEGRATED and other data from THOMAS G. THOMPSON in the Bering Sea from 1978-04-10 to 1980-08-15 (NODC Accession 9100027)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD), Primary production and underway data were collected as part of Processes and Resources of the Bering Sea Shelf...

  18. Plankton and other data collected from net casts in the Gulf of Alaska and Bering Sea from NOAA Ship MILLER FREEMAN from 1976-04-26 to 1976-05-31 (NCEI Accession 7700419)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Plankton and other data were collected using net casts in the Gulf of Alaska and Bering Sea from NOAA Ship MILLER FREEMAN from 26 April 1976 to 31 May 1976. Data...

  19. AFSC/RACE/EcoFOCI: NPRB project number 926: Assessing the condition of walleye pollock, Theragra chalcogramma, larvae in the eastern Bering Sea with muscle-based flow cytometry cell cycle analysis

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Walleye pollock are an important component of the eastern Bering Sea ecosystem due to their vast numbers and biomass and are of great commercial importance. Their...

  20. Zooplankton, physical, and other data collected by CHELAN in Bering Sea using CTD, bottle, net, and tide gauge casts from 18 July 1934 to 25 August 1934 (NODC Accession 9500110)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Zooplankton, physical, and other data were collected using CTD, bottle, net, and tide gauge casts from CHELAN in the Bering Sea. Data were collected from 18 July...

  1. Physical, current, and other data from CTD and current meters from FIXED PLATFORMS in the southeast Bering Sea as part of Fisheries-Oceanography Cooperative Investigations (FOCI) from 05 May 1995 to 24 February 1998 (NODC Accession 0000642)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical, current, and other data were collected from CTD and current meters attached to FIXED PLATFORMS in the southeast Bering Sea from 05 May 1995 to 24 February...

  2. Temperature and Salinity Profile Data Collected from the Bering Sea in Support of the Inner Shelf Transfer and Recycling Project from from 15 September 1985 to 22 September 1985 (NODC Accession 0000414)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — CTD and other data were collected from the Bering Sea from the ALPHA HELIX from 15 September 1985 to 22 September 1985. Data were collected by the University of...

  3. Killer whale surveys conducted in the Aleutian Islands, Bering Sea, and western and central Gulf of Alaska by Alaska Fisheries Science Center, National Marine Mammal Laboratory from 2001-07-01 to 2010-07-12 (NCEI Accession 0137766)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is a compilation of line-transect data collected on surveys in the Aleutian Islands, Bering Sea, and western and central Gulf of Alaska, 2001 - 2010....

  4. Acoustics short-term passive monitoring using sonobuoys in the Bering, Chukchi, and Western Beaufort Seas conducted by Alaska Fisheries Scientific Center, National Marine Mammal Laboratory from 2007-08-01 to 2015-09-28 (NCEI Accession 0138863)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The National Marine Mammal Laboratory (NMML) has conducted passive acoustic monitoring in the Bering, Chukchi, and Western Beaufort Seas to determine spatio-temporal...

  5. AFSC/RACE/EcoFOCI - Fish diet analyses performed in support of FOCI assessment surveys and ecosystem observations in the Bering Sea and the Gulf of Alaska. 1990's - 2010

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data set focuses on the diets of young of the year Gadus chalcogrammus from the Eastern Gulf of Alaska and the South Eastern Bering Sea. Diet data is available...

  6. NPRB 1117 Cooperative research to develop new trawl footrope designs to reduce mortality of southern Tanner and snow crabs (Chionoecetes bairdi and C. opilio) incidental to Bering Sea bottom trawl fisheries

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Alaska’s Bering Sea is home to some of the world’s most productive groundfish and crab stocks and the fisheries that depend on them. Their spatial overlap creates...

  7. Plankton and nutrients data collected using net and CTD casts from the OSHORO MARU in the Bering Sea and North Pacific Ocean from 07 June 1997 to 31 July 1999 (NODC Accession 0000803)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Plankton and nutrients data were collected using net and CTD casts in the Bering Sea and North Pacific Ocean from the OSHORO MARU. Data were collected from 07 June...

  8. A comparison of the physics of the northern and southern shelves of the eastern Bering Sea and some implications for the ecosystem

    Science.gov (United States)

    Stabeno, Phyllis J.; Farley, Edward V., Jr.; Kachel, Nancy B.; Moore, Sue; Mordy, Calvin W.; Napp, Jeffrey M.; Overland, James E.; Pinchuk, Alexei I.; Sigler, Michael F.

    2012-06-01

    Sufficient oceanographic measurements have been made in recent years to describe the latitudinal variation in the physics of the eastern Bering Sea shelf and the potential impact of climate change on the species assemblages in the two ecosystems (north and south). Many of the predicted ecosystem changes will result from alterations in the timing and extent of sea ice. It is predicted that the sea ice in the northern Bering Sea will be less common in May, but will continue to be extensive through April. In contrast, the southern shelf will have, on average, much less sea ice than currently observed, but with large interannual and multiyear variability until at least 2050. Thus, even under current climate warming scenarios, bottom temperatures on the northern shelf will remain cold. Based on biophysical measurements, the southern and northern ecosystems were divided by a North-South Transition at ˜60°N. The northern middle shelf was characterized by a freshwater lens at the surface, cold bottom temperatures, and a thicker pycnocline than found on the southern shelf. Subsurface phytoplankton blooms were common. In contrast, the southern shelf stratification was largely determined by temperature alone; the pycnocline was thin (oftenstomias, respectively) are unlikely to become common in the north. The projected warming of the southern shelf will limit the distribution of arctic species (e.g., snow crab, Chionoecetes opilio) to the northern shelf and will likely permit expansion of subarctic species into the southern Bering Sea. The distribution and abundance of baleen whales will respond to shifts in prey availability; for instance, if prey are advected northward from the southeastern Bering Sea, an extension of range and an increase in seasonally migratory baleen whale numbers is anticipated. Thus, alteration of this ecosystem in response to climate change is expected to result in something other than a simple northward shift in the distribution of all species.

  9. Pacific halibut bycatch in Pacific cod fisheries in the Bering Sea: an analysis to evaluate area-time management

    Science.gov (United States)

    Adlerstein, Sara A.; Trumble, Robert J.

    1998-03-01

    Mortality of discarded Pacific halibut bycatch from Pacific cod fisheries in the Bering Sea leads to significant losses in the halibut setline and in the Pacific cod fisheries. The commercial halibut fishery loses yield because of catch limit reductions to compensate the resource for lost spawning potential and because halibut killed as bycatch will not be available for subsequent harvest, and the cod fisheries may lose harvest if they reach a bycatch mortality limit before reaching allowed catch. In this study, significant differences in Pacific halibut bycatch rates and associated yield losses were found among months and areas of the Bering Sea in the longline and trawl fisheries for Pacific cod in 1990-1992. Bycatch rates were usually highest in late spring and early summer and in areas close to the Unimak Pass. With the exception of 1992, yield loss in the longline fishery was around 1 kg per kg of bycatch mortality, irrespective of where or when bycatch occurred. In the trawl fishery, loss of halibut yield varied from 1 to 4 kg per kg of bycatch mortality. Highest halibut net yield losses per tonne of groundfish harvest usually coincided with highest bycatch rates. When both fisheries operated in one area, trawl bycatch often imposed higher yield losses than longline bycatch, despite lower bycatch rates. Bycatch was affected by the strong 1987 halibut year class. Highest bycatch and yield loss rates occurred in the trawl fishery in 1990 and 1991 when the population was dominated by halibut age-3 and -4, and in the longline fishery in 1992 as fish reached age-5.

  10. Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from the ODEN in the Arctic Ocean, Beaufort Sea and Bering Sea from 2005-08-19 to 2005-09-25 (NODC Accession 0108129)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0108129 includes chemical, discrete sample, physical and profile data collected from ODEN in the Arctic Ocean, Beaufort Sea and Bering Sea from...

  11. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer and other instruments from New Century 2 in the Bering Sea, Caribbean Sea and others from 2014-04-11 to 2015-01-12 (NCEI Accession 0157356)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0157356 includes Surface underway, chemical and physical data collected from New Century 2 in the Bering Sea, Caribbean Sea, Coastal Waters of...

  12. Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from MIRAI in the Beaufort Sea and Bering Sea from 2006-08-21 to 2006-09-29 (NODC Accession 0112268)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0112268 includes chemical, discrete sample, optical, physical and profile data collected from MIRAI in the Beaufort Sea and Bering Sea from 2006-08-21...

  13. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from Pyxis in the Bering Sea, Caribbean Sea and others from 2001-11-06 to 2013-04-25 (NODC Accession 0081041)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0081041 includes Surface underway, chemical, meteorological and physical data collected from Pyxis in the Bering Sea, Caribbean Sea, Coastal Waters of...

  14. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer and other instruments from Sikuliaq in the Arctic Ocean, Beaufort Sea and Bering Sea from 2015-08-13 to 2015-09-02 (NCEI Accession 0157261)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0157261 includes Surface underway, chemical, meteorological and physical data collected from Sikuliaq in the Arctic Ocean, Beaufort Sea and Bering Sea...

  15. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from the MIRAI in the Arctic Ocean, Beaufort Sea and Bering Sea from 2000-08-03 to 2000-10-13 (NODC Accession 0112352)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0112352 includes chemical, discrete sample, physical and profile data collected from MIRAI in the Arctic Ocean, Beaufort Sea and Bering Sea from...

  16. Basin scale variability of active diazotrophs and nitrogen fixation in the North Pacific, from the tropics to the subarctic Bering Sea

    Science.gov (United States)

    Shiozaki, Takuhei; Bombar, Deniz; Riemann, Lasse; Hashihama, Fuminori; Takeda, Shigenobu; Yamaguchi, Tamaha; Ehama, Makoto; Hamasaki, Koji; Furuya, Ken

    2017-06-01

    Nitrogen-fixing microorganisms (diazotrophs) provide biologically available nitrogen to plankton communities and thereby greatly influence the productivity in many marine regions. Various cyanobacterial groups have traditionally been considered the major oceanic diazotrophs, but later noncyanobacterial and presumably heterotrophic diazotrophs were also found to be widespread and potentially important in nitrogen fixation. However, the distribution and activity of different diazotroph groups is still poorly constrained for most oceanic ecosystems. Here we examined diazotroph community structure and activity along a 7500 km south-north transect between the central equatorial Pacific and the Bering Sea. Nitrogen fixation contributed up to 84% of new production in the upper waters of the subtropical gyre, where the diazotroph community included the gammaproteobacterium γ-24774A11 and highly active cyanobacterial phylotypes (>50% of total nifH transcript abundance). Nitrogen fixation was sometimes detectable down to 150 m depth and extended horizontally to the edge of the gyre at around 35°N. Nitrogen fixation was even detected far north on the Bering Sea shelf. In the Alaskan Coastal Waters on the Bering Sea shelf, low nitrate together with high dissolved iron concentrations seemed to foster diazotroph growth, including a prominent role of UCYN-A2, which was abundant near the surface (1.2×105 nifH gene copies L-1). Our study provides evidence for nitrogen fixation in the Bering Sea and suggests a clear contrast in the composition of diazotrophs between the tropical/subtropical gyre and the separate waters in the cold northern regions of the North Pacific.

  17. Phosphorus burial and diagenesis in the central Bering Sea (Bowers Ridge, IODP Site U1341): Perspectives on the marine P cycle

    OpenAIRE

    März, C; Poulton, SW; Wagner, T; Schnetger, B; Brumsack, H-J

    2014-01-01

    To reconstruct the cycling of reactive phosphorus (P) in the Bering Sea, a P speciation record covering the last ~4Ma was generated from sediments recovered during Integrated Ocean Drilling Program (IODP) Expedition 323 at Site U1341 (Bowers Ridge). A chemical extraction procedure distinguishing between different operationally defined P fractions provides new insight into reactive P input, burial and diagenetic transformations. Reactive P mass accumulation rates (MARs) are ~20-110μmol/cm/ka, ...

  18. Accumulation and maternal transfer of polychlorinated biphenyls in Steller Sea Lions (Eumetopias jubatus) from Prince William Sound and the Bering Sea, Alaska

    International Nuclear Information System (INIS)

    Wang Jun; Huelck, Kathrin; Hong, Su-Myeong; Atkinson, Shannon; Li, Qing X.

    2011-01-01

    The western stock of the Steller sea lion (Eumetopias jubatus) in the northern Pacific Ocean has declined by approximately 80% over the past 30 years. This led to the listing of this sea lion population as an endangered species in 1997. Chemical pollution is a one of several contributing causes. In the present study, 145 individual PCBs were determined in tissues of male sea lions from Tatitlek (Prince William Sound) and St. Paul Island (Bering Sea), and placentae from the Aleutian Islands. PCBs 90/101, 118, and 153 were abundant in all the samples. The mean toxic equivalents (TEQ) were 2.6, 4.7 and 7.4 pg/g lw in the kidney, liver, and blubber samples, respectively. The mean TEQ in placentae was 8 pg/g lw. Total PCBs concentrations (2.6-7.9 μg/g lw) in livers of some males were within a range known to cause physiological effects. Further suggesting the possibility of adverse effects on this stock. - PCBs at median concentrations of 1.2-3.7 μg/g lipid weight in different tissues of the western stock of Steller sea lions have physiological effects.

  19. Ichthyophonus-infected walleye pollock Theragra chalcogramma (Pallas) in the eastern Bering Sea: a potential reservoir of infections in the North Pacific.

    Science.gov (United States)

    White, V C; Morado, J F; Friedman, C S

    2014-07-01

    In 2003, the Alaska walleye pollock industry reported product quality issues attributed to an unspecified parasite in fish muscle. Using molecular and histological methods, we identified the parasite in Bering Sea pollock as Ichthyophonus. Infected pollock were identified throughout the study area, and prevalence was greater in adults than in juveniles. This study not only provides the first documented report of Ichthyophonus in any fish species captured in the Bering Sea, but also reveals that the parasite has been present in this region for nearly 20 years and is not a recent introduction. Sequence analysis of 18S rDNA from Ichthyophonus in pollock revealed that consensus sequences were identical to published parasite sequences from Pacific herring and Yukon River Chinook salmon. Results from this study suggest potential for Ichthyophonus exposures from infected pollock via two trophic pathways; feeding on whole fish as prey and scavenging on industry-discharged offal. Considering the notable Ichthyophonus levels in pollock, the low host specificity of the parasite and the role of this host as a central prey item in the Bering Sea, pollock likely serve as a key Ichthyophonus reservoir for other susceptible hosts in the North Pacific. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

  20. Salmon on the Edge: Growth and Condition of Juvenile Chum and Pink Salmon in the Northeastern Bering Sea

    Science.gov (United States)

    McPhee, M. V.

    2016-02-01

    As the Arctic and Subarctic regions warm, Pacific salmon (Oncorhynchus spp.) are expected to expand their range northward during ice-free periods in the Bering and Chukchi seas. The oscillating control hypothesis, which describes energetic differences of primary consumers between ice-associated and pelagic production phases, provides a framework for understanding how juvenile salmon might respond to changing conditions at the northern edge of their marine range. Additionally, relationships between growth/condition and temperature, salinity and bottom depth will help identify marine habitats supporting growth at the Arctic-Subarctic interface. In this study, we used survey data from NOAA and Arctic Ecosystem Integrated Survey project to 1) compare growth and condition of juvenile pink (O. gorbuscha) and chum (O. keta) salmon in the NE Bering Sea between warm and cool spring phases, and 2) describe relationships between summer environmental conditions and juvenile salmon growth and condition from 2006 - 2010. Chum and pink salmon were shorter, and chum salmon exhibited greater energy density, in years with cool springs; however, no other aspects of size and condition differed significantly between phases. Over all years, longer and more energy dense individuals of both species were caught at stations with greater bottom depths and in cooler sea-surface temperatures. We found little evidence that chlorophyll-a explained much of the variation in size or condition. We used insulin-like growth factor-1 (IGF-1) concentration as an indicator of relative growth rate for fishes sampled in 2009-2012 and that found juvenile salmon exhibited higher IGF-1 concentrations in 2010-2012 than in 2009. IGF-1 concentrations tended to increase with SST in chum salmon and with bottom depth (a proxy for distance from shore) in pink salmon, but more years of data are needed to adequately describe the relationship of IGF with environmental conditions. This study, although descriptive in

  1. Change in coccolith size and morphology due to response to temperature and salinity in coccolithophore Emiliania huxleyi (Haptophyta) isolated from the Bering and Chukchi seas

    Science.gov (United States)

    Saruwatari, Kazuko; Satoh, Manami; Harada, Naomi; Suzuki, Iwane; Shiraiwa, Yoshihiro

    2016-05-01

    Strains of the coccolithophore Emiliania huxleyi (Haptophyta) collected from the subarctic North Pacific and Arctic oceans in 2010 were established as clone cultures and have been maintained in the laboratory at 15 °C and 32 ‰ salinity. To study the physiological responses of coccolith formation to changes in temperature and salinity, growth experiments and morphometric investigations were performed on two strains, namely MR57N isolated from the northern Bering Sea and MR70N at the Chukchi Sea. This is the first report of a detailed morphometric and morphological investigation of Arctic Ocean coccolithophore strains. The specific growth rates at the logarithmic growth phases in both strains markedly increased as temperature was elevated from 5 to 20 °C, although coccolith productivity (estimated as the percentage of calcified cells) was similar at 10-20 % at all temperatures. On the other hand, the specific growth rate of MR70N was affected less by changes in salinity in the range 26-35 ‰, but the proportion of calcified cells decreased at high and low salinities. According to scanning electron microscopy (SEM) observations, coccolith morphotypes can be categorized into Type B/C on the basis of their biometrical parameters. The central area elements of coccoliths varied from thin lath type to well-calcified lath type when temperature was increased or salinity was decreased, and coccolith size decreased simultaneously. Coccolithophore cell size also decreased with increasing temperature, although the variation in cell size was slightly greater at the lower salinity level. This indicates that subarctic and arctic coccolithophore strains can survive in a wide range of seawater temperatures and at lower salinities with change in their morphology. Because all coccolith biometric parameters followed the scaling law, the decrease in coccolith size was caused simply by the reduced calcification. Taken together, our results suggest that calcification productivity may

  2. Development of a Seasonal Extratropical Cyclone Activity Outlook for the North Pacific, Bering Sea, and Alaskan Regions

    Science.gov (United States)

    Shippee, N. J.; Atkinson, D. E.; Walsh, J. E.; Partain, J.; Gottschalck, J.; Marra, J. J.

    2013-12-01

    Storm activity (i.e. 'storminess') and associated forecasting skill in the North Pacific, Bering Sea, and Alaska is relatively well understood on a daily to weekly scale, however, two important elements are missing from current capacity. First, there is no way to predict storm activity at the monthly to seasonal time frame. Second, storm activity is characterized in terms that best serve weather specialists, and which are often not very informative for different sectors of the public. Increasing the utility of forecasts for end users requires consultation with these groups, and can include expressing storm activity in terms of, for example, strong-wind return intervals or ship hull strength. These types of forecasts can provide valuable information for use in community planning, resource allocation, or potential risk assessment. A preliminary study of seasonal storminess predictability in the North Pacific and Alaska regions has shown that a key factor related to the annual variation of seasonal storminess is the strength of the Aleutian Low as measured using indices such as the North Pacific Index (NPI) or Aleutian Low Pressure Index (ALPI). Use of Empirical Orthogonal Function (EOF) analysis to identify patterns in storminess variability indicates that the primary mode of annual variation is found to be best explained by the variation in the strength of the Aleutian Low. NPI and the first component of storm activity for the entire region are found to be are highly correlated (R = 0.83). This result is supported by the works of others such as Rodionov et al. (2007), who note the impact of the strength of the Aleutian Low on storm track and speed. Additionally, the phase of the Pacific Decadal Oscillation (PDO), along with NPI, have been shown to be highly correlated with annual variance in the seasonal storminess for the North Pacific and Alaska. Additional skill has been identified when the phase of the Pacific Decadal Oscillation (PDO) is explicitly considered

  3. A comparison between late summer 2012 and 2013 water masses, macronutrients, and phytoplankton standing crops in the northern Bering and Chukchi Seas

    Science.gov (United States)

    Danielson, Seth L.; Eisner, Lisa; Ladd, Carol; Mordy, Calvin; Sousa, Leandra; Weingartner, Thomas J.

    2017-01-01

    Survey data from the northern Bering and Chukchi sea continental shelves in August-September 2012 and 2013 reveal inter-annual differences in the spatial structure of water masses along with statistically significant differences in thermohaline properties, chemical properties, and phytoplankton communities. We provide a set of water mass definitions applicable to the northern Bering and Chukchi continental shelves, and we find that the near-bottom Bering-Chukchi Summer Water (BCSW) was more saline in 2012 and Alaskan Coastal Water (ACW) was warmer in 2013. Both of these water masses carried higher nutrient concentrations in 2012, supporting a larger chlorophyll a biomass that was comprised primarily of small (<10 μm) size class phytoplankton, so the classical relation between higher nutrient loads and larger phytoplankton does not hold for this region in late summer. The distributions of phytoplankton biomass and size structure reveal linkages between the wind fields, seafloor topography, water mass distributions and the pelagic production. The water mass structure, including the strength and location of stratification and fronts, respectively, differed primarily because of the August regional wind field, which was more energetic in 2012 but was more persistent in direction in 2013. High concentrations of ice in winter and early spring in 2012 and 2013 resembled conditions of the 1980s and early 1990s but the regional ice retreat rate has accelerated in the late 1990s and 2000s so the summer and fall ice concentrations more closely resembled those of the last two decades. Our data show that wind forcing can shut down the Alaskan Coastal Current in the NE Chukchi Sea for periods of weeks to months during the ice-covered winter and during the summer when buoyancy forcing is at its annual maximum. We hypothesize that a decrease in salinity and nutrients from 2012 to 2013 was a consequence of a decreased net Bering Strait transport from 2011 to 2012. Biological

  4. Carbon isotope ratios of organic matter in Bering Sea settling particles. Extremely high remineralization of organic carbon derived from diatoms

    International Nuclear Information System (INIS)

    Yasuda, Saki; Akagi, Tasuku; Naraoka, Hiroshi; Kitajima, Fumio; Takahashi, Kozo

    2016-01-01

    The carbon isotope ratios of organic carbon in settling particles collected in the highly-diatom-productive Bering Sea were determined. Wet decomposition was employed to oxidize relatively fresh organic matter. The amount of unoxidised organic carbon in the residue following wet decomposition was negligible. The δ 13 C of organic carbon in the settling particles showed a clear relationship against SiO 2 /CaCO 3 ratio of settling particles: approximately -26‰ and -19‰ at lower and higher SiO 2 /CaCO 3 ratios, respectively. The δ 13 C values were largely interpreted in terms of mixing of two major plankton sources. Both δ 13 C and compositional data can be explained consistently only by assuming that more than 98% of diatomaceous organic matter decays and that organic matter derived from carbonate-shelled plankton may remain much less remineralized. A greater amount of diatom-derived organic matter is discovered to be trapped with the increase of SiO 2 /CaCO 3 ratio of the settling particles. The ratio of organic carbon to inorganic carbon, known as the rain ratio, therefore, tends to increase proportionally with the SiO 2 /CaCO 3 ratio under an extremely diatom-productive condition. (author)

  5. The Structure of Genetic Diversity in Eelgrass (Zostera marina L.) along the North Pacific and Bering Sea Coasts of Alaska

    Science.gov (United States)

    Talbot, Sandra L.; Sage, Kevin; Rearick, Jolene; Fowler, Megan C.; Muñiz-Salazar, Raquel; Baibak, Bethany; Wyllie-Echeverria, Sandy; Cabello-Pasini, Alehandro; Ward, David H.

    2016-01-01

    Eelgrass (Zostera marina) populations occupying coastal waters of Alaska are separated by a peninsula and island archipelago into two Large Marine Ecosystems (LMEs). From populations in both LMEs, we characterize genetic diversity, population structure, and polarity in gene flow using nuclear microsatellite fragment and chloroplast and nuclear sequence data. An inverse relationship between genetic diversity and latitude was observed (heterozygosity: R2 = 0.738, P < 0.001; allelic richness: R2 = 0.327, P = 0.047), as was significant genetic partitioning across most sampling sites (θ = 0.302, P < 0.0001). Variance in allele frequency was significantly partitioned by region only in cases when a population geographically in the Gulf of Alaska LME (Kinzarof Lagoon) was instead included with populations in the Eastern Bering Sea LME (θp = 0.128–0.172; P < 0.003), suggesting gene flow between the two LMEs in this region. Gene flow among locales was rarely symmetrical, with notable exceptions generally following net coastal ocean current direction. Genetic data failed to support recent proposals that multiple Zostera species (i.e. Z. japonica and Z. angustifolia) are codistributed with Z. marina in Alaska. Comparative analyses also failed to support the hypothesis that eelgrass populations in the North Atlantic derived from eelgrass retained in northeastern Pacific Last Glacial Maximum refugia. These data suggest northeastern Pacific populations are derived from populations expanding northward from temperate populations following climate amelioration at the terminus of the last Pleistocene glaciation.

  6. Body Size Regression Formulae, Proximate Composition and Energy Density of Eastern Bering Sea Mesopelagic Fish and Squid.

    Science.gov (United States)

    Sinclair, Elizabeth H; Walker, William A; Thomason, James R

    2015-01-01

    The ecological significance of fish and squid of the mesopelagic zone (200 m-1000 m) is evident by their pervasiveness in the diets of a broad spectrum of upper pelagic predators including other fishes and squids, seabirds and marine mammals. As diel vertical migrators, mesopelagic micronekton are recognized as an important trophic link between the deep scattering layer and upper surface waters, yet fundamental aspects of the life history and energetic contribution to the food web for most are undescribed. Here, we present newly derived regression equations for 32 species of mesopelagic fish and squid based on the relationship between body size and the size of hard parts typically used to identify prey species in predator diet studies. We describe the proximate composition and energy density of 31 species collected in the eastern Bering Sea during May 1999 and 2000. Energy values are categorized by body size as a proxy for relative age and can be cross-referenced with the derived regression equations. Data are tabularized to facilitate direct application to predator diet studies and food web models.

  7. Structure-forming corals and sponges and their use as fish habitat in Bering Sea submarine canyons.

    Directory of Open Access Journals (Sweden)

    Robert J Miller

    Full Text Available Continental margins are dynamic, heterogeneous settings that can include canyons, seamounts, and banks. Two of the largest canyons in the world, Zhemchug and Pribilof, cut into the edge of the continental shelf in the southeastern Bering Sea. Here currents and upwelling interact to produce a highly productive area, termed the Green Belt, that supports an abundance of fishes and squids as well as birds and marine mammals. We show that in some areas the floor of these canyons harbors high densities of gorgonian and pennatulacean corals and sponges, likely due to enhanced surface productivity, benthic currents and seafloor topography. Rockfishes, including the commercially important Pacific ocean perch, Sebastes alutus, were associated with corals and sponges as well as with isolated boulders. Sculpins, poachers and pleuronectid flounders were also associated with corals in Pribilof Canyon, where corals were most abundant. Fishes likely use corals and sponges as sources of vertical relief, which may harbor prey as well as provide shelter from predators. Boulders may be equivalent habitat in this regard, but are sparse in the canyons, strongly suggesting that biogenic structure is important fish habitat. Evidence of disturbance to the benthos from fishing activities was observed in these remote canyons. Bottom trawling and other benthic fishing gear has been shown to damage corals and sponges that may be very slow to recover from such disturbance. Regulation of these destructive practices is key to conservation of benthic habitats in these canyons and the ecosystem services they provide.

  8. Structure-forming corals and sponges and their use as fish habitat in Bering Sea submarine canyons.

    Science.gov (United States)

    Miller, Robert J; Hocevar, John; Stone, Robert P; Fedorov, Dmitry V

    2012-01-01

    Continental margins are dynamic, heterogeneous settings that can include canyons, seamounts, and banks. Two of the largest canyons in the world, Zhemchug and Pribilof, cut into the edge of the continental shelf in the southeastern Bering Sea. Here currents and upwelling interact to produce a highly productive area, termed the Green Belt, that supports an abundance of fishes and squids as well as birds and marine mammals. We show that in some areas the floor of these canyons harbors high densities of gorgonian and pennatulacean corals and sponges, likely due to enhanced surface productivity, benthic currents and seafloor topography. Rockfishes, including the commercially important Pacific ocean perch, Sebastes alutus, were associated with corals and sponges as well as with isolated boulders. Sculpins, poachers and pleuronectid flounders were also associated with corals in Pribilof Canyon, where corals were most abundant. Fishes likely use corals and sponges as sources of vertical relief, which may harbor prey as well as provide shelter from predators. Boulders may be equivalent habitat in this regard, but are sparse in the canyons, strongly suggesting that biogenic structure is important fish habitat. Evidence of disturbance to the benthos from fishing activities was observed in these remote canyons. Bottom trawling and other benthic fishing gear has been shown to damage corals and sponges that may be very slow to recover from such disturbance. Regulation of these destructive practices is key to conservation of benthic habitats in these canyons and the ecosystem services they provide.

  9. The structure of genetic diversity in eelgrass (Zostera marina L.) along the North Pacific and Bering Sea coasts of Alaska

    Science.gov (United States)

    Talbot, Sandra L.; Sage, Kevin; Rearick, Jolene; Fowler, Megan C.; Muñiz-Salazar, Raquel; Baibak, Bethany; Wyllie-Echeverria, Sandy; Cabello-Pasini, Alehandro; Ward, David H.

    2016-01-01

    Eelgrass (Zostera marina) populations occupying coastal waters of Alaska are separated by a peninsula and island archipelago into two Large Marine Ecosystems (LMEs). From populations in both LMEs, we characterize genetic diversity, population structure, and polarity in gene flow using nuclear microsatellite fragment and chloroplast and nuclear sequence data. An inverse relationship between genetic diversity and latitude was observed (heterozygosity: R2 = 0.738, P < 0.001; allelic richness: R2 = 0.327, P = 0.047), as was significant genetic partitioning across most sampling sites (θ = 0.302, P < 0.0001). Variance in allele frequency was significantly partitioned by region only in cases when a population geographically in the Gulf of Alaska LME (Kinzarof Lagoon) was instead included with populations in the Eastern Bering Sea LME (θp = 0.128–0.172; P < 0.003), suggesting gene flow between the two LMEs in this region. Gene flow among locales was rarely symmetrical, with notable exceptions generally following net coastal ocean current direction. Genetic data failed to support recent proposals that multiple Zostera species (i.e. Z. japonica and Z. angustifolia) are codistributed with Z. marina in Alaska. Comparative analyses also failed to support the hypothesis that eelgrass populations in the North Atlantic derived from eelgrass retained in northeastern Pacific Last Glacial Maximum refugia. These data suggest northeastern Pacific populations are derived from populations expanding northward from temperate populations following climate amelioration at the terminus of the last Pleistocene glaciation.

  10. Patterns in connectivity and retention of simulated Tanner crab (Chionoecetes bairdi) larvae in the eastern Bering Sea

    Science.gov (United States)

    Richar, Jonathan I.; Kruse, Gordon H.; Curchitser, Enrique; Hermann, Albert J.

    2015-11-01

    The eastern Bering Sea (EBS) population of Tanner crab (Chionoecetes bairdi) has exhibited high variability in recruitment to the commercially exploited stock since the late 1970s. Concurrently, apparent shifts in crab distribution have also been observed. Larval advection patterns and associated local retention offer a potential mechanism for these observations. The Regional Ocean Modeling System (ROMS) was used to simulate larval Tanner crab advection patterns over 1978-2004 based on larval hatching sites inferred from the distributions of reproductive females sampled during annual National Marine Fisheries Service trawl surveys. Connectivity among EBS subregions was examined by comparing start and end float locations after 60 days of simulated drift. High levels of retention (>50% of floats) were observed in the majority of source subregions, and contributed significantly to the total number of endpoints in each region. Patterns in advection and resultant interregional connectivity were variable, with strongest sustained connectivity occurring along shelf, within individual domains. Increased settlement potential in the outer domain and southern middle domain after 1990 is consistent with an observed geographic shift in fishery productivity. Apparent reliance of Bristol Bay on local larval retention validates recent spatial fishery management to conserve this area as a subpopulation.

  11. Foraging responses of black-legged kittiwakes to prolonged food-shortages around colonies on the Bering Sea shelf.

    Directory of Open Access Journals (Sweden)

    Rosana Paredes

    Full Text Available We hypothesized that changes in southeastern Bering Sea foraging conditions for black-legged kittiwakes (Rissa tridactyla have caused shifts in habitat use with direct implications for population trends. To test this, we compared at-sea distribution, breeding performance, and nutritional stress of kittiwakes in three years (2008-2010 at two sites in the Pribilof Islands, where the population has either declined (St. Paul or remained stable (St. George. Foraging conditions were assessed from changes in (1 bird diets, (2 the biomass and distribution of juvenile pollock (Theragra chalcogramma in 2008 and 2009, and (3 eddy kinetic energy (EKE; considered to be a proxy for oceanic prey availability. In years when biomass of juvenile pollock was low and patchily distributed in shelf regions, kittiwake diets included little or no neritic prey and a much higher occurrence of oceanic prey (e.g. myctophids. Birds from both islands foraged on the nearby shelves, or made substantially longer-distance trips overnight to the basin. Here, feeding was more nocturnal and crepuscular than on the shelf, and often occurred near anticyclonic, or inside cyclonic eddies. As expected from colony location, birds from St. Paul used neritic waters more frequently, whereas birds from St. George typically foraged in oceanic waters. Despite these distinctive foraging patterns, there were no significant differences between colonies in chick feeding rates or fledging success. High EKE in 2010 coincided with a 63% increase in use of the basin by birds from St. Paul compared with 2008 when EKE was low. Nonetheless, adult nutritional stress, which was relatively high across years at both colonies, peaked in birds from St. Paul in 2010. Diminishing food resources in nearby shelf habitats may have contributed to kittiwake population declines at St Paul, possibly driven by increased adult mortality or breeding desertion due to high foraging effort and nutritional stress.

  12. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from HEALY in the Arctic Ocean, Beaufort Sea and Bering Sea from 2002-07-18 to 2002-08-21 (NODC Accession 0113953)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0113953 includes biological, chemical, discrete sample, physical and profile data collected from HEALY in the Arctic Ocean, Beaufort Sea and Bering...

  13. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from underway - surface observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from the XUE LONG in the Arctic Ocean, Beaufort Sea and Bering Sea from 2008-07-30 to 2008-09-11 (NODC Accession 0109932)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0109932 includes chemical, meteorological, physical and underway - surface data collected from XUE LONG in the Arctic Ocean, Beaufort Sea and Bering...

  14. Taxonomy of the early life stages of arrowtooth flounder (Atheresthes stomias) and Kamchatka flounder (A. evermanni) in the eastern Bering Sea, with notes on distribution and condition

    Science.gov (United States)

    De Forest, Lisa; Duffy-Anderson, J. T.; Heintz, R. A.; Matarese, A. C.; Siddon, E. C.; Smart, T. I.; Spies, I. B.

    2014-11-01

    Arrowtooth flounder (Atheresthes stomias) and Kamchatka flounder (A. evermanni) are closely related flatfish species that co-occur in the eastern Bering Sea. As adults, arrowtooth flounder can be distinguished from Kamchatka flounder; however, larvae and early juveniles can only be indentified to the genus level due to morphological similarities. This has precluded studies of ecology for the early life stages of both species in the eastern Bering Sea. In this study, we developed a genetic technique to identify the larvae and early juveniles of the two species using mtDNA cytochrome oxidase subunit I (COI). Genetically identified specimens were then examined to determine a visual identification method based on pigment patterns and morphology. Specimens 6.0-12.0 mm SL and≥18.0 mm SL can be identified to the species level, but species identification of individuals 12.1-17.9 mm SL by visual means alone remains elusive. The distribution of larvae (<25.0 mm SL) of both arrowtooth flounder and Kamchatka flounder is similar in the eastern Bering Sea; however, juvenile (≥25.0 mm SL) Kamchatka flounder occur closer to the shelf break and in deeper water than juvenile arrowtooth flounder. Condition was determined for larvae and juveniles of each species by analyzing lipid content (%) and energy density (kJ/g dry mass). Kamchatka flounder larvae on average had higher lipid content than arrowtooth flounder larvae, but were also larger on average than arrowtooth flounder larvae in the summer. When corrected for length, both species had similar lipid content in the larval and juvenile stages.

  15. Lipid markers of diet history and their retention during experimental starvation in the Bering Sea euphausiid Thysanoessa raschii

    Science.gov (United States)

    Pleuthner, Rachel L.; Shaw, C. Tracy; Schatz, Megan J.; Lessard, Evelyn J.; Harvey, H. Rodger

    2016-12-01

    Two extended pulsed feeding experiments, following the spring bloom period, investigated lipid retention in the prominent Bering Sea euphausiid (krill) Thysanoessa raschii. These experiments occurred during late spring and early summer of 2010. Concurrent taxonomic analysis of the natural algal community allowed prey type to be linked to lipid composition of the natural communities. In late spring, experimental periods of feeding followed by starvation showed an overall decrease in total lipid for T. raschii. In early summer, no consistent trend was observed for total lipid with the visible presence of storage lipid in some animals. Polar lipids, as phospholipids, were the dominant krill lipid class in both experiments constituting ≥88% of total lipid, and triacylglycerols reached a maximum of 5% of total lipid. The sterols cholesterol and brassicasterol+desmosterol comprised 98-99% of total sterol abundances in T. raschii throughout both experiments, even after feeding periods when alternative sterols (i.e. the algal sterol 24-methylenecholesterol) accounted for up to 39% of sterols in potential food particles. Cholesterol abundance and concentration increased during both incubations, likely due to the metabolism of dietary sterols. Major fatty acids observed in krill included C14:0n, C16:0n, C16:1(n-7), C18:1(n-7), C18:1(n-9), C20:5(n-3), and C22:6(n-3) with the diatom-attributed C16:1(n-7) decreasing in abundance and concentration during starvation. Low concentrations of the dinoflagellate-derived sterol and a novel C28:8 PUFA, typically found in dinoflagellates and prymnesiophytes, indicated predation on protozooplankton in early summer when diatom abundances were low. The stability of lipid distributions over periods of starvation and intermittent feeding suggest that fatty acid and sterol biomarkers present in this polar euphausiid principally reflect long-term diet history rather than short-term feeding episodes.

  16. Synergistic effects of pCO2 and iron availability on nutrient consumption ratio of the Bering Sea phytoplankton community

    Directory of Open Access Journals (Sweden)

    K. Sugie

    2013-10-01

    Full Text Available Little is known concerning the effect of CO2 on phytoplankton ecophysiological processes under nutrient and trace element-limited conditions, because most CO2 manipulation experiments have been conducted under elements-replete conditions. To investigate the effects of CO2 and iron availability on phytoplankton ecophysiology, we conducted an experiment in September 2009 using a phytoplankton community in the iron limited, high-nutrient, low-chlorophyll (HNLC region of the Bering Sea basin . Carbonate chemistry was controlled by the bubbling of the several levels of CO2 concentration (180, 380, 600, and 1000 ppm controlled air, and two iron conditions were established, one with and one without the addition of inorganic iron. We demonstrated that in the iron-limited control conditions, the specific growth rate and the maximum photochemical quantum efficiency (Fv/Fm of photosystem (PS II decreased with increasing CO2 levels, suggesting a further decrease in iron bioavailability under the high-CO2 conditions. In addition, biogenic silica to particulate nitrogen and biogenic silica to particulate organic carbon ratios increased from 2.65 to 3.75 and 0.39 to 0.50, respectively, with an increase in the CO2 level in the iron-limited controls. By contrast, the specific growth rate, Fv/Fm values and elemental compositions in the iron-added treatments did not change in response to the CO2 variations, indicating that the addition of iron canceled out the effect of the modulation of iron bioavailability due to the change in carbonate chemistry. Our results suggest that high-CO2 conditions can alter the biogeochemical cycling of nutrients through decreasing iron bioavailability in the iron-limited HNLC regions in the future.

  17. Updated analysis of flatfish recruitment response to climate variability and ocean conditions in the Eastern Bering Sea

    Science.gov (United States)

    Wilderbuer, Thomas; Stockhausen, William; Bond, Nicholas

    2013-10-01

    This study provides a retrospective analysis of the relationship between physical oceanography, biology and recruitment of three Eastern Bering Sea flatfish stocks: flathead sole (Hippoglossoides elassodon), northern rock sole (Lepidopsetta polyxystra), and arrowtooth flounder (Atheresthes stomias) during the period 1978-2005. Stock assessment model estimates of recruitment and spawning stock size indicate that temporal patterns in productivity are consistent with decadal scale (or shorter) patterns in climate variability, which may influence marine survival during the early life history phases. Density-dependence (through spawning stock size) was statistically significant in a Ricker stock-recruit model of flatfish recruitment that included environmental terms. Wind-driven advection of northern rock sole and flathead sole larvae to favorable nursery grounds was found to coincide with years of above-average recruitment. Ocean forcing of Bristol Bay surface waters during springtime was mostly on-shelf (eastward) during the 1980s and again in the early 2000s, but was off-shelf (westerly) during the 1990s, corresponding with periods of good and poor recruitment, respectively. Finally, the Arctic Oscillation was found to be an important indicator of arrowtooth flounder productivity. Model results were applied to IPCC (Intergovernmental Panel on Climate Change) future springtime wind scenarios to predict the future impact of climate on northern rock sole productivity and indicated that a moderate future increase in recruitment might be expected because the climate trends favor on-shelf transport but that density-dependence will dampen this effect such that northern rock sole abundance will not be substantially affected by climate change.

  18. Change in coccolith morphology by responding to temperature and salinity in coccolithophore Emiliania huxleyi (Haptophyta) isolated from the Bering and Chukchi Seas

    Science.gov (United States)

    Saruwatari, K.; Satoh, M.; Harada, N.; Suzuki, I.; Shiraiwa, Y.

    2015-11-01

    Strains of the coccolithophore Emiliania huxleyi (Haptophyta) collected from the subarctic North Pacific and Arctic Oceans during the R/V MIRAI cruise in 2010 (MR10-05) were established as clone cultures and have been maintained in the laboratory at 15 °C and 32 ‰ salinity. To study the physiological responses of coccolith formation to changes in temperature and salinity, growth experiments and morphometric investigations were performed on two strains of MR57N isolated from the northern Bering Sea (56°58' N, 167°11' W) and MR70N at the Chukchi Sea (69°99' N, 168° W). This is the first report of a detailed morphometric and morphological investigation of Arctic Ocean coccolithophore strains. The specific growth rates at the logarithmic growth phases in both strains markedly increased as temperature was elevated from 5 to 20 °C, although coccolith productivity (the percentage of calcified cells) was similar at 10-20 % at all temperatures. On the other hand, the specific growth rate of strain MR70N was affected less by changes in salinity in the range 26-35 ‰, but the proportion of calcified cells decreased at high and low salinities. According to scanning electron microscopy (SEM) observations, coccolith morphotypes can be categorized into Type B/C on the basis of their biometrical parameters, such as length of the distal shield (LDS), length of the inner central area (LICA), and the thickness of distal shield elements. The central area elements of coccoliths varied from grilled type to closed type when temperature was increased or salinity was decreased, and coccolith size decreased simultaneously. Coccolithophore cell size also decreased with increasing temperature, although the variation in cell size was slightly greater at the lower salinity level. This indicates that subarctic and arctic coccolithophore strains can survive in a wide range of seawater temperatures and at lower salinities due to their marked morphometric adaptation ability. Because all

  19. Differential responses of seabirds to environmental variability over 2 years in the continental shelf and oceanic habitats of southeastern Bering Sea

    Science.gov (United States)

    Yamamoto, Takashi; Kokubun, Nobuo; Kikuchi, Dale M.; Sato, Nobuhiko; Takahashi, Akinori; Will, Alexis P.; Kitaysky, Alexander S.; Watanuki, Yutaka

    2016-04-01

    Seasonal sea-ice cover has been decreasing in the southeastern Bering Sea shelf, which might affect ecosystem dynamics and availability of food resources to marine top predators breeding in the region. In this study, we investigated the foraging responses of two seabird species, surface-foraging red-legged kittiwakes Rissa brevirostris (hereafter, RLKI) and pursuit-diving foraging thick-billed murres Uria lomvia (TBMU) to different marine environmental conditions over 2 years. At-sea distributions of RLKI and TBMU breeding on St. George Island, the largest seabird colony in the region, were recorded using GPS loggers, and blood samples were taken to examine their physiological condition and isotopic foraging niche in a given year. Between the study years, winter ice retreated earlier and summer water temperatures were relatively warmer in 2014 compared to those in 2013. RLKI foraging occurred mostly over the oceanic basin in both years. TBMU, however, foraged mostly over the shelf but showed a relatively higher use of the shelf break and oceanic basin in 2013. The foraging distances from the colony peaked at 250-300 km in 2013 and bimodally at 150-250 and 300-350 km in 2014 for RLKI and tended to be farther in 2013 compared to those in 2014 for TBMU. Plasma levels of corticosterone did not differ between the years in RLKI but differed in TBMU, showing higher levels of physiological stress incurred by murres in 2013, the year of relatively cooler sea surface temperatures with later sea-ice retreat. δ13N (a proxy of trophic level of prey) did not differ between the years in either RLKI or TBMU. These results suggest that the response of ecosystem dynamics to climate variability in the southeastern Bering Sea may differ between the ocean basin and continental shelf regions, which, in turn, may generate differential responses in seabirds relying on those habitats for foraging.

  20. Surface Ocean Radiocarbon Reservoir Ages From Land-Sea Tephra Correlation Constrains Deglacial Chronology and Ocean Circulation in the Southeast Bering Sea

    Science.gov (United States)

    Cook, M. S.; Miller, R.; White-Nockleby, C.; Chapman, A.; Mix, A. C.

    2017-12-01

    Radiocarbon estimates of the past ocean are valuable because unlike passive tracers, radiocarbon has the potential to trace both the distribution and rate of transport of water masses. Most studies using paired radiocarbon measurements on planktonic and benthic foraminifera assume that the surface reservoir age was constant at the preindustrial value, which if incorrect, can strongly bias radiocarbon reconstructions. The subarctic Pacific is ringed by volcanic arcs, and there is great potential to use tephrochronology as a stratigraphic tool in sediments from the last glacial and deglaciation, and assign calendar ages to the marine sediment without relying on calibrated planktonic radiocarbon ages. In this study, we use major and trace element analysis of volcanic glass to match tephras between radiocarbon-dated lake cores from Sanak Island in the eastern Aleutians to marine cores from Umnak Plateau in the southeast Bering Sea. There are numerous thin tephras preserved in laminated sediments from the Bolling-Allerod and early Holocene in marine cores from depths (1000-1500 m) within the modern oxygen minimum zone. We find that trace elements are crucial in distinguishing tephras from individual eruptions. Our preliminary radiocarbon measurements suggest that the benthic-atmosphere radiocarbon differences and marine surface reservoir ages in the Bolling-Allerod are similar to pre-industrial values, supporting previously published radiocarbon reconstructions from the region.

  1. Partial pressure (or fugacity) of carbon dioxide, salinity and sea surface temperature collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments during R/V Oden cruise Beringia_2005 (EXPOCODE 77DN20050720) in the Northwest Passage, Can. Archipelago, Bering Strait, Chukchi Sea, East Siberian Sea and Arctic Ocean from 2005-07-20 to 2005-08-17 (NCEI Accession 0164210)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0164210 includes Surface underway data collected from R/V Oden in the Northwest Passage, Can. Archipelago, Bering Strait, Chukchi Sea, East Siberian...

  2. Climate change, pink salmon, and the nexus between bottom-up and top-down forcing in the subarctic Pacific Ocean and Bering Sea.

    Science.gov (United States)

    Springer, Alan M; van Vliet, Gus B

    2014-05-06

    Climate change in the last century was associated with spectacular growth of many wild Pacific salmon stocks in the North Pacific Ocean and Bering Sea, apparently through bottom-up forcing linking meteorology to ocean physics, water temperature, and plankton production. One species in particular, pink salmon, became so numerous by the 1990s that they began to dominate other species of salmon for prey resources and to exert top-down control in the open ocean ecosystem. Information from long-term monitoring of seabirds in the Aleutian Islands and Bering Sea reveals that the sphere of influence of pink salmon is much larger than previously known. Seabirds, pink salmon, other species of salmon, and by extension other higher-order predators, are tightly linked ecologically and must be included in international management and conservation policies for sustaining all species that compete for common, finite resource pools. These data further emphasize that the unique 2-y cycle in abundance of pink salmon drives interannual shifts between two alternate states of a complex marine ecosystem.

  3. Release of Methane from Bering Sea Sediments During the Last Glacial Period

    Energy Technology Data Exchange (ETDEWEB)

    Mea Cook; Lloyd Keigwin

    2007-11-30

    Several lines of evidence suggest that during times of elevated methane flux the sulfate-methane transition zone (SMTZ) was positioned near the sediment-water interface. We studied two cores (from 700 m and 1457 m water depth) from the Umnak Plateau region. Anomalously low d13C and high d18O in benthic and planktonic foraminifera in these cores are the consequence of diagenetic overgrowths of authigenic carbonates. There are multiple layers of authigenic-carbonate-rich sediment in these cores, and the stable isotope compositions of the carbonates are consistent with those formed during anaerobic oxidation of methane (AOM). The carbonate-rich layers are associated with biomarkers produced by methane-oxidizing archaea, archaeol and glyceryl dibiphytanyl glyceryl tetraether (GDGT). The d13C of the archaeol and certain GDGTs are isotopically depleted. These carbonate- and AOM-biomarker-rich layers were emplaced in the SMTZ during episodes when there was a high flux of methane or methane-rich fluids upward in the sediment column. The sediment methane in the Umnak Plateau region appears to have been very dynamic during the glacial period, and interacted with the ocean-atmosphere system at millennial time scales. The upper-most carbonate-rich layers are in radiocarbon-dated sediment deposited during interstitials 2 and 3, 28-20 ka, and may be associated with the climate warming during this time.

  4. The Bering Sea: Communication with the Western Subarctic Gyre, Mesoscale Activity, Shelf-Basin Exchange, and the Flow Through Bering Strait

    Science.gov (United States)

    2011-03-01

    teardrop viscous-plastic rheology (Zhang and Rothrock 2005), a mechanical redistribution function for ice ridging ( Thorndike et al. 1975; Hibler 1980...293:85–89. Thorndike A.S., Rothrock D.A., Maykut G.A., Colony R. (1975) The thickness distribution of sea ice. Journal of Geophysical Research 80

  5. Organic storage of CO/sub 2/ on the continental slope off the mid-Atlantic bight, the southeastern Bering Sea, and the Peru coast

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, J.J.; Premuzic, E.T.; Gaffney, J.S.; Rowe, G.T.; Harbottle, G.; Stoenner, R.W.; Balsam, W.L.; Betzer, P.R.; Macko, S.A.

    1985-01-01

    A comparison is made of organic content, sedimentation rates derived from /sup 14/C and /sup 210/Pb analyses, /sup 13/C and /sup 15/N isotope ratios, amorphous silica, particle size, and calcium carbonate within sediments from slopes off the mid-Atlantic bight, the southeastern Bering Sea, and the Peru coast. These sediments are mainly marine, diatom-rich, and about one-third of the organic carbon is recent, reflecting a possible transient of shelf export in response to man's increased activities since the industrial revolution. Using a combination of sedimentation and mixing rates of carbon, the C:N ratio of sediments within the upper 50 cm, and the amount of nitrogen thought to be released from the coastal zone, independent estimates suggest a carbon loading to world slopes of approx. 0.3 to 0.5 x 10/sup 9/ tons C y/sup -1/. The Bering slope exhibits no anthropogenic transients, however, while increased carbon loading may have occurred off Peru in response to overfishing and off the mid-Atlantic bight in response to eutrophication. The generality of their results depends on which of the three systems is most representative of world slopes.

  6. Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from Surface underway, discrete sample and profile observations using Alkalinity titrator, CTD and other instruments from MIRAI in the Bering Sea, North Pacific Ocean and South Pacific Ocean from 2007-10-08 to 2007-12-26 (NODC Accession 0108123)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0108123 includes Surface underway, discrete sample and profile data collected from MIRAI in the Bering Sea, North Pacific Ocean and South Pacific...

  7. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using Alkalinity titrator, CTD and other instruments from HEALY in the Bering Sea from 2008-03-29 to 2008-05-06 (NCEI Accession 0144549)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144549 includes discrete sample and profile data collected from HEALY in the Bering Sea from 2008-03-29 to 2008-05-06. These data include AMMONIUM...

  8. Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from the MIRAI in the Bering Sea and North Pacific Ocean from 2002-10-11 to 2002-11-06 (NODC Accession 0112258)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0112258 includes chemical, discrete sample, physical and profile data collected from MIRAI in the Bering Sea and North Pacific Ocean from 2002-10-11...

  9. Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from the MIRAI in the Bering Sea and North Pacific Ocean from 2008-10-11 to 2008-11-07 (NODC Accession 0112271)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0112271 includes chemical, discrete sample, physical and profile data collected from MIRAI in the Bering Sea and North Pacific Ocean from 2008-10-11...

  10. Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from THOMAS G. THOMPSON in the Bering Sea, North Pacific Ocean and South Pacific Ocean from 1993-07-05 to 1993-09-02 (NODC Accession 0115008)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0115008 includes chemical, discrete sample, physical and profile data collected from THOMAS G. THOMPSON in the Bering Sea, North Pacific Ocean and...

  11. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using Alkalinity titrator, CTD and other instruments from HEALY in the Bering Sea from 2008-07-03 to 2008-07-31 (NCEI Accession 0144981)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144981 includes discrete sample and profile data collected from HEALY in the Bering Sea from 2008-07-03 to 2008-07-31. These data include AMMONIUM...

  12. Dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from the MIRAI in the Bering Sea and North Pacific Ocean from 2004-08-07 to 2004-08-30 (NODC Accession 0113609)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0113609 includes chemical, discrete sample, physical and profile data collected from MIRAI in the Bering Sea and North Pacific Ocean from 2004-08-07...

  13. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the JOHN V. VICKERS in the Bering Sea, North Pacific Ocean and South Pacific Ocean from 1992-08-16 to 1992-10-21 (NODC Accession 0115003)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0115003 includes chemical, discrete sample, physical and profile data collected from JOHN V. VICKERS in the Bering Sea, North Pacific Ocean and South...

  14. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from MIRAI in the Bering Sea, North Pacific Ocean and South Pacific Ocean from 2007-10-08 to 2007-12-26 (NCEI Accession 0157449)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0157449 includes Surface underway, chemical, meteorological and physical data collected from MIRAI in the Bering Sea, North Pacific Ocean and South...

  15. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Barometric pressure sensor, Carbon dioxide (CO2) gas analyzer and other instruments from NOAA Ship OSCAR DYSON in the Bering Sea, Gulf of Alaska and North Pacific Ocean from 2014-03-03 to 2014-08-13 (NCEI Accession 0144980)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144980 includes Surface underway data collected from NOAA Ship OSCAR DYSON in the Bering Sea, Gulf of Alaska and North Pacific Ocean from 2014-03-03...

  16. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from MELVILLE in the Bering Sea, North Pacific Ocean and others from 1973-08-22 to 1974-06-09 (NCEI Accession 0163184)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0163184 includes chemical, discrete sample, physical and profile data collected from MELVILLE in the Bering Sea, North Pacific Ocean,...

  17. Millennial-scale variations of late Pleistocene radiolarian assemblages in the Bering Sea related to environments in shallow and deep waters

    Science.gov (United States)

    Itaki, Takuya; Kim, Sunghan; Rella, Stephan F.; Uchida, Masao; Tada, Ryuji; Khim, Boo-Keun

    2012-02-01

    A high-resolution record of the radiolarian assemblage from 60 to 10 ka was investigated using a piston core (PC-23A) obtained from the northern slope of the Bering Sea. Faunal changes based on the 29 major radiolarian taxa demonstrated that the surface and deep water conditions in the Bering Sea were related to the orbital and millennial-scale climatic variations known as glacial-interglacial and Dansgaard-Oeschger (D-O) cycles, respectively. During interstadial periods of the D-O cycles, the assemblage was characterized by increases in the high-latitude coastal species Rhizoplegma boreale and the upper-intermediate water species Cycladophora davisiana, while the sea-ice related species Actinomma boreale and A. leptodermum and many deep-water species such as Dictyophimus crisiae and D. hirundo tended to be reduced. This trend was more apparent in two laminated intervals at 15-13.5 and 11.5-11 ka, which were correlated with well-known ice-sheet collapse events that occurred during the last deglaciation: melt-water pulse (MWP)-1A and MWP-1B, respectively. The radiolarian faunal composition in these periods suggests that oceanic conditions were different from today: (1) surface water was affected by increased melt-water discharge from continental ice-sheet, occurring at the same time as an abrupt increase in atmospheric temperature, (2) upper-intermediate water (ca. 200-500 m) was well-ventilated and organic-rich, and (3) lower-intermediate water (ca. 500-1000 m) was oxygen-poor. Conversely, the sea-ice season might have been longer during stadial periods of the D-O cycles and the last glacial maximum (LGM) compared to the interstadial periods and the earliest Holocene. In these colder periods, deep-water species were very abundant, and this corresponded to increases in the oxygen isotope value of benthic foraminifera. Our findings suggest that the oxygen-rich water was present in the lower-intermediate layer resulting from intensified ventilation.

  18. Differential responses of seabirds to inter-annual environmental change in the continental shelf and oceanic habitats of southeastern Bering Sea

    Science.gov (United States)

    Yamamoto, T.; Kokubun, N.; Kikuchi, D. M.; Sato, N.; Takahashi, A.; Will, A.; Kitaysky, A. S.; Watanuki, Y.

    2015-11-01

    Seasonal sea-ice cover has been decreasing in the southeastern Bering Sea shelf, which might affect ecosystem dynamics and availability of food resources to marine top predators breeding in the region. In this study, we investigated the foraging responses of two seabird species, surface-foraging red-legged kittiwakes Rissa brevirostris (hereafter, RLKI) and pursuit-diving foraging thick-billed murres Uria lomvia (TBMU) to the inter-annual change in environmental conditions. Between the study years, winter ice retreated earlier and summer water temperatures were warmer in 2014 compared to those in 2013. At-sea distributions of RLKI and TBMU breeding on St. George Island, the largest seabird colony in the region, were recorded using GPS loggers, and blood samples were taken to examine their physiological condition and isotopic foraging niche in a given year. RLKI foraging occurred mostly over the oceanic basin in both years. TBMU, however, foraged mostly over the shelf, but showed a relatively higher use of the shelf break and oceanic basin in the colder year, 2013. The foraging distances from the colony peaked at 250-300 km in 2013 and, bimodally, at 150-250 and 300-350 km in 2014 for RLKI, and tended to be farther in 2013 compared to those in 2014 for TBMU. Plasma levels of corticosterone did not differ between years in RLKI, but differed in TBMU, showing higher levels of physiological stress incurred by murres during the colder year, 2013. δ13N (a proxy of trophic level of prey) did not differ between the years in either RLKI or TBMU, while δ13C (a proxy of prey origin) were lower in 2014 than in 2013 in both species, suggesting possible differences in influx of oceanic prey items into foraging areas. These results suggest that the response of ecosystem dynamics to climate variability in the southeast Bering Sea may differ between the ocean basin and continental shelf regions, which, in turn, may generate differential responses in seabirds relying on those

  19. Elevated CO2 stimulates marsh elevation gain, counterbalancing sea-level rise.

    Science.gov (United States)

    Langley, J Adam; McKee, Karen L; Cahoon, Donald R; Cherry, Julia A; Megonigal, J Patrick

    2009-04-14

    Tidal wetlands experiencing increased rates of sea-level rise (SLR) must increase rates of soil elevation gain to avoid permanent conversion to open water. The maximal rate of SLR that these ecosystems can tolerate depends partly on mineral sediment deposition, but the accumulation of organic matter is equally important for many wetlands. Plant productivity drives organic matter dynamics and is sensitive to global change factors, such as rising atmospheric CO(2) concentration. It remains unknown how global change will influence organic mechanisms that determine future tidal wetland viability. Here, we present experimental evidence that plant response to elevated atmospheric [CO(2)] stimulates biogenic mechanisms of elevation gain in a brackish marsh. Elevated CO(2) (ambient + 340 ppm) accelerated soil elevation gain by 3.9 mm yr(-1) in this 2-year field study, an effect mediated by stimulation of below-ground plant productivity. Further, a companion greenhouse experiment revealed that the CO(2) effect was enhanced under salinity and flooding conditions likely to accompany future SLR. Our results indicate that by stimulating biogenic contributions to marsh elevation, increases in the greenhouse gas, CO(2), may paradoxically aid some coastal wetlands in counterbalancing rising seas.

  20. Elevated CO2 stimulates marsh elevation gain, counterbalancing sea-level rise

    Science.gov (United States)

    Langley, J. Adam; McKee, Karen L.; Cahoon, Donald R.; Cherry, Julia A.; Megonigal, J. Patrick

    2009-01-01

    Tidal wetlands experiencing increased rates of sea-level rise (SLR) must increase rates of soil elevation gain to avoid permanent conversion to open water. The maximal rate of SLR that these ecosystems can tolerate depends partly on mineral sediment deposition, but the accumulation of organic matter is equally important for many wetlands. Plant productivity drives organic matter dynamics and is sensitive to global change factors, such as rising atmospheric CO2 concentration. It remains unknown how global change will influence organic mechanisms that determine future tidal wetland viability. Here, we present experimental evidence that plant response to elevated atmospheric [CO2] stimulates biogenic mechanisms of elevation gain in a brackish marsh. Elevated CO2 (ambient + 340 ppm) accelerated soil elevation gain by 3.9 mm yr−1 in this 2-year field study, an effect mediated by stimulation of below-ground plant productivity. Further, a companion greenhouse experiment revealed that the CO2 effect was enhanced under salinity and flooding conditions likely to accompany future SLR. Our results indicate that by stimulating biogenic contributions to marsh elevation, increases in the greenhouse gas, CO2, may paradoxically aid some coastal wetlands in counterbalancing rising seas. PMID:19325121

  1. Measurement of Ice-nucleating Particles over the Western North Pacific, Bering Sea, and Arctic Ocean during a R/V Mirai Cruise in 2016

    Science.gov (United States)

    Murata, K.; Tobo, Y.; Taketani, F.; Miyakawa, T.; Kanaya, Y.

    2017-12-01

    Measurement of ice-nucleating particles (INPs) was performed using aerosol samples collected during a cruise of R/V Mirai across the western North Pacific, Bering Sea, and Arctic Ocean from August to October, 2016. We used the National Institute of Polar Research Cryogenic Refrigerator Applied to Freezing Test (NIPR-CRAFT) device to examine the immersion freezing efficiency of the collected aerosols in the temperature range of -25°C to 0°C and measured the number concentration of atmospheric INPs. The INP concentrations varied over about three orders of magnitude during the cruise. Over the Arctic Ocean (i.e., >70°N), the INPs were simulations, extremely high concentrations of INPs during the returning leg would be attributed to transport of smoke from fires in Siberia. Different INP concentrations during the cruise indicates that INPs in marine air can vary dramatically in response to long-range transport of continental aerosols, such as smoke, in addition to local emissions from the sea surface. The observed concentrations of INPs were reasonably well expressed by power law fits with the number concentration of fluorescent biological aerosol particles simultaneously measured with a Waveband Integrated Bioaerosol Sensor (WIBS-4) during the cruise, which suggests that biological aerosol particles may play a role in determining INP populations in the marine air of this case.

  2. Nineteen-year time-series sediment trap study of Coccolithus pelagicus and Emiliania huxleyi (calcareous nannoplankton) fluxes in the Bering Sea and subarctic Pacific Ocean

    Science.gov (United States)

    Tsutsui, Hideto; Takahashi, Kozo; Asahi, Hirofumi; Jordan, Richard W.; Nishida, Shiro; Nishiwaki, Niichi; Yamamoto, Sumito

    2016-03-01

    Coccolithophore fluxes at two sediment trap stations, Station AB in the Bering Sea and Station SA in the subarctic Pacific Ocean, were studied over a nineteen-year (August 1990-July 2009) interval. Two major species, Coccolithus pelagicus and Emiliania huxleyi, occur at both stations, with Gephyrocapsa oceanica, Umbilicosphaera sibogae, Braarudosphaera bigelowii, and Syracosphaera spp. as minor components. The mean coccolithophore fluxes at Stations AB and SA increased from 28.9×106 m2 d-1 and 61.9×106 m2 d-1 in 1990-1999 to 54.4×106 m2 d-1 and 130.2×106 m2 d-1 in 2002-2009, respectively. Furthermore, in late 1999 to early 2000, there was a significant shift in the most dominant species from E. huxleyi to C. pelagicus. High abundances of E. huxleyi correspond to the positive mode of the Pacific Decadal Oscillation (PDO), while those of C. pelagicus respond to the PDO negative mode and are related to water temperature changes at huxleyi. At both stations the mean seawater temperature in the top 45 m from August to October increased ca. 1 °C with linear recurrence from 1990 to 2008. The coccosphere fluxes after Year 2000 at Stations AB and SA, and the shift in species dominance, may have been influenced by this warming.

  3. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from NOAA Ship MILLER FREEMAN in the Bering Sea, Coastal Waters of SE Alaska and others from 2009-05-16 to 2010-10-08 (NODC Accession 0117502)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0117502 includes Surface underway, chemical, meteorological and physical data collected from NOAA Ship MILLER FREEMAN in the Bering Sea, Coastal...

  4. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from NOAA Ship RONALD H. BROWN in the Bering Sea, Channel Islands National Marine Sanctuary and others from 2001-02-07 to 2001-12-03 (NODC Accession 0081015)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0081015 includes Surface underway, chemical and physical data collected from NOAA Ship RONALD H. BROWN in the Bering Sea, Channel Islands National...

  5. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from NATHANIEL B. PALMER in the Bering Sea, Coastal Waters of Southeast Alaska and British Columbia and others from 1994-11-04 to 1994-12-16 (NCEI Accession 0157274)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0157274 includes Surface underway, chemical, meteorological and physical data collected from NATHANIEL B. PALMER in the Bering Sea, Coastal Waters of...

  6. High-Resolution Mg/Ca Ratios in a Coralline Red Alga as a Proxy for Bering Sea Temperature Variations and Teleconnections

    Science.gov (United States)

    Halfar, J.; Steffen, H.; Kronz, A.; Steneck, R. S.; Adey, W.; Lebednik, P. A.

    2009-05-01

    We present the first continuous high-resolution record of Mg/Ca variations within an encrusting coralline red alga of the species Clathromorphum nereostratum from Amchitka Island, Aleutian Islands. Mg/Ca ratios of individual growth increments were analyzed by measuring a single point electron microprobe transect yielding a resolution of 15 samples/year on average, generating a continuous record from 1830 to 1967 of algal Mg/Ca variations. Results show that Mg/Ca ratios in the high-Mg calcite skeleton display pronounced annual cyclicity and archive late spring to late fall sea surface temperature (SST) corresponding to the main season of algal growth. Mg/Ca values correlate well to local SST (ERSSTJun-Nov, 1902-1967; r = 0.73 for 5-year mean), as well as to an air temperature record from the same region. Our data correlate well to a shorter Mg/Ca record from a second site, corroborating the ability of the alga to reliably record regional environmental signals. In addition, Mg/Ca ratios relate well to a 29-year stable oxygen isotope time series measured on the same sample, which provides additional support for the use of Mg as a paleotemperature proxy in coralline red algae, that is, unlike stable oxygen isotopes, not influenced by salinity fluctuations. High spatial correlation to large-scale SST variability in the North Pacific is observed, with patterns of strongest correlation following the direction of major oceanographic features (i.e., the signature of the Alaska Current and the Alaskan Stream), which play a key role in the exchange of water masses between the North Pacific and the Bering Sea through Aleutian Island passages. The time series further displays significant teleconnections with the signature of the Pacific Decadal Oscillation in the northeast Pacific and the Atlantic Multidecadal Oscillation.

  7. Influence of pycnocline topography and water-column structure on marine distributions of alcids (Aves: Alcidae) in Anadyr Strait, Northern Bering Sea, Alaska

    Science.gov (United States)

    Haney, J. Christopher

    1991-01-01

    Systematic ship-board surveys were used to simultaneously record seabird abundances and resolve coarse-scale (3 to 10 km) horizontal and fine-scale (1 to 10 m) vertical variability in water-column structure and bathymetry for portions of the coastal zone in Anadyr Strait near western St. Lawrence Island, northern Bering Sea, Alaska, during August and September 1987. Three plankton-feeding alcids, parakeet (Cyclorrhynchus psittacula), crested (Aethia cristatella) and least (A. pusilla) auklets, each exhibited distinct associations for different pycnocline characteristics. Least auklets were more abundant in mixed water, but they also occurred within stratified water where the pycnocline and upper-mixed layer were shallow (≤8 m) and thin (≤10 m), respectively. Low body mass (85 g), high buoyancy, and relatively poor diving ability may have restricted this auklet to areas where water-column strata nearly intersected the surface, or to areas from which strata were absent altogether due to strong vertical mixing. Parakeet and crested auklets, which are larger-bodied (ca. 260 g) planktivores with presumably greater diving ability, were more abundant in stratified water, and both species exhibited less specific affinities for water-column characteristic at intermediate and shallow levels. All three auklets avoided locations with strong pycnocline gradients (≤0.22σtm−1), a crude index of the strong, subsurface shear in water velocities characteristic of this region. Auklet distributions in Anadyr Strait were consistent with: (1) strata accessibility, as estimated from relationships between body mass and relative diving ability, (2) possible avoidance of strong subsurface water motions, and (3) habits and distributions of plankton prey. In contrast, largebodied (>450 g) alcids [i.e., common (Uria aalge) and thick-billed (U. lomvia) murres, pigeon guillemots (Cephus columba), tufted (Fratercula cirrhata), and horned (F. corniculata) puffins feeding on fish or

  8. 77 FR 52674 - Fisheries of the Exclusive Economic Zone Off Alaska; Groundfish Fisheries in the Bering Sea and...

    Science.gov (United States)

    2012-08-30

    ... Dillingham/Katmai room at the Hilton Hotel, 500 West 3rd Street, Anchorage, AK. You may submit comments on... the legal authority, history of the Steller sea lion protection measures, litigation, potential...

  9. Spatial match-mismatch between juvenile fish and prey provides a mechanism for recruitment variability across contrasting climate conditions in the eastern Bering Sea.

    Science.gov (United States)

    Siddon, Elizabeth Calvert; Kristiansen, Trond; Mueter, Franz J; Holsman, Kirstin K; Heintz, Ron A; Farley, Edward V

    2013-01-01

    Understanding mechanisms behind variability in early life survival of marine fishes through modeling efforts can improve predictive capabilities for recruitment success under changing climate conditions. Walleye pollock (Theragra chalcogramma) support the largest single-species commercial fishery in the United States and represent an ecologically important component of the Bering Sea ecosystem. Variability in walleye pollock growth and survival is structured in part by climate-driven bottom-up control of zooplankton composition. We used two modeling approaches, informed by observations, to understand the roles of prey quality, prey composition, and water temperature on juvenile walleye pollock growth: (1) a bioenergetics model that included local predator and prey energy densities, and (2) an individual-based model that included a mechanistic feeding component dependent on larval development and behavior, local prey densities and size, and physical oceanographic conditions. Prey composition in late-summer shifted from predominantly smaller copepod species in the warmer 2005 season to larger species in the cooler 2010 season, reflecting differences in zooplankton composition between years. In 2010, the main prey of juvenile walleye pollock were more abundant, had greater biomass, and higher mean energy density, resulting in better growth conditions. Moreover, spatial patterns in prey composition and water temperature lead to areas of enhanced growth, or growth 'hot spots', for juvenile walleye pollock and survival may be enhanced when fish overlap with these areas. This study provides evidence that a spatial mismatch between juvenile walleye pollock and growth 'hot spots' in 2005 contributed to poor recruitment while a higher degree of overlap in 2010 resulted in improved recruitment. Our results indicate that climate-driven changes in prey quality and composition can impact growth of juvenile walleye pollock, potentially severely affecting recruitment variability.

  10. Paleoecology of late-glacial peats from the bering land bridge, Chukchi Sea shelf region, northwestern Alaska

    Science.gov (United States)

    Elias, S.A.; Short, S.K.; Phillips, R.L.

    1992-01-01

    Insect fossils and pollen from late Pleistocene nonmarine peat layers were recovered from cores from the shelf region of the Chukchi Sea at depths of about 50 m below sea level. The peats date to 11,300-11,000 yr B.P. and provide a limiting age for the regional Pleistocene-Holocene marine transgression. The insect fossils are indicative of arctic coastal habitats like those of the Mackenzie Delta region (mean July temperatures = 10.6-14??C) suggesting that 11,000 yr ago the exposed Chukchi Sea shelf had a climate substantially warmer than modern coastal regions of the Alaskan north slope. The pollen spectra are consistent with the age assignment to the Birch Interval (14,000-9000 yr B.P.). The data suggest a meadow-like graminoid tundra with birch shrubs and some willow shrubs growing in sheltered areas. ?? 1992.

  11. Climate to fish: Synthesizing field work, data and models in a 39-year retrospective analysis of seasonal processes on the eastern Bering Sea shelf and slope

    Science.gov (United States)

    Ortiz, Ivonne; Aydin, Kerim; Hermann, Albert J.; Gibson, Georgina A.; Punt, André E.; Wiese, Francis K.; Eisner, Lisa B.; Ferm, Nissa; Buckley, Troy W.; Moffitt, Elizabeth A.; Ianelli, James N.; Murphy, James; Dalton, Michael; Cheng, Wei; Wang, Muyin; Hedstrom, Kate; Bond, Nicholas A.; Curchitser, Enrique N.; Boyd, Charlotte

    2016-12-01

    We combined field data and the output from a climate-to-fish coupled biophysical model to calculate weekly climatologies and 1971-2009 time series of physical and biological drivers for 16 distinct regions of the eastern Bering Sea shelf and slope. We focus on spatial trends and physical-biological interactions as a framework to compare model output to localized or season-specific observations. Data on pollock (≥8 cm) diet were used to evaluate energy flows and zooplankton dynamics predicted by the model. Model validation shows good agreement to sea-ice cover albeit with a one month delay in ice retreat. Likewise, the timing of spring phytoplankton blooms in the model were delayed approximately one month in the south and extend further into summer, but the relative timing between the spring and fall bloom peaks was consistent with observations. Ice-related primary producers may shift the timing of the spring bloom maximum biomass earlier in years when sea ice was still present after mid-March in the southern regions. Including the effects of explicit, dynamic fish predation on zooplankton in the model shifts the seasonal spring peak and distribution of zooplankton later in the year relative to simulations with implicit predation dependent only on zooplankton biomass and temperature; the former capturing the dynamic demand on zooplankton prey by fish. Pollock diets based on stomach samples collected in late fall and winter from 1982-2013 show overwintering euphausiids and small pollock as key prey items in the outer and southern Bering Sea shelf; a characteristic not currently present in the model. The model captured two large-scale gradients, supported by field data, characterizing the overall dynamics: 1) inshore to off-shelf physical and biological differences with a gradient in inter-annual variability from higher frequency inshore to lower frequency offshore; and 2) latitudinal gradients in the timing of events. The combined effects of length of day

  12. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from time series observations using Bubble type equilibrator for autonomous carbon dioxide (CO2) measurement, Carbon dioxide (CO2) gas analyzer and other instruments from MOORING_M2_164W_57N in the Bering Sea from 2013-05-06 to 2014-10-19 (NCEI Accession 0157599)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0157599 includes chemical, meteorological, physical and time series data collected from MOORING_M2_164W_57N in the Bering Sea from 2013-05-06 to...

  13. Diving Behaviors and Habitat Use of Adult Female Steller Sea Lion (Eumetopias jubatus), A Top Predator of the Bering Sea and North Pacific Ocean Ecosystems

    Science.gov (United States)

    Lander, M. E.; Fadely, B.; Gelatt, T.; Sterling, J.; Johnson, D.; Haulena, M.; McDermott, S.

    2016-02-01

    Decreased natality resulting from nutritional stress is one hypothesized mechanism for declines of Steller sea lions (SSLs; Eumetopias jubatus) in western Alaska, but little is known of the winter foraging habitats or behavior of adult females. To address this critical data need, adult female Steller sea lions were chemically immobilized and tagged with Fastloc® GPS satellite transmitters during the fall at Southeast Alaska (SEAK) during 2010 (n=3), and the central and western Aleutian Islands (AI) from 2011-2014 (n=9). To identify habitat features of biological importance to these animals, location data were processed with a continuous-time correlated random walk model and kernel density estimates of predicted locations were used to compute individual-based utilization distributions. Kernel density estimates and diving behaviors (i.e. mean, maximum, and frequency of dive depths) were examined with respect to a series of static and dynamic environmental variables using linear mixed-effects models. Habitat use varied within and among individuals, but overall, all response variables were significantly related to a combination of the predictor variables season, distance to nearest SSL site, bathymetric slope, on/off shelf, sea surface temperature, sea surface height, proportion of daylight, and some interaction effects (P≤0.05). The habitat use of SSL from SEAK was consistent with previous reports and reflected the seasonal distribution of predictable forage fish, whereas SSL from the AI used a variety of marine ecosystems and habitat use was more variable, likely reflecting specific prey behaviors encountered in different areas. These results have improved our understanding of the habitat features necessary for the conservation of adult female SSL and have been useful for reviewing designated critical habitat for Steller sea lions throughout the U.S. range.

  14. Sea level and turbidity controls on mangrove soil surface elevation change

    Science.gov (United States)

    Lovelock, Catherine E.; Fernanda Adame, Maria; Bennion, Vicki; Hayes, Matthew; Reef, Ruth; Santini, Nadia; Cahoon, Donald R.

    2015-01-01

    Increases in sea level are a threat to seaward fringing mangrove forests if levels of inundation exceed the physiological tolerance of the trees; however, tidal wetlands can keep pace with sea level rise if soil surface elevations can increase at the same pace as sea level rise. Sediment accretion on the soil surface and belowground production of roots are proposed to increase with increasing sea level, enabling intertidal habitats to maintain their position relative to mean sea level, but there are few tests of these predictions in mangrove forests. Here we used variation in sea level and the availability of sediments caused by seasonal and inter-annual variation in the intensity of La Nina-El Nino to assess the effects of increasing sea level on surface elevation gains and contributing processes (accretion on the surface, subsidence and root growth) in mangrove forests. We found that soil surface elevation increased with mean sea level (which varied over 250 mm during the study) and with turbidity at sites where fine sediment in the water column is abundant. In contrast, where sediments were sandy, rates of surface elevation gain were high, but not significantly related to variation in turbidity, and were likely to be influenced by other factors that deliver sand to the mangrove forest. Root growth was not linked to soil surface elevation gains, although it was associated with reduced shallow subsidence, and therefore may contribute to the capacity of mangroves to keep pace with sea level rise. Our results indicate both surface (sedimentation) and subsurface (root growth) processes can influence mangrove capacity to keep pace with sea level rise within the same geographic location, and that current models of tidal marsh responses to sea level rise capture the major feature of the response of mangroves where fine, but not coarse, sediments are abundant.

  15. Seasonal calcareous nannoplankton and other biogenic particle fluxes for 1990-2009: twenty-year long records from the central subarctic Pacific Ocean and the Bering Sea

    Science.gov (United States)

    Takahashi, Kozo; Tsutsui, Hideto

    2017-04-01

    Time-series sediment traps were deployed for nearly 20 years (1990-2009) at two long-term locations: Station SA (49°N, 174°W, trap depth 4,800 m, water depth 5,400 m) in the central subarctic Pacific, and Station AB (53.5°N, 177°W, trap depth 3,200 m, water depth 3,800 m) in the southern Bering Sea. Among many biogenic particles, calcareous nannoplankton represented nearly half or more of the entire calcium carbonate fluxes of the regions. Dominant taxa include Coccolithus pelagicus and Emiliania huxleyi. The flux maxima of the former taxon occurred twice a year during June and October-November, whereas that of the latter taxon only occurred primarily once a year in November at both stations, indicating environmental preferences of the taxa. Among many environmental conditions, the fluxes of Emiliania huxleyi showed strong correlations with both water temperatures above 45 m depth and air temperatures (these parameters taken with one-month lag [earlier values] considering sinking time of ca. a month to the respective trap depths). Coccolithus pelagicus, on the other hand, showed lower values in the correlation with temperatures (Tsutsui et al., 2016), indicating that this taxon is somewhat more dependent on other factors such as nutrients compared to those of E. huxleyi. The timings of the seasonal flux maxima of calcareous nannoplankton are quite different from and later than those of other taxonomic groups such as diatoms and silicoflagellates. The primary seasonal flux maxima of diatoms and silicoflagellates, for example, occurred in May, a month earlier than the June maximum of C. pelagicus, and secondary seasonal flux maxima occurred in August, 2-3 months earlier than those of calcareous nannoplankton at both stations, based on 8 year flux records for diatoms (Onodera and Takahashi, 2009) and 4 year records for silicoflagellates (Onodera and Takahashi, 2012). By examining seasonal changes of nitrate and phosphate concentrations above 50 m depth from ERDDAP

  16. Comparison of AltiKa and CryoSat-2 Elevation and Elevation Rates over the Amundsen Sea Sector

    Science.gov (United States)

    Otosaka, I.; Shepherd, A.; Hogg, A.

    2017-12-01

    Altimeters have been successfully used for more than two decades to observe changes in the ice sheet surface and to estimate the contribution of ice sheets to sea level rise. The Satellite for Argos and AltiKa (SARAL) was launched in February 2013 as a joint mission between the French space agency (CNES) and the Indian Space Research Organisation (ISRO). While the altimeters previously launched into space are operating at Ku-band (13.6 GHz), the altimeter on board SARAL, AltiKa, is the first instrument to operate at Ka-band (36.8 GHz). The higher frequency of AltiKa is expected to lead to reduced penetration of the radar signal into the snowpack, compared to Ku-band. A comparison of ice sheet elevation measurements recorded at the two frequencies may therefore provide useful information on surface and its scattering properties. In this study, we compare elevation and elevation rates recorded by AltiKa and CryoSat-2 between March 2013 and April 2017 over the Amundsen Sea Sector (ASS), one of the most rapidly changing sectors of West Antarctica. Elevation and elevation rates are computed within 5 km grid cells using a plane fit method, taking into account the contributions of topography and fluctuations in elevation and backscatter. The drifting orbit and imaging modes of CryoSat-2 result in 78,7 % sampling of the study area, whereas AltiKa samples 39,7 % due to its sparser orbit pattern and due to loss of signal in steeply sloping coastal margins. Over the study period, the root mean square difference between elevation and elevation change recorded at Ka-band and Ku-band were 40.3 m and 0.54 m/yr, respectively. While the broad spatial pattern of elevation change is well resolved by both satellites, data gaps along the Getz coastline may be partly responsible for the lower elevation change rate observed at Ka-band. We also compared CryoSat-2 and AltiKa to coincident airborne data from NASA's Operation IceBridge (OIB). The mean difference of elevation rate between

  17. Bering-Okhotsk Seal Survey (BOSS) Identified Hot Spots (2012-13)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — US surveys were conducted of the Bering Sea pack ice for bearded, spotted, ribbon, and ringed seals using digital cameras and thermal imagers mounted in the belly...

  18. Bering-Okhotsk Seal Survey (BOSS) Color Imagery (2012-13)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — US surveys were conducted of the Bering Sea pack ice for bearded, spotted, ribbon, and ringed seals using digital cameras and thermal imagers mounted in the belly...

  19. MAPPING OF THE RUSSIAN NORTHERN SEAS BOTTOM RELIEF USING DIGITAL ELEVATION MODELS

    Directory of Open Access Journals (Sweden)

    S. M. Koshel

    2014-01-01

    Full Text Available The task of the project is the design of the digital elevation models (DEM of the bottoms of Barents Sea, Pechora Sea, and the White Sea. Accuracy (resolution of DEMs allows for adequate delineation of morphological structures and peculiarities of the sea bottoms and the design of bathymetrical and derivative maps. DEMs of the sea bottom were compiled using data from navigation charts of different scales, where additional isobaths were drawn manually taking into account the classification features of the bottom topography forms. Next procedures were carried out: scanning of these charts, processing of scanned images, isobaths vectorization and creation of attribute tables, vector layers transformation to geographical coordinates as well editing, merging and joining of the map sheets, correction of geometry and attributes. For generation of digital model of bottom topography it is important to choose algorithm which allows for representation all of the sea bottom features expressed by isobaths in most details. The original algorithm based on fast calculation of distances to the two different nearest isobaths was used. Interpretation of isolines as vector linear objects is the main peculiarity of this algorithm. The resulted DEMs were used to design bathymetrical maps of Barents Sea of 1:2 500 000 scale, Pechora Sea of 1:1 000 000 scale, and White Sea of 1:750 000 scale. Different derivative maps were compiled based on DEM of the White Sea.

  20. Caribbean mangroves adjust to rising sea level through biotic controls on change in soil elevation

    Science.gov (United States)

    McKee, K.L.; Cahoon, D.R.; Feller, Ilka C.

    2007-01-01

    Aim The long-term stability of coastal ecosystems such as mangroves and salt marshes depends upon the maintenance of soil elevations within the intertidal habitat as sea level changes. We examined the rates and processes of peat formation by mangroves of the Caribbean Region to better understand biological controls on habitat stability. Location Mangrove-dominated islands on the Caribbean coasts of Belize, Honduras and Panama were selected as study sites. Methods Biological processes controlling mangrove peat formation were manipulated (in Belize) by the addition of nutrients (nitrogen or phosphorus) to Rhizophora mangle (red mangrove), and the effects on the dynamics of soil elevation were determined over a 3-year period using rod surface elevation tables (RSET) and marker horizons. Peat composition and geological accretion rates were determined at all sites using radiocarbon-dated cores. Results The addition of nutrients to mangroves caused significant changes in rates of mangrove root accumulation, which influenced both the rate and direction of change in elevation. Areas with low root input lost elevation and those with high rates gained elevation. These findings were consistent with peat analyses at multiple Caribbean sites showing that deposits (up to 10 m in depth) were composed primarily of mangrove root matter. Comparison of radiocarbon-dated cores at the study sites with a sea-level curve for the western Atlantic indicated a tight coupling between peat building in Caribbean mangroves and sea-level rise over the Holocene. Main conclusions Mangroves common to the Caribbean region have adjusted to changing sea level mainly through subsurface accumulation of refractory mangrove roots. Without root and other organic inputs, submergence of these tidal forests is inevitable due to peat decomposition, physical compaction and eustatic sea-level rise. These findings have relevance for predicting the effects of sea-level rise and biophysical processes on tropical

  1. Tidal marsh plant responses to elevated CO2 , nitrogen fertilization, and sea level rise.

    Science.gov (United States)

    Adam Langley, J; Mozdzer, Thomas J; Shepard, Katherine A; Hagerty, Shannon B; Patrick Megonigal, J

    2013-05-01

    Elevated CO2 and nitrogen (N) addition directly affect plant productivity and the mechanisms that allow tidal marshes to maintain a constant elevation relative to sea level, but it remains unknown how these global change drivers modify marsh plant response to sea level rise. Here we manipulated factorial combinations of CO2 concentration (two levels), N availability (two levels) and relative sea level (six levels) using in situ mesocosms containing a tidal marsh community composed of a sedge, Schoenoplectus americanus, and a grass, Spartina patens. Our objective is to determine, if elevated CO2 and N alter the growth and persistence of these plants in coastal ecosystems facing rising sea levels. After two growing seasons, we found that N addition enhanced plant growth particularly at sea levels where plants were most stressed by flooding (114% stimulation in the + 10 cm treatment), and N effects were generally larger in combination with elevated CO2 (288% stimulation). N fertilization shifted the optimal productivity of S. patens to a higher sea level, but did not confer S. patens an enhanced ability to tolerate sea level rise. S. americanus responded strongly to N only in the higher sea level treatments that excluded S. patens. Interestingly, addition of N, which has been suggested to accelerate marsh loss, may afford some marsh plants, such as the widespread sedge, S. americanus, the enhanced ability to tolerate inundation. However, if chronic N pollution reduces the availability of propagules of S. americanus or other flood-tolerant species on the landscape scale, this shift in species dominance could render tidal marshes more susceptible to marsh collapse. © 2013 Blackwell Publishing Ltd.

  2. Surge of a Complex Glacier System - The Current Surge of the Bering-Bagley Glacier System, Alaska

    Science.gov (United States)

    Herzfeld, U. C.; McDonald, B.; Trantow, T.; Hale, G.; Stachura, M.; Weltman, A.; Sears, T.

    2013-12-01

    Understanding fast glacier flow and glacial accelerations is important for understanding changes in the cryosphere and ultimately in sea level. Surge-type glaciers are one of four types of fast-flowing glaciers --- the other three being continuously fast-flowing glaciers, fjord glaciers and ice streams --- and the one that has seen the least amount of research. The Bering-Bagley Glacier System, Alaska, the largest glacier system in North America, surged in 2011 and 2012. Velocities decreased towards the end of 2011, while the surge kinematics continued to expand. A new surge phase started in summer and fall 2012. In this paper, we report results from airborne observations collected in September 2011, June/July and September/October 2012 and in 2013. Airborne observations include simultaneously collected laser altimeter data, videographic data, GPS data and photographic data and are complemented by satellite data analysis. Methods range from classic interpretation of imagery to analysis and classification of laser altimeter data and connectionist (neural-net) geostatistical classification of concurrent airborne imagery. Results focus on the characteristics of surge progression in a large and complex glacier system (as opposed to a small glacier with relatively simple geometry). We evaluate changes in surface elevations including mass transfer and sudden drawdowns, crevasse types, accelerations and changes in the supra-glacial and englacial hydrologic system. Supraglacial water in Bering Glacier during Surge, July 2012 Airborne laser altimeter profile across major rift in central Bering Glacier, Sept 2011

  3. Legal regime of the Bering Strait and security of navigation

    Directory of Open Access Journals (Sweden)

    Aleksandr S. Skaridov

    2016-12-01

    Full Text Available Objective to establish the legal regime and security of navigation in the Bering Strait. Methods formal logical method systemic method comparative legal method statistical method. Results in the recent years specialized publications contain numerous publications on the problems of development of Arctic shipping and the future intensification of the use of the Northern Sea Route. Whatever Arctic routes may be chosen by the skippers the vessels will have to overcome the narrowness of the Bering Strait. If the existing estimates are reasonable and the navigation of the NorthWest Sea Passage will increase it is appropriate to ask whether the legal regime and security means are adapted to the possible increase of commercial shipping and military navigation. In this respect the author formulates the legal measures aimed at ensuring security in the Bering Strait area with the account of growing cargo traffic. Scientific novelty for the first time the article proves the necessity to include into the Bering Strait area the territories bounded from the north by the east and west passages formed by the Diomede Islands and continental coasts of the Russian Federation and the United States and from the south ndash by the passages between the Cape of Chukotka and Cape Sevuokuk of St. Lawrence Island Cape Sivuka and the mainland of Alaska in order to protect the sea natural landscape and to ensure the maritime safety. The opinion is substantiated about the necessity to equip the marine passages forming the waters of the Bering Strait with a security system. The proposed legal regime of ensuring the safety of navigation in the Bering Strait which includes the common navigation rules establishing the areas of the vessel traffic separation designation of areas of marine reserves and organizationallegal means for damping the dangerous situations. Practical significance the findings and conclusions of the article can be used in scientific educational and law

  4. Elevated CO2 enhances biological contributions to elevation change in coastal wetlands by offsetting stressors associated with sea-level rise

    Science.gov (United States)

    Cherry, J.A.; McKee, K.L.; Grace, J.B.

    2009-01-01

    1. Sea-level rise, one indirect consequence of increasing atmospheric CO2, poses a major challenge to long-term stability of coastal wetlands. An important question is whether direct effects of elevated CO 2 on the capacity of marsh plants to accrete organic material and to maintain surface elevations outweigh indirect negative effects of stressors associated with sea-level rise (salinity and flooding). 2. In this study, we used a mesocosm approach to examine potential direct and indirect effects of atmospheric CO2 concentration, salinity and flooding on elevation change in a brackish marsh community dominated by a C3 species, Schoenoplectus americanus, and a C4 grass, Spartina patens. This experimental design permitted identification of mechanisms and their role in controlling elevation change, and the development of models that can be tested in the field. 3. To test hypotheses related to CO2 and sea-level rise, we used conventional anova procedures in conjunction with structural equation modelling (SEM). SEM explained 78% of the variability in elevation change and showed the direct, positive effect of S. americanus production on elevation. The SEM indicated that C3 plant response was influenced by interactive effects between CO2 and salinity on plant growth, not a direct CO2 fertilization effect. Elevated CO2 ameliorated negative effects of salinity on S. americanus and enhanced biomass contribution to elevation. 4. The positive relationship between S. americanus production and elevation change can be explained by shoot-base expansion under elevated CO 2 conditions, which led to vertical soil displacement. While the response of this species may differ under other environmental conditions, shoot-base expansion and the general contribution of C3 plant production to elevation change may be an important mechanism contributing to soil expansion and elevation gain in other coastal wetlands. 5. Synthesis. Our results revealed previously unrecognized interactions and

  5. AFSC/RACE/EcoFOCI: Chlorophyll: variability in spring chlorophyll concentrations and zooplankotn on the eastern Bering Sea shelf - cruise Healy 07-01

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data were collected under NSF Grant # ARC-0722448 ("BEST: Impacts of Sea-ice on the Hydrographic Structure, Nutrients, and Mesozooplankton over the Eastern...

  6. Barrier island response to an elevated sea-level anomaly: Onslow Beach, North Carolina, USA

    Science.gov (United States)

    Theuerkauf, E. J.; Rodriguez, A. B.; Fegley, S. R.; Luettich, R.

    2012-12-01

    Variations in sea level over time scales ranging from hours to millennia influence coastal processes and evolution. At annual time scales, elevated sea-level anomalies produce coastal flooding and promote beach erosion. This study examines the coastal response of Onslow Beach, North Carolina to the summer 2009 East Coast sea-level anomaly. Onslow Beach is a 12-km-long wave-dominated barrier island with highly variable along-barrier morphology. The transgressive southern portion of the island is characterized by a narrow beach, low dunes, and multiple washover fans, while the regressive northern portion is characterized by a wide beach and continuous tall dunes. Hourly tide gauge data from adjacent NOAA stations (Beaufort and Wrightsville Beach) are used to determine the timing and extent of elevated water levels. The seasonal and longer term trends (relative sea level rise) are removed from both of the water level series and the sea-level anomaly is represented by a large residual between the observed and predicted water levels. Beach response is quantified using terrestrial laser scanning for morphology and from geoprobe cores to determine the maximum depth of erosion (MDOE). The mean high water (MHW) shoreline and dune toe are digitized from digital elevation models derived from the laser scans and analyzed using the Digital Shoreline Analysis System (DSAS). Landward (negative) movement of these contacts indicates erosion. Wave data collected from an Acoustic Wave and Current Meter (AWAC) located offshore of the southern end of Onslow Beach is used to characterize the wave regime throughout the study. Water level is elevated in the tide gauge data from June 2009 to March 2010. This sea-level anomaly corresponds with an increase in the maximum depth of erosion between 2009 and 2010. Landward movement of the MHW shoreline and the dunetoe increased during the period between September 2009 and May 2010 indicating an increase in beach erosion during the sea

  7. Geological evolution and analysis of confirmed or suspected gas hydrate localities: Volume 10, Basin analysis, formation and stability of gas hydrates of the Aleutian Trench and the Bering Sea

    Energy Technology Data Exchange (ETDEWEB)

    Krason, J.; Ciesnik, M.

    1987-01-01

    Four major areas with inferred gas hydrates are the subject of this study. Two of these areas, the Navarin and the Norton Basins, are located within the Bering Sea shelf, whereas the remaining areas of the Atka Basin in the central Aleutian Trench system and the eastern Aleutian Trench represent a huge region of the Aleutian Trench-Arc system. All four areas are geologically diverse and complex. Particularly the structural features of the accretionary wedge north of the Aleutian Trench still remain the subjects of scientific debates. Prior to this study, suggested presence of the gas hydrates in the four areas was based on seismic evidence, i.e., presence of bottom simulating reflectors (BSRs). Although the disclosure of the BSRs is often difficult, particularly under the structural conditions of the Navarin and Norton basins, it can be concluded that the identified BSRs are mostly represented by relatively weak and discontinuous reflectors. Under thermal and pressure conditions favorable for gas hydrate formation, the relative scarcity of the BSRs can be attributed to insufficient gas supply to the potential gas hydrate zone. Hydrocarbon gas in sediment may have biogenic, thermogenic or mixed origin. In the four studied areas, basin analysis revealed limited biogenic hydrocarbon generation. The migration of the thermogenically derived gases is probably diminished considerably due to the widespread diagenetic processes in diatomaceous strata. The latter processes resulted in the formation of the diagenetic horizons. The identified gas hydrate-related BSRs seem to be located in the areas of increased biogenic methanogenesis and faults acting as the pathways for thermogenic hydrocarbons.

  8. A new bed elevation model for the Weddell Sea sector of the West Antarctic Ice Sheet

    Science.gov (United States)

    Jeofry, Hafeez; Ross, Neil; Corr, Hugh F. J.; Li, Jilu; Morlighem, Mathieu; Gogineni, Prasad; Siegert, Martin J.

    2018-04-01

    We present a new digital elevation model (DEM) of the bed, with a 1 km gridding, of the Weddell Sea (WS) sector of the West Antarctic Ice Sheet (WAIS). The DEM has a total area of ˜ 125 000 km2 covering the Institute, Möller and Foundation ice streams, as well as the Bungenstock ice rise. In comparison with the Bedmap2 product, our DEM includes new aerogeophysical datasets acquired by the Center for Remote Sensing of Ice Sheets (CReSIS) through the NASA Operation IceBridge (OIB) program in 2012, 2014 and 2016. We also improve bed elevation information from the single largest existing dataset in the region, collected by the British Antarctic Survey (BAS) Polarimetric radar Airborne Science Instrument (PASIN) in 2010-2011, from the relatively crude measurements determined in the field for quality control purposes used in Bedmap2. While the gross form of the new DEM is similar to Bedmap2, there are some notable differences. For example, the position and size of a deep subglacial trough (˜ 2 km below sea level) between the ice-sheet interior and the grounding line of the Foundation Ice Stream have been redefined. From the revised DEM, we are able to better derive the expected routing of basal water and, by comparison with that calculated using Bedmap2, we are able to assess regions where hydraulic flow is sensitive to change. Given the potential vulnerability of this sector to ocean-induced melting at the grounding line, especially in light of the improved definition of the Foundation Ice Stream trough, our revised DEM will be of value to ice-sheet modelling in efforts to quantify future glaciological changes in the region and, from this, the potential impact on global sea level. The new 1 km bed elevation product of the WS sector can be found at https://doi.org/10.5281/zenodo.1035488" target="_blank">https://doi.org/10.5281/zenodo.1035488.

  9. Aerial Surveys of Endangered Whales in the Northern Bering, Eastern Chukchi, and Alaskan Beaufort Seas, 1984: with a Six Year Review, 1979-1984.

    Science.gov (United States)

    1985-06-01

    I- * I 4 ?2 7- /’PT L0~ *70 BATRIS. K ERSCHIE I 158 158 154 152 1SO 148 146 144 142 140 138 9EAUFORT SEA 72 D 71 70 - -BRE i" isI ISO 154 152... ISO 146 146 144 142 140 136 Figure 19. (Continued). 51 Sp In October, 99 bowheads were sighted in the Beaufort Sea along and seaward of the 20-m isobath...04501T 51% 2% 43% 3% 27001 09001 27001 09001 21% 19% 4% 22501 9% 13501 22501 4% 3% 13501 18001 18001 n 47, R :226 0T n - 10, R 211 IT z2740,pɘD01 z -39.86

  10. Diomede Islands, Bering Straight

    Science.gov (United States)

    2008-01-01

    The Diomede Islands consisting of the western island Big Diomede (also known as Imaqliq, Nunarbuk or Ratmanov Island), and the eastern island Little Diomede (also known as Krusenstern Island or Inaliq), are two rocky islands located in the middle of the Bering Strait between Russia and Alaska. The islands are separated by an international border and the International Date Line which is approximately 1.5 km from each island; you can look from Alaska into tomorrow in Russia. At the closest land approach between the United States, which controls Little Diomede, and Russia, which controls Big Diomede, they are 3 km apart. Little Diomede Island constitutes the Alaskan City of Diomede, while Big Diomede Island is Russia's easternmost point. The first European to reach the islands was the Russian explorer Semyon Dezhnev in 1648. The text of the 1867 treaty finalizing the sale of Alaska uses the islands to designate the border between the two nations. The image was acquired July 8, 2000, covers an area of 13.5 x 10.8 km, and is located at 65.8 degrees north latitude, 169 degrees west longitude. The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  11. Consideration of vertical uncertainty in elevation-based sea-level rise assessments: Mobile Bay, Alabama case study

    Science.gov (United States)

    Gesch, Dean B.

    2013-01-01

    The accuracy with which coastal topography has been mapped directly affects the reliability and usefulness of elevationbased sea-level rise vulnerability assessments. Recent research has shown that the qualities of the elevation data must be well understood to properly model potential impacts. The cumulative vertical uncertainty has contributions from elevation data error, water level data uncertainties, and vertical datum and transformation uncertainties. The concepts of minimum sealevel rise increment and minimum planning timeline, important parameters for an elevation-based sea-level rise assessment, are used in recognition of the inherent vertical uncertainty of the underlying data. These concepts were applied to conduct a sea-level rise vulnerability assessment of the Mobile Bay, Alabama, region based on high-quality lidar-derived elevation data. The results that detail the area and associated resources (land cover, population, and infrastructure) vulnerable to a 1.18-m sea-level rise by the year 2100 are reported as a range of values (at the 95% confidence level) to account for the vertical uncertainty in the base data. Examination of the tabulated statistics about land cover, population, and infrastructure in the minimum and maximum vulnerable areas shows that these resources are not uniformly distributed throughout the overall vulnerable zone. The methods demonstrated in the Mobile Bay analysis provide an example of how to consider and properly account for vertical uncertainty in elevation-based sea-level rise vulnerability assessments, and the advantages of doing so.

  12. Oceanographic profile plankton, nitrate, silicate and other measurements collected using net and high resolution CTD in the Pacific, Bering, Tsugaru Strait, and Okhotsk from 1988 to 1998 (NODC Accession 0000824)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Plankton and nutrients data were collected using net and CTD casts from the Hokusei Maru in the Sea of Okhotsk, NW Pacific (limit-180), and Bering Sea from 08 March...

  13. A new bed elevation model for the Weddell Sea sector of the West Antarctic Ice Sheet

    Directory of Open Access Journals (Sweden)

    H. Jeofry

    2018-04-01

    Full Text Available We present a new digital elevation model (DEM of the bed, with a 1 km gridding, of the Weddell Sea (WS sector of the West Antarctic Ice Sheet (WAIS. The DEM has a total area of ∼ 125 000 km2 covering the Institute, Möller and Foundation ice streams, as well as the Bungenstock ice rise. In comparison with the Bedmap2 product, our DEM includes new aerogeophysical datasets acquired by the Center for Remote Sensing of Ice Sheets (CReSIS through the NASA Operation IceBridge (OIB program in 2012, 2014 and 2016. We also improve bed elevation information from the single largest existing dataset in the region, collected by the British Antarctic Survey (BAS Polarimetric radar Airborne Science Instrument (PASIN in 2010–2011, from the relatively crude measurements determined in the field for quality control purposes used in Bedmap2. While the gross form of the new DEM is similar to Bedmap2, there are some notable differences. For example, the position and size of a deep subglacial trough (∼ 2 km below sea level between the ice-sheet interior and the grounding line of the Foundation Ice Stream have been redefined. From the revised DEM, we are able to better derive the expected routing of basal water and, by comparison with that calculated using Bedmap2, we are able to assess regions where hydraulic flow is sensitive to change. Given the potential vulnerability of this sector to ocean-induced melting at the grounding line, especially in light of the improved definition of the Foundation Ice Stream trough, our revised DEM will be of value to ice-sheet modelling in efforts to quantify future glaciological changes in the region and, from this, the potential impact on global sea level. The new 1 km bed elevation product of the WS sector can be found at https://doi.org/10.5281/zenodo.1035488.

  14. Novel insights from NMR spectroscopy into seasonal changes in the composition of dissolved organic matter exported to the Bering Sea by the Yukon River

    Science.gov (United States)

    Cao, Xiaoyan; Aiken, George R.; Spencer, Robert G. M.; Butler, Kenna D.; Mao, Jingdong; Schmidt-Rohr, Klaus

    2016-01-01

    Seasonal (spring freshet, summer–autumn, and winter) variability in the chemical composition of dissolved organic matter (DOM) from the Yukon River was determined using advanced one- and two-dimensional (2D) solid-state NMR spectroscopy, coupled with isotopic measurements and UV–visible spectroscopy. Analyses were performed on two major DOM fractions, the hydrophobic organic acid (HPOA) and transphilic organic acid (TPIA) fractions obtained using XAD resins. Together these two fractions comprised 64–74% of the total DOM. Carboxyl-rich alicyclic molecules (CRAM) accounted for the majority of carbon atoms in the HPOA (63–77%) and TPIA (54–78%) samples, and more so in winter and summer than in spring samples. 2D and selective NMR data revealed association of abundant nonprotonated O-alkyl and quaternary alkyl C (OCnp, OCnpO and Cq, 13–17% of HPOA and 15–20% of TPIA) and isolated O–CH structures with CRAM, which were not recognized in previous studies. Spectral editing and 2D NMR allowed for the discrimination of carbohydrate-like O-alkyl C from non-carbohydrate O-alkyl C. Whereas two spring freshet TPIA samples contained carbohydrate clusters such as carboxylated carbohydrates (16% and 26%), TPIA samples from other seasons or HPOA samples mostly had small amounts (<8%) of sugar rings dispersed in a nonpolar alkyl environment. Though nonprotonated aromatic C represented the largest fraction of aromatic C in all HPOA/TPIA isolates, only a small fraction (∼5% in HPOA and 3% in TPIA) was possibly associated with dissolved black carbon. Our results imply a relatively stable portion of DOM exported by the Yukon River across different seasons, due to the predominance of CRAM and their associated nonprotonated C–O and O–C–O structures, and elevated reactivity (bio- and photo-lability) of spring DOM due to the presence of terrestrial inputs enriched in carbohydrates and aromatic structures.

  15. Analysis of lidar elevation data for improved identification and delineation of lands vulnerable to sea-level rise

    Science.gov (United States)

    Gesch, Dean B.

    2009-01-01

    The importance of sea-level rise in shaping coastal landscapes is well recognized within the earth science community, but as with many natural hazards, communicating the risks associated with sea-level rise remains a challenge. Topography is a key parameter that influences many of the processes involved in coastal change, and thus, up-to-date, high-resolution, high-accuracy elevation data are required to model the coastal environment. Maps of areas subject to potential inundation have great utility to planners and managers concerned with the effects of sea-level rise. However, most of the maps produced to date are simplistic representations derived from older, coarse elevation data. In the last several years, vast amounts of high quality elevation data derived from lidar have become available. Because of their high vertical accuracy and spatial resolution, these lidar data are an excellent source of up-to-date information from which to improve identification and delineation of vulnerable lands. Four elevation datasets of varying resolution and accuracy were processed to demonstrate that the improved quality of lidar data leads to more precise delineation of coastal lands vulnerable to inundation. A key component of the comparison was to calculate and account for the vertical uncertainty of the elevation datasets. This comparison shows that lidar allows for a much more detailed delineation of the potential inundation zone when compared to other types of elevation models. It also shows how the certainty of the delineation of lands vulnerable to a given sea-level rise scenario is much improved when derived from higher resolution lidar data.

  16. Surface elevation change and susceptibility of different mangrove zones to sea-level rise on Pacific high islands of Micronesia

    Science.gov (United States)

    Krauss, K.W.; Cahoon, D.R.; Allen, J.A.; Ewel, K.C.; Lynch, J.C.; Cormier, N.

    2010-01-01

    Mangroves on Pacific high islands offer a number of important ecosystem services to both natural ecological communities and human societies. High islands are subjected to constant erosion over geologic time, which establishes an important source of terrigeneous sediment for nearby marine communities. Many of these sediments are deposited in mangrove forests and offer mangroves a potentially important means for adjusting surface elevation with rising sea level. In this study, we investigated sedimentation and elevation dynamics of mangrove forests in three hydrogeomorphic settings on the islands of Kosrae and Pohnpei, Federated States of Micronesia (FSM). Surface accretion rates ranged from 2.9 to 20.8 mm y-1, and are high for naturally occurring mangroves. Although mangrove forests in Micronesian high islands appear to have a strong capacity to offset elevation losses by way of sedimentation, elevation change over 61/2 years ranged from -3.2 to 4.1 mm y-1, depending on the location. Mangrove surface elevation change also varied by hydrogeomorphic setting and river, and suggested differential, and not uniformly bleak, susceptibilities among Pacific high island mangroves to sea-level rise. Fringe, riverine, and interior settings registered elevation changes of -1.30, 0.46, and 1.56 mm y-1, respectively, with the greatest elevation deficit (-3.2 mm y-1) from a fringe zone on Pohnpei and the highest rate of elevation gain (4.1 mm y-1) from an interior zone on Kosrae. Relative to sea-level rise estimates for FSM (0.8-1.8 mm y-1) and assuming a consistent linear trend in these estimates, soil elevations in mangroves on Kosrae and Pohnpei are experiencing between an annual deficit of 4.95 mm and an annual surplus of 3.28 mm. Although natural disturbances are important in mediating elevation gain in some situations, constant allochthonous sediment deposition probably matters most on these Pacific high islands, and is especially helpful in certain hydrogeomorphic zones

  17. DY1207 Bering Sea ME70

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Scientists from the Midwater Assessment and Conservation Engineering (MACE) Program of the Alaska Fisheries Science Center (AFSC) have conducted summer surveys to...

  18. Counts of Alaska Steller sea lion adult and juvenile (non-pup) conducted on rookeries and haul-outs in Alaska Aleutian Islands, Bering Sea, and others from 1904-01-01 to 2015-07-18 (NCEI Accession 0128190)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains counts of adult and juvenile (non-pup) Steller sea lions on rookeries and haul-outs in Alaska made between 1904 and 2015. Non-pup counts have...

  19. Exposure to elevated sea-surface temperatures below the bleaching threshold impairs coral recovery and regeneration following injury.

    Science.gov (United States)

    Bonesso, Joshua Louis; Leggat, William; Ainsworth, Tracy Danielle

    2017-01-01

    Elevated sea surface temperatures (SSTs) are linked to an increase in the frequency and severity of bleaching events due to temperatures exceeding corals' upper thermal limits. The temperatures at which a breakdown of the coral- Symbiodinium endosymbiosis (coral bleaching) occurs are referred to as the upper thermal limits for the coral species. This breakdown of the endosymbiosis results in a reduction of corals' nutritional uptake, growth, and tissue integrity. Periods of elevated sea surface temperature, thermal stress and coral bleaching are also linked to increased disease susceptibility and an increased frequency of storms which cause injury and physical damage to corals. Herein we aimed to determine the capacity of corals to regenerate and recover from injuries (removal of apical tips) sustained during periods of elevated sea surface temperatures which result in coral stress responses, but which do not result in coral bleaching (i.e., sub-bleaching thermal stress events). In this study, exposure of the species Acropora aspera to an elevated SST of 32 °C (2 °C below the bleaching threshold, 34 °C) was found to result in reduced fluorescence of green fluorescent protein (GFP), reduced skeletal calcification and a lack of branch regrowth at the site of injury, compared to corals maintained under ambient SST conditions (26 °C). Corals maintained under normal, ambient, sea surface temperatures expressed high GFP fluorescence at the injury site, underwent a rapid regeneration of the coral branch apical tip within 12 days of sustaining injury, and showed extensive regrowth of the coral skeleton. Taken together, our results have demonstrated that periods of sustained increased sea surface temperatures, below the corals' bleaching threshold but above long-term summertime averages, impair coral recovery from damage, regardless of the onset or occurrence of coral bleaching.

  20. Created mangrove wetlands store belowground carbon and surface elevation change enables them to adjust to sea-level rise

    Science.gov (United States)

    Krauss, Ken W.; Cormier, Nicole; Osland, Michael J.; Kirwan, Matthew L.; Stagg, Camille L.; Nestlerode, Janet A.; Russell, Marc J.; From, Andrew; Spivak, Amanda C.; Dantin, Darrin D.; Harvey, James E.; Almario, Alejandro E.

    2017-01-01

    Mangrove wetlands provide ecosystem services for millions of people, most prominently by providing storm protection, food and fodder. Mangrove wetlands are also valuable ecosystems for promoting carbon (C) sequestration and storage. However, loss of mangrove wetlands and these ecosystem services are a global concern, prompting the restoration and creation of mangrove wetlands as a potential solution. Here, we investigate soil surface elevation change, and its components, in created mangrove wetlands over a 25 year developmental gradient. All created mangrove wetlands were exceeding current relative sea-level rise rates (2.6 mm yr−1), with surface elevation change of 4.2–11.0 mm yr−1 compared with 1.5–7.2 mm yr−1 for nearby reference mangroves. While mangrove wetlands store C persistently in roots/soils, storage capacity is most valuable if maintained with future sea-level rise. Through empirical modeling, we discovered that properly designed creation projects may not only yield enhanced C storage, but also can facilitate wetland persistence perennially under current rates of sea-level rise and, for most sites, for over a century with projected medium accelerations in sea-level rise (IPCC RCP 6.0). Only the fastest projected accelerations in sea-level rise (IPCC RCP 8.5) led to widespread submergence and potential loss of stored C for created mangrove wetlands before 2100.

  1. Created mangrove wetlands store belowground carbon and surface elevation change enables them to adjust to sea-level rise.

    Science.gov (United States)

    Krauss, Ken W; Cormier, Nicole; Osland, Michael J; Kirwan, Matthew L; Stagg, Camille L; Nestlerode, Janet A; Russell, Marc J; From, Andrew S; Spivak, Amanda C; Dantin, Darrin D; Harvey, James E; Almario, Alejandro E

    2017-04-21

    Mangrove wetlands provide ecosystem services for millions of people, most prominently by providing storm protection, food and fodder. Mangrove wetlands are also valuable ecosystems for promoting carbon (C) sequestration and storage. However, loss of mangrove wetlands and these ecosystem services are a global concern, prompting the restoration and creation of mangrove wetlands as a potential solution. Here, we investigate soil surface elevation change, and its components, in created mangrove wetlands over a 25 year developmental gradient. All created mangrove wetlands were exceeding current relative sea-level rise rates (2.6 mm yr -1 ), with surface elevation change of 4.2-11.0 mm yr -1 compared with 1.5-7.2 mm yr -1 for nearby reference mangroves. While mangrove wetlands store C persistently in roots/soils, storage capacity is most valuable if maintained with future sea-level rise. Through empirical modeling, we discovered that properly designed creation projects may not only yield enhanced C storage, but also can facilitate wetland persistence perennially under current rates of sea-level rise and, for most sites, for over a century with projected medium accelerations in sea-level rise (IPCC RCP 6.0). Only the fastest projected accelerations in sea-level rise (IPCC RCP 8.5) led to widespread submergence and potential loss of stored C for created mangrove wetlands before 2100.

  2. Geodetic Control Points, Benchmarks; Vertical elevation bench marks for monumented geodetic survey control points for which mean sea level elevations have been determined., Published in 1995, 1:24000 (1in=2000ft) scale, Rhode Island and Providence Plantations.

    Data.gov (United States)

    NSGIC State | GIS Inventory — Geodetic Control Points dataset current as of 1995. Benchmarks; Vertical elevation bench marks for monumented geodetic survey control points for which mean sea level...

  3. Effects of long-term elevated temperature on covering, sheltering and righting behaviors of the sea urchin Strongylocentrotus intermedius

    Science.gov (United States)

    Zhang, Lisheng; Zhang, Lingling; Shi, Dongtao; Wei, Jing; Chang, Yaqing

    2017-01-01

    Increases in ocean temperature due to climate change are predicted to change the behaviors of marine invertebrates. Altered behaviors of keystone ecosystem engineers such as echinoderms will have consequences for the fitness of individuals, which are expected to flow on to the local ecosystem. Relatively few studies have investigated the behavioral responses of echinoderms to long-term elevated temperature. We investigated the effects of exposure to long-term (∼31 weeks) elevated temperature (∼3 °C above the ambient water temperature) on covering, sheltering and righting behaviors of the sea urchin Strongylocentrotus intermedius. Long-term elevated temperature showed different effects on the three behaviors. It significantly decreased covering behavior, including both covering behavior reaction (time to first covering) and ability (number of covered sea urchins and number of shells used for covering). Conversely, exposure to long-term elevated temperature significantly increased sheltering behavior. Righting response in S. intermedius was not significantly different between temperature treatments. The results provide new information into behavioral responses of echinoderms to ocean warming. PMID:28348933

  4. Reconstruction of the sea surface elevation from the analysis of the data collected by a wave radar system

    Science.gov (United States)

    Ludeno, Giovanni; Soldovieri, Francesco; Serafino, Francesco; Lugni, Claudio; Fucile, Fabio; Bulian, Gabriele

    2016-04-01

    X-band radar system is able to provide information about direction and intensity of the sea surface currents and dominant waves in a range of few kilometers from the observation point (up to 3 nautical miles). This capability, together with their flexibility and low cost, makes these devices useful tools for the sea monitoring either coastal or off-shore area. The data collected from wave radar system can be analyzed by using the inversion strategy presented in [1,2] to obtain the estimation of the following sea parameters: peak wave direction; peak period; peak wavelength; significant wave height; sea surface current and bathymetry. The estimation of the significant wave height represents a limitation of the wave radar system because of the radar backscatter is not directly related to the sea surface elevation. In fact, in the last period, substantial research has been carried out to estimate significant wave height from radar images either with or without calibration using in-situ measurements. In this work, we will present two alternative approaches for the reconstruction of the sea surface elevation from wave radar images. In particular, the first approach is based on the basis of an approximated version of the modulation transfer function (MTF) tuned from a series of numerical simulation, following the line of[3]. The second approach is based on the inversion of radar images using a direct regularised least square technique. Assuming a linearised model for the tilt modulation, the sea elevation has been reconstructed as a least square fitting of the radar imaging data[4]. References [1]F. Serafino, C. Lugni, and F. Soldovieri, "A novel strategy for the surface current determination from marine X-band radar data," IEEE Geosci.Remote Sens. Lett., vol. 7, no. 2, pp. 231-235, Apr. 2010. [2]Ludeno, G., Brandini, C., Lugni, C., Arturi, D., Natale, A., Soldovieri, F., Serafino, F. (2014). Remocean System for the Detection of the Reflected Waves from the Costa

  5. Evaluation of sea-surface photosynthetically available radiation algorithms under various sky conditions and solar elevations.

    Science.gov (United States)

    Somayajula, Srikanth Ayyala; Devred, Emmanuel; Bélanger, Simon; Antoine, David; Vellucci, V; Babin, Marcel

    2018-04-20

    In this study, we report on the performance of satellite-based photosynthetically available radiation (PAR) algorithms used in published oceanic primary production models. The performance of these algorithms was evaluated using buoy observations under clear and cloudy skies, and for the particular case of low sun angles typically encountered at high latitudes or at moderate latitudes in winter. The PAR models consisted of (i) the standard one from the NASA-Ocean Biology Processing Group (OBPG), (ii) the Gregg and Carder (GC) semi-analytical clear-sky model, and (iii) look-up-tables based on the Santa Barbara DISORT atmospheric radiative transfer (SBDART) model. Various combinations of atmospheric inputs, empirical cloud corrections, and semi-analytical irradiance models yielded a total of 13 (11 + 2 developed in this study) different PAR products, which were compared with in situ measurements collected at high frequency (15 min) at a buoy site in the Mediterranean Sea (the "BOUée pour l'acquiSition d'une Série Optique à Long termE," or, "BOUSSOLE" site). An objective ranking method applied to the algorithm results indicated that seven PAR products out of 13 were well in agreement with the in situ measurements. Specifically, the OBPG method showed the best overall performance with a root mean square difference (RMSD) (bias) of 19.7% (6.6%) and 10% (6.3%) followed by the look-up-table method with a RMSD (bias) of 25.5% (6.8%) and 9.6% (2.6%) at daily and monthly scales, respectively. Among the four methods based on clear-sky PAR empirically corrected for cloud cover, the Dobson and Smith method consistently underestimated daily PAR while the Budyko formulation overestimated daily PAR. Empirically cloud-corrected methods using cloud fraction (CF) performed better under quasi-clear skies (CF0.7), however, all methods showed larger RMSD differences (biases) ranging between 32% and 80.6% (-54.5%-8.7%). Finally, three methods tested for low sun elevations revealed

  6. NODC Standard Product: International ocean atlas Volume 12 - Climatic atlas of the North Pacific Seas 2009 (NODC Accession 0098576)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This Atlas contains monthly climatic charts of temperature, salinity, and oxygen at the sea surface and at standard depth levels for the Bering Sea, Sea of Okhotsk,...

  7. The Bering Target Tracking Instrumentation

    DEFF Research Database (Denmark)

    Denver, Troelz; Jørgensen, John Leif; Betto, Maurizio

    2003-01-01

    The key science instrument on the Bering satellite mission is a relative small telescope with an entrance aperture of 300 mm and a focal length between 500 and 1000 mm. The detection of potential targets is performed by one of the target scanning advanced stellar compasses (ASCs). This procedure...... results in a simple prioritized list of right ascension, declination, proper motion and intensity of each prospective target. The telescope itself has a dedicated ASC Camera Head Unit (CHU) mounted on the secondary mirror, largely co-aligned with the telescope. This CHU accurately determines the telescope......'s pointing direction. To achieve fast tracking over a large solid angle, the telescope pointing is achieved by means of a folding mirror in the optical pathway. When a prospective target approaches the telescope FOV, the ASC on the secondary will guide the folding mirror into position such that the target...

  8. The Bering Autonomous Target Detection

    DEFF Research Database (Denmark)

    Jørgensen, John Leif; Denver, Troelz; Betto, Maurizio

    2003-01-01

    An autonomous asteroid target detection and tracking method has been developed. The method features near omnidirectionality and focus on high speed operations and completeness of search of the near space rather than the traditional faint object search methods, employed presently at the larger...... telescopes. The method has proven robust in operation and is well suited for use onboard spacecraft. As development target for the method and the associated instrumentation the asteroid research mission Bering has been used. Onboard a spacecraft, the autonomous detection is centered around the fully...... autonomous star tracker the Advanced Stellar Compass (ASC). One feature of this instrument is that potential targets are registered directly in terms of date, right ascension, declination, and intensity, which greatly facilitates both tracking search and registering. Results from ground and inflight tests...

  9. Sources and burial fluxes of soot black carbon in sediments on the Mackenzie, Chukchi, and Bering Shelves

    Science.gov (United States)

    Yang, Weifeng; Guo, Laodong

    2018-03-01

    Black carbon (BC) has been recognized as a climate forcing and a major component in the global carbon budget. However, studies on BC in the Arctic Ocean remain scarce. We report here variations in the abundance, sources and burial fluxes of sedimentary soot black carbon (soot-BC) in the western Arctic Ocean. The soot-BC contents averaged 1.6 ± 0.3, 0.46 ± 0.04 and 0.56 ± 0.10 mg-C g-1 on the Mackenzie, Chukchi and Bering Shelves, respectively, accounting for 16.6%, 10.2% and 10.4% of the total organic carbon in surface sediment. Temporally, contents of soot-BC remained fairly stable before 1910, but increased rapidly after the 1970s on the Mackenzie Shelf, indicating enhanced source input related to warming. Comparable δ13C signatures of soot-BC (- 24.95‰ to - 24.57‰) to C3 plants pointed to a major biomass source of soot-BC to the Beaufort Sea. Soot-BC showed similar temporal patterns with large fluctuations in the Chukchi/Bering shelf regions, implying the same source terms for soot-BC in these areas. Two events with elevated soot-BC corresponded to a simultaneous increase in biomass combustion and fossil fuel (coal and oil) consumption in Asia. The similar temporal variability in sedimentary soot-BC between the Arctic shelves and Asian lakes and the comparable δ13C values manifested that anthropogenic emission from East Asia was an important source of soot-BC in the western Arctic and subarctic regions. The burial fluxes of soot-BC, estimated from both 137Cs- and 210Pb-derived sedimentation rates, were 2.43 ± 0.42 g-C m-2 yr-1 on the Mackenzie Shelf, representing an efficient soot-BC sink. Soot-BC showed an increase in buried fluxes from 0.56 ± 0.02 g-C m-2 yr-1 during 1963-1986 to 0.88 ± 0.05 g-C m-2 yr-1 after 1986 on the Chukchi Shelf, and from 1.00 ± 0.18 g-C m-2 yr-1 to 2.58 ± 1.70 g-C m-2 yr-1 on the Bering Shelf, which were consistent with recent anthropogenically enhanced BC input observed especially in Asia. Overall, the three Arctic

  10. Post-glacial flooding of the Bering Land Bridge dated to 11 cal ka BP based on new geophysical and sediment records

    Science.gov (United States)

    Jakobsson, Martin; Pearce, Christof; Cronin, Thomas M.; Backman, Jan; Anderson, Leif G.; Barrientos, Natalia; Bjork, Goran; Coxhall, Helen; de Boer, Agatha; Mayer, Larry; Morth, Carl-Magnus; Nilsson, Johan; Rattray, Jayne; Sranne, Christian; Semiletov, Igor; O'Regan, Matt

    2017-01-01

    The Bering Strait connects the Arctic and Pacific oceans and separates the North American and Asian landmasses. The presently shallow ( ∼  53 m) strait was exposed during the sea level lowstand of the last glacial period, which permitted human migration across a land bridge today referred to as the Bering Land Bridge. Proxy studies (stable isotope composition of foraminifera, whale migration into the Arctic Ocean, mollusc and insect fossils and paleobotanical data) have suggested a range of ages for the Bering Strait reopening, mainly falling within the Younger Dryas stadial (12.9–11.7 cal ka BP). Here we provide new information on the deglacial and post-glacial evolution of the Arctic–Pacific connection through the Bering Strait based on analyses of geological and geophysical data from Herald Canyon, located north of the Bering Strait on the Chukchi Sea shelf region in the western Arctic Ocean. Our results suggest an initial opening at about 11 cal ka BP in the earliest Holocene, which is later than in several previous studies. Our key evidence is based on a well-dated core from Herald Canyon, in which a shift from a near-shore environment to a Pacific-influenced open marine setting at around 11 cal ka BP is observed. The shift corresponds to meltwater pulse 1b (MWP1b) and is interpreted to signify relatively rapid breaching of the Bering Strait and the submergence of the large Bering Land Bridge. Although the precise rates of sea level rise cannot be quantified, our new results suggest that the late deglacial sea level rise was rapid and occurred after the end of the Younger Dryas stadial.

  11. Post-glacial flooding of the Bering Land Bridge dated to 11 cal ka BP based on new geophysical and sediment records

    Directory of Open Access Journals (Sweden)

    M. Jakobsson

    2017-08-01

    Full Text Available The Bering Strait connects the Arctic and Pacific oceans and separates the North American and Asian landmasses. The presently shallow ( ∼  53 m strait was exposed during the sea level lowstand of the last glacial period, which permitted human migration across a land bridge today referred to as the Bering Land Bridge. Proxy studies (stable isotope composition of foraminifera, whale migration into the Arctic Ocean, mollusc and insect fossils and paleobotanical data have suggested a range of ages for the Bering Strait reopening, mainly falling within the Younger Dryas stadial (12.9–11.7 cal ka BP. Here we provide new information on the deglacial and post-glacial evolution of the Arctic–Pacific connection through the Bering Strait based on analyses of geological and geophysical data from Herald Canyon, located north of the Bering Strait on the Chukchi Sea shelf region in the western Arctic Ocean. Our results suggest an initial opening at about 11 cal ka BP in the earliest Holocene, which is later than in several previous studies. Our key evidence is based on a well-dated core from Herald Canyon, in which a shift from a near-shore environment to a Pacific-influenced open marine setting at around 11 cal ka BP is observed. The shift corresponds to meltwater pulse 1b (MWP1b and is interpreted to signify relatively rapid breaching of the Bering Strait and the submergence of the large Bering Land Bridge. Although the precise rates of sea level rise cannot be quantified, our new results suggest that the late deglacial sea level rise was rapid and occurred after the end of the Younger Dryas stadial.

  12. Downscaling of Open Coarse Precipitation Data through Spatial and Statistical Analysis, Integrating NDVI, NDWI, Elevation, and Distance from Sea

    Directory of Open Access Journals (Sweden)

    Hicham Ezzine

    2017-01-01

    Full Text Available This study aims to improve the statistical spatial downscaling of coarse precipitation (TRMM 3B43 product and also to explore its limitations in the Mediterranean area. It was carried out in Morocco and was based on an open dataset including four predictors (NDVI, NDWI, DEM, and distance from sea that explain TRMM 3B43 product. For this purpose, four groups of models were established based on different combinations of the four predictors, in order to compare from one side NDVI and NDWI based models and the other side stepwise with multiple regression. The models that have given rise to the best approximations and best fits were used to downscale TRMM 3B43 product. The resulting downscaled and calibrated precipitations were validated by independent RGS. Aside from that, the limitations of the proposed approach were assessed in five bioclimatic stages. Furthermore, the influence of the sea was analyzed in five classes of distance. The findings showed that the models built using NDVI and NDWI have a high correlation and therefore can be used to downscale precipitation. The integration of elevation and distance improved the correlation models. According to R2, RMSE, bias, and MAE, the study revealed that there is a great agreement between downscaled precipitations and RGS measurements. In addition, the analysis showed that the contribution of the variable (distance from sea is evident around the coastal area and decreases progressively. Likewise, the study demonstrated that the approach performs well in humid and arid bioclimatic stages compared to others.

  13. Surge dynamics on Bering Glacier, Alaska, in 2008–2011

    Directory of Open Access Journals (Sweden)

    M. Braun

    2012-11-01

    Full Text Available A surge cycle of the Bering Glacier system, Alaska, is examined using observations of surface velocity obtained using synthetic aperture radar (SAR offset tracking, and elevation data obtained from the University of Alaska Fairbanks LiDAR altimetry program. After 13 yr of quiescence, the Bering Glacier system began to surge in May 2008 and had two stages of accelerated flow. During the first stage, flow accelerated progressively for at least 10 months and reached peak observed velocities of ~ 7 m d−1. The second stage likely began in 2010. By 2011 velocities exceeded 9 m d−1 or ~ 18 times quiescent velocities. Fast flow continued into July 2011. Surface morphology indicated slowing by fall 2011; however, it is not entirely clear if the surge is yet over. The quiescent phase was characterized by small-scale acceleration events that increased driving stresses up to 70%. When the surge initiated, synchronous acceleration occurred throughout much of the glacier length. Results suggest that downstream propagation of the surge is closely linked to the evolution of the driving stress during the surge, because driving stress appears to be tied to the amount of resistive stress provided by the bed. In contrast, upstream acceleration and upstream surge propagation is not dependent on driving stress evolution.

  14. Partial pressure (or fugacity) of carbon dioxide, salinity and SEA SURFACE TEMPERATURE collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from Marcus G. Langseth in the Arctic Ocean, Beaufort Sea and others from 2010-05-07 to 2013-06-25 (NODC Accession 0109901)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0109901 includes Surface underway data collected from Marcus G. Langseth in the Arctic Ocean, Beaufort Sea, Bering Sea, Caribbean Sea, Cordell Bank...

  15. Additive pressures of elevated sea surface temperatures and herbicides on symbiont-bearing foraminifera.

    Directory of Open Access Journals (Sweden)

    Joost W van Dam

    Full Text Available Elevated ocean temperatures and agrochemical pollution individually threaten inshore coral reefs, but these pressures are likely to occur simultaneously. Experiments were conducted to evaluate the combined effects of elevated temperature and the photosystem II (PSII inhibiting herbicide diuron on several types of symbiotic algae (diatom, dinoflagellate or rhodophyte of benthic foraminifera in hospite. Diuron was shown to evoke a direct effect on photosynthetic efficiency (reduced effective PSII quantum yield ΔF/F'(m, while elevated temperatures (>30 °C, only 2 °C above current average summer temperatures were observed to impact photosynthesis more indirectly by causing reductions in maximum PSII quantum yield (F(v/F(m, interpreted as photodamage. Additionally, elevated temperatures were shown to cause bleaching through loss of chlorophyll a in foraminifera hosting either diatoms or dinoflagellates. A significant linear correlation was found between reduced F(v/F(m and loss of chlorophyll a. In most cases, symbionts within foraminifera proved more sensitive to thermal stress in the presence of diuron (≥ 1 µg L(-1. The mixture toxicity model of Independent Action (IA described the combined effects of temperature and diuron on the photosystem of species hosting diatoms or dinoflagellates convincingly and in agreement with probabilistic statistics, so a response additive joint action can be assumed. We thus demonstrate that improving water quality can improve resilience of symbiotic phototrophs to projected increases in ocean temperatures. As IA described the observed combined effects from elevated temperature and diuron stress it may therefore be employed for prediction of untested mixtures and for assessing the efficacy of management measures.

  16. Additive pressures of elevated sea surface temperatures and herbicides on symbiont-bearing foraminifera.

    Science.gov (United States)

    van Dam, Joost W; Negri, Andrew P; Mueller, Jochen F; Altenburger, Rolf; Uthicke, Sven

    2012-01-01

    Elevated ocean temperatures and agrochemical pollution individually threaten inshore coral reefs, but these pressures are likely to occur simultaneously. Experiments were conducted to evaluate the combined effects of elevated temperature and the photosystem II (PSII) inhibiting herbicide diuron on several types of symbiotic algae (diatom, dinoflagellate or rhodophyte) of benthic foraminifera in hospite. Diuron was shown to evoke a direct effect on photosynthetic efficiency (reduced effective PSII quantum yield ΔF/F'(m)), while elevated temperatures (>30 °C, only 2 °C above current average summer temperatures) were observed to impact photosynthesis more indirectly by causing reductions in maximum PSII quantum yield (F(v)/F(m)), interpreted as photodamage. Additionally, elevated temperatures were shown to cause bleaching through loss of chlorophyll a in foraminifera hosting either diatoms or dinoflagellates. A significant linear correlation was found between reduced F(v)/F(m) and loss of chlorophyll a. In most cases, symbionts within foraminifera proved more sensitive to thermal stress in the presence of diuron (≥ 1 µg L(-1)). The mixture toxicity model of Independent Action (IA) described the combined effects of temperature and diuron on the photosystem of species hosting diatoms or dinoflagellates convincingly and in agreement with probabilistic statistics, so a response additive joint action can be assumed. We thus demonstrate that improving water quality can improve resilience of symbiotic phototrophs to projected increases in ocean temperatures. As IA described the observed combined effects from elevated temperature and diuron stress it may therefore be employed for prediction of untested mixtures and for assessing the efficacy of management measures.

  17. Comparing elevation and freeboard from IceBridge and four different CryoSat-2 retrackers for coincident sea ice observations

    Science.gov (United States)

    Yi, D.; Kurtz, N. T.; Harbeck, J.

    2017-12-01

    The airborne IceBridge and spaceborne Cryosat-2 missions observe polar sea ice at different altitudes with different footprint sizes and often at different time and locations. Many studies use different retrackers to derive Cryosat-2 surface elevation, which we find causes large differences in the elevation and freeboard comparisons of IceBridge and Cryosat-2. In this study, we compare sea ice surface elevation and freeboard using 8 coincident CryoSat-2, ATM, and LVIS observations with IceBridge airplanes under flying the Cryosat-2 ground tracks. We apply identical ellipsoid, geoid model, tide model, and atmospheric correction to CryoSat-2 and IceBridge data to reduce elevation bias due to their differences. IceBridge's ATM and LVIS elevation and freeboard and Snow Radar snow depth are averaged at each CryoSat-2 footprint for comparison. The four different Cryosat-2 retrackers (ESA, GSFC, AWI, and JPL) show distinct differences in mean elevation up to 0.35 meters over leads and over floes, which suggests that systematic elevation bias exists between the retrackers. The mean IceBridge elevation over leads is within the mean elevation distribution of the four Cryosat-2 retrackers. The mean IceBridge elevation over floes is above the mean elevation distribution of the four Cryosat-2 retrackers. After removing the snow depth from IceBridge elevation, over floe, the mean elevation of IceBridge is within the mean elevation distribution of the four Cryosat-2 retrackers. By identifying the strengths and weaknesses of the retrackers, this study provides a mechanism to improve freeboard retrievals from existing methods.

  18. Antarctic krill under sea ice: elevated abundance in a narrow band just south of ice edge.

    Science.gov (United States)

    Brierley, Andrew S; Fernandes, Paul G; Brandon, Mark A; Armstrong, Frederick; Millard, Nicholas W; McPhail, Steven D; Stevenson, Peter; Pebody, Miles; Perrett, James; Squires, Mark; Bone, Douglas G; Griffiths, Gwyn

    2002-03-08

    We surveyed Antarctic krill (Euphausia superba) under sea ice using the autonomous underwater vehicle Autosub-2. Krill were concentrated within a band under ice between 1 and 13 kilometers south of the ice edge. Within this band, krill densities were fivefold greater than that of open water. The under-ice environment has long been considered an important habitat for krill, but sampling difficulties have previously prevented direct observations under ice over the scale necessary for robust krill density estimation. Autosub-2 enabled us to make continuous high-resolution measurements of krill density under ice reaching 27 kilometers beyond the ice edge.

  19. The embryonic life history of the tropical sea hare Stylocheilus striatus (Gastropoda: Opisthobranchia under ambient and elevated ocean temperatures

    Directory of Open Access Journals (Sweden)

    Rael Horwitz

    2017-02-01

    Full Text Available Ocean warming represents a major threat to marine biota worldwide, and forecasting ecological ramifications is a high priority as atmospheric carbon dioxide (CO2 emissions continue to rise. Fitness of marine species relies critically on early developmental and reproductive stages, but their sensitivity to environmental stressors may be a bottleneck in future warming oceans. The present study focuses on the tropical sea hare, Stylocheilus striatus (Gastropoda: Opisthobranchia, a common species found throughout the Indo-West Pacific and Atlantic Oceans. Its ecological importance is well-established, particularly as a specialist grazer of the toxic cyanobacterium, Lyngbya majuscula. Although many aspects of its biology and ecology are well-known, description of its early developmental stages is lacking. First, a detailed account of this species’ life history is described, including reproductive behavior, egg mass characteristics and embryonic development phases. Key developmental features are then compared between embryos developed in present-day (ambient and predicted end-of-century elevated ocean temperatures (+3 °C. Results showed developmental stages of embryos reared at ambient temperature were typical of other opisthobranch species, with hatching of planktotrophic veligers occurring 4.5 days post-oviposition. However, development times significantly decreased under elevated temperature, with key embryonic features such as the velum, statocysts, operculum, eyespots and protoconch developing approximately 24 h earlier when compared to ambient temperature. Although veligers hatched one day earlier under elevated temperature, their shell size decreased by approximately 20%. Our findings highlight how an elevated thermal environment accelerates planktotrophic development of this important benthic invertebrate, possibly at the cost of reducing fitness and increasing mortality.

  20. Effects of elevated temperatures and rising sea level on Arctic Coast

    Science.gov (United States)

    Barnes, Peter W.

    1990-01-01

    Ice is a major agent on the inner shelf, gouging the bottom, increasing hydraulic scour, transporting sediment, and influencing river flood patterns. Rapid coastal retreat is common and low barrier islands and beaches are constantly changing due to the influence of permafrost, ice-push, waves, and currents. Coastal processes are presently a balance between the influence of ice and the action of waves and currents. Quantitative values for processes are poorly known, however our qualitative understanding is nearly complete. Climatic warming and rising sea levels would decrease the temporal and aerial extent of coastal ice thereby expanding the role of waves and currents. As a result, shoreline retreat rates would increase, producing a transgressive erosional surface on the low coastal plain. With increased wave activity, beaches and barrier islands presently nourished by ice push processes would decay and disappear. Increased sediment supply from a deeply thawed, active layer would release more sediments to rivers and coasts. Additional research should be focused on permafrost and sea ice processes active during freeze up and breakup; the two seasons of most vigorous activity and change.

  1. Maternal Steller sea lion diets elevate fetal mercury concentrations in an area of population decline

    Energy Technology Data Exchange (ETDEWEB)

    Rea, Lorrie D., E-mail: lorrie.rea@alaska.gov [Division of Wildlife Conservation, Alaska Department of Fish and Game, Fairbanks, AK 99701 (United States); Castellini, J. Margaret, E-mail: maggie.c@alaska.edu [Wildlife Toxicology Laboratory, School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Correa, Lucero, E-mail: lucero.correa@alaska.gov [Division of Wildlife Conservation, Alaska Department of Fish and Game, Fairbanks, AK 99701 (United States); Wildlife Toxicology Laboratory, College of Natural Sciences and Mathematics, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States); Fadely, Brian S., E-mail: brian.fadely@noaa.gov [National Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Seattle, WA 98115 (United States); O' Hara, Todd M., E-mail: tmohara@alaska.edu [Wildlife Toxicology Laboratory, College of Natural Sciences and Mathematics, University of Alaska Fairbanks, Fairbanks, AK 99775 (United States)

    2013-06-01

    Total mercury concentrations ([THg]) measured in western Aleutian Island Steller sea lion pup hair were the highest maximum [THg] documented in this endangered species to date. Some pups exceeded concentrations at which other fish-eating mammals can exhibit adverse neurological and reproductive effects (21% and 15% pups above 20 and 30 μg/g in hair, respectively). Of particular concern is fetal exposure to mercury during a particularly vulnerable stage of neurological development in late gestation. Hair and blood [THg] were highly correlated and 20% of pups sampled in the western Aleutian Islands of Alaska exceeded mammalian risk thresholds established for each of these tissues. Higher nitrogen isotope ratios suggested that pups accumulated the highest [THg] when their dams fed on higher trophic level prey during late gestation. - Highlights: • High total mercury concentrations in western Aleutian Island Steller sea lions • Some pups exceeded thresholds for adverse neurological and reproductive effects. • Fetal exposure to mercury during a vulnerable stage of neurological development • Mercury concentrations in hair were highly correlated with circulating blood levels. • High mercury levels in pups related to dams feeding on high trophic level prey.

  2. Maternal Steller sea lion diets elevate fetal mercury concentrations in an area of population decline

    International Nuclear Information System (INIS)

    Rea, Lorrie D.; Castellini, J. Margaret; Correa, Lucero; Fadely, Brian S.; O'Hara, Todd M.

    2013-01-01

    Total mercury concentrations ([THg]) measured in western Aleutian Island Steller sea lion pup hair were the highest maximum [THg] documented in this endangered species to date. Some pups exceeded concentrations at which other fish-eating mammals can exhibit adverse neurological and reproductive effects (21% and 15% pups above 20 and 30 μg/g in hair, respectively). Of particular concern is fetal exposure to mercury during a particularly vulnerable stage of neurological development in late gestation. Hair and blood [THg] were highly correlated and 20% of pups sampled in the western Aleutian Islands of Alaska exceeded mammalian risk thresholds established for each of these tissues. Higher nitrogen isotope ratios suggested that pups accumulated the highest [THg] when their dams fed on higher trophic level prey during late gestation. - Highlights: • High total mercury concentrations in western Aleutian Island Steller sea lions • Some pups exceeded thresholds for adverse neurological and reproductive effects. • Fetal exposure to mercury during a vulnerable stage of neurological development • Mercury concentrations in hair were highly correlated with circulating blood levels. • High mercury levels in pups related to dams feeding on high trophic level prey

  3. Ship-based Observations of Atmospheric Black Carbon Particles over the Arctic Ocean, Bering Sea, and North Western Pacific Ocean on 2016: Comparisons with Regional Chemical Transport Model simulations

    Science.gov (United States)

    Taketani, F.; Miyakawa, T.; Takigawa, M.; Yamaguchi, M.; Kanaya, Y.; Komazaki, Y.; Takashima, H.; Mordovskoi, P.; Tohjima, Y.

    2017-12-01

    Black carbon (BC), formed through the incomplete combustion of fossil fuels, biofuels, and biomass, is a major component of light-absorbing particulate matter in the atmosphere, causing positive radiative forcing. Also, BC deposition on the surface reduces the Earth's albedo and accelerates snow/ice melting by absorbing the sunlight. Therefore, the impact of BC on the Arctic climate needs to be assessed; however, observational information has been still insufficient. Over the Arctic Ocean, we have been conducting ship-based BC observations using a single particle soot photometer (SP2) on R/V Mirai every summer since 2014. To estimate the transport pathways of BC, we have also conducted model simulations during the period of cruise using a regional transport model (WRF-Chem 3.8.1). Here we focus on observations conducted on-board the R/V Mirai from 22 August to 5 October 2016 in a round trip to the Arctic Ocean through the Bering Strait from a port of Hachinohe (40.52N, 141.51E), Japan. We captured relatively high BC mass concentration events in this observation. The observed average BC mass concentration during 2016 was 0.8 ± 1.4 ng/m3 in >70N, similar to the levels ( 1.0ng/m3) recorded during our previous observations in the Arctic during 2014 and 2015. The variations in the observed concentrations in 2016 were qualitatively well reproduced by the regional chemical transport model. Quantitatively, however, the model tended to overestimate the BC levels, suggesting the possibilities that the emission rates were overestimated and/or the removal rates were underestimated. We will present further analysis on the size distribution, coating, and possible sources.

  4. Monitoring Rates of Subsidence and Relative Sea-Level Rise in Low-Elevation Coastal Zones: A New Approach

    Science.gov (United States)

    Tornqvist, T. E.; Jankowski, K. L.; Fernandes, A. M.; Keogh, M.; Nienhuis, J.

    2017-12-01

    Low-elevation coastal zones (LECZs) that often host large population centers are particularly vulnerable to accelerating rates of relative sea-level rise (RSLR). Traditionally, tide-gauge records are used to obtain quantitative data on rates of RSLR, given that they are perceived to capture the rise of the sea surface, as well as land subsidence which is often substantial in such settings. We argue here that tide gauges in LECZs often provide ambiguous data because they ultimately measure RSLR with respect to a benchmark that is typically anchored tens of meters deep. This is problematic because the prime target of interest is usually the rate of RSLR with respect to the land surface. We illustrate this problem with newly obtained rod surface elevation table - marker horizon (RSET-MH) data from coastal Louisiana (n = 274) that show that shallow subsidence in the uppermost 5-10 m accounts for 60-85% of total subsidence. Since benchmarks in this region are anchored at 23 m depth on average, tide-gauge records by definition do not capture this important process and thus underestimate RSLR by a considerable amount. We show how RSET-MH data, combined with GPS and satellite altimetry data, enable us to bypass this problem. Rates of RSLR in coastal Louisiana over the past 6-10 years are 12 ± 8 mm/yr, considerably higher than numbers reported in recent studies based on tide-gauge analysis. Subsidence rates, averaged across this region, total about 9 mm/yr. It is likely that the problems with tide-gauge data are not unique to coastal Louisiana, so we suggest that our new approach to RSLR measurements may be useful in LECZs worldwide, with considerable implications for metropolitan areas like New Orleans that are located within such settings.

  5. Grains of Nonferrous and Noble Metals in Iron-Manganese Formations and Igneous Rocks of Submarine Elevations of the Sea of Japan

    Science.gov (United States)

    Kolesnik, O. N.; Astakhova, N. V.

    2018-01-01

    Iron-manganese formations and igneous rocks of submarine elevations in the Sea of Japan contain overlapping mineral phases (grains) with quite identical morphology, localization, and chemical composition. Most of the grains conform to oxides, intermetallic compounds, native elements, sulfides, and sulfates in terms of the set of nonferrous, noble, and certain other metals (Cu, Zn, Sn, Pb, Ni, Mo, Ag, Pd, and Pt). The main conclusion that postvolcanic hydrothermal fluids are the key sources of metals is based upon a comparison of the data of electron microprobe analysis of iron-manganese formations and igneous rocks dredged at the same submarine elevations in the Sea of Japan.

  6. Maternal Steller sea lion diets elevate fetal mercury concentrations in an area of population decline.

    Science.gov (United States)

    Rea, Lorrie D; Castellini, J Margaret; Correa, Lucero; Fadely, Brian S; O'Hara, Todd M

    2013-06-01

    Total mercury concentrations ([THg]) measured in western Aleutian Island Steller sea lion pup hair were the highest maximum [THg] documented in this endangered species to date. Some pups exceeded concentrations at which other fish-eating mammals can exhibit adverse neurological and reproductive effects (21% and 15% pups above 20 and 30 μg/g in hair, respectively). Of particular concern is fetal exposure to mercury during a particularly vulnerable stage of neurological development in late gestation. Hair and blood [THg] were highly correlated and 20% of pups sampled in the western Aleutian Islands of Alaska exceeded mammalian risk thresholds established for each of these tissues. Higher nitrogen isotope ratios suggested that pups accumulated the highest [THg] when their dams fed on higher trophic level prey during late gestation. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. BAROMETRIC PRESSURE and Other Data from ALPHA HELIX From Chukchi Sea and Others from 19930709 to 19930807 (NODC Accession 9400062)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Conductivity, Temperature and Depth (CTD) and other data were collected in Bering Sea, Chukchi Sea. Data was collected from Ship ALPHA HELIX cruise Aleutian...

  8. Progression of the 2011-2012 Surge of Bering Glacier and Bagley Ice Field, Alaska

    Science.gov (United States)

    Herzfeld, U. C.; McDonald, B.; Stachura, M.; Hale, R.; Trantow, T.; Weltman, A.; Chen, P.

    2012-12-01

    Bering Glacier, Alaska, started a surge in late spring 2011. The surge reached the ice front in May 2011 and extended into Bagley Ice Field by summer 2011. New surge-related crevassing was observed in July 2012. We collected aerial observations, including systematic videographic and photographic imagery, GPS data and laser altimeter data in September 2011 and in July 2012. In this talk, an analysis of surge progression and comparison to the early, mature and late stages of the 1993-1995 surge of Bering Glacier and Bagley Ice Field will be presented. A suite of approaches will be used to this end: Analysis of elevation changes based on CryoSat data, 2009 and 2010 IceBridge data and 2011 and 2012 laser altimeter data collected by our group, geostatistical classification of crevasse types based on imagery, classification of laser altimeter data and analysis of high-resolution satellite imagery (Worldview and GEOS).

  9. Search and rescue helicopter-assisted transfer of ST-elevation myocardial infarction patients from an island in the Baltic Sea

    DEFF Research Database (Denmark)

    Schoos, Mikkel Malby; Kelbæk, Henning; Pedersen, Frants

    2014-01-01

    BACKGROUND: Since 2005, ST-elevation myocardial infarction (STEMI) patients from the island of Bornholm in the Baltic Sea have been transferred for primary percutaneous coronary intervention (pPCI) by an airborne service. We describe the result of pPCI as part of the Danish national reperfusion s...

  10. The relation between Arctic sea ice surface elevation and draft: A case study using coincident AUV sonar and airborne scanning laser

    DEFF Research Database (Denmark)

    Doble, Martin J.; Skourup, Henriette; Wadhams, Peter

    2011-01-01

    Data are presented from a survey by airborne scanning laser profilometer and an AUV-mounted, upward looking swath sonar in the spring Beaufort Sea. The air-snow (surface elevation) and water-ice (draft) surfaces were mapped at 1 x 1 m resolution over a 300 x 300 m area. Data were separated into l...

  11. Effect of uncertainty in surface mass balance–elevation feedback on projections of the future sea level contribution of the Greenland ice sheet

    Directory of Open Access Journals (Sweden)

    T. L. Edwards

    2014-01-01

    Régional: Fettweis, 2007 climate projections are for 2000–2199, forced by the ECHAM5 and HadCM3 global climate models (GCMs under the SRES A1B emissions scenario. The additional sea level contribution due to the SMB–elevation feedback averaged over five ISM projections for ECHAM5 and three for HadCM3 is 4.3% (best estimate; 95% credibility interval 1.8–6.9% at 2100, and 9.6% (best estimate; 95% credibility interval 3.6–16.0% at 2200. In all results the elevation feedback is significantly positive, amplifying the GrIS sea level contribution relative to the MAR projections in which the ice sheet topography is fixed: the lower bounds of our 95% credibility intervals (CIs for sea level contributions are larger than the "no feedback" case for all ISMs and GCMs. Our method is novel in sea level projections because we propagate three types of modelling uncertainty – GCM and ISM structural uncertainties, and elevation feedback parameterisation uncertainty – along the causal chain, from SRES scenario to sea level, within a coherent experimental design and statistical framework. The relative contributions to uncertainty depend on the timescale of interest. At 2100, the GCM uncertainty is largest, but by 2200 both the ISM and parameterisation uncertainties are larger. We also perform a perturbed parameter ensemble with one ISM to estimate the shape of the projected sea level probability distribution; our results indicate that the probability density is slightly skewed towards higher sea level contributions.

  12. Rapid sedimentation and overpressure in shallow sediments of the Bering Trough, offshore southern Alaska

    Science.gov (United States)

    Daigle, Hugh; Worthington, Lindsay L.; Gulick, Sean P. S.; Van Avendonk, Harm J. A.

    2017-04-01

    Pore pressures in sediments at convergent margins play an important role in driving chemical fluxes and controlling deformation styles and localization. In the Bering Trough offshore Southern Alaska, extreme sedimentation rates over the last 140 kyr as a result of glacial advance/retreats on the continental shelf have resulted in elevated pore fluid pressures in slope sediments overlying the Pamplona Zone fold and thrust belt, the accretionary wedge resulting from subduction of the Yakutat microplate beneath the North American Plate. Based on laboratory experiments and downhole logs acquired at Integrated Ocean Drilling Program Site U1421, we predict that the overpressure in the slope sediments may be as high as 92% of the lithostatic stress. Results of one-dimensional numerical modeling accounting for changes in sedimentation rate over the last 130 kyr predicted overpressures that are consistent with our estimates, suggesting that the overpressure is a direct result of the rapid sedimentation experienced on the Bering shelf and slope. Comparisons with other convergent margins indicate that such rapid sedimentation and high overpressure are anomalous in sediments overlying accretionary wedges. We hypothesize that the shallow overpressure on the Bering shelf/slope has fundamentally altered the deformation style within the Pamplona Zone by suppressing development of faults and may inhibit seismicity by focusing faulting elsewhere or causing deformation on existing faults to be aseismic. These consequences are probably long-lived as it may take several million years for the excess pressure to dissipate.

  13. Partial pressure (or fugacity) of carbon dioxide, salinity and SEA SURFACE TEMPERATURE collected from underway - surface observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from the NATHANIEL B. PALMER in the Arctic Ocean, Beaufort Sea and others from 1994-11-04 to 2012-08-31 (NODC Accession 0083189)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0083189 includes chemical, physical and underway - surface data collected from NATHANIEL B. PALMER in the Arctic Ocean, Beaufort Sea, Bering Sea,...

  14. Partial pressure (or fugacity) of carbon dioxide, salinity and SEA SURFACE TEMPERATURE collected from underway - surface observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from the HEALY in the Arctic Ocean, Beaufort Sea and others from 2011-05-17 to 2012-10-26 (NODC Accession 0083197)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0083197 includes chemical, physical and underway - surface data collected from HEALY in the Arctic Ocean, Beaufort Sea, Bering Sea, Coastal Waters of...

  15. ICESat-2, its retrievals of ice sheet elevation change and sea ice freeboard, and potential synergies with CryoSat-2

    Science.gov (United States)

    Neumann, Thomas; Markus, Thorsten; Smith, Benjamin; Kwok, Ron

    2017-04-01

    Understanding the causes and magnitudes of changes in the cryosphere remains a priority for Earth science research. Over the past decade, NASA's and ESA's Earth-observing satellites have documented a decrease in both the areal extent and thickness of Arctic sea ice, and an ongoing loss of grounded ice from the Greenland and Antarctic ice sheets. Understanding the pace and mechanisms of these changes requires long-term observations of ice-sheet mass, sea-ice thickness, and sea-ice extent. NASA's ICESat-2 mission is the next-generation space-borne laser altimeter mission and will use three pairs of beams, each pair separated by about 3 km across-track with a pair spacing of 90 m. The spot size is 17 m with an along-track sampling interval of 0.7 m. This measurement concept is a result of the lessons learned from the original ICESat mission. The multi-beam approach is critical for removing the effects of ice sheet surface slope from the elevation change measurements of most interest. For sea ice, the dense spatial sampling (eliminating along-track gaps) and the small footprint size are especially useful for sea surface height measurements in the, often narrow, leads needed for sea ice freeboard and ice thickness retrievals. Currently, algorithms are being developed to calculate ice sheet elevation change and sea ice freeboard from ICESat-2 data. The orbits of ICESat-2 and Cryosat-2 both converge at 88 degrees of latitude, though the orbit altitude differences result in different ground track patterns between the two missions. This presentation will present an overview of algorithm approaches and how ICESat-2 and Cryosat-2 data may augment each other.

  16. Synergism between elevated pCO2 and temperature on the Antarctic sea ice diatom Nitzschia lecointei

    Directory of Open Access Journals (Sweden)

    A. Torstensson

    2013-10-01

    Full Text Available Polar oceans are particularly susceptible to ocean acidification and warming. Diatoms play a significant role in sea ice biogeochemistry and provide an important food source to grazers in ice-covered oceans, especially during early spring. However, the ecophysiology of ice-living organisms has received little attention in terms of ocean acidification. In this study, the synergism between temperature and partial pressure of CO2 (pCO2 was investigated in relationship to the optimal growth temperature of the Antarctic sea ice diatom Nitzschia lecointei. Diatoms were kept in cultures at controlled levels of pCO2 (∼390 and ∼960 μatm and temperature (−1.8 and 2.5 °C for 14 days. Synergism between temperature and pCO2 was detected in growth rate and acyl lipid fatty acid (FA content. Optimal growth rate was observed around 5 °C in a separate experiment. Carbon enrichment only promoted (6% growth rate closer to the optimal growth, but not at the control temperature (−1.8 °C. At −1.8 °C and at ∼960 μatm pCO2, the total FA content was reduced relative to the ∼390 μatm treatment, although no difference between pCO2 treatments was observed at 2.5 °C. A large proportion (97% of the total FAs comprised on average of polyunsaturated fatty acids (PUFA at −1.8 °C. Cellular PUFA content was reduced at ∼960 relative to ∼390 μatm pCO2. Effects of carbon enrichment may be different depending on ocean warming scenario or season, e.g. reduced cellular FA content in response to elevated CO2 at low temperatures only, reflected as reduced food quality for higher trophic levels. Synergy between warming and acidification may be particularly important in polar areas since a narrow thermal window generally limits cold-water organisms.

  17. AFSC/RACE/MACE: Results of 2012 Chukchi Sea Acoustic/Trawl Survey

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — We conducted acoustic-trawl (AT) surveys of the Alaska northern Bering and Chukchi Seas during ice-free periods with a focus on Arctic cod (Boreogadus saida), a key...

  18. The Asian-Bering-North American teleconnection: seasonality, maintenance, and climate impact on North America

    Science.gov (United States)

    Yu, Bin; Lin, H.; Wu, Z. W.; Merryfield, W. J.

    2018-03-01

    The Asian-Bering-North American (ABNA) teleconnection index is constructed from the normalized 500-hPa geopotential field by excluding the Pacific-North American pattern contribution. The ABNA pattern features a zonally elongated wavetrain originating from North Asia and flowing downstream across Bering Sea and Strait towards North America. The large-scale teleconnection is a year-round phenomenon that displays strong seasonality with the peak variability in winter. North American surface temperature and temperature extremes, including warm days and nights as well as cold days and nights, are significantly controlled by this teleconnection. The ABNA pattern has an equivalent barotropic structure in the troposphere and is supported by synoptic-scale eddy forcing in the upper troposphere. Its associated sea surface temperature anomalies exhibit a horseshoe-shaped structure in the North Pacific, most prominent in winter, which is driven by atmospheric circulation anomalies. The snow cover anomalies over the West Siberian plain and Central Siberian Plateau in autumn and spring and over southern Siberia in winter may act as a forcing influence on the ABNA pattern. The snow forcing influence in winter and spring can be traced back to the preceding season, which provides a predictability source for this teleconnection and for North American temperature variability. The ABNA associated energy budget is dominated by surface longwave radiation anomalies year-round, with the temperature anomalies supported by anomalous downward longwave radiation and damped by upward longwave radiation at the surface.

  19. Model-data comparisons of crevasses in accelerating glaciers exemplified for the 2011-2013 surge of Bering Glacier, Alaska

    Science.gov (United States)

    Trantow, T.; Herzfeld, U. C.

    2017-12-01

    Glacier acceleration, ubiquitous along the periphery of the major icesheets, presents one of the main uncertainties in modeling future global sea-level rise according to the IPCC 5th Assessment Report (2013). The surge phenomenon is one type of glacial acceleration and is the least understood. During a surge, large-scale elevation change and significant crevassing occurs throughout the entire ice system. Crevasses are the most obvious manifestations of the surge dynamics and provide a source of geophysical information that allows reconstruction of deformation processes. The recent surge of the Bering-Bagley Glacier System (BBGS), Alaska, in 2011-2013 provides an excellent test case to study surging through airborne and satellite observations together with numerical modeling. A 3D full-Stokes finite element model of the BBGS has been created using the Elmer/Ice software for structural and dynamical investigations of the surge. A von Mises condition is applied to modeled surface stresses to predict where crevassing would occur during the surge. The model uses CryoSat-2 derived surface topography (Baseline-C), bedrock topography, Glen's flow law with an isothermal assumption and a uniform linear friction law at the ice/bedrock boundary to represent the surge state in early 2011 when peak velocities were observed. Additionally, geostatistical characterization applied to optical satellite imagery provides an observational data set for model-data comparisons. Observed and modeled crevasse characteristics are compared with respect to their location, magnitude and orientation. Similarity mapping applied to the modeled von Mises stress and observed surface roughness values indicates that the two quantities are correlated. Results indicate that large-scale surface crevasses resulting from a surge are connected to the bedrock topography of the glacier system. The model-data comparisons used in this analysis serve to validate the numerical model and provide insight into the

  20. 76 FR 2027 - Fisheries of the Exclusive Economic Zone Off Alaska; Steller Sea Lion Protection Measures for the...

    Science.gov (United States)

    2011-01-12

    .... 101006495-0498-01] RIN 0648-BA31 Fisheries of the Exclusive Economic Zone Off Alaska; Steller Sea Lion... 13, 2010, to implement Steller sea lion protection measures to ensure that the Bering Sea and... existence of the western distinct population segment of Steller sea lions or adversely modify its designated...

  1. 75 FR 77535 - Fisheries of the Exclusive Economic Zone Off Alaska; Steller Sea Lion Protection Measures for the...

    Science.gov (United States)

    2010-12-13

    ... (Steller sea lion sites). A lottery system assigned vessels to platoons that were allowed to fish inside.... 101006495-0498-01] RIN 0648-BA31 Fisheries of the Exclusive Economic Zone Off Alaska; Steller Sea Lion... sea lion protection measures to insure that the Bering Sea and Aleutian Islands management area (BSAI...

  2. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, Coulometer for DIC measurement and other instruments from the MIRAI in the Arctic Ocean, Beaufort Sea and others from 2002-08-22 to 2002-10-10 (NODC Accession 0112355)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0112355 includes biological, chemical, discrete sample, physical and profile data collected from MIRAI in the Arctic Ocean, Beaufort Sea, Bering Sea...

  3. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from the MELVILLE in the Arabian Sea, Bay of Bengal and others from 1972-07-18 to 1978-04-28 (NODC Accession 0117677)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0117677 includes chemical, discrete sample, physical and profile data collected from MELVILLE in the Arabian Sea, Bay of Bengal, Bering Sea, Gulf of...

  4. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from HEALY in the Arctic Ocean, Beaufort Sea and others from 2014-05-05 to 2014-08-30 (NCEI Accession 0144350)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144350 includes Surface underway data collected from HEALY in the Arctic Ocean, Beaufort Sea, Bering Sea, Coastal Waters of SE Alaska, Gulf of...

  5. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from HEALY in the Arctic Ocean, Beaufort Sea and others from 2013-08-06 to 2013-10-29 (NCEI Accession 0144346)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144346 includes Surface underway data collected from HEALY in the Arctic Ocean, Beaufort Sea, Bering Sea and Northwest Passage from 2013-08-06 to...

  6. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer and other instruments from HEALY in the Arctic Ocean, Beaufort Sea and others from 2015-08-09 to 2015-10-12 (NCEI Accession 0157049)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0157049 includes Surface underway, chemical, meteorological and physical data collected from HEALY in the Arctic Ocean, Beaufort Sea, Bering Sea,...

  7. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from Marcus G. Langseth in the Arctic Ocean, Beaufort Sea and others from 2011-04-13 to 2011-12-28 (NCEI Accession 0144305)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144305 includes Surface underway data collected from Marcus G. Langseth in the Arctic Ocean, Beaufort Sea, Bering Sea, Gulf of Alaska, Hawaiian...

  8. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from HEALY in the Arctic Ocean, Beaufort Sea and others from 2015-07-14 to 2015-10-28 (NCEI Accession 0144530)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144530 includes Surface underway data collected from HEALY in the Arctic Ocean, Beaufort Sea, Bering Sea, Coastal Waters of SE Alaska, Gulf of Alaska...

  9. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from HEALY in the Arctic Ocean, Beaufort Sea and others from 2012-08-01 to 2012-10-24 (NCEI Accession 0144338)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144338 includes Surface underway data collected from HEALY in the Arctic Ocean, Beaufort Sea, Bering Sea, Coastal Waters of SE Alaska and North...

  10. Partial pressure (or fugacity) of carbon dioxide, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from HEALY in the Arctic Ocean, Beaufort Sea and others from 2011-05-27 to 2011-12-16 (NCEI Accession 0144345)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144345 includes Surface underway data collected from HEALY in the Arctic Ocean, Beaufort Sea, Bering Sea, Coastal Waters of SE Alaska, Gulf of...

  11. Improving estimation of glacier volume change: a GLIMS case study of Bering Glacier System, Alaska

    Directory of Open Access Journals (Sweden)

    M. J. Beedle

    2008-04-01

    Full Text Available The Global Land Ice Measurements from Space (GLIMS project has developed tools and methods that can be employed by analysts to create accurate glacier outlines. To illustrate the importance of accurate glacier outlines and the effectiveness of GLIMS standards we conducted a case study on Bering Glacier System (BGS, Alaska. BGS is a complex glacier system aggregated from multiple drainage basins, numerous tributaries, and many accumulation areas. Published measurements of BGS surface area vary from 1740 to 6200 km2, depending on how the boundaries of this system have been defined. Utilizing GLIMS tools and standards we have completed a new outline (3630 km2 and analysis of the area-altitude distribution (hypsometry of BGS using Landsat images from 2000 and 2001 and a US Geological Survey 15-min digital elevation model. We compared this new hypsometry with three different hypsometries to illustrate the errors that result from the widely varying estimates of BGS extent. The use of different BGS hypsometries results in highly variable measures of volume change and net balance (bn. Applying a simple hypsometry-dependent mass-balance model to different hypsometries results in a bn rate range of −1.0 to −3.1 m a−1 water equivalent (W.E., a volume change range of −3.8 to −6.7 km3 a−1 W.E., and a near doubling in contributions to sea level equivalent, 0.011 mm a−1 to 0.019 mm a−1. Current inaccuracies in glacier outlines hinder our ability to correctly quantify glacier change. Understanding of glacier extents can become comprehensive and accurate. Such accuracy is possible with the increasing volume of satellite imagery of glacierized regions, recent advances in tools and standards, and dedication to this important task.

  12. In situ developmental responses of tropical sea urchin larvae to ocean acidification conditions at naturally elevated pCO2 vent sites.

    Science.gov (United States)

    Lamare, Miles D; Liddy, Michelle; Uthicke, Sven

    2016-11-30

    Laboratory experiments suggest that calcifying developmental stages of marine invertebrates may be the most ocean acidification (OA)-sensitive life-history stage and represent a life-history bottleneck. To better extrapolate laboratory findings to future OA conditions, developmental responses in sea urchin embryos/larvae were compared under ecologically relevant in situ exposures on vent-elevated pCO 2 and ambient pCO 2 coral reefs in Papua New Guinea. Echinometra embryos/larvae were reared in meshed chambers moored in arrays on either venting reefs or adjacent non-vent reefs. After 24 and 48 h, larval development and morphology were quantified. Compared with controls (mean pH (T) = 7.89-7.92), larvae developing in elevated pCO 2 vent conditions (pH (T) = 7.50-7.72) displayed a significant reduction in size and increased abnormality, with a significant correlation of seawater pH with both larval size and larval asymmetry across all experiments. Reciprocal transplants (embryos from vent adults transplanted to control conditions, and vice versa) were also undertaken to identify if adult acclimatization can translate resilience to offspring (i.e. transgenerational processes). Embryos originating from vent adults were, however, no more tolerant to reduced pH. Sea temperature and chlorophyll-a concentrations (i.e. larval nutrition) did not contribute to difference in larval size, but abnormality was correlated with chlorophyll levels. This study is the first to examine the response of marine larvae to OA scenarios in the natural environment where, importantly, we found that stunted and abnormal development observed in situ are consistent with laboratory observations reported in sea urchins, in both the direction and magnitude of the response. © 2016 The Author(s).

  13. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, PAR Sensor and other instruments from HEALY in the Arctic Ocean, Beaufort Sea and Bering Sea from 2002-05-05 to 2002-06-15 (NODC Accession 0113952)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0113952 includes biological, chemical, discrete sample, optical, physical and profile data collected from HEALY in the Arctic Ocean, Beaufort Sea and...

  14. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, PAR Sensor and other instruments from HEALY in the Arctic Ocean, Beaufort Sea and Bering Sea from 2004-05-15 to 2004-06-23 (NODC Accession 0115592)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0115592 includes biological, chemical, discrete sample, optical, physical and profile data collected from HEALY in the Arctic Ocean, Beaufort Sea and...

  15. Temperature, salinity and other variables collected from discrete sample and profile observations using CTD, PAR Sensor and other instruments from the NATHANIEL B. PALMER in the Arctic Ocean, Beaufort Sea and Bering Sea from 2003-07-05 to 2003-08-20 (NODC Accession 0116064)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NODC Accession 0116064 includes biological, chemical, discrete sample, physical and profile data collected from NATHANIEL B. PALMER in the Arctic Ocean, Beaufort Sea...

  16. Dissolved inorganic carbon, alkalinity, temperature, salinity and other variables collected from discrete sample and profile observations using CTD, bottle and other instruments from HEALY in the Arctic Ocean, Beaufort Sea and Bering Sea from 2004-07-18 to 2004-08-26 (NODC Accession 0115707)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0115707 includes biological, chemical, discrete sample, optical, physical and profile data collected from HEALY in the Arctic Ocean, Beaufort Sea and...

  17. The Deglacial to Holocene Paleoceanography of Bering Strait: Results From the SWERUS-C3 Program

    Science.gov (United States)

    Jakobsson, M.; Anderson, L. G.; Backman, J.; Barrientos, N.; Björk, G. M.; Coxall, H.; Cronin, T. M.; De Boer, A. M.; Gemery, L.; Jerram, K.; Johansson, C.; Kirchner, N.; Mayer, L. A.; Mörth, C. M.; Nilsson, J.; Noormets, R. R. N. N.; O'Regan, M.; Pearce, C.; Semiletov, I. P.; Stranne, C.

    2017-12-01

    The climate-carbon-cryosphere (C3) interactions in the East Siberian Arctic Ocean and related ocean, river and land areas of the Arctic have been the focus for the SWERUS-C3 Program (Swedish - Russian - US Arctic Ocean Investigation of Climate-Cryosphere-Carbon Interactions). This multi-investigator, multi-disciplinary program was carried out on a two-leg 90-day long expedition in 2014 with Swedish icebreaker Oden. One component of the expedition consisted of geophysical mapping and coring of Herald Canyon, located on the Chukchi Sea shelf north of the Bering Strait in the western Arctic Ocean. Herald Canyon is strategically placed to capture the history of the Pacific-Arctic Ocean connection and related changes in Arctic Ocean paleoceanography. Here we present a summary of key results from analyses of the marine geophysical mapping data and cores collected from Herald Canyon on the shelf and slope that proved to be particularly well suited for paleoceanographic reconstruction. For example, we provide a new age constraint of 11 cal ka BP on sediments from the uppermost slope for the initial flooding of the Bering Land Bridge and reestablishment of the Pacific-Arctic Ocean connection following the last glaciation. This age corresponds to meltwater pulse 1b (MWP1b) known as a post-Younger Dryas warming in many sea level and paleoclimate records. In addition, high late Holocene sedimentation rates that range between about 100 and 300 cm kyr-1, in Herald Canyon permitted paleoceanographic reconstructions of ocean circulation and sea ice cover at centennial scales throughout the late Holocene. Evidence suggests varying influence from inflowing Pacific water into the western Arctic Ocean including some evidence for quasi-cyclic variability in several paleoceanographic parameters, e.g. micropaleontological assemblages, isotope geochemistry and sediment physical properties.

  18. The Bering Strait Region: A Window into Changing Benthic Populations in Response to Varying Subarctic-Arctic Connectivity and Ecosystem Dynamics

    Science.gov (United States)

    Grebmeier, J. M.; Cooper, L. W.; Moore, S. E.

    2016-02-01

    A key ecological organizing principle for the northern Bering Sea and the adjoining southern Chukchi Sea just north of Bering Strait is that the shallow, seasonally productive waters lead to strong pelagic-benthic coupling to the sea floor, with deposition of fresh chlorophyll coinciding with the spring bloom as sea ice retreats. Both in situ production and advection of upstream phytodetritus to these regions support persistent biological hotspots that connect benthic prey to upper trophic benthivores. This northern marine ecosystem is dominated by marine macroinvertebrates (e.g. clams, polychaetes, sipunculids, and amphipods) that feed on the high production deposited rapidly to the seafloor, which in turn serve as food resources for diving mammals and seabirds, such as gray whales, bearded seals, eiders, and walruses. Between St. Lawrence Island and Bering Strait and northwards into the Chukchi Sea, the persistence of seasonal sea ice has significantly declined over the past two decades, and along with warming seawater temperatures, these changes have potential ramifications to ecosystem structure. Times-series data over the last 25 years indicate that these regions have experienced a northward shift in macrofaunal composition and a decline in core benthic biomass that matches patterns of reduced sea ice, warming seawater, and changing sediment grain size that relates to varying current patterns. This presentation will discuss these data in the context of both process studies from the region and results from the Distributed Biological Observatory (DBO), an international network of time series transects that is providing a framework to evaluate status and trends on a latitudinal bases in the Pacific Arctic region.

  19. Coastal erosion and mass wasting along the Canadian Beaufort Sea based on annual airborne LiDAR elevation data

    Science.gov (United States)

    Obu, Jaroslav; Lantuit, Hugues; Grosse, Guido; Günther, Frank; Sachs, Torsten; Helm, Veit; Fritz, Michael

    2017-09-01

    Erosion of permafrost coasts has received increasing scientific attention since 1990s because of rapid land loss and the mobilisation potential of old organic carbon. The majority of permafrost coastal erosion studies are limited to time periods from a few years to decades. Most of these studies emphasize the spatial variability of coastal erosion, but the intensity of inter-annual variations, including intermediate coastal aggradation, remains poorly documented. We used repeat airborne Light Detection And Ranging (LiDAR) elevation data from 2012 and 2013 with 1 m horizontal resolution to study coastal erosion and accompanying mass-wasting processes in the hinterland. Study sites were selected to include different morphologies along the coast of the Yukon Coastal Plain and on Herschel Island. We studied elevation and volume changes and coastline movement and compared the results between geomorphic units. Results showed simple uniform coastal erosion from low coasts (up to 10 m height) and a highly diverse erosion pattern along coasts with higher backshore elevation. This variability was particularly pronounced in the case of active retrogressive thaw slumps, which can decrease coastal erosion or even cause temporary progradation by sediment release. Most of the extremes were recorded in study sites with active slumping (e.g. 22 m of coastline retreat and 42 m of coastline progradation). Coastline progradation also resulted from the accumulation of slope collapse material. These occasional events can significantly affect the coastline position on a specific date and can affect coastal retreat rates as estimated in long term by coastline digitalisation from air photos and satellite imagery. These deficiencies can be overcome by short-term airborne LiDAR measurements, which provide detailed and high-resolution information about quickly changing elevations in coastal areas.

  20. Created mangrove wetlands store belowground carbon and surface elevation change enables them to adjust to sea-level rise

    OpenAIRE

    Krauss, Ken W.; Cormier, Nicole; Osland, Michael J.; Kirwan, Matthew L.; Stagg, Camille L.; Nestlerode, Janet A.; Russell, Marc J.; From, Andrew S.; Spivak, Amanda C.; Dantin, Darrin D.; Harvey, James E.; Almario, Alejandro E.

    2017-01-01

    Mangrove wetlands provide ecosystem services for millions of people, most prominently by providing storm protection, food and fodder. Mangrove wetlands are also valuable ecosystems for promoting carbon (C) sequestration and storage. However, loss of mangrove wetlands and these ecosystem services are a global concern, prompting the restoration and creation of mangrove wetlands as a potential solution. Here, we investigate soil surface elevation change, and its components, in created mangrove w...

  1. Late Quaternary vegetation and climate history of the central Bering land bridge from St. Michael Island, western Alaska

    Science.gov (United States)

    Ager, T.A.

    2003-01-01

    Pollen analysis of a sediment core from Zagoskin Lake on St. Michael Island, northeast Bering Sea, provides a history of vegetation and climate for the central Bering land bridge and adjacent western Alaska for the past ???30,000 14C yr B.P. During the late middle Wisconsin interstadial (???30,000-26,000 14C yr B.P.) vegetation was dominated by graminoid-herb tundra with willows (Salix) and minor dwarf birch (Betula nana) and Ericales. During the late Wisconsin glacial interval (26,000-15,000 14C yr B.P.) vegetation was graminoid-herb tundra with willows, but with fewer dwarf birch and Ericales, and more herb types associated with dry habitats and disturbed soils. Grasses (Poaceae) dominated during the peak of this glacial interval. Graminoid-herb tundra suggests that central Beringia had a cold, arid climate from ???30,000 to 15,000 14C yr B.P. Between 15,000 and 13,000 14C yr B.P., birch shrub-Ericales-sedge-moss tundra began to spread rapidly across the land bridge and Alaska. This major vegetation change suggests moister, warmer summer climates and deeper winter snows. A brief invasion of Populus (poplar, aspen) occurred ca. 11,000-9500 14C yr B.P., overlapping with the Younger Dryas interval of dry, cooler(?) climate. During the latest Wisconsin to middle Holocene the Bering land bridge was flooded by rising seas. Alder shrubs (Alnus crispa) colonized the St. Michael Island area ca. 8000 14C yr B.P. Boreal forests dominated by spruce (Picea) spread from interior Alaska into the eastern Norton Sound area in middle Holocene time, but have not spread as far west as St. Michael Island. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

  2. Elevated gas hydrate saturation within silt and silty clay sediments in the Shenhu area, South China Sea

    Science.gov (United States)

    Wang, Xiujuan; Hutchinson, Deborah R.; Wu, Shiguo; Yang, Shengxiong; Guo, Yiqun

    2011-01-01

    Gas hydrate saturations were estimated using five different methods in silt and silty clay foraminiferous sediments from drill hole SH2 in the South China Sea. Gas hydrate saturations derived from observed pore water chloride values in core samples range from 10 to 45% of the pore space at 190–221 m below seafloor (mbsf). Gas hydrate saturations estimated from resistivity (Rt) using wireline logging results are similar and range from 10 to 40.5% in the pore space. Gas hydrate saturations were also estimated by P wave velocity obtained during wireline logging by using a simplified three-phase equation (STPE) and effective medium theory (EMT) models. Gas hydrate saturations obtained from the STPE velocity model (41.0% maximum) are slightly higher than those calculated with the EMT velocity model (38.5% maximum). Methane analysis from a 69 cm long depressurized core from the hydrate-bearing sediment zone indicates that gas hydrate saturation is about 27.08% of the pore space at 197.5 mbsf. Results from the five methods show similar values and nearly identical trends in gas hydrate saturations above the base of the gas hydrate stability zone at depths of 190 to 221 mbsf. Gas hydrate occurs within units of clayey slit and silt containing abundant calcareous nannofossils and foraminifer, which increase the porosities of the fine-grained sediments and provide space for enhanced gas hydrate formation. In addition, gas chimneys, faults, and fractures identified from three-dimensional (3-D) and high-resolution two-dimensional (2-D) seismic data provide pathways for fluids migrating into the gas hydrate stability zone which transport methane for the formation of gas hydrate. Sedimentation and local canyon migration may contribute to higher gas hydrate saturations near the base of the stability zone.

  3. Elevated concentrations of dissolved Ba, Fe and Mn in a mangrove subterranean estuary: Consequence of sea level rise?

    Science.gov (United States)

    Sanders, Christian J.; Santos, Isaac R.; Barcellos, Renato; Silva Filho, Emmanoel V.

    2012-07-01

    Groundwater underlying a mangrove habitat was studied to determine the geochemical nature of Ba, Fe and Mn as related to dissolved organic carbon (DOC), SO4 and salinity (Sepetiba Bay, Brazil). Wells were placed across geobotanic facies and sampled monthly for a year. We observed non-conservative behavior and elevated concentrations of dissolved metals relative to local end-members (i.e., fresh river water and seawater). Average Ba concentrations were near 2000 nM in an area with low salinity (˜5.3). Dissolved Fe (up to 654 μM) was two orders of magnitude greater in fresh groundwater than in the seaward sampling stations. Manganese concentrations were greatest (112 μM) in the high salinity (˜65) zone, being directly influenced by salinity. Groundwater Ba, Fe and Mn showed differing site specific concentrations, likely related to ion exchange processes and redox-controlled cycling along distinct mangrove facies. The results of this work show that metal concentrations are altered relative to conservative mixing between terrestrial and marine endmembers, illustrating the importance of mangrove subterranean estuaries as biogeochemical reactors. Roughly-estimated submarine groundwater discharge-derived dissolved Ba, Fe and Mn fluxes were at least one order of magnitude greater than river-derived fluxes into Sepetiba Bay.

  4. Elevating your elevator talk

    Science.gov (United States)

    An important and often overlooked item that every early career researcher needs to do is compose an elevator talk. The elevator talk, named because the talk should not last longer than an average elevator ride (30 to 60 seconds), is an effective method to present your research and yourself in a clea...

  5. Mid-Holocene Strengthening of the Bering Strait Inflow to the Arctic and its Linkage With the North Atlantic Subpolar Gyre Circulation

    Science.gov (United States)

    Yamamoto, M.; Nam, S. I.; Polyak, L.; Kobayashi, D.; Suzuki, K.; Irino, T.; Shimada, K.

    2017-12-01

    The Bering Strait inflow (BSI) is an important element of the Arctic Ocean circulation system. We report records of the chlorite/illite ratios in three sediment cores from the northern Chukchi Sea providing insights into the long-term dynamics of the BSI during the Holocene. The BSI approximation by the chlorite/illite record, despite a considerable geographic variability, consistently shows intensified flow from the Bering Sea to the Arctic during the middle Holocene, which is attributed primarily to the effect of higher atmospheric pressure over the Aleutian Basin. The intensified BSI was associated with decrease in sea-ice concentrations and increase in marine production, as indicated by biomarker concentrations, suggesting a major influence of the BSI on sea-ice and biological conditions in the Chukchi Sea. Multi-century to millennial fluctuations, presumably controlled by solar activity, were also identified. This middle Holocene strengthening of the BSI was coeval with intense subpolar gyre circulation in the North Atlantic. We propose that the BSI is linked with the North Atlantic circulation via an atmospheric teleconnection between the Aleutian and Icelandic Lows.

  6. Numerical experiments of dynamical processes during the 2011-2013 surge of the Bering-Bagley Glacier System, using a full-Stokes finite element model

    Science.gov (United States)

    Trantow, Thomas

    The Bering-Bagley Glacial System (BBGS) is the largest glacier system outside of the Greenland and Antarctic ice sheets, and is the Earth's largest surge-type glacier. Surging is one of three types of glacial acceleration and the least understood one. Understanding glacial acceleration is paramount when trying to explain ice discharge to the oceans and the glacial contribution to sea-level rise, yet there are currently no numerical glacial models that account for surging. The recent 2011-2013 surge of the BBGS provides a rare opportunity to study the surge process through observations and the subsequent data analysis and numerical modeling. Using radar, altimeter, and image data collected from airborne and satellite missions, various descriptions of ice geometry are created at different times throughout the surge. Using geostatistical estimation techniques including variography and ordinary kriging, surface and bedrock Digital Elevation Maps (DEMs) are derived. A time series analysis of elevation change during the current surge is then conducted and validated using a complete error analysis along with airborne observations. The derived DEMs are then used as inputs to a computer simulated model of glacier dynamics in the BBGS. Using the Finite Element software Elmer/Ice, a full-Stokes simulation, with Glen's flow law for temperate ice, is created for numerical experiments. With consideration of free surface evolution, glacial hydrology and surface mass balance, the model is able to predict a variety of field variables including velocity, stress, strain-rate, pressure and surface elevation change at any point forward in time. These outputs are compared and validated using observational data such as CryoSat-2 altimetry, airborne field data, imagery and previous detailed analysis of the BBGS. Preliminary results reveal that certain surge phenomena such as surface elevation changes, surge progression and locations at which the surge starts, can be recreated using the

  7. Quantification of vertical movement of low elevation topography combining a new compilation of global sea-level curves and scattered marine deposits (Armorican Massif, western France)

    Science.gov (United States)

    Bessin, Paul; Guillocheau, François; Robin, Cécile; Braun, Jean; Bauer, Hugues; Schroëtter, Jean-Michel

    2017-07-01

    A wide range of methods are available to quantify Earth's surface vertical movements but most of these methods cannot track low amplitude (5 Ma, e.g. cosmogenic isotope studies) vertical movements characteristic of plate interiors. The difference between the present-day elevation of ancient sea-level markers (deduced from well dated marine deposits corrected from their bathymetry of deposition) and a global sea-level (GSL) curve are sometimes used to estimate these intraplate vertical movements. Here, we formalized this method by re-assessing the reliability of published GSL curves to build a composite curve that combines the most reliable ones at each stage, based on the potential bias and uncertainties inherent to each curve. We suggest i) that curves which reflect ocean basin volume changes are suitable for the ca. 100 to 35 Ma ;greenhouse; period ii) whereas curves that reflects ocean water volume changes are better suited for the ca. 35 to 0 Ma ;icehouse; interval and iii) that, for these respective periods, the fit is best when using curves that accounts for both volume changes. We used this composite GSL curve to investigate the poorly constrained Paleogene to Neogene vertical motions of the Armorican Massif (western France). It is characterized by a low elevation topography, a Variscan basement with numerous well dated Cenozoic marine deposits scattered upon it. Using our method, we identify low amplitude vertical movements ranging from 66 m of subsidence to 89 m of uplift over that time period. Their spatial distribution argues for a preferred scale of deformation at medium wavelengths (i.e., order 100 km), which we relate to the deformation history of northwestern European lithosphere in three distinct episodes. i) A phase of no deformation between 38 and 34 Ma, that has been previously recognized at the scale of northwestern Europe, ii) a phase of low subsidence between 30 and 3.6 Ma, possibly related to buckling of the lithosphere and iii) a phase of

  8. Regionalizing indicators for marine ecosystems: Bering Sea–Aleutian Island seabirds, climate, and competitors

    Science.gov (United States)

    Sydeman, William J.; Thompson, Sarah Ann; Piatt, John F.; García-Reyes, Marisol; Zador, Stephani; Williams, Jeffrey C.; Romano, Marc; Renner, Heather

    2017-01-01

    Seabirds are thought to be reliable, real-time indicators of forage fish availability and the climatic and biotic factors affecting pelagic food webs in marine ecosystems. In this study, we tested the hypothesis that temporal trends and interannual variability in seabird indicators reflect simultaneously occurring bottom-up (climatic) and competitor (pink salmon) forcing of food webs. To test this hypothesis, we derived multivariate seabird indicators for the Bering Sea–Aleutian Island (BSAI) ecosystem and related them to physical and biological conditions known to affect pelagic food webs in the ecosystem. We examined covariance in the breeding biology of congeneric pelagic gulls (kittiwakes Rissa tridactyla and R. brevirostris) andauks (murres Uria aalge and U. lomvia), all of whichare abundant and well-studiedinthe BSAI. At the large ecosystem scale, kittiwake and murre breeding success and phenology (hatch dates) covaried among congeners, so data could be combined using multivariate techniques, but patterns of responsedifferedsubstantially betweenthe genera.Whiledata fromall sites (n = 5)inthe ecosystemcould be combined, the south eastern Bering Sea shelf colonies (St. George, St. Paul, and Cape Peirce) provided the strongest loadings on indicators, and hence had the strongest influence on modes of variability. The kittiwake breeding success mode of variability, dominated by biennial variation, was significantly related to both climatic factors and potential competitor interactions. The murre indicator mode was interannual and only weakly related to the climatic factors measured. The kittiwake phenology indicator mode of variability showed multi-year periods (“stanzas”) of late or early breeding, while the murre phenology indicator showed a trend towards earlier timing. Ocean climate relationships with the kittiwake breeding success indicator suggestthat early-season (winter–spring) environmental conditions and the abundance of pink salmon affect the

  9. Space use of a dominant Arctic vertebrate: Effects of prey, sea ice, and land on Pacific walrus resource selection

    Science.gov (United States)

    Beatty, William; Jay, Chadwick V.; Fischbach, Anthony S.; Grebmeier, Jacqueline M.; Taylor, Rebecca L.; Blanchard, Arny L.; Jewett, Stephen C.

    2016-01-01

    Sea ice dominates marine ecosystems in the Arctic, and recent reductions in sea ice may alter food webs throughout the region. Sea ice loss may also stress Pacific walruses (Odobenus rosmarus divergens), which feed on benthic macroinvertebrates in the Bering and Chukchi seas. However, no studies have examined the effects of sea ice on foraging Pacific walrus space use patterns. We tested a series of hypotheses that examined walrus foraging resource selection as a function of proximity to resting substrates and prey biomass. We quantified walrus prey biomass with 17 benthic invertebrate families, which included bivalves, polychaetes, amphipods, tunicates, and sipunculids. We included covariates for distance to sea ice and distance to land, and systematically developed a series of candidate models to examine interactions among benthic prey biomass and resting substrates. We ranked candidate models with Bayesian Information Criterion and made inferences on walrus resource selection based on the top-ranked model. Based on the top model, biomass of the bivalve family Tellinidae, distance to ice, distance to land, and the interaction of distances to ice and land all positively influenced walrus foraging resource selection. Standardized model coefficients indicated that distance to ice explained the most variation in walrus foraging resource selection followed by Tellinidae biomass. Distance to land and the interaction of distances to ice and land accounted for similar levels of variation. Tellinidae biomass likely represented an index of overall bivalve biomass, indicating walruses focused foraging in areas with elevated levels of bivalve and tellinid biomass. Our results also emphasize the importance of sea ice to walruses. Projected sea ice loss will increase the duration of the open water season in the Chukchi Sea, altering the spatial distribution of resting sites relative to current foraging areas and possibly affecting the spatial structure of benthic communities.

  10. Mortality of seabirds in high-seas salmon gillnets

    Science.gov (United States)

    Ainley, D.G.; DeGange, A.R.; Jones, L.L.; Beach, R.J.

    1981-01-01

    Since 1952, the Japanese have operated a large salmon driftnet.fishery in the northern North Pacific Ocean and Bering Sea. This fishery is divided into two components: the high-seas mothership fleet, which consists of several processing ships and their numerous, smaller catcher boats that remain at sea during the entire fishing season, and the land-based fleet, which consists of independent fishing boats that catch and store their own fish and return to Japan at more frequent intervals (Sanger 1976; Fredin et al. 2 ). A similar fishery in the North Atlantic between 1965 and 1976 was responsible for the deaths of large numbers of the thick-billed murre, Uria lomvia, and significant reductions in its breeding populations (Tull et al. 1972). Recent work in the North Pacific and Bering Sea by Sana (1978) and King et al. (1979) indicated that large numbers of seabirds are killed annually in the Japanese salmon fishery also.

  11. 50 CFR Table 4 to Part 679 - Steller Sea Lion Protection Areas Pollock Fisheries Restrictions

    Science.gov (United States)

    2010-10-01

    ....05 N 150°15.40 W 10 Seal Rocks (Kenai) Gulf of Alaska 59°31.20 N 149°37.50 W 10 Chiswell Islands Gulf..., NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE (CONTINUED) FISHERIES OF THE... Sea 60°37.00 N 173°00.00 W 20 St. Paul I./Sea Lion Rock Bering Sea 57°06.00 N 170°17.50 W 3 St. Paul I...

  12. Effect of ocean acidification and elevated fCO2 on trace gas production by a Baltic Sea summer phytoplankton community

    NARCIS (Netherlands)

    Webb, A.L.; Leedham-Elvidge, E.; Hughes, C.; Hopkins, F.E.; Malin, G.; Bach, L.T.; Schulz, K.; Crawfurd, K.; Brussaard, C.P.D.; Stuhr, A.; Riebesell, U.; Liss, P.S.

    2016-01-01

    The Baltic Sea is a unique environment as the largest body of brackish water in the world. Acidification of the surface oceans due to absorption of anthropogenic CO2 emissions is an additional stressor facing the pelagic community of the already challenging Baltic Sea. To investigate its impact on

  13. Dendrochronology and late Holocene history of Bering piedmont glacier, Alaska

    Science.gov (United States)

    Wiles, G.C.; Post, A.; Muller, E.H.; Molnia, B.F.

    1999-01-01

    Fluctuations of the piedmont lobe of Bering Glacier and its sublobe Steller Glacier over the past two millennia are reconstructed using 34 radiocarbon dates and tree-ring data from 16 sites across the glaciers' forelands. The general sequence of glacial activity is consistent with well-dated fluctuations of tidewater and land-terminating glaciers elsewhere along the Gulf of Alaska. Extensive forested areas along 25 km of the Bering ice margin were inundated by glacio-lacustrine and glacio-fluvial sediments during a probable ice advance shortly before 500 cal yr A.D. Regrowth of forests followed the retreating ice as early as the 7th century A.D., with frequent interruptions of tree growth due to outwash aggradation. Forests overrun by ice and buried in outwash indicate readvance about 1080 cal yr A.D. Retreat followed, with ice-free conditions maintained along the distal portions of the forefield until the early 17th century after which the ice advanced to within a few kilometers of its outer Neoglacial moraine. Ice reached this position after the mid-17th century and prior to 200 yr ago. Since the early 20th century, glacial retreat has been punctuated by periodic surges. The record from forests overrun by the nonsurging Steller Lobe shows that this western ice margin was advancing by 1250 A.D., reaching near its outer moraine after 1420 cal yr A.D. Since the late 19th century, the lobe has dominantly retreated.

  14. Variability, trends, and predictability of seasonal sea ice retreat and advance in the Chukchi Sea

    Science.gov (United States)

    Serreze, Mark C.; Crawford, Alex D.; Stroeve, Julienne C.; Barrett, Andrew P.; Woodgate, Rebecca A.

    2016-10-01

    As assessed over the period 1979-2014, the date that sea ice retreats to the shelf break (150 m contour) of the Chukchi Sea has a linear trend of -0.7 days per year. The date of seasonal ice advance back to the shelf break has a steeper trend of about +1.5 days per year, together yielding an increase in the open water period of 80 days. Based on detrended time series, we ask how interannual variability in advance and retreat dates relate to various forcing parameters including radiation fluxes, temperature and wind (from numerical reanalyses), and the oceanic heat inflow through the Bering Strait (from in situ moorings). Of all variables considered, the retreat date is most strongly correlated (r ˜ 0.8) with the April through June Bering Strait heat inflow. After testing a suite of statistical linear models using several potential predictors, the best model for predicting the date of retreat includes only the April through June Bering Strait heat inflow, which explains 68% of retreat date variance. The best model predicting the ice advance date includes the July through September inflow and the date of retreat, explaining 67% of advance date variance. We address these relationships by discussing heat balances within the Chukchi Sea, and the hypothesis of oceanic heat transport triggering ocean heat uptake and ice-albedo feedback. Developing an operational prediction scheme for seasonal retreat and advance would require timely acquisition of Bering Strait heat inflow data. Predictability will likely always be limited by the chaotic nature of atmospheric circulation patterns.

  15. Bering-Okhotsk Seal Survey (BOSS) On-Effort Flight Tracks (2012-13)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Aerial surveys were flown during the spring of 2012 and 2013 as part of the Bering Okhotsk Seal Surveys (BOSS) project to gather data on distribution and abundance...

  16. Assessment of clinical pathology and pathogen exposure in sea otters (Enhydra lutris) bordering the threatened population in Alaska

    Science.gov (United States)

    Goldstein, Tracey; Gill, Verena A.; Tuomi, Pamela A.; Monson, Daniel H.; Burdin, Alexander; Conrad, Patricia A.; Dunn, J. Lawrence; Field, Cara L.; Johnson, Christine K.; Jessup, David A.; Bodkin, James L.; Doroff, Angela M.

    2011-01-01

    Northern sea otter (Enhydra lutris kenyoni) abundance has decreased dramatically over portions of southwest Alaska, USA, since the mid-1980s, and this stock is currently listed as threatened under the Endangered Species Act. In contrast, adjacent populations in south central Alaska, USA, and Russia have been stable to increasing during the same period. Sea otters bordering the area classified in the recent decline were live-captured during 2004–2006 at Bering Island, Russia, and the Kodiak Archipelago, Alaska, USA, to evaluate differences in general health and current exposure status to marine and terrestrial pathogens. Although body condition was lower in animals captured at Bering Island, Russia, than it was at Kodiak, USA, clinical pathology values did not reveal differences in general health between the two regions. Low prevalences of antibodies (>5%) were found in Kodiak, USA, and on Bering Island, Russia, to Toxoplasma gondii, Sarcocystis neurona, and Leptospira interrogans. Exposure to phocine herpesvirus-1 was found in both Kodiak, USA (15.2%), and Bering Island, Russia (2.3%). Antibodies to Brucella spp. were found in 28% of the otters tested on Bering Island, Russia, compared with only 2.7% of the samples from Kodiak, USA. Prevalence of exposure to Phocine distemper virus (PDV) was 41% in Kodiak, USA, but 0% on Bering Island, Russia. Archived sera from southwest and south-central Alaska dating back to 1989 were negative for PDV, indicating exposure occurred in sea otters in Kodiak, USA, in recent years. Because PDV can be highly pathogenic in naïve and susceptible marine mammal populations, tissues should be examined to explore the contribution of this virus to otter deaths. Our results reveal an increase in exposure to pathogens in sea otters in Kodiak, Alaska, USA, since the 1990s.

  17. How Vulnerable is Perennial Sea Ice? Insights from Earth's Late Cenozoic Natural Experiments (Invited)

    Science.gov (United States)

    Brigham-Grette, J.; Polyak, L. V.; Caissie, B.; Sharko, C. J.; Petsch, S.

    2010-12-01

    Sea ice is an important component of the climate system. Yet, reconstructions of Arctic sea ice conditions reflecting glacial and interglacial change over the past 3 million years are almost nonexistent. Our work to evaluate the sea ice and sea surface temperature record of the Bering Strait region builds on a review of the sea ice history of the pan-Arctic. The best estimates of sea ice make use of indirect proxies based on reconstructions of treeline, sea surface temperatures, depositional systems, and the ecological preferences of extant marine microfossil species. The development of new proxies of past sea ice extent including microfossil assemblages (diatoms, ostracodes) and biomarker proxies (IP25) show promise for quantifying seasonal concentrations of sea ice cover on centennial to millennial timescales. Using both marine and terrestrial information, periods of restricted sea ice and ice-free Arctic conditions can be inferred for parts of the late Cenozoic. The Arctic Ocean borderlands contain clear stratigraphic evidence for forested conditions at intervals over the past 50 million years, recording the migration of treeline from High Arctic coastal locations within the Canadian Archipelago. Metasequoia forests of the peak Eocene gave way to a variety of biomass-rich circumarctic redwood forests by 46 Ma. Between 23 and 16 Ma, cool-temperate metasequoia forests dominated NE Alaska and the Yukon while mixed conifer-hardwood forests (similar to those of modern southern maritime Canada and New England) dominated the central Canadian Archipelago. By 16 Ma, these forests gave way to larch and spruce. From 5 to 3 Ma the braid plains of the Beaufort Fm were dominated by over 100 vascular plants including pine and birch, while other locations remained dominated by spruce and larch. Boreal conditions across northern Greenland and arctic Alaska are consistent with the presence of bivalve Arctica islandica in marine sediments capping the Beaufort Formation on Meighen

  18. Vegetation death and rapid loss of surface elevation in two contrasting Mississippi delta salt marshes: The role of sedimentation, autocompaction and sea-level rise

    Science.gov (United States)

    Day, J.W.; Kemp, G.P.; Reed, D.J.; Cahoon, D.R.; Boumans, R.M.; Suhayda, J.M.; Gambrell, R.

    2011-01-01

    From 1990 to 2004, we carried out a study on accretionary dynamics and wetland loss in salt marshes surrounding two small ponds in the Mississippi delta; Old Oyster Bayou (OB), a sediment-rich area near the mouth of the Atchafalaya River and Bayou Chitigue (BC), a sediment-poor area about 70. km to the east. The OB site was stable, while most of the marsh at BC disappeared within a few years. Measurements were made of short-term sedimentation, vertical accretion, change in marsh surface elevation, pond wave activity, and marsh soil characteristics. The OB marsh was about 10. cm higher than BC; the extremes of the elevation range for Spartina alterniflora in Louisiana. Vertical accretion and short-term sedimentation were about twice as high at BC than at OB, but the OB marsh captured nearly all sediments deposited, while the BC marsh captured <30%. The OB and BC sites flooded about 15% and 85% of the time, respectively. Marsh loss at BC was not due to wave erosion. The mineral content of deposited sediments was higher at OB. Exposure and desiccation of the marsh surface at OB increased the efficiency that deposited sediments were incorporated into the marsh soil, and displaced the marsh surface upward by biological processes like root growth, while also reducing shallow compaction. Once vegetation dies, there is a loss of soil volume due to loss of root turgor and oxidation of root organic matter, which leads to elevation collapse. Revegetation cannot occur because of the low elevation and weak soil strength. The changes in elevation at both marsh sites are punctuated, occurring in steps that can either increase or decrease elevation. When a marsh is low as at BC, a step down can result in an irreversible change. At this point, the option is not restoration but creating a new marsh with massive sediment input either from the river or via dredging. ?? 2010 Elsevier B.V.

  19. Behavior of bowhead whales of the Davis Strait and Bering/Beaufort stocks versus regional differences in human activities. Final report on Phase 2

    International Nuclear Information System (INIS)

    Miller, G.W.; Davis, R.A.; Richardson, W.J.

    1991-07-01

    The objectives were to determine (1) whether there are differences in behavior between the Bering/Chukchi/Beaufort and the Davis Strait/Baffin Bay populations and (2), if so, whether the differences might be attributable to the long-term cumulative effects of exposure to the presumed greater amount of human activity in the former area. Phase 1 showed that there are some differences in behavior. The Phase 2 report documents the relative amounts of human activity in the two areas in 1974-86, and evaluates whether regional differences in whale behavior and in human activities may be related. Activities considered include bowhead hunting and other subsistence activities, commercial fishing and shipping, marine seismic exploration, offshore oil exploration, and low-level aircraft flights. Bering/Beaufort bowheads were subjected to at least 3-5 times as much human activity in 1974-86. Most differences in behavior between the two stocks were better explained by environmental or biological factors than by disturbance. However, for bowheads migrating in autumn, regional differences in behavior may be related to the whaling that occurs in the Beaufort Sea in autumn

  20. The Bering Land Bridge: a moisture barrier to the dispersal of steppe-tundra biota?

    Science.gov (United States)

    Elias, Scott A.; Crocker, Barnaby

    2008-12-01

    The Bering Land Bridge (BLB) connected the two principal arctic biological refugia, Western and Eastern Beringia, during intervals of lowered sea level in the Pleistocene. Fossil evidence from lowland BLB organic deposits dating to the Last Glaciation indicates that this broad region was dominated by shrub tundra vegetation, and had a mesic climate. The dominant ecosystem in Western Beringia and the interior regions of Eastern Beringia was steppe-tundra, with herbaceous plant communities and arid climate. Although Western and Eastern Beringia shared many species in common during the Late Pleistocene, there were a number of species that were restricted to only one side of the BLB. Among the vertebrate fauna, the woolly rhinoceros was found only to the west of the BLB, North American camels, bonnet-horned musk-oxen and some horse species were found only to the east of the land bridge. These were all steppe-tundra inhabitants, adapted to grazing. The same phenomenon can be seen in the insect faunas of the Western and Eastern Beringia. The steppe-tundra beetle fauna of Western Beringia was dominated by weevils of the genus Stephanocleonus, a group that was virtually absent from Eastern Beringia. The dry-adapted weevils, Lepidophorus lineaticollis and Vitavitus thulius were important members of steppe-tundra communities in Eastern Beringia, but were either absent or rare in Western Beringia. The leaf beetles Chrysolina arctica, C. brunnicornis bermani, and Galeruca interrupta circumdata were typical members of the Pleistocene steppe-tundra communities of Western Beringia, but absent from Eastern Beringia. On the other hand, some steppe tundra-adapted leaf beetles managed to occupy both sides of the BLB, such as Phaedon armoraciae. Much of the BLB remains unstudied, but on biogeographic grounds, it appears that there was some kind of biological filter that blocked the movements of some steppe-tundra plants and animals across the BLB.

  1. A Newly Recorded Sea Cucumber (Holothuroidea: Aspidochirotida: Synallactidae from East Sea, Korea

    Directory of Open Access Journals (Sweden)

    Lee, Taekjun

    2014-04-01

    Full Text Available Five sea cucumbers were collected from Gisamun and Gonghyeonjin of Gangwon-do, in the East Sea, Korea from 27 December 2009 to 14 November 2012. These specimens were classified as Synallactes nozawai Mitsukuri, 1912 belonging to the family Synallactidae of order Aspidochirotida based on morphological characteristics. The family, genus and species are recorded for the first time from Korea. The distinct morphological characteristics of this species are as follows: body flexible, with thin gelatinous body wall; presence of numerous tubercles along dorsal ambulacra table of body wall consisted of three- or four-armed disk and a spire-form pillar. This species usually inhabits the deep sea and is distributed in the Northwest Pacific from northern Japan to Bering Sea.

  2. Highly variable Pliocene sea surface conditions in the Norwegian Sea

    Directory of Open Access Journals (Sweden)

    P. E. Bachem

    2017-09-01

    Full Text Available The Pliocene was a time of global warmth with small sporadic glaciations, which transitioned towards the larger-scale Pleistocene glacial–interglacial variability. Here, we present high-resolution records of sea surface temperature (SST and ice-rafted debris (IRD in the Norwegian Sea from 5.32 to 3.14 Ma, providing evidence that the Pliocene surface conditions of the Norwegian Sea underwent a series of transitions in response to orbital forcing and gateway changes. Average SSTs are 2 °C above the regional Holocene mean, with notable variability on millennial to orbital timescales. Both gradual changes and threshold effects are proposed for the progression of regional climate towards the Late Pliocene intensification of Northern Hemisphere glaciation. Cooling from 4.5 to 4.3 Ma may be linked to the onset of poleward flow through the Bering Strait. This cooling was further intensified by a period of cool summers due to weak obliquity forcing. A 7 °C warming of the Norwegian Sea at 4.0 Ma suggests a major increase in northward heat transport from the North Atlantic, leading to an enhanced zonal SST gradient in the Nordic Seas, which may be linked to the expansion of sea ice in the Arctic and Nordic Seas. A warm Norwegian Sea and enhanced zonal temperature gradient between 4.0 and 3.6 Ma may have been a priming factor for increased glaciation around the Nordic Seas due to enhanced evaporation and precipitation at high northern latitudes.

  3. The acclimation process of phytoplankton biomass, carbon fixation and respiration to the combined effects of elevated temperature and pCO2 in the northern South China Sea.

    Science.gov (United States)

    Gao, Guang; Jin, Peng; Liu, Nana; Li, Futian; Tong, Shanying; Hutchins, David A; Gao, Kunshan

    2017-05-15

    We conducted shipboard microcosm experiments at both off-shore (SEATS) and near-shore (D001) stations in the northern South China Sea (NSCS) under three treatments, low temperature and low pCO 2 (LTLC), high temperature and low pCO 2 (HTLC), and high temperature and high pCO 2 (HTHC). Biomass of phytoplankton at both stations were enhanced by HT. HTHC did not affect phytoplankton biomass at station D001 but decreased it at station SEATS. HT alone increased net primary productivity by 234% at station SEATS and by 67% at station D001 but the stimulating effect disappeared when HC was combined. HT also increased respiration rate by 236% at station SEATS and by 87% at station D001 whereas HTHC reduced it by 61% at station SEATS and did not affect it at station D001. Overall, our findings indicate that the positive effect of ocean warming on phytoplankton assemblages in NSCS could be damped or offset by ocean acidification. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Prolonged exposure to elevated CO2 promotes growth of the algal symbiont Symbiodinium muscatinei in the intertidal sea anemone Anthopleura elegantissima

    Science.gov (United States)

    Towanda, Trisha; Thuesen, Erik V.

    2012-01-01

    Summary Some photosynthetic organisms benefit from elevated levels of carbon dioxide, but studies on the effects of elevated PCO2 on the algal symbionts of animals are very few. This study investigated the impact of hypercapnia on a photosynthetic symbiosis between the anemone Anthopleura elegantissima and its zooxanthella Symbiodinium muscatinei. Anemones were maintained in the laboratory for 1 week at 37 Pa PCO2 and pH 8.1. Clonal pairs were then divided into two groups and maintained for 6 weeks under conditions naturally experienced in their intertidal environment, 45 Pa PCO2, pH 8.1 and 231 Pa PCO2, pH 7.3. Respiration and photosynthesis were measured after the 1-week acclimation period and after 6 weeks in experimental conditions. Density of zooxanthellal cells, zooxanthellal cell size, mitotic index and chlorophyll content were compared between non-clonemate anemones after the 1-week acclimation period and clonal anemones at the end of the experiment. Anemones thrived in hypercapnia. After 6 weeks, A. elegantissima exhibited higher rates of photosynthesis at 45 Pa (4.2 µmol O2 g−1 h−1) and 231 Pa (3.30 µmol O2 g−1 h−1) than at the initial 37 Pa (1.53 µmol O2 g−1 h−1). Likewise, anemones at 231 Pa received more of their respiratory carbon from zooxanthellae (CZAR  = 78.2%) than those at 37 Pa (CZAR  = 66.6%) but less than anemones at 45 Pa (CZAR  = 137.3%). The mitotic index of zooxanthellae was significantly greater in the hypercapnic anemones than in anemones at lower PCO2. Excess zooxanthellae were expelled by their hosts, and cell densities, cell diameters and chlorophyll contents were not significantly different between the groups. The response of A. elegantissima to hypercapnic acidification reveals the potential adaptation of an intertidal, photosynthetic symbiosis for high PCO2. PMID:23213455

  5. Prolonged exposure to elevated CO2 promotes growth of the algal symbiont Symbiodinium muscatinei in the intertidal sea anemone Anthopleura elegantissima

    Directory of Open Access Journals (Sweden)

    Trisha Towanda

    2012-05-01

    Some photosynthetic organisms benefit from elevated levels of carbon dioxide, but studies on the effects of elevated PCO2 on the algal symbionts of animals are very few. This study investigated the impact of hypercapnia on a photosynthetic symbiosis between the anemone Anthopleura elegantissima and its zooxanthella Symbiodinium muscatinei. Anemones were maintained in the laboratory for 1 week at 37 Pa PCO2 and pH 8.1. Clonal pairs were then divided into two groups and maintained for 6 weeks under conditions naturally experienced in their intertidal environment, 45 Pa PCO2, pH 8.1 and 231 Pa PCO2, pH 7.3. Respiration and photosynthesis were measured after the 1-week acclimation period and after 6 weeks in experimental conditions. Density of zooxanthellal cells, zooxanthellal cell size, mitotic index and chlorophyll content were compared between non-clonemate anemones after the 1-week acclimation period and clonal anemones at the end of the experiment. Anemones thrived in hypercapnia. After 6 weeks, A. elegantissima exhibited higher rates of photosynthesis at 45 Pa (4.2 µmol O2 g−1 h−1 and 231 Pa (3.30 µmol O2 g−1 h−1 than at the initial 37 Pa (1.53 µmol O2 g−1 h−1. Likewise, anemones at 231 Pa received more of their respiratory carbon from zooxanthellae (CZAR  = 78.2% than those at 37 Pa (CZAR  = 66.6% but less than anemones at 45 Pa (CZAR  = 137.3%. The mitotic index of zooxanthellae was significantly greater in the hypercapnic anemones than in anemones at lower PCO2. Excess zooxanthellae were expelled by their hosts, and cell densities, cell diameters and chlorophyll contents were not significantly different between the groups. The response of A. elegantissima to hypercapnic acidification reveals the potential adaptation of an intertidal, photosynthetic symbiosis for high PCO2.

  6. Prolonged exposure to elevated CO(2) promotes growth of the algal symbiont Symbiodinium muscatinei in the intertidal sea anemone Anthopleura elegantissima.

    Science.gov (United States)

    Towanda, Trisha; Thuesen, Erik V

    2012-07-15

    Some photosynthetic organisms benefit from elevated levels of carbon dioxide, but studies on the effects of elevated PCO(2) on the algal symbionts of animals are very few. This study investigated the impact of hypercapnia on a photosynthetic symbiosis between the anemone Anthopleura elegantissima and its zooxanthella Symbiodinium muscatinei. Anemones were maintained in the laboratory for 1 week at 37 Pa PCO(2) and pH 8.1. Clonal pairs were then divided into two groups and maintained for 6 weeks under conditions naturally experienced in their intertidal environment, 45 Pa PCO(2), pH 8.1 and 231 Pa PCO(2), pH 7.3. Respiration and photosynthesis were measured after the 1-week acclimation period and after 6 weeks in experimental conditions. Density of zooxanthellal cells, zooxanthellal cell size, mitotic index and chlorophyll content were compared between non-clonemate anemones after the 1-week acclimation period and clonal anemones at the end of the experiment. Anemones thrived in hypercapnia. After 6 weeks, A. elegantissima exhibited higher rates of photosynthesis at 45 Pa (4.2 µmol O(2) g(-1) h(-1)) and 231 Pa (3.30 µmol O(2) g(-1) h(-1)) than at the initial 37 Pa (1.53 µmol O(2) g(-1) h(-1)). Likewise, anemones at 231 Pa received more of their respiratory carbon from zooxanthellae (CZAR  = 78.2%) than those at 37 Pa (CZAR  = 66.6%) but less than anemones at 45 Pa (CZAR  = 137.3%). The mitotic index of zooxanthellae was significantly greater in the hypercapnic anemones than in anemones at lower PCO(2). Excess zooxanthellae were expelled by their hosts, and cell densities, cell diameters and chlorophyll contents were not significantly different between the groups. The response of A. elegantissima to hypercapnic acidification reveals the potential adaptation of an intertidal, photosynthetic symbiosis for high PCO(2).

  7. Data Elevator

    Energy Technology Data Exchange (ETDEWEB)

    2017-04-29

    Data Elevator: Efficient Asynchronous Data Movement in Hierarchical Storage Systems Multi-layer storage subsystems, including SSD-based burst buffers and disk-based parallel file systems (PFS), are becoming part of HPC systems. However, software for this storage hierarchy is still in its infancy. Applications may have to explicitly move data among the storage layers. We propose Data Elevator for transparently and efficiently moving data between a burst buffer and a PFS. Users specify the final destination for their data, typically on PFS, Data Elevator intercepts the I/O calls, stages data on burst buffer, and then asynchronously transfers the data to their final destination in the background. This system allows extensive optimizations, such as overlapping read and write operations, choosing I/O modes, and aligning buffer boundaries. In tests with large-scale scientific applications, Data Elevator is as much as 4.2X faster than Cray DataWarp, the start-of-art software for burst buffer, and 4X faster than directly writing to PFS. The Data Elevator library uses HDF5's Virtual Object Layer (VOL) for intercepting parallel I/O calls that write data to PFS. The intercepted calls are redirected to the Data Elevator, which provides a handle to write the file in a faster and intermediate burst buffer system. Once the application finishes writing the data to the burst buffer, the Data Elevator job uses HDF5 to move the data to final destination in an asynchronous manner. Hence, using the Data Elevator library is currently useful for applications that call HDF5 for writing data files. Also, the Data Elevator depends on the HDF5 VOL functionality.

  8. An elevator

    Energy Technology Data Exchange (ETDEWEB)

    Loginovskiy, V.I.; Medinger, N.V.; Rasskazov, V.A.; Solonitsyn, V.A.

    1983-01-01

    An elevator is proposed which includes a body, spring loaded cams and a shut-off ring. To increase the reliability of the elevator by eliminating the possibility of spontaneous shifting of the shut-off ring, the latter is equipped with handles hinged to it and is made with evolvent grooves. The cams are equipped with rollers installed in the evolvent grooves of the shut off ring, where the body is made with grooves for the handles.

  9. The distribution of seabirds and fish in relation to ocean currents in the southeastern Chukchi Sea

    Science.gov (United States)

    Piatt, John F.; Wells, John L.; MacCharles, Andrea; Fadely, Brian S.; Montevecchi, W.A.; Gaston, A.J.

    1991-01-01

    In late August 1988, we studied the distribution of seabirds in the southeastern Chukchi Sea, particularly in waters near a major seabird colony at Cape Thompson. Foraging areas were characterized using hydrographic data obtained from hydroacoustic surveys for fish. Murres (Uria spp.) and Black-legged Kitttiwakes Rissa tridactyla breeding at Cape Thompson fed mostly on Arctic cod, which are known from previous studies to be the most abundant pelagic fish in the region. Our hydroacoustic surveys revealed that pelagic fish were distributed widely, but densities were estimated to be low (e.g., 0.1-10 g∙m-3) throughout the study area and a few schools were recorded. Large feeding flocks of murres and kittiwakes were observed over fish schools with densities estimated to exceed 15 g∙m-3. Fish densities were higher in shallow Alaska Coastal Current waters than offshore in Bering Sea waters, and most piscivorous seabirds foraged in coastal waters. Poor kittiwake breeding success and a low frequency of fish in murre and kittiwake stomachs in late August suggested that fish densities were marginal for sustaining breeding seabirds at that time. Planktivorous Least Auklets Aethia pusilla and Parakeet Auklets Cyclorrhynchus psittacula foraged almost exclusively in Bering Sea waters. Short-tailed Shearwaters Puffinus tenuirostris and Tufted Puffins Fratercula cirrhata foraged in transitional waters at the front between Coastal and Bering Sea currents.

  10. Trends in Sea Ice Cover, Sea Surface Temperature, and Chlorophyll Biomass Across a Marine Distributed Biological Observatory in the Pacific Arctic Region

    Science.gov (United States)

    Frey, K. E.; Grebmeier, J. M.; Cooper, L. W.; Wood, C.; Panday, P. K.

    2011-12-01

    The northern Bering and Chukchi Seas in the Pacific Arctic Region (PAR) are among the most productive marine ecosystems in the world and act as important carbon sinks, particularly during May and June when seasonal sea ice-associated phytoplankton blooms occur throughout the region. Recent dramatic shifts in seasonal sea ice cover across the PAR should have profound consequences for this seasonal phytoplankton production as well as the intimately linked higher trophic levels. In order to investigate ecosystem responses to these observed recent shifts in sea ice cover, the development of a prototype Distributed Biological Observatory (DBO) is now underway in the PAR. The DBO is being developed as an internationally-coordinated change detection array that allows for consistent sampling and monitoring at five spatially explicit biologically productive locations across a latitudinal gradient: (1) DBO-SLP (south of St. Lawrence Island (SLI)), (2) DBO-NBS (north of SLI), (3) DBO-SCS (southern Chukchi Sea), (4) DBO-CCS (central Chukchi Sea), and (5) DBO-BCA (Barrow Canyon Arc). Standardized measurements at many of the DBO sites were made by multiple research cruises during the 2010 and 2011 pilot years, and will be expanded with the development of the DBO in coming years. In order to provide longer-term context for the changes occurring across the PAR, we utilize multi-sensor satellite data to investigate recent trends in sea ice cover, chlorophyll biomass, and sea surface temperatures for each of the five DBO sites, as well as a sixth long-term observational site in the Bering Strait. Satellite observations show that over the past three decades, trends in sea ice cover in the PAR have been heterogeneous, with significant declines in the Chukchi Sea, slight declines in the Bering Strait region, but increases in the northern Bering Sea south of SLI. Declines in the persistence of seasonal sea ice cover in the Chukchi Sea and Bering Strait region are due to both earlier sea

  11. Monocular Elevation Deficiency - Double Elevator Palsy

    Science.gov (United States)

    ... Español Condiciones Chinese Conditions Monocular Elevation Deficiency/ Double Elevator Palsy En Español Read in Chinese What is monocular elevation deficiency (Double Elevator Palsy)? Monocular Elevation Deficiency, also known by the ...

  12. 33 CFR 334.1330 - Bering Strait, Alaska; naval restricted area off Cape Prince of Wales.

    Science.gov (United States)

    2010-07-01

    ... restricted area off Cape Prince of Wales. 334.1330 Section 334.1330 Navigation and Navigable Waters CORPS OF....1330 Bering Strait, Alaska; naval restricted area off Cape Prince of Wales. (a) The area. An area 2,000 feet wide extending from a point on Cape Prince of Wales marked by a triangular cable marker located...

  13. Water temperature, salinity, and velocity including ADCP ice tracking from Bering Strait moorings A2, A3, A4 in Bering Strait from 2015-07-02 to 2016-07-10 (NCEI Accession 0164166)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is an archive of data from moorings deployed in Bering Strait from summer 2015 to summer 2016. Mooring deployments were funded by the NSF-Arctic Observing...

  14. Physical oceanographic mooring data (temperature, salinity, velocity including ADCP ice tracking) collected from Bering Strait Moorings A2, A3, A4 in Bering Strait from 2014-07-02 to 2015-07-05 (NCEI Accession 0155760)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is an archive of data from moorings deployed in Bering Strait from summer 2014 to summer 2015. Mooring deployments were funded by the NSF-Arctic Observing...

  15. AFSC/NMML: North Pacific Right Whale Vessel Surveys in the Southeastern Bering Sea, 2007 - 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The North Pacific right whale (NPRW) was heavily hunted between the 17th and the 20th centuries. Protection was supposedly afforded by international treaties in the...

  16. AFSC/ABL: Juvenile chum salmon allozyme stock identification, Bering Sea 2002

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Genetic stock identification techniques were used to identify the origin and provide stock-specific migration and distribution patterns of juvenile chum...

  17. Coastal Environment, Bathymetry and Physical Oceanography along the Beaufort, Chukchi and Bering Seas.

    Science.gov (United States)

    1980-01-01

    24 36 48 waters per tidal day; successive high water and Time (hours) low water stands are approximately equal. Mixed tides are most common... successive high water and low water stands occur twice daily but differ appreciably in height. Adapted from: M.G. Gross. 1967. Oceanorphy. Figure 114...77all Stt70,9677 24 74 07 68877.770. P... la007870 2 40 d IIVad ikea CO.0 C. PW7 6 Pw.00,,e7 99 T.,than U. S Godn.. L H a - 1 1977 C7.78.7ea7’s77 0

  18. AFSC/ABL: Gulf of Alaska and Bering Sea Capelin Microsatellite data, 2005 & 2007

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Capelin are important forage fish in Alaska for marine mammals, birds, and predatory fish. Capelin prefer cold water and are very sensitive to changing environmental...

  19. Mercury in organs of Pacific walruses (Odobenus rosmarus divergens) from the Bering Sea.

    Science.gov (United States)

    Trukhin, Alexey M; Simokon, Mikhail V

    2018-02-01

    The Pacific walrus (Odobenus rosmarus divergens) is still used as an important source of protein-rich food by indigenous peoples of Chukotka, Alaska, and other Arctic regions. Total mercury (THg) concentration was measured in eight internal organs of walruses. Samples were taken from 22 individuals (11 males and 11 females). Age of the animals ranged from 1 to 30 years. All the walruses were harvested by local hunters from the coastal waters off the Chukchi Peninsula (Russia) during the autumn of 2011. Total mercury concentration in the samples was determined by atomic absorption method. No statistically significant difference in the level of mercury was found between males and females. Mercury was detected in all the organs of the studied walruses. The highest total mercury concentration was recorded from excretory organs: liver and kidneys. The level of mercury in liver (mean = 1.87 μg/g, range = 0.05-5.87) was by an order of magnitude higher than in kidneys (mean = 0.54 μg/g, range = 0.09-1.64.); in kidneys, it was by an order of magnitude higher than in the rest of the organs. The analyzed organs can be arranged in the order of decreasing Hg concentration as follows: liver > kidney > muscle > spleen ≥ heart ≥ intestine > lung ≥ testis. The mercury concentration values in walruses from the coastal waters off the Chukchi Peninsula are lower than those obtained from walruses in Alaska and the Canadian Arctic. Our findings may provide a basis for the further long-term monitoring of the condition of the Pacific walrus population and pollution of the Arctic ecosystem.

  20. Avian cholera causes marine bird mortality in the Bering Sea of Alaska

    Science.gov (United States)

    Bodenstein, Barbara L.; Kimberlee Beckmen,; Gay Sheffield,; Kathy Kuletz,; Van Hemert, Caroline R.; Berlowski-Zier, Brenda M.; Shearn-Bochsler, Valerie I.

    2015-01-01

    The first known avian cholera outbreak among wild birds in Alaska occurred during November 2013. Liver, intestinal, and splenic necrosis consistent with avian cholera was noted, and Pasteurella multocida serotype 1 was isolated from liver and lung or spleen in Crested Auklets (Aethia cristatella), Thick-billed Murres (Uria lomvia), Common Eider (Somateria mollissima), Northern Fulmars (Fulmarus glacialis), and Glaucous-winged Gulls (Larus glaucescens).

  1. Acoustic-Trawl Survey of Walleye Pollock in the Eastern Bering Sea (DY1608, EK60)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Midwater Assessment and Conservation Engineering (MACE) program of NOAA National Marine Fisheries Service (NMFS), Alaska Fisheries Science Center (AFSC)...

  2. 75 FR 5945 - Proposed Information Collection; Comment Request; Alaska Cooperatives in the Bering Sea and...

    Science.gov (United States)

    2010-02-05

    ... rational manner, and to protect non-AFA participants in other fisheries. In addition, a voluntary civil... appeals. Estimated Total Annual Burden Hours: 470. Estimated Total Annual Cost to Public: $225. IV...

  3. Bering Sea Helicopter Surveys for Ice-Associated Seals (2007-08)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In the spring of 2007 and 2008, researchers from the Alaska Fisheries Science Center conducted aerial surveys for ribbon, bearded, and spotted seals in the US sector...

  4. AFSC/ABL: Genetic Analysis of Immature Bering Sea Chum Salmon: Part I. Baseline Evaluation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Chum salmon populations from across their geographic distribution have been analyzed with a set of SNP and microsatellite markers. As is typical for chum salmon...

  5. Nitrogen utilization during spring phytoplankton bloom development in the southeast Bering Sea

    International Nuclear Information System (INIS)

    Sambrotto, R.N.

    1983-01-01

    Interactions beween a high latitude, continental shelf, spring phytoplankton bloom and water column physics and chemistry were studied using 15 N measured rates of nitrogen uptake. Peak bloom conditions commenced when the mixed layer shallowed and minimized respirational losses. Integrative light-mixing growth models were accurate during early bloom stages. An advection-diffusion model associated peak bloom nitrate uptake with pycnocline mixing rates of 2.1 m d -1 in an 18 m mixed layer. Maximum nitrogen specific uptake rates (hr -1 ), unlike those of carbon, coincided with peak bloom conditions. Although species compositions among peak bloom periods were similar, particulate C/N ratios were not. Apparently, both intercellular factors and prevailing mixing conditions influence specific uptake rates and cell composition. A large proportion of new (nitrate) to total productivity was associated with the dominance of the early bloom forming diatoms in the mixed layer. In the absence of these net plankton the residual nanoplankton dominated community exhibited a greater dependence on regenerated nitrogen. Nitrate uptake averaged 700 mg-at m -2 during the spring bloom and 1 g-at m -2 year -1 . The yearly f factor was 0.40. Nitrogen uptake based carbon productivity was 188 g C m -2 year -1

  6. AFSC/RACE/SAP/Armistead: 1975 - 2016 eastern Bering Sea Crab Distribution For Web

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Resource Assessment and Conservation Engineering Division (RACE) of the Alaska Fisheries Science Center (AFSC) conducts bottom trawl surveys to monitor the...

  7. 76 FR 3090 - Proposed Information Collection; Comment Request; Alaska Region; Bering Sea and Aleutian Islands...

    Science.gov (United States)

    2011-01-19

    ... submitted on or before March 21, 2011. ADDRESSES: Direct all written comments to Diana Hynek, Departmental... fisheries. Program components include quota share allocation, processor quota share allocation, individual... Binding Arbitration process, and fee collection. II. Method of Collection Responses are mailed, except the...

  8. AFSC/RACE/GAP/Orr: Bering Sea Slope groundfish surveys Identification Confidence

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This report includes an identification confidence matrix for all fishes and invertebrates identified from the EBS slope triennial and biennial surveys from 1976...

  9. 50 CFR 600.1103 - Bering Sea and Aleutian Islands (BSAI) Crab species program.

    Science.gov (United States)

    2010-10-01

    ... ever fish anywhere in the world; (4) Crab reduction permit requirements. (i) Except as otherwise... fisheries and in the Norton Sound fishery by adding each of the products of the multiplications in paragraph... endorsement is for the Norton Sound fishery; (4) Basis of lists. NMFS will base both the lists on the RAM...

  10. EBSSED database-Surficial sediments of the eastern Bering Sea continental shelf

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In order to facilitate descriptions of groundfish habitat over a large portion of the EBS shelf, the NMFS/AFSC has assembled a single comprehensive database of the...

  11. Eastern Bering Sea Acoustic-Trawl Survey of Walleye Pollock (DY1006, ME70)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Midwater Assessment and Conservation Engineering (MACE) program of the Alaska Fisheries Science Center (AFSC; NOAA National Marine Fisheries Service) conducted...

  12. AFSC/RACE/MACE: Results of 2006 Pollock Acoustic-Trawl Survey Bering Sea- DY0606

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Scientists from the Alaska Fisheries Science Center’s (AFSC) Midwater Assessment and Conservation Engineering (MACE) Program conduct biennial echo...

  13. 75 FR 41123 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea Subarea

    Science.gov (United States)

    2010-07-15

    ... nonpelagic trawl fishing industry. Modified Nonpelagic Trawl Gear Nonpelagic trawl gear uses a pair of long lines called sweeps to herd fish into the net. These lines drag across the bottom and may adversely... flatfish species. In 2008 and 2009, the AFSC and NOAA Office for Law Enforcement worked with the fishing...

  14. Elevator wheel

    Energy Technology Data Exchange (ETDEWEB)

    Zhornik, V.I.; Cherkov, Ye.M.; Simonov, A.A.

    1982-01-01

    An elevator wheel is suggested for unloading a sunken product from a bath of a heavy-average separator including discs of a bucket with inner walls, and covering sheets hinged to the buckets. In order to improve the degree of dehydration of the removed product, the inner wall of each bucket is made of sheets installed in steps with gaps of one in relation to the other.

  15. 75 FR 31361 - Proposed Flood Elevation Determinations

    Science.gov (United States)

    2010-06-03

    ... source(s) elevation ground [caret] Elevation Communities affected in meters (MSL) Effective Modified... American Vertical Datum. Depth in feet above ground. [caret] Mean Sea Level, rounded to the nearest 0.1.... Stone County, Mississippi, and Incorporated Areas Church House Branch Approximately 0.5 mile None +211...

  16. Contaminant exposure and effects in pinnipeds: implications for Steller sea lion declines in Alaska.

    Science.gov (United States)

    Barron, Mace G; Heintz, Ron; Krahn, Margaret M

    2003-07-20

    After nearly 3 decades of decline, the western stock of Steller sea lions (SSL; Eumetopias jubatus) was listed as an endangered species in 1997. While the cause of the decline in the 1970s and 1980s has been attributed to nutritional stress, recent declines are unexplained and may result from other factors including the presence of environmental contaminants. SSL tissues show accumulation of butyltins, mercury, PCBs, DDTs, chlordanes and hexachlorobenzene. SSL habitats and prey are contaminated with additional chemicals including mirex, endrin, dieldrin, hexachlorocyclohexanes, tetrachlorodibenzo-p-dioxin (TCDD) and related compounds, cadmium and lead. In addition, many SSL haulouts and rookeries are located near other hazards including radioactivity, solvents, ordnance and chemical weapon dumps. PCB and DDT concentrations measured in a few SSL during the 1980s were the highest recorded for any Alaskan pinniped. Some contaminant exposures in SSL appear to be elevated in the Gulf of Alaska and Bering Sea compared to southeast Alaska, but there are insufficient data to evaluate geospatial relationships with any certainty. Based on very limited blubber data, current levels of PCBs may not pose a risk to SSL based on comparison to immunotoxicity tissue benchmarks, but SSL may have been at risk from pre-1990 PCB exposures. While exposure to PCBs and DDTs may be declining, SSL are likely exposed to a multitude of other contaminants that have not been monitored. The impacts of these exposures on SSL remain unknown because causal effects have not been established. Field studies with SSL have been limited in scope and have not yet linked contaminant exposures to adverse animal health or population effects. Several biomarkers may prove useful for monitoring exposure and additional research is needed to evaluate their utility in SSL. We conclude that there are insufficient data to reject the hypothesis that contaminants play a role in the continued decline of SSL, and suggest

  17. An elevator

    Energy Technology Data Exchange (ETDEWEB)

    Gusev, A.S.; Peshkov, L.P.; Rozin, M.M.; Shestov, A.G.

    1983-01-01

    An elevator is proposed which includes a body, a flap, a lock with a catch and a spring-loaded shut-off clamp in the form of upper and lower horizontal levers which are connected by a handle and an axle and one end of which is made in the form of an eccentric cam. The size of the eccentricity of the cam of the levers is increased toward the handle of the clamp in order to increase the operational reliability and to extend the service life.

  18. An elevator

    Energy Technology Data Exchange (ETDEWEB)

    Rastorguyev, M.A.; Maloyarovslavtesv, D.A.; Prokopov, O.I.; Tukayev, Sh.V.; Zanilov, I.F.

    1983-01-01

    An elevator is proposed which includes a body with a turning collar locking device and a rod with longitudinal grooves, which are flexibly linked with jaws positioned in grooves in the body. To increase safety through ensuring automatic locking of the jaws in the closed position, the locking device is made in the form of head on wedges, spring loaded relative to the collar and made with cams and positioned with the capability of interacting with the grooves of the rod and through the cams with the collar.

  19. Flow Patterns in the Eastern Chukchi Sea: 2010-2015

    Science.gov (United States)

    Stabeno, Phyllis; Kachel, Nancy; Ladd, Carol; Woodgate, Rebecca

    2018-02-01

    From 2010 to 2015, moorings were deployed on the northern Chukchi Sea at nine sites. Deployment duration varied from 5 years at a site off Icy Cape to 1 year at a site north of Hanna Shoal. In addition, 39 satellite-tracked drifters (drogue depth 25-30 m) were deployed in the region during 2012-2015. The goals of this manuscript are to describe currents in the Chukchi Sea and their relationship to ice and winds. The north-south pressure gradient results in, on average, a northward flow over the Chukchi shelf, which is modified by local winds. The volume transport near Icy Cape (˜0.4 Sv) was ˜40% of flow through Bering Strait and varied seasonally, accounting for >50% of summer and ˜20% of winter transport in Bering Strait. Current direction was strongly influenced by bathymetry, with northward flow through the Central Channel and eastward flow south of Hanna Shoal. The latter joined the coastal flow exiting the shelf via Barrow Canyon. Drifter trajectories indicated the transit from Bering Strait to the mouth of Barrow Canyon took ˜90 days during the ice-free season. Most (˜70%) of the drifters turned westward at the mouth of Barrow Canyon and continued westward in the Chukchi Slope Current. This slope flow was largely confined to the upper 300 m, and although it existed year-round, it was strongest in spring and summer. Drifter trajectories indicated that the Chukchi Slope Current extends as far west as the mouth of Herald Canyon. The remaining ˜30% of the drifters turned eastward or were intercepted by sea ice.

  20. Walrus areas of use in the Chukchi Sea during sparse sea ice cover

    Science.gov (United States)

    Jay, Chadwick V.; Fischbach, Anthony S.; Kochnev, Anatoly A.

    2012-01-01

    The Pacific walrus Odobenus rosmarus divergens feeds on benthic invertebrates on the continental shelf of the Chukchi and Bering Seas and rests on sea ice between foraging trips. With climate warming, ice-free periods in the Chukchi Sea have increased and are projected to increase further in frequency and duration. We radio-tracked walruses to estimate areas of walrus foraging and occupancy in the Chukchi Sea from June to November of 2008 to 2011, years when sea ice was sparse over the continental shelf in comparison to historical records. The earlier and more extensive sea ice retreat in June to September, and delayed freeze-up of sea ice in October to November, created conditions for walruses to arrive earlier and stay later in the Chukchi Sea than in the past. The lack of sea ice over the continental shelf from September to October caused walruses to forage in nearshore areas instead of offshore areas as in the past. Walruses did not frequent the deep waters of the Arctic Basin when sea ice retreated off the shelf. Walruses foraged in most areas they occupied, and areas of concentrated foraging generally corresponded to regions of high benthic biomass, such as in the northeastern (Hanna Shoal) and southwestern Chukchi Sea. A notable exception was the occurrence of concentrated foraging in a nearshore area of northwestern Alaska that is apparently depauperate in walrus prey. With increasing sea ice loss, it is likely that walruses will increase their use of coastal haul-outs and nearshore foraging areas, with consequences to the population that are yet to be understood.

  1. Bucket elevator

    OpenAIRE

    Chromek, Jiří

    2013-01-01

    Cílem této bakalářské práce je návrh svislého korečkového elevátoru, který má sloužit k dopravě obilovin s dopravní výškou 19 m a dopravovaným množstvím 100 t/hod. Práce se skládá z popisu korečkového elevátoru a jeho hlavních částí, zmiňující se v úvodní rešerši. Tato práce je zaměřena na funkční a kapacitní výpočet, určení pohonu a napínacího zařízení. Další výpočet je kontrolní, skládající se z pevnostní kontroly hnacího hřídele, výpočtu pera, životnosti ložisek a výpočtu napínacího zaříze...

  2. 20th-century glacial-marine sedimentation in Vitus Lake, Bering Glacier, Alaska, U.S.A.

    Science.gov (United States)

    Molnia, B.F.; Post, A.; Carlson, P.R.

    1996-01-01

    Vitus Lake, the ice-marginal basin at the southeastern edge of Bering Glacier, Alaska, U.S.A., is a site of modern, rapid, glacial-marine sedimentation. Rather than being a fresh-water lake, Vitus Lake is a tidally influenced, marine to brackish embayment connected to the Pacific Ocean by an inlet, the Seal River. Vitus Lake consists of five deep bedrock basins, separated by interbasinal highs. Glacial erosion has cut these basins as much as 250 m below sea level. High-resolution seismic reflection surveys conducted in 1991 and 1993 of four of Vitus Lake's basins reveal a complex, variable three-component acoustic stratigraphy. Although not fully sampled, the stratigraphy is inferred to be primarily glacial-marine units of (1) basal contorted and deformed glacial-marine and glacial sediments deposited by basal ice-contact processes and submarine mass-wasting; (2) acoustically well-stratified glacial-marine sediment, which unconformably overlies the basal unit and which grades upward into (3) acoustically transparent or nearly transparent glacial-marine sediment. Maximum thicknesses of conformable glacial-marine sediment exceed 100 m. All of the acoustically transparent and stratified deposits in Vitus Lake are modern in age, having accumulated between 1967 and 1993. The basins where these three-part sequences of "present-day" glacial-marine sediment are accumulating are themselves cut into older sequences of stratified glacial and glacial-marine deposits. These older units outcrop on the islands in Vitus Lake. In 1967, as the result of a major surge, glacier ice completely filled all five basins. Subsequent terminus retreat, which continued through August 1993, exposed these basins, providing new locations for glacial-marine sediment accumulation. A correlation of sediment thicknesses measured from seismic profiles at specific locations within the basins, with the year that each location became ice-free, shows that the sediment accumulation at some locations

  3. Pliocene palaeoceanography of the Arctic Ocean and subarctic seas.

    Science.gov (United States)

    Matthiessen, Jens; Knies, Jochen; Vogt, Christoph; Stein, Ruediger

    2009-01-13

    The Pliocene is important in the geological evolution of the high northern latitudes. It marks the transition from restricted local- to extensive regional-scale glaciations on the circum-Arctic continents between 3.6 and 2.4Ma. Since the Arctic Ocean is an almost land-locked basin, tectonic activity and sea-level fluctuations controlled the geometry of ocean gateways and continental drainage systems, and exerted a major influence on the formation of continental ice sheets, the distribution of river run-off, and the circulation and water mass characteristics in the Arctic Ocean. The effect of a water mass exchange restricted to the Bering and Fram Straits on the oceanography is unknown, but modelling experiments suggest that this must have influenced the Atlantic meridional overturning circulation. Cold conditions associated with perennial sea-ice cover might have prevailed in the central Arctic Ocean throughout the Pliocene, whereas colder periods alternated with warmer seasonally ice-free periods in the marginal areas. The most pronounced oceanographic change occurred in the Mid-Pliocene when the circulation through the Bering Strait reversed and low-salinity waters increasingly flowed from the North Pacific into the Arctic Ocean. The excess freshwater supply might have facilitated sea-ice formation and contributed to a decrease in the Atlantic overturning circulation.

  4. A Quantitative Proxy for Sea-Ice Based on Diatoms: A Cautionary Tale.

    Science.gov (United States)

    Nesterovich, A.; Caissie, B.

    2016-12-01

    Sea ice in the Polar Regions supports unique and productive ecosystems, but the current decline in the Arctic sea ice extent prompts questions about previous sea ice declines and the response of ice related ecosystems. Since satellite data only extend back to 1978, the study of sea ice before this time requires a proxy. Being one of the most productive, diatom-dominated regions in the world and having a wide range of sea ice concentrations, the Bering and Chukchi seas are a perfect place to find a relationship between the presence of sea ice and diatom community composition. The aim of this work is to develop a diatom-based proxy for the sea ice extent. A total of 473 species have been identified in 104 sediment samples, most of which were collected on board the US Coast Guard Cutter Healy ice breaker (2006, 2007) and the Norseman II (2008). The study also included some of the archived diatom smear slides made from sediments collected in 1969. The assemblages were compared to satellite-derived sea ice extent data averaged over the 10 years preceding the sampling. Previous studies in the Arctic and Antarctic regions demonstrated that the Generalized Additive Model (GAM) is one of the best choices for proxy construction. It has the advantage of using only several species instead of the whole assemblage, thus including only sea ice-associated species and minimizing the noise created by species responding to other environmental factors. Our GAM on three species (Connia compita, Fragilariopsis reginae-jahniae, and Neodenticula seminae) has low standard deviation, high level of explained variation, and holds under the ten-fold cross-validation; the standard residual analysis is acceptable. However, a spatial residual analysis revealed that the model consistently over predicts in the Chukchi Sea and under predicts in the Bering Sea. Including a spatial model into the GAM didn't improve the situation. This has led us to test other methods, including a non-parametric model

  5. Late Holocene sea ice conditions in Herald Canyon, Chukchi Sea

    Science.gov (United States)

    Pearce, C.; O'Regan, M.; Rattray, J. E.; Hutchinson, D. K.; Cronin, T. M.; Gemery, L.; Barrientos, N.; Coxall, H.; Smittenberg, R.; Semiletov, I. P.; Jakobsson, M.

    2017-12-01

    Sea ice in the Arctic Ocean has been in steady decline in recent decades and, based on satellite data, the retreat is most pronounced in the Chukchi and Beaufort seas. Historical observations suggest that the recent changes were unprecedented during the last 150 years, but for a longer time perspective, we rely on the geological record. For this study, we analyzed sediment samples from two piston cores from Herald Canyon in the Chukchi Sea, collected during the 2014 SWERUS-C3 Arctic Ocean Expedition. The Herald Canyon is a local depression across the Chukchi Shelf, and acts as one of the main pathways for Pacific Water to the Arctic Ocean after entering through the narrow and shallow Bering Strait. The study site lies at the modern-day seasonal sea ice minimum edge, and is thus an ideal location for the reconstruction of past sea ice variability. Both sediment cores contain late Holocene deposits characterized by high sediment accumulation rates (100-300 cm/kyr). Core 2-PC1 from the shallow canyon flank (57 m water depth) is 8 meter long and extends back to 4200 cal yrs BP, while the upper 3 meters of Core 4-PC1 from the central canyon (120 mwd) cover the last 3000 years. The chronologies of the cores are based on radiocarbon dates and the 3.6 ka Aniakchak CFE II tephra, which is used as an absolute age marker to calculate the marine radiocarbon reservoir age. Analysis of biomarkers for sea ice and surface water productivity indicate stable sea ice conditions throughout the entire late Holocene, ending with an abrupt increase of phytoplankton sterols in the very top of both sediment sequences. The shift is accompanied by a sudden increase in coarse sediments (> 125 µm) and a minor change in δ13Corg. We interpret this transition in the top sediments as a community turnover in primary producers from sea ice to open water biota. Most importantly, our results indicate that the ongoing rapid ice retreat in the Chukchi Sea of recent decades was unprecedented during the

  6. Arctic sea ice a major determinant in Mandt's black guillemot movement and distribution during non-breeding season

    Science.gov (United States)

    Divoky, G.J.; Douglas, David C.; Stenhouse, I. J.

    2016-01-01

    Mandt's black guillemot (Cepphus grylle mandtii) is one of the few seabirds associated in all seasons with Arctic sea ice, a habitat that is changing rapidly. Recent decreases in summer ice have reduced breeding success and colony size of this species in Arctic Alaska. Little is known about the species' movements and distribution during the nine month non-breeding period (September–May), when changes in sea ice extent and composition are also occurring and predicted to continue. To examine bird movements and the seasonal role of sea ice to non-breeding Mandt's black guillemots, we deployed and recovered (n = 45) geolocators on individuals at a breeding colony in Arctic Alaska during 2011–2015. Black guillemots moved north to the marginal ice zone (MIZ) in the Beaufort and Chukchi seas immediately after breeding, moved south to the Bering Sea during freeze-up in December, and wintered in the Bering Sea January–April. Most birds occupied the MIZ in regions averaging 30–60% sea ice concentration, with little seasonal variation. Birds regularly roosted on ice in all seasons averaging 5 h d−1, primarily at night. By using the MIZ, with its roosting opportunities and associated prey, black guillemots can remain in the Arctic during winter when littoral waters are completely covered by ice.

  7. Environmental variability facilitates coexistence within an alcid community at sea

    Science.gov (United States)

    Haney, J. Christopher; Schauer, Amy E.S.

    1994-01-01

    We examined coexistence at sea among 7 taxa of diving, wing-propelled seabirds (Alcidae) in the genera Aethia, Uria, Cepphus, and Fratercula. Species abundances were measured simultaneously with a suite of environmental factors in the northern Bering Sea, Alaska, USA; data from 260 adjacent and non-adjacent sites occupied by alcids foraging offshore near breeding colonies were then subjected to principal component analysis (PCA). We used PCA to group redundant environmental descriptors, to identify orthogonal axes for constructing a multi-dimensional niche, and to differentiate species associations within niche dimensions from species associations among niche dimensions. Decomposition of the correlation matrix for 22 environmental and 7 taxonomic variables with PCA gave 14 components (10 environmental and 4 species interactions) that retained 90% of the original available variance. Alcid abundances (all species) were most strongly correlated with axes representing tidal stage, a time-area interaction (due to sampling layout), water masses, and a temporal or intra-seasonal trend partially associated with weather changes. Axes representing tidal stage, 2 gradients in macro-habitat (Anadyr and Bering Shelf Water masses), the micro-habitat of the sea surface, and an air-sea interaction were most important for detecting differences among species within niche dimensions. Contrary to assumptions of competition, none of 4 compound variables describing primarily species-interactions gave strong evidence for negative associations between alcid taxa sharing similar body sizes and feeding requirements. This exploratory analysis supports the view that alcids may segregate along environmental gradients at sea. But in this community, segregation was unrelated to foraging distance from colonies, in part because foraging 'substrate' was highly variable in structure, location, and area1 extent. We contend that coexistence within this seabird group is facilitated via expanded niche

  8. Building resilience through interlocal relations: case studies of polar bear and walrus management in the Bering Strait

    Science.gov (United States)

    Chanda L. Meek; Amy Lauren Lovecraft; Martin D. Robards; Gary P. Kofinas

    2008-01-01

    Arctic coastal communities in the Bering Strait region of Alaska (USA) and Chukotka (Russia) share a close relationship with their natural environments that can be characterized as a social-ecological system. This system is complex, featuring changing ecosystem conditions, multiple jurisdictions, migratory animal populations, and several cultures. We argue that...

  9. National Elevation Dataset (NED)

    Data.gov (United States)

    Kansas Data Access and Support Center — The U.S. Geological Survey has developed a National Elevation Database (NED). The NED is a seamless mosaic of best-available elevation data. The 7.5-minute elevation...

  10. Elevated Liver Enzymes

    Science.gov (United States)

    Symptoms Elevated liver enzymes By Mayo Clinic Staff Elevated liver enzymes may indicate inflammation or damage to cells in the liver. Inflamed or ... than normal amounts of certain chemicals, including liver enzymes, into the bloodstream, which can result in elevated ...

  11. The climatic change and the coastal areas. The sea level rise: risks and answers; Le changement climatique et les espaces cotiers. L'elevation du niveau de la mer: risques et reponses

    Energy Technology Data Exchange (ETDEWEB)

    Paskoff, R

    2000-07-01

    This colloquium aimed to analyze the ecological, economic and human effects of the earth warming on coastal regions and more particularly the deltas. It also aimed aware the experts, the socio-economic and political actors of these regions on the consequences of the unavoidable sea level rise and on the measures that people can implemented to limit its effects. (A.L.B.)

  12. The climatic change and the coastal areas. The sea level rise: risks and answers; Le changement climatique et les espaces cotiers. L'elevation du niveau de la mer: risques et reponses

    Energy Technology Data Exchange (ETDEWEB)

    Paskoff, R

    2000-07-01

    This colloquium aimed to analyze the ecological, economic and human effects of the earth warming on coastal regions and more particularly the deltas. It also aimed aware the experts, the socio-economic and political actors of these regions on the consequences of the unavoidable sea level rise and on the measures that people can implemented to limit its effects. (A.L.B.)

  13. Physical, biological and optical oceanographic data collected from moored buoys in the Bering Strait from 08/16/2004 to 09/03/2007 (NODC Accession 0045300)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Physical, current meter, biological, and optical oceanographic data were collected in the Bering Strait from August 16, 2004 to September 3, 2007. These data were...

  14. Arctic Sea Ice: Using Airborne Topographic Mapper Measurements (ATM) to Determine Sea Ice Thickness

    Science.gov (United States)

    2011-05-10

    Track Distance (Km) E le v a ti o n ( m ) ATM Elevation Profile Elevation 18 Figure 13: Geoid shape of earth’s equipotential surface , which is...inferred for the region between successive leads. Therefore, flying over a lead in the ice is very important for determining the exact sea surface elevation...inferred for the region between successive leads. Therefore, flying over a lead in the ice is very important for determining the exact sea surface

  15. The Sea Ice for Walrus Outlook: A collaboration between scientific and Indigenous communities to support safety and food security in a changing Arctic

    Science.gov (United States)

    Sheffield Guy, L.; Wiggins, H. V.; Schreck, M. B.; Metcalf, V. K.

    2017-12-01

    The Sea Ice for Walrus Outlook (SIWO) provides Alaskan Native subsistence walrus hunters and Bering Strait coastal communities with weekly reports on spring sea ice and weather conditions to promote hunter safety, food security, and preservation of cultural heritage. These reports integrate scientific and Indigenous knowledge into a co-produced tool that is used by both local and scientific communities. SIWO is a team effort led by the Arctic Research Consortium of the U.S. (ARCUS, with funding from NSF Arctic Sciences Section), with the Eskimo Walrus Commission, National Weather Service - Alaska Sea Ice Program, University of Alaska Fairbanks - International Arctic Research Center, and local observers. For each weekly outlook, the National Weather Service provides location-specific weather and sea ice forecasts and regional satellite imagery. Local observations of sea ice, weather, and hunting conditions are provided by observers from five Alaskan communities in the Bering Strait region: Wales, Shishmaref, Nome, Gambell, and Savoonga. These observations typically include a written description of conditions accompanied by photographs of sea ice or subsistence activities. Outlooks are easily accessible and provide a platform for sharing of knowledge among hunters in neighboring communities. The opportunity to contribute is open, and Indigenous language and terms are encouraged. These observations from local hunters and community members also provide a valuable tool for validation of weather forecasts, satellite products, and other information for scientists. This presentation will discuss the process, products, and mutually beneficial outcomes of the Sea Ice for Walrus Outlook.

  16. Decadal shifts in autumn migration timing by Pacific Arctic beluga whales are related to delayed annual sea ice formation.

    Science.gov (United States)

    Hauser, Donna D W; Laidre, Kristin L; Stafford, Kathleen M; Stern, Harry L; Suydam, Robert S; Richard, Pierre R

    2017-06-01

    Migrations are often influenced by seasonal environmental gradients that are increasingly being altered by climate change. The consequences of rapid changes in Arctic sea ice have the potential to affect migrations of a number of marine species whose timing is temporally matched to seasonal sea ice cover. This topic has not been investigated for Pacific Arctic beluga whales (Delphinapterus leucas) that follow matrilineally maintained autumn migrations in the waters around Alaska and Russia. For the sympatric Eastern Chukchi Sea ('Chukchi') and Eastern Beaufort Sea ('Beaufort') beluga populations, we examined changes in autumn migration timing as related to delayed regional sea ice freeze-up since the 1990s, using two independent data sources (satellite telemetry data and passive acoustics) for both populations. We compared dates of migration between 'early' (1993-2002) and 'late' (2004-2012) tagging periods. During the late tagging period, Chukchi belugas had significantly delayed migrations (by 2 to >4 weeks, depending on location) from the Beaufort and Chukchi seas. Spatial analyses also revealed that departure from Beaufort Sea foraging regions by Chukchi whales was postponed in the late period. Chukchi beluga autumn migration timing occurred significantly later as regional sea ice freeze-up timing became later in the Beaufort, Chukchi, and Bering seas. In contrast, Beaufort belugas did not shift migration timing between periods, nor was migration timing related to freeze-up timing, other than for southward migration at the Bering Strait. Passive acoustic data from 2008 to 2014 provided independent and supplementary support for delayed migration from the Beaufort Sea (4 day yr -1 ) by Chukchi belugas. Here, we report the first phenological study examining beluga whale migrations within the context of their rapidly transforming Pacific Arctic ecosystem, suggesting flexible responses that may enable their persistence yet also complicate predictions of how

  17. Passive seismic monitoring of the Bering Glacier during its last surge event

    Science.gov (United States)

    Zhan, Z.

    2017-12-01

    The physical causes behind glacier surges are still unclear. Numerous evidences suggest that they probably involve changes in glacier basal conditions, such as switch of basal water system from concentrated large tunnels to a distributed "layer" as "connected cavities". However, most remote sensing approaches can not penetrate to the base to monitor such changes continuously. Here we apply seismic interferometry using ambient noise to monitor glacier seismic structures, especially to detect possible signatures of the hypothesized high-pressure water "layer". As an example, we derive an 11-year long history of seismic structure of the Bering Glacier, Alaska, covering its latest surge event. We observe substantial drops of Rayleigh and Love wavespeeds across the glacier during the surge event, potentially caused by changes in crevasse density, glacier thickness, and basal conditions.

  18. Collaborations for Arctic Sea Ice Information and Tools

    Science.gov (United States)

    Sheffield Guy, L.; Wiggins, H. V.; Turner-Bogren, E. J.; Rich, R. H.

    2017-12-01

    The dramatic and rapid changes in Arctic sea ice require collaboration across boundaries, including between disciplines, sectors, institutions, and between scientists and decision-makers. This poster will highlight several projects that provide knowledge to advance the development and use of sea ice knowledge. Sea Ice for Walrus Outlook (SIWO: https://www.arcus.org/search-program/siwo) - SIWO is a resource for Alaskan Native subsistence hunters and other interested stakeholders. SIWO provides weekly reports, during April-June, of sea ice conditions relevant to walrus in the northern Bering and southern Chukchi seas. Collaboration among scientists, Alaskan Native sea-ice experts, and the Eskimo Walrus Commission is fundamental to this project's success. Sea Ice Prediction Network (SIPN: https://www.arcus.org/sipn) - A collaborative, multi-agency-funded project focused on seasonal Arctic sea ice predictions. The goals of SIPN include: coordinate and evaluate Arctic sea ice predictions; integrate, assess, and guide observations; synthesize predictions and observations; and disseminate predictions and engage key stakeholders. The Sea Ice Outlook—a key activity of SIPN—is an open process to share and synthesize predictions of the September minimum Arctic sea ice extent and other variables. Other SIPN activities include workshops, webinars, and communications across the network. Directory of Sea Ice Experts (https://www.arcus.org/researchers) - ARCUS has undertaken a pilot project to develop a web-based directory of sea ice experts across institutions, countries, and sectors. The goal of the project is to catalyze networking between individual investigators, institutions, funding agencies, and other stakeholders interested in Arctic sea ice. Study of Environmental Arctic Change (SEARCH: https://www.arcus.org/search-program) - SEARCH is a collaborative program that advances research, synthesizes research findings, and broadly communicates the results to support

  19. Role of the Bering Strait on the hysteresis of the ocean conveyor belt circulation and glacial climate stability.

    Science.gov (United States)

    Hu, Aixue; Meehl, Gerald A; Han, Weiqing; Timmermann, Axel; Otto-Bliesner, Bette; Liu, Zhengyu; Washington, Warren M; Large, William; Abe-Ouchi, Ayako; Kimoto, Masahide; Lambeck, Kurt; Wu, Bingyi

    2012-04-24

    Abrupt climate transitions, known as Dansgaard-Oeschger and Heinrich events, occurred frequently during the last glacial period, specifically from 80-11 thousand years before present, but were nearly absent during interglacial periods and the early stages of glacial periods, when major ice-sheets were still forming. Here we show, with a fully coupled state-of-the-art climate model, that closing the Bering Strait and preventing its throughflow between the Pacific and Arctic Oceans during the glacial period can lead to the emergence of stronger hysteresis behavior of the ocean conveyor belt circulation to create conditions that are conducive to triggering abrupt climate transitions. Hence, it is argued that even for greenhouse warming, abrupt climate transitions similar to those in the last glacial time are unlikely to occur as the Bering Strait remains open.

  20. Role of the Bering Strait on the hysteresis of the ocean conveyor belt circulation and glacial climate stability

    OpenAIRE

    Hu, Aixue; Meehl, Gerald A.; Han, Weiqing; Timmermann, Axel; Otto-Bliesner, Bette; Liu, Zhengyu; Washington, Warren M.; Large, William; Abe-Ouchi, Ayako; Kimoto, Masahide; Lambeck, Kurt; Wu, Bingyi

    2012-01-01

    Abrupt climate transitions, known as Dansgaard-Oeschger and Heinrich events, occurred frequently during the last glacial period, specifically from 80–11 thousand years before present, but were nearly absent during interglacial periods and the early stages of glacial periods, when major ice-sheets were still forming. Here we show, with a fully coupled state-of-the-art climate model, that closing the Bering Strait and preventing its throughflow between the Pacific and Arctic Oceans during the g...

  1. Iowa Bedrock Surface Elevation

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This Digital Elevation Model (DEM) of the bedrock surface elevation in Iowa was compiled using all available data, principally information from GEOSAM, supplemented...

  2. Coastal Sea Levels, Impacts, and Adaptation

    Directory of Open Access Journals (Sweden)

    Thomas Wahl

    2018-02-01

    Full Text Available Sea-level rise (SLR poses a great threat to approximately 10% of the world’s population residing in low-elevation coastal zones (i.e., land located up to 10 m of present-day mean sea-level (MSL[...

  3. Thin Ice Area Extraction in the Seasonal Sea Ice Zones of the Northern Hemisphere Using Modis Data

    Science.gov (United States)

    Hayashi, K.; Naoki, K.; Cho, K.

    2018-04-01

    Sea ice has an important role of reflecting the solar radiation back into space. However, once the sea ice area melts, the area starts to absorb the solar radiation which accelerates the global warming. This means that the trend of global warming is likely to be enhanced in sea ice areas. In this study, the authors have developed a method to extract thin ice area using reflectance data of MODIS onboard Terra and Aqua satellites of NASA. The reflectance of thin sea ice in the visible region is rather low. Moreover, since the surface of thin sea ice is likely to be wet, the reflectance of thin sea ice in the near infrared region is much lower than that of visible region. Considering these characteristics, the authors have developed a method to extract thin sea ice areas by using the reflectance data of MODIS (NASA MYD09 product, 2017) derived from MODIS L1B. By using the scatter plots of the reflectance of Band 1 (620 nm-670 nm) and Band 2 (841 nm-876 nm)) of MODIS, equations for extracting thin ice area were derived. By using those equations, most of the thin ice areas which could be recognized from MODIS images were well extracted in the seasonal sea ice zones in the Northern Hemisphere, namely the Sea of Okhotsk, the Bering Sea and the Gulf of Saint Lawrence. For some limited areas, Landsat-8 OLI images were also used for validation.

  4. Sea Dragon

    National Research Council Canada - National Science Library

    1997-01-01

    .... In preparation for these changes, the Navy is exploring new command and control relationships, and the Marine Corps established Sea Dragon to experiment with emerging technologies, operational...

  5. 75 FR 48298 - Groundfish Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea/Aleutian Islands Crab...

    Science.gov (United States)

    2010-08-10

    ... exclusion memorandum may be obtained from the Alaska Region website at http://alaskafisheries.noaa.gov... 680-SHELLFISH FISHERIES OF THE EXCLUSIVE ECONOMIC ZONE OFF ALASKA 1. The authority citation for part...

  6. 75 FR 76372 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; Proposed...

    Science.gov (United States)

    2010-12-08

    ... meeting, the Council's groundfish Plan Teams recommended the formation of a total catch accounting working.../ processor sector endorsements, unless the Regional Administrator receives a cooperative contract that... cooperatives and open access sector. These allocations are based on the submission of AFA inshore cooperative...

  7. Mapping human interaction with the Bering Sea ecosystem: Comparing seasonal use areas, lifetime use areas, and "calorie-sheds"

    Science.gov (United States)

    Huntington, Henry P.; Ortiz, Ivonne; Noongwook, George; Fidel, Maryann; Childers, Dorothy; Morse, Muriel; Beaty, Julia; Alessa, Lilian; Kliskey, Andrew

    2013-10-01

    Alaska Native coastal communities interact with the marine environment in many ways, especially through the harvest of fish, marine mammals, and seabirds. The spatial characteristics of this interaction are often depicted in terms of subsistence use areas: the places where harvests and associated travel occur. Another way to consider the interaction is to examine the areas where harvested species range during their lifecycle or annual migratory path. In this paper, we compare seasonal subsistence use areas, lifetime subsistence use areas, and "calorie-sheds," or the area over which harvested species range. Each perspective offers useful information concerning not only the nature of human-environment interactions but also the scope for potential conflict with other human activity and the means by which such conflicts could be reduced, avoided, or otherwise addressed. Seasonal subsistence use areas can be used to manage short-term activities, such as seasonal vessel traffic during community re-supply. Lifetime subsistence use areas indicate the area required to allow hunters and fishers the flexibility to adjust to interannual variability and perhaps to adapt to a changing environment. Calorie-sheds indicate the areas about which a community may be concerned due to potential impacts on the species they harvest.

  8. 75 FR 38454 - Fisheries of the Exclusive Economic Zone Off Alaska; Skates Management in the Bering Sea and...

    Science.gov (United States)

    2010-07-02

    ... overfishing and minimize adverse economic impacts to fishing communities, to the extent practicable... requirements regarding ACLs and AMs, which reinforce existing requirements to prevent overfishing and rebuild... existing provisions related to overfishing, rebuilding overfished stocks, and achieving optimum yield...

  9. 76 FR 47493 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands King and...

    Science.gov (United States)

    2011-08-05

    ... overfishing limit and prevent overfishing. Amendment 39 modifies the snow crab rebuilding plan to define the..., the ABC control rule will be used to set the maximum ABC for each crab stock below the overfishing... overfishing is less than 50 percent. Amendment 38 establishes accountability measures to comply with the...

  10. 78 FR 17341 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2013-03-21

    ... Purchased. contracting custom processing must report. Raw pounds by crab fishery. Product and processes by... purchased (raw Purchased. pounds) by crab fishery. Custom processing services purchased (product and process... greatest information value to the management decision making process. The EDR is required to be submitted...

  11. 78 FR 59908 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Science.gov (United States)

    2013-09-30

    ... Area; Amendment 99 AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric... comments. SUMMARY: The North Pacific Fishery Management Council submitted Amendment 99 to the Fishery... review. If approved, Amendment 99 would enable the holders of license limitation program (LLP) licenses...

  12. 77 FR 20339 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Science.gov (United States)

    2012-04-04

    ... intended to facilitate an increase in the processing capabilities of the fleet to improve the retention and... non- AFA trawl C/P subsector set forth in section 219(a)(7) of the BSAI Catcher Processor Capacity... PSC sideboard limit by the number of seasons, and into two species complexes: the shallow-water and...

  13. MGL111 Chirp - US Extended Continental Shelf Project: Bering Sea CHIRP high-resolution Seismic Profile data.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Knudsen 2620 acquired sub-bottom profiles continuously throughout the cruise. The Knudsen was operated in 3.5 kHz Chirp mode, emitting a 1.5 kHz to 5 kHz (3 kHz...

  14. Bottom Sediment Granulometric Data for the Continental Margins of the Bering, Chukchi, East Siberia, Laptev, and Beaufort Seas

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are part of Roberts, Richard W., University of Washington, Department of Oceanography Special Report No. 70, Bottom Sediment Granulometric Data for the...

  15. 76 FR 25295 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands King and...

    Science.gov (United States)

    2011-05-04

    ... following methods: Electronic Submissions: Submit all electronic public comments via the Federal eRulemaking... of the Magnuson-Stevens Act, as amended in 2007, establish, either expressly or by logical extension... sustainable yield. Tier 4 stocks have a stock assessment model that estimates biomass using the historical...

  16. 75 FR 56485 - Groundfish Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea/Aleutian Islands Crab...

    Science.gov (United States)

    2010-09-16

    .../Aleutian Islands Crab Rationalization Program; Recordkeeping and Reporting AGENCY: National Marine... rule. SUMMARY: NMFS issues regulations to remove the Crab Rationalization Program requirements for.... Background The Crab Rationalization (CR) Program is a limited-access system that allocates crab managed under...

  17. 76 FR 11139 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; Final 2011...

    Science.gov (United States)

    2011-03-01

    .... Based on 2010 survey data, Tanner crab (Chionoecetes bairdi) abundance is estimated at 379 million... was derived using 2010 survey data and an age-structured biomass projection model developed by the...

  18. 77 FR 10669 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; Final 2012...

    Science.gov (United States)

    2012-02-23

    ... developing an age-structured model for the Aleutian Islands Pacific cod stock assessment that will be.... This is due to model changes for the calculation of octopuses OFL and ABC, and recommendations by the... the Council's recommendation. Based on 2011 survey data, Tanner crab (Chionoecetes bairdi) abundance...

  19. AFSC/RACE/EcoFOCI: 2011 Fall Bering Sea Mooring Cruise DY11-04/3DY11

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Our scheduled departure time was delayed due to a combination of weather and shipb??s equipment problems (navigation light, engine). The weather slowed our transit...

  20. Northern fur seal foraging behavior and prey fields in the Bering Sea, Alaska during July-October 2006

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data were used by Kuhn et al. (2015) to investigate how conclusions about predator-prey relationships change with increasing temporal disparity between...

  1. 78 FR 14932 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Pollock in the Bering Sea...

    Science.gov (United States)

    2013-03-08

    ... most recent fisheries data in a timely fashion and would delay the reallocation of AI pollock. Since the pollock fishery is currently open, it is important to immediately inform the industry as to the... orderly conduct and efficient operation of this fishery; allow the industry to plan for the fishing season...

  2. 77 FR 13253 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Science.gov (United States)

    2012-03-06

    ... Fisheries Division, Alaska Region NMFS, Attn: Ellen Sebastian. Mail comments to P.O. Box 21668, Juneau, AK... comments to 709 West 9th Street, Room 420A, Juneau, AK. Instructions: Comments must be submitted by one of... certificate of documentation consistent with 46 U.S.C. 12113 and MARAD regulations at 46 CFR 356.47. Under...

  3. 76 FR 81873 - Fisheries of the Exclusive Economic Zone Off Alaska; Inseason Adjustment to the 2012 Bering Sea...

    Science.gov (United States)

    2011-12-29

    ... NMFS, Attn: Ellen Sebastian. Mail comments to P.O. Box 21668, Juneau, AK 99802-1668. Fax: Address... 420A, Juneau, AK. Instructions: Comments must be submitted by one of the above methods to ensure that... more than 47% of ABC, and Atka mackerel harvests for Amendment 80 cooperatives and CDQ groups within...

  4. 76 FR 1539 - Fisheries of the Exclusive Economic Zone Off Alaska; Inseason Adjustment to the 2011 Bering Sea...

    Science.gov (United States)

    2011-01-11

    ....gov . Mail: P.O. Box 21668, Juneau, AK 99802. Fax: (907) 586-7557. Hand delivery to the Federal Building: 709 West 9th Street, Room 420A, Juneau, AK. All comments received are a part of the public record... 679.20(a)(8)(ii)(C) requires the TAC in area 542 shall be no more than 47% of ABC, and Amendment 80...

  5. 78 FR 63951 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Management...

    Science.gov (United States)

    2013-10-25

    ... Sebastian. Mail comments to P.O. Box 21668, Juneau, AK 99802-1668. Fax: Address written comments to Glenn....47(a) and (c). These vessels are able to participate in the fishery because they received a fishery... management measures in accordance with regulations implementing the AFA at 46 CFR 356.47, to allow vessels...

  6. Multi-Decadal Variability in the Bering Sea: A Synthesis of Model Results and Observations from 1948 to the Present

    Science.gov (United States)

    2013-12-01

    stated that the development and use of high-resolution Arctic climate and systems models are important stepping stones for dedicated studies of...W., J. L. Clement Kinney, D. C. Marble , and J. Jakacki, 2008: Towards eddy resolving models of the Arctic Ocean: Ocean Modeling in an Eddying

  7. 50 CFR 600.1104 - Bering Sea and Aleutian Islands (BSAI) crab species fee payment and collection system.

    Science.gov (United States)

    2010-10-01

    ... endorsement for Norton Sound red king. More specifically, the reduction endorsement fisheries, and the crab... COMMERCE MAGNUSON-STEVENS ACT PROVISIONS Specific Fishery or Program Fishing Capacity Reduction Regulations....1012 of subpart L, establish: (i) The borrower's obligation to repay a reduction loan, and (ii) The...

  8. 77 FR 72791 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; 2013 and...

    Science.gov (United States)

    2012-12-06

    .../processors within the action area, and entities receiving direct allocations of groundfish. Catcher vessels... following methods: Electronic Submission: Submit all electronic public comments via the Federal e-Rulemaking... 420A, Juneau, AK. Instructions: Comments must be submitted by one of the above methods to ensure that...

  9. 76 FR 49423 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2011-08-10

    ... market information used to conduct arbitration proceedings. This action is intended to promote the goals and objectives of the Magnuson-Stevens Fishery Conservation and Management Act, the FMP, and other... Conservation and Management Act. Amendments 18 and 19 to the FMP implemented the CR Program. Regulations...

  10. 76 FR 68358 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2011-11-04

    ... action is necessary to improve the quality and timeliness of market information used to conduct... Fishery Conservation and Management Act, the FMP, and other applicable law. DATES: Effective December 5... Fishery Management Council (Council) under the Magnuson-Stevens Fishery Conservation and Management Act...

  11. 75 FR 54792 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Pollock in the Bering Sea...

    Science.gov (United States)

    2010-09-09

    ... applicable BSAI sectors and, (2) the harvest capacity and stated intent on future harvesting patterns of... (ii), the annual AI pollock TAC, after subtracting first for the CDQ directed fishing allowance--10.... In the AI subarea, the A season is allocated 40 percent of the ABC and the B season is allocated the...

  12. 75 FR 11778 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; Final 2010...

    Science.gov (United States)

    2010-03-12

    ... near future. For 2011, the model produces an ABC 15,000 mt higher than the proposed ABC. The SSC...,110,000 815,000 295,000 AI 19,000 19,000 0 19,000 19,000 0 Bogoslof 50 10 40 50 10 40 Pacific cod BSAI 168,780 193,030 -24,250 207,580 193,030 14,550 Sablefish BS 2,790 2,520 270 2,500 2,520 -20 AI 2,070 2...

  13. 78 FR 74063 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; 2014 and...

    Science.gov (United States)

    2013-12-10

    ... Analysis (IRFA) prepared for this action may be obtained from http://www.regulations.gov or from the Alaska... degrees west longitude in the BS subarea equal to 3 percent of the Pacific cod ABC in the BSAI. The action... TAC because the combined TAC and GHL (252,381 mt) are less than the proposed ABC of 300,390 mt. For...

  14. NPRB 1319 Assessment of the benthic impacts of raised groundgear for the Eastern Bering Sea pollock fishery.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Alaska pollock fishing industry, in collaboration with scientists at Alaska Pacific University, the Alaska Fisheries Science Center, and members of the fishing...

  15. 76 FR 40628 - Groundfish Fisheries of the EEZ Off Alaska; Pacific Halibut Fisheries; CDQ Program; Bering Sea...

    Science.gov (United States)

    2011-07-11

    ... additives 30 Whole fish/ or shellfish/food fish 01 Wings. On skates, side fins are cut off next to body... landing report number and an ADF&G electronic fish ticket number upon completion of data entry... fish from the landing site. * * * * * (8) * * * (iii) * * * (B) Operation type and port code--(1) If a...

  16. 50 CFR 600.1105 - Longline catcher processor subsector of the Bering Sea and Aleutian Islands (BSAI) non-pollock...

    Science.gov (United States)

    2010-10-01

    .... (b) Definitions. Unless otherwise defined in this section, the terms defined in § 600.1000 of subpart... will examine applications for completeness and inconsistencies, whether on the face of the documents or... Subsector Member shall not affect the validity of the Reduction Agreement with respect to any other...

  17. AFSC/NMML: Marine Mammal Aerial Surveys in the Bering, Chukchi and Beaufort Seas . 1979-2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Bureau of Ocean Energy Management (BOEM), formerly the Minerals Management Service (MMS), and its precursor, the Bureau of Land Management, have funded aerial...

  18. 78 FR 15677 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2013-03-12

    ... accessible. Do not submit confidential business information or otherwise sensitive or protected information... activities for that fishing season. The Council and NMFS use the EDR to assess the success of the CR Program... be added. Reporting of labor data (i.e., man-hours, total processing labor payments, and crab...

  19. 78 FR 42970 - Notice of Intent To Prepare a Resource Management Plan for the Bering Sea-Western Interior...

    Science.gov (United States)

    2013-07-18

    ... integrated into the entire planning process, from preparing the pre-plan to implementation and monitoring; 17... allocations for these lands. Considering wilderness characteristics in the land use planning process may... impacts on Indian trust assets and potential impacts to cultural resources, will be given due...

  20. 78 FR 6279 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2013-01-30

    ... conditions could potentially be at a disadvantage when negotiating terms of the exemption. Once the parties... Department of Fish and Game for five of the six CR Program fisheries subject to this proposed rule. NMFS..., and understand English; the ability to use a personal computer and the Internet; and the authority to...

  1. AFSC/NMML Location-only satellite telemetry data for North Pacific Humpback Whales in the Bering Sea, 2007 - 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains ARGOS location data (latitude and longitude in decimal format) and associated time (date and time) and location quality (as defined by Argos...

  2. 77 FR 14994 - Fisheries of the Exclusive Economic Zone Off Alaska; Reallocation of Pollock in the Bering Sea...

    Science.gov (United States)

    2012-03-14

    ... error on page 12215 in row 16 of the third column. The 2012 A season directed fishing allowance for the... \\1\\ 2013 B season \\1\\ season \\1\\ Area and sector 2012 2013 Allocations A season SCA harvest B season... allocated as a DFA as follows: inshore sector--50 percent, catcher/processor sector (C/P)--40 percent, and...

  3. AFSC/NMML: North Pacific right whale aerial surveys in the southeastern Bering Sea, 2008-2009.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — As part of an inter-agency agreement between the National Marine Mammal Laboratory and the Bureau of Ocean Energy Management, aerial surveys of the North Aleutian...

  4. 76 FR 8700 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands Crab...

    Science.gov (United States)

    2011-02-15

    ... application for an annual exemption would require a decision-making process that would be subject to...-designated IPQ. However, processing capacity may not be available each season. Amendment 37 is necessary to....gov without change. All Personal Identifying Information (for example, name, address, etc...

  5. AFSC/RACE/SAP/Pathobiology: 2016 Bitter crab disease prevalence in Chionoecetes spp. from eastern Bering Sea upper continental slope

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset contains crab data from a field survey of Chionoecetes spp. collected during the 2016 NOAA/NMFS/AFSC/RACE groundfish and invertebrate resources bottom...

  6. 75 FR 19561 - Fisheries of the Economic Exclusive Zone Off Alaska; Pacific Cod in the Bering Sea and Aleutian...

    Science.gov (United States)

    2010-04-15

    ... is opening directed fishing for Pacific cod by catcher vessels less than 60 feet (18.3 meters) length... meters) length overall using hook-and-line or pot gear in the BSAI under Sec. 679.20(d)(1)(iii) on March... 400 metric tons of Pacific cod remain in the 2010 Pacific cod apportionment for catcher vessels less...

  7. 78 FR 13813 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; 2013 and...

    Science.gov (United States)

    2013-03-01

    ..., sculpins, sharks, squids, and octopuses. \\5\\ In December 2012 the Council recommended that the red king... decreased because of smaller OFLs and ABCs resulting from lower biomass estimates. The TACS for octopuses... Squids BSAI 2,620 1,970 700 595 0 2,620 1,970 700 595 0 Octopuses BSAI 3,450 2,590 500 425 0 3,450 2,590...

  8. 75 FR 5541 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; Final 2009...

    Science.gov (United States)

    2010-02-03

    ...\\ BSAI trawl limited access fisheries Red king crab C. opilio C. bairdi (animals) Halibut mortality (mt..., skates, and octopus. Classification This action is authorized under 50 CFR 679.20 and is exempt from...

  9. Climatic Atlas of the Outer Continental Shelf Waters and Coastal Regions of Alaska. Volume 2. Bering Sea. Revision

    Science.gov (United States)

    1988-01-01

    Joe D. Elms , for their editorial evaluation of the vironmental Assessmant Program. Additional depends to a large extent on weather condi- isopleth...waves, icing rates are open waters and coastal sectionsofAlaska.The temperatures less than 8°C, winds of 25 knots lower. icing causes slippery decks...thereby bias the oceanic climatology towards fair weather. A recent study by Elms (1986), in which he compared the Volunteer Observing Ship (VOS) data

  10. 76 FR 17034 - Fisheries of the Exclusive Economic Zone Off Alaska; Bering Sea and Aleutian Islands; Final 2011...

    Science.gov (United States)

    2011-03-28

    ... Islands Management Area (BSAI). Two tables within the document contained errors. DATES: Effective from... listed an incidental catch allowance (ICA) of rock sole at ``10,000'' metric tons (mt), instead of the... Federal Register listed the phrase ``ICA rock sole'' in the ``sector'' column rather than the ``species...

  11. 75 FR 21600 - Groundfish Fisheries of the Bering Sea and Aleutian Islands Area and the Gulf of Alaska; King and...

    Science.gov (United States)

    2010-04-26

    ... Essential Fish Habitat (EFH) pursuant to the Magnuson-Stevens Fishery Conservation and Management Act.... ACTION: Notification of a call for proposals for Habitat Areas of Particular Concern (HAPCs) and... specific types or areas of habitat within EFH as HAPCs based on the following considerations: (1) the...

  12. Demersal and larval fish assemblages in the Chukchi Sea

    Science.gov (United States)

    Norcross, Brenda L.; Holladay, Brenda A.; Busby, Morgan S.; Mier, Kathryn L.

    2010-01-01

    A multidisciplinary research cruise was conducted in the Chukchi Sea in summer 2004 during which we investigated assemblages of small demersal fishes and ichthyoplankton and the water masses associated with these assemblages. This study establishes a baseline of 30 demersal fish and 25 ichthyoplankton taxa in US and Russian waters of the Chukchi Sea. Presence/absence of small demersal fish clustered into four assemblages: Coastal Fishes, Western Chukchi Fishes, South Central Chukchi Fishes, and North Central Chukchi Fishes. Habitats occupied by small demersal fishes were characterized by sediment type, bottom salinity, and bottom temperature. Abundance of ichthyoplankton grouped into three assemblages with geographical extent similar to that of the bottom assemblages, except that there was a single assemblage for Central Chukchi Fishes. Water-column temperature and salinity characterized ichthyoplankton habitats. Three water masses, Alaska Coastal Water, Bering Sea Water, and Winter Water, were identified from both bottom and depth-averaged water-column temperature and salinity. A fourth water mass, Resident Chukchi Water, was identified only in the bottom water. The water mass and habitat characteristics with which demersal and larval fish assemblages were associated create a baseline to measure anticipated effects of climate change that are expected to be most severe at high latitudes. Monitoring fish assemblages could be a tool for assessing the effects of climate change. Climate-induced changes in distributions of species would result in a restructuring of fish assemblages in the Chukchi Sea.

  13. Sea otters in the northern Pacific Ocean

    Science.gov (United States)

    Bodkin, James L.; Jameson, Ronald J.; Estes, James A.; LaRoe, Edward T.; Farris, Gaye S.; Puckett, Catherine E.; Doran, Peter D.; Mac, Michael J.

    1995-01-01

    forest communities. At the same time, sea otter predation on other marine invertebrates can lead to direct competition with humans for resources. These interactions add complex dimensions to the conservation and management of sea otters, in large part because of wide-ranging social, ecological, and economic consequences of sea otter foraging.Long-term data on abundance and distribution are available for relatively few sea otter populations. Here we summarize such data from three populations: Being Island, Russia; Prince William Sound, Alaska; and Olympic Peninsula, Washington. The Bering Island population resulted from natural emigration and represents complete recovery. Prince William Sounds represents near recovery of a remnant population, whereas the Washington population was established via translocations from Alaska and is just beginning to recover. We will compare growth rates and current status among these populations. Because of its unique status and growth characteristics, the California sea otter is not treated in this article.

  14. De stille elever

    DEFF Research Database (Denmark)

    Winther-Lindqvist, Ditte Alexandra

    2012-01-01

    Det er blevet en afgørende samværskompetence i uddannelsessystemet at stå aktivt frem og deltage verbalt i skoleklassens liv både fagligt og socialt. Men ikke alle elever deltager lige villigt verbalt i plenum. Artiklen handler om de stille elever og konsekvenserne af stillehed i skolen. Det...... foreslås at skolesystemet sanktionerer ældre elever hårdere for stillehed end yngre elever og det forklares med at skolelivet også er en kultivering henimod elevhed som social identitet og denne er der forventning om at eleverne mestrer i udskolingen....

  15. Deglacial climate modulated by the storage and release of Arctic sea ice

    Science.gov (United States)

    Condron, A.; Coletti, A. J.; Bradley, R. S.

    2017-12-01

    Periods of abrupt climate cooling during the last deglaciation (20 - 8 kyr ago) are often attributed to glacial outburst floods slowing the Atlantic meridional overturning circulation (AMOC). Here, we present results from a series of climate model simulations showing that the episodic break-up and mobilization of thick, perennial, Arctic sea ice during this time would have released considerable volumes of freshwater directly to the Nordic Seas, where processes regulating large-scale climate occur. Massive sea ice export events to the North Atlantic are generated whenever the transport of sea ice is enhanced, either by changes in atmospheric circulation, rising sea level submerging the Bering land bridge, or glacial outburst floods draining into the Arctic Ocean from the Mackenzie River. We find that the volumes of freshwater released to the Nordic Seas are similar to, or larger than, those estimated to have come from terrestrial outburst floods, including the discharge at the onset of the Younger Dryas. Our results provide the first evidence that the storage and release of Arctic sea ice helped drive deglacial climate change by modulating the strength of the AMOC.

  16. Projecting future sea level

    Science.gov (United States)

    Cayan, Daniel R.; Bromirski, Peter; Hayhoe, Katharine; Tyree, Mary; Dettinger, Mike; Flick, Reinhard

    2006-01-01

    global sea level rises in examining possible impacts at California coastal and estuarine stations. Two climate models and three scenarios considered in this scenarios study provide a set of possible future weather and short-period climate fluctuations, and a range of potential long-term sea level rise values. A range of mean sea level rise was considered in combination with weather and El Niño fluctuations extracted from two global climate models and two GHG emissions scenarios. The mean sea level rise values, determined from a survey of several climate models, range from approximately 10–80 cm (3.9–31 in) between 2000 and 2100. The middle to higher end of this range would substantially exceed the historical rate of sea level rise of 15–20 cm (5.9–7.9 in)per century observed at San Francisco and San Diego during the last 100 years. Gradual sea level rise progressively worsens the impacts of high tides and the surge and waves associated with storms. The potential for impacts of future sea level rise was assessed from the occurrence of hourly sea level extremes. The occurrence of extreme events follows a sharply escalating pattern as the magnitude of future sea level rise increases. The confluence of Low barometric pressures from storms and the presence large waves at the same time substantially increases the likelihood of high, damaging sea levels along the California coast. Similarly, astronomical tides and disturbances in sea level that are caused by weather and climate fluctuations are x transmitted into the San Francisco Bay and Delta, and on into the lower reaches of the Sacramento River. In addition to elevating Bay and Delta sea levels directly through inverse barometer and wind effects, storms may generate heavy precipitation and high fresh water runoff and cause floods in the Sacramento/San Joaquin Delta, increasing the potential for inundation of levees and other structures. There may also be increased risk of levee failure due to the hydraulics and

  17. Large Scale Variability of Phytoplankton Blooms in the Arctic and Peripheral Seas: Relationships with Sea Ice, Temperature, Clouds, and Wind

    Science.gov (United States)

    Comiso, Josefino C.; Cota, Glenn F.

    2004-01-01

    Spatially detailed satellite data of mean color, sea ice concentration, surface temperature, clouds, and wind have been analyzed to quantify and study the large scale regional and temporal variability of phytoplankton blooms in the Arctic and peripheral seas from 1998 to 2002. In the Arctic basin, phytoplankton chlorophyll displays a large symmetry with the Eastern Arctic having about fivefold higher concentrations than those of the Western Arctic. Large monthly and yearly variability is also observed in the peripheral seas with the largest blooms occurring in the Bering Sea, Sea of Okhotsk, and the Barents Sea during spring. There is large interannual and seasonal variability in biomass with average chlorophyll concentrations in 2002 and 2001 being higher than earlier years in spring and summer. The seasonality in the latitudinal distribution of blooms is also very different such that the North Atlantic is usually most expansive in spring while the North Pacific is more extensive in autumn. Environmental factors that influence phytoplankton growth were examined, and results show relatively high negative correlation with sea ice retreat and strong positive correlation with temperature in early spring. Plankton growth, as indicated by biomass accumulation, in the Arctic and subarctic increases up to a threshold surface temperature of about 276-277 degree K (3-4 degree C) beyond which the concentrations start to decrease suggesting an optimal temperature or nutrient depletion. The correlation with clouds is significant in some areas but negligible in other areas, while the correlations with wind speed and its components are generally weak. The effects of clouds and winds are less predictable with weekly climatologies because of unknown effects of averaging variable and intermittent physical forcing (e.g. over storm event scales with mixing and upwelling of nutrients) and the time scales of acclimation by the phytoplankton.

  18. The Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Naik, H.; Narvekar, P.V.

    high chI are also encountered offshore, presumably associated with the mesoscale features such as filaments and eddies. In conformity with the satellite data, elevated chI levels persist~lOOOkmfrom the Omani coast. During the Sl, chI levels are quite... is consumed rapidly for the degradation of copious amounts of organic matter produced within the Arabian Sea itself. Consequently, 02 levels fall very close to zero while nutrients accumulate in high concentrations within a zone that extends from the base...

  19. Undervisning af tosprogede elever

    DEFF Research Database (Denmark)

    Horst, Christian

    2003-01-01

    Artiklen fremdrager hovedresultaterne fra Virginia P. Collier's og Wayne P. Thomas's længdeundersøgelser af tosprogede elever i USA, som formentlig er de mest omfattende undersøgelser af undervisningen af tosprogede elever overhovedet. Resultaterne diskuteres i relation til udviklingen af en...

  20. Effects of elevated CO

    NARCIS (Netherlands)

    Xue, Sha; Yang, Xiaomei; Liu, Guobin; Gai, Lingtong; Zhang, Changsheng; Ritsema, Coen J.; Geissen, Violette

    2017-01-01

    Elevated CO2 and drought are key consequences of climate change and affect soil processes and plant growth. This study investigated the effects of elevated CO2 and drought on the microbial biomass and enzymatic activities in the rhizospheres of Bothriochloa ischaemum and

  1. The Barbados Sea Level Record

    Science.gov (United States)

    Fairbanks, R. G.; Mortlock, R. A.; Abdul, N. A.; Wright, J. D.; Cao, L.; Mey, J. L.

    2013-12-01

    Additional offshore drill cores, nearly 100 new radiometric dates, and more than 1000 kilometers of Multibeam mapping greatly enhance the Barbados Sea Level record. Extensive Multibeam mapping around the entire island covers approximately 2650 km2 of the sea bottom and now integrates the offshore reef topography and Barbados Sea Level Record with the unparalleled onshore core collection, digital elevation maps, and Pleistocene sea level record spanning the past one million years. The reef crest coral, Acropora palmata, remains the stalwart indicator of sea level for many reasons that are validated by our redundant sea level records and redundant dating via Th/U and Pa/U analyses. Microanalysis and densitometry studies better explain why Acropora palmata is so well preserved in the Pleistocene reef records and therefore why it is the species of choice for sea level reconstructions and radiometric dating. New drill cores into reefs that formed during Marine Isotope Stage 3 lead us to a model of diagenesis that allows us to better prospect for unaltered coral samples in older reefs that may be suitable for Th/U dating. Equally important, our diagenesis model reinforces our rigorous sample quality criteria in a more quantitative manner. The Barbados Sea Level record has a sampling resolution of better than 100 years throughout much of the last deglaciation showing unprecedented detail in redundant drill cores. The Melt Water Pulses (MWP1A and MWP1B) are well resolved and the intervening interval that includes the Younger Dryas reveals sea level changes in new detail that are consistent with the terrestrial records of ice margins (see Abdul et al., this section). More than 100 paired Th/U and radiocarbon ages place the Barbados Sea Level Record unambiguously on the radiocarbon time scale for direct comparisons with the terrestrial records of ice margin changes.

  2. GLAS/ICESat L2 Sea Ice Altimetry Data (HDF5) V034

    Data.gov (United States)

    National Aeronautics and Space Administration — GLAH13 contains sea ice and open ocean elevations corrected for geodetic and atmospheric affects, calculated from algorithms fine-tuned for sea ice returns. Granules...

  3. GLAS/ICESat L2 Sea Ice Altimetry Data V033

    Data.gov (United States)

    National Aeronautics and Space Administration — GLA13 contains sea ice and open ocean elevations corrected for geodetic and atmospheric affects, calculated from algorithms fine-tuned for sea ice returns. Granules...

  4. Elevator and hydraulics; Elevator to yuatsu

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, I. [Hitachi, Ltd., Tokyo (Japan)

    1994-07-15

    A hydraulic type elevator is installed in relatively lower buildings as compared with a rope type elevator, but the ratio in the number of installation of the former elevator is increasing. This paper explains from its construction and features to especially various control systems for the riding comfort and safety. A direct push-up system with hydraulic jacks arranged beneath a car, and an indirect push-up system that has hydraulic jacks arranged on flank of a car and transmits the movement of a plunger via a rope are available. The latter system eliminates the need of large holes to embed hydraulic jacks. While the speed is controlled by controlling flow rates of high-pressure oil, the speed, position, acceleration and even time differential calculus of the acceleration must be controlled severely. The system uses two-step control for the through-speed and the landing speed. Different systems that have been realized may include compensation for temperatures in flow rate control valves, load pressures, and oil viscosity, from learning control to fuzzy control for psychological effects, or control of inverters in motors. 13 refs., 12 figs., 1 tab.

  5. Density-dependent changes in effective area occupied for sea-bottom-associated marine fishes

    DEFF Research Database (Denmark)

    Thorson, James T.; Rindorf, Anna; Gao, Jin

    2016-01-01

    among taxa and regions. The average relationship is weak but significant (0.6% increase in area for a 10% increase in abundance), whereas only a small proportion of species–region combinations show a negative relationship (i.e. shrinking area when abundance increases). Approximately one...... for every 10% abundance increase) followed by Pleuronectiformes and Scorpaeniformes, and the Eastern Bering Sea shows a strong relationship between abundance and area occupied relative to other regions. We conclude that the BM explains a small but important portion of spatial dynamics for sea......The spatial distribution of marine fishes can change for many reasons, including density-dependent distributional shifts. Previous studies show mixed support for either the proportional-density model (PDM; no relationship between abundance and area occupied, supported by ideal-free distribution...

  6. Elevators or stairs?

    Science.gov (United States)

    Shah, Sachin; O’Byrne, Michael; Wilson, Merne; Wilson, Thomas

    2011-01-01

    Background: Staff in hospitals frequently travel between floors and choose between taking the stairs or elevator. We compared the time savings with these two options. Methods: Four people aged 26–67 years completed 14 trips ranging from one to six floors, both ascending and descending. We compared the amount of time per floor travelled by stairs and by two banks of elevators. Participants reported their fatigue levels using a modified Borg scale. We performed two-way analysis of variance to compare the log-transformed data, with participant and time of day as independent variables. Results: The mean time taken to travel between each floor was 13.1 (standard deviation [SD] 1.7) seconds by stairs and 37.5 (SD 19.0) and 35.6 (SD 23.1) seconds by the two elevators (F = 8.61, p elevator equaled about 15 minutes a day. Self-reported fatigue was less than 13 (out of 20) on the Borg scale for all participants, and they all stated that they were able to continue their duties without resting. The extra time associated with elevator use was because of waiting for its arrival. There was a difference in the amount of time taken to travel by elevator depending on the time of day and day of the week. Interpretation: Taking the stairs rather than the elevator saved about 15 minutes each workday. This 3% savings per workday could translate into improved productivity as well as increased fitness. PMID:22159365

  7. Sea Legs

    Science.gov (United States)

    Macdonald, Kenneth C.

    Forty-foot, storm-swept seas, Spitzbergen polar bears roaming vast expanses of Arctic ice, furtive exchanges of forbidden manuscripts in Cold War Moscow, the New York city fashion scene, diving in mini-subs to the sea floor hot srings, life with the astronauts, romance and heartbreak, and invading the last bastions of male exclusivity: all are present in this fast-moving, non-fiction account of one woman' fascinating adventures in the world of marine geology and oceanography.

  8. Ecosystem variability in the offshore northeastern Chukchi Sea

    Science.gov (United States)

    Blanchard, Arny L.; Day, Robert H.; Gall, Adrian E.; Aerts, Lisanne A. M.; Delarue, Julien; Dobbins, Elizabeth L.; Hopcroft, Russell R.; Questel, Jennifer M.; Weingartner, Thomas J.; Wisdom, Sheyna S.

    2017-12-01

    Understanding influences of cumulative effects from multiple stressors in marine ecosystems requires an understanding of the sources for and scales of variability. A multidisciplinary ecosystem study in the offshore northeastern Chukchi Sea during 2008-2013 investigated the variability of the study area's two adjacent sub-ecosystems: a pelagic system influenced by interannual and/or seasonal temporal variation at large, oceanographic (regional) scales, and a benthic-associated system more influenced by small-scale spatial variations. Variability in zooplankton communities reflected interannual oceanographic differences in waters advected northward from the Bering Sea, whereas variation in benthic communities was associated with seafloor and bottom-water characteristics. Variations in the planktivorous seabird community were correlated with prey distributions, whereas interaction effects in ANOVA for walruses were related to declines of sea-ice. Long-term shifts in seabird distributions were also related to changes in sea-ice distributions that led to more open water. Although characteristics of the lower trophic-level animals within sub-ecosystems result from oceanographic variations and interactions with seafloor topography, distributions of apex predators were related to sea-ice as a feeding platform (walruses) or to its absence (i.e., open water) for feeding (seabirds). The stability of prey resources appears to be a key factor in mediating predator interactions with other ocean characteristics. Seabirds reliant on highly-variable zooplankton prey show long-term changes as open water increases, whereas walruses taking benthic prey in biomass hotspots respond to sea-ice changes in the short-term. A better understanding of how variability scales up from prey to predators and how prey resource stability (including how critical prey respond to environmental changes over space and time) might be altered by climate and anthropogenic stressors is essential to

  9. Arctic Sea Ice Variability and Trends, 1979-2006

    Science.gov (United States)

    Parkinson, Claire L.; Cavalieri, Donald J.

    2008-01-01

    Analysis of Arctic sea ice extents derived from satellite passive-microwave data for the 28 years, 1979-2006 yields an overall negative trend of -45,100 +/- 4,600 km2/yr (-3.7 +/- 0.4%/decade) in the yearly averages, with negative ice-extent trends also occurring for each of the four seasons and each of the 12 months. For the yearly averages the largest decreases occur in the Kara and Barents Seas and the Arctic Ocean, with linear least squares slopes of -10,600 +/- 2,800 km2/yr (-7.4 +/- 2.0%/decade) and -10,100 +/- 2,200 km2/yr (-1.5 +/- 0.3%/decade), respectively, followed by Baffin Bay/Labrador Sea, with a slope of -8,000 +/- 2,000 km2/yr) -9.0 +/- 2.3%/decade), the Greenland Sea, with a slope of -7,000 +/- 1,400 km2/yr (-9.3 +/- 1.9%/decade), and Hudson Bay, with a slope of -4,500 +/- 900 km2/yr (-5.3 +/- 1.1%/decade). These are all statistically significant decreases at a 99% confidence level. The Seas of Okhotsk and Japan also have a statistically significant ice decrease, although at a 95% confidence level, and the three remaining regions, the Bering Sea, Canadian Archipelago, and Gulf of St. Lawrence, have negative slopes that are not statistically significant. The 28-year trends in ice areas for the Northern Hemisphere total are also statistically significant and negative in each season, each month, and for the yearly averages.

  10. Elevated temperature fracture mechanics

    International Nuclear Information System (INIS)

    Tomkins, B.

    1979-01-01

    The application of fracture mechanics concepts to cracks at elevated temperatures is examined. Particular consideration is given to the characterisation of crack tip stress-strain fields and parameters controlling crack extension under static and cyclic loads. (author)

  11. Arctic marine mammal population status, sea ice habitat loss, and conservation recommendations for the 21st century

    Science.gov (United States)

    Stern, Harry; Kovacs, Kit M.; Lowry, Lloyd; Moore, Sue E.; Regehr, Eric V.; Ferguson, Steven H.; Wiig, Øystein; Boveng, Peter; Angliss, Robyn P.; Born, Erik W.; Litovka, Dennis; Quakenbush, Lori; Lydersen, Christian; Vongraven, Dag; Ugarte, Fernando

    2015-01-01

    Abstract Arctic marine mammals (AMMs) are icons of climate change, largely because of their close association with sea ice. However, neither a circumpolar assessment of AMM status nor a standardized metric of sea ice habitat change is available. We summarized available data on abundance and trend for each AMM species and recognized subpopulation. We also examined species diversity, the extent of human use, and temporal trends in sea ice habitat for 12 regions of the Arctic by calculating the dates of spring sea ice retreat and fall sea ice advance from satellite data (1979–2013). Estimates of AMM abundance varied greatly in quality, and few studies were long enough for trend analysis. Of the AMM subpopulations, 78% (61 of 78) are legally harvested for subsistence purposes. Changes in sea ice phenology have been profound. In all regions except the Bering Sea, the duration of the summer (i.e., reduced ice) period increased by 5–10 weeks and by >20 weeks in the Barents Sea between 1979 and 2013. In light of generally poor data, the importance of human use, and forecasted environmental changes in the 21st century, we recommend the following for effective AMM conservation: maintain and improve comanagement by local, federal, and international partners; recognize spatial and temporal variability in AMM subpopulation response to climate change; implement monitoring programs with clear goals; mitigate cumulative impacts of increased human activity; and recognize the limits of current protected species legislation. PMID:25783745

  12. The response of the Goddard general circulation model to sea ice boundary conditions

    Science.gov (United States)

    Herman, G.; Johnson, W. T.

    1979-01-01

    The effect of variation in the location of Arctic sea ice boundaries on the model's mean monthly climatology was examined. When sea ice boundaries were at their maximum extent the differences resulted in the January-February climatology. Sea level pressure was higher over the Barents Sea, in the Davis Strait, and in the Sea of Okhotsk. Pressure was lower by as much as 8 mb in the North Atlantic between Iceland and the British Isles, and in the Gulf of Alaska. Pressure rises in the eastern subtropical regions of the North Atlantic and North Pacific accompanied pressure falls in the Gulf of Alaska and Icelandic region. Geopotential heights at 500 mb were more than 100 gpm lower in the Bering Sea, and more than 120 gpm lower in the Icelandic region. Zonally averaged temperatures were cooler by 4 deg C below 3800 mb between 50 deg and 70 deg N with little change elsewhere. Zonally averaged geopotentials were lower by as much as 70 gpm in the mid-troposphere between 50/-70 deg N and zonal winds increased by as much as 3 m s in the mid-troposphere between 35/-50 deg N.

  13. Early Pliocene onset of modern Nordic Seas circulation related to ocean gateway changes.

    Science.gov (United States)

    De Schepper, Stijn; Schreck, Michael; Beck, Kristina Marie; Matthiessen, Jens; Fahl, Kirsten; Mangerud, Gunn

    2015-10-28

    The globally warm climate of the early Pliocene gradually cooled from 4 million years ago, synchronous with decreasing atmospheric CO2 concentrations. In contrast, palaeoceanographic records indicate that the Nordic Seas cooled during the earliest Pliocene, before global cooling. However, a lack of knowledge regarding the precise timing of Nordic Seas cooling has limited our understanding of the governing mechanisms. Here, using marine palynology, we show that cooling in the Nordic Seas was coincident with the first trans-Arctic migration of cool-water Pacific mollusks around 4.5 million years ago, and followed by the development of a modern-like Nordic Seas surface circulation. Nordic Seas cooling precedes global cooling by 500,000 years; as such, we propose that reconfiguration of the Bering Strait and Central American Seaway triggered the development of a modern circulation in the Nordic Seas, which is essential for North Atlantic Deep Water formation and a precursor for more widespread Greenland glaciation in the late Pliocene.

  14. Indsatser for tosprogede elever

    DEFF Research Database (Denmark)

    Andersen, Dines; Jakobsen, Vibeke; Jensen, Vibeke Myrup

    Fagligt set klarer tosprogede elever sig dårligere i skolen og det videre uddannelsessystem end ’danske’ elever. Kommuner og folkeskoler har derfor sat en række tiltag i værk, som sigter mod at forbedre de tosprogede elevers skole- og uddannelsessituation. Rapporten kortlægger og analyserer...... af klasseundervisningen. Analysen viser, at de elever, der bliver taget ud af klassen for at få ekstra undervisning i dansk som andetsprog, klarer sig dårligere end elever, der modtager ekstraundervisningen i klassen eller uden for skoletid. Undersøgelsen er baseret på spørgeskemaundersøgelser blandt...... kommunale forvaltningschefer, skoleledere, lærere og forældre til børn i 2. klasse samt lærere til og elever i 9. klasse, SFI’s forløbsundersøgelse af årgang 1995 og registerdata. Undersøgelsen er via Ministeriet for Børn og Undervisning betalt med midler fra satspuljeaftalen 2009 om integration....

  15. Denali Ice Core Record of North Pacific Sea Surface Temperatures and Marine Primary Productivity

    Science.gov (United States)

    Polashenski, D.; Osterberg, E. C.; Kreutz, K. J.; Winski, D.; Wake, C. P.; Ferris, D. G.; Introne, D.; Campbell, S. W.

    2016-12-01

    Chemical analyses of precipitation preserved in glacial ice cores provide a unique opportunity to study changes in atmospheric circulation patterns and ocean surface conditions through time. In this study, we aim to investigate changes in both the physical and biological parameters of the north-central Pacific Ocean and Bering Sea over the twentieth century using the deuterium excess (d-excess) and methanesulfonic acid (MSA) records from the Mt. Hunter ice cores drilled in Denali National Park, Alaska. These parallel, 208 m-long ice cores were drilled to bedrock during the 2013 field season on the Mt. Hunter plateau (63° N, 151° W, 3,900 m above sea level) by a collaborative research team consisting of members from Dartmouth College and the Universities of Maine and New Hampshire. The cores were sampled on a continuous melter system at Dartmouth College and analyzed for the concentrations major ions (Dionex IC) and trace metals (Element2 ICPMS), and for stable water isotope ratios (Picarro). The depth-age scale has been accurately dated to 400 AD using annual layer counting of several chemical species and further validated using known historical volcanic eruptions and the Cesium-137 spike associated with nuclear weapons testing in 1963. We use HYSPLIT back trajectory modeling to identify likely source areas of moisture and aerosol MSA being transported to the core site. Satellite imagery allows for a direct comparison between chlorophyll a concentrations in these source areas and MSA concentrations in the core record. Preliminary analysis of chlorophyll a and MSA concentrations, both derived almost exclusively from marine biota, suggest that the Mt. Hunter ice cores reflect changes in North Pacific and Bering Sea marine primary productivity. Analysis of the water isotope and MSA data in conjunction with climate reanalysis products shows significant correlations (psea surface temperatures in the Bering Sea and North Central Pacific. These findings, coupled with

  16. Assessment of Competition between Fisheries and Steller Sea Lions in Alaska Based on Estimated Prey Biomass, Fisheries Removals and Predator Foraging Behaviour.

    Directory of Open Access Journals (Sweden)

    Tabitha C Y Hui

    Full Text Available A leading hypothesis to explain the dramatic decline of Steller sea lions (Eumetopias jubatus in western Alaska during the latter part of the 20th century is a change in prey availability due to commercial fisheries. We tested this hypothesis by exploring the relationships between sea lion population trends, fishery catches, and the prey biomass accessible to sea lions around 33 rookeries between 2000 and 2008. We focused on three commercially important species that have dominated the sea lion diet during the population decline: walleye pollock, Pacific cod and Atka mackerel. We estimated available prey biomass by removing fishery catches from predicted prey biomass distributions in the Aleutian Islands, Bering Sea and Gulf of Alaska; and modelled the likelihood of sea lions foraging at different distances from rookeries (accessibility using satellite telemetry locations of tracked animals. We combined this accessibility model with the prey distributions to estimate the prey biomass accessible to sea lions by rookery. For each rookery, we compared sea lion population change to accessible prey biomass. Of 304 comparisons, we found 3 statistically significant relationships, all suggesting that sea lion populations increased with increasing prey accessibility. Given that the majority of comparisons showed no significant effect, it seems unlikely that the availability of pollock, cod or Atka mackerel was limiting sea lion populations in the 2000s.

  17. Bowhead whale body condition and links to summer sea ice and upwelling in the Beaufort Sea

    Science.gov (United States)

    George, John C.; Druckenmiller, Matthew L.; Laidre, Kristin L.; Suydam, Robert; Person, Brian

    2015-08-01

    We examined the response of bowhead whale (Balaena mysticetus) body condition to summer sea ice conditions and upwelling-favorable winds. We used a long-term dataset collected from whales of the Bering-Chukchi-Beaufort Seas (BCB) stock to estimate various body condition indices (BCI's) for individual whales that were harvested by Alaskan Eskimos. A series of offshore regions frequented by bowhead whales in summer were delineated and used to quantify interannual summertime environmental conditions including: (a) mean open water fraction, (b) duration of melt season, (c) date of continuous freeze-up, and (d) mean upwelling-favorable wind stress. Body condition was analyzed relative to these metrics for both the preceding summer feeding season and the previous three seasons combined. Our analysis indicates a significant increase in the long-term trend in an axillary girth-based body condition index (BCIG) over the study period (1989-2011). The increase in BCIG is likely associated with the trend in overall reduction of sea ice, including increased duration of open water, changes in upwelling potential (wind stress), and possibly higher primary production in the Pacific Arctic marine ecosystem favoring water-column invertebrates. We found strong significant positive correlations between BCIG and late summer open water fraction in the Beaufort Sea and smaller nearshore areas off the Mackenzie Delta and west of Banks Island. Additionally, BCIG was positively and significantly correlated with duration of melt season, later date of freeze-up in the Beaufort Sea, and upwelling-favorable winds on the Mackenzie shelf and west of Banks Island. A strong seasonal difference in BCI's was noted for subadult bowheads, presumably associated with summer feeding; however, yearlings were found to drop in BCI over at least the first summer after weaning. Our results indicate an overall increase in bowhead whale body condition and a positive correlation with summer sea ice loss over the

  18. Sea level trends in South East Asian Seas (SEAS)

    Science.gov (United States)

    Strassburg, M. W.; Hamlington, B. D.; Leben, R. R.; Manurung, P.; Lumban Gaol, J.; Nababan, B.; Vignudelli, S.; Kim, K.-Y.

    2014-10-01

    Southeast Asian Seas (SEAS) span the largest archipelago in the global ocean and provide a complex oceanic pathway connecting the Pacific and Indian Oceans. The SEAS regional sea level trends are some of the highest observed in the modern satellite altimeter record that now spans almost two decades. Initial comparisons of global sea level reconstructions find that 17 year sea level trends over the past 60 years exhibit good agreement in areas and at times of strong signal to noise associated decadal variability forced by low frequency variations in Pacific trade winds. The SEAS region exhibits sea level trends that vary dramatically over the studied time period. This historical variation suggests that the strong regional sea level trends observed during the modern satellite altimeter record will abate as trade winds fluctuate on decadal and longer time scales. Furthermore, after removing the contribution of the Pacific Decadal Oscillation (PDO) to sea level trends in the past twenty years, the rate of sea level rise is greatly reduced in the SEAS region. As a result of the influence of the PDO, the SEAS regional sea level trends during 2010s and 2020s are likely to be less than the global mean sea level (GMSL) trend if the observed oscillations in wind forcing and sea level persist. Nevertheless, long-term sea level trends in the SEAS will continue to be affected by GMSL rise occurring now and in the future.

  19. Faunal record identifies Bering isthmus conditions as constraint to end-Pleistocene migration to the New World

    Science.gov (United States)

    Meiri, Meirav; Lister, Adrian M.; Collins, Matthew J.; Tuross, Noreen; Goebel, Ted; Blockley, Simon; Zazula, Grant D.; van Doorn, Nienke; Dale Guthrie, R.; Boeskorov, Gennady G.; Baryshnikov, Gennady F.; Sher, Andrei; Barnes, Ian

    2014-01-01

    Human colonization of the New World is generally believed to have entailed migrations from Siberia across the Bering isthmus. However, the limited archaeological record of these migrations means that details of the timing, cause and rate remain cryptic. Here, we have used a combination of ancient DNA, 14C dating, hydrogen and oxygen isotopes, and collagen sequencing to explore the colonization history of one of the few other large mammals to have successfully migrated into the Americas at this time: the North American elk (Cervus elaphus canadensis), also known as wapiti. We identify a long-term occupation of northeast Siberia, far beyond the species’s current Old World distribution. Migration into North America occurred at the end of the last glaciation, while the northeast Siberian source population became extinct only within the last 500 years. This finding is congruent with a similar proposed delay in human colonization, inferred from modern human mitochondrial DNA, and suggestions that the Bering isthmus was not traversable during parts of the Late Pleistocene. Our data imply a fundamental constraint in crossing Beringia, placing limits on the age and mode of human settlement in the Americas, and further establish the utility of ancient DNA in palaeontological investigations of species histories. PMID:24335981

  20. Sea Ice Evolution in the Pacific Arctic by Selected CMIP5 Models: the Present and the Future

    Science.gov (United States)

    Wang, M.; Yang, Q.; Overland, J. E.; Stabeno, P. J.

    2016-12-01

    With fast declining of sea ice cover in the Arctic, the timing of sea ice break-up and freeze-up is an urgent economic, social and scientific issue. Based on daily sea ice concentration data we assess three parameters: the dates of sea ice break-up and freeze-up and the annual sea ice duration in the Pacific Arctic. The sea ice duration is shrinking, with the largest trend during the past decade (1990-2015); this declining trend will continue based on CMIP5 model projections. The seven CMIP5 models used in current study are able to simulate all three parameters well when compared with observations. Comparisons made at eight Chukchi Sea mooring sites and the eight Distributed Biological Observatory (DBO) boxes show consistent results as well. The 30-year averaged trend for annual sea ice duration is projected to be -0.68 days/year to -1.2 days/year for 2015-2044. This is equivalent 20 to 36 days reduction in the annual sea ice duration. A similar magnitude of the negative trend is also found at all eight DBO boxes. The reduction in annual sea ice duration will include both earlier break-up dates and later freeze-up date. However, models project that a later freeze-up contributes more than early break-up to the overall shortening of annual sea ice duration. Around the Bering Strait future changes are the smallest, with less than 20-days change in duration during next 30 years. Upto 60 days reduction of the sea ice duration is projected for the decade of 2030-2044 in the East Siberia, the Chukchi and the Beaufort Seas.

  1. Recent Changes in Arctic Sea Ice Melt Onset, Freeze-Up, and Melt Season Length

    Science.gov (United States)

    Markus, Thorsten; Stroeve, Julienne C.; Miller, Jeffrey

    2010-01-01

    In order to explore changes and trends in the timing of Arctic sea ice melt onset and freeze-up and therefore melt season length, we developed a method that obtains this information directly from satellite passive microwave data, creating a consistent data set from 1979 through present. We furthermore distinguish between early melt (the first day of the year when melt is detected) and the first day of continuous melt. A similar distinction is made for the freeze-up. Using this method we analyze trends in melt onset and freeze-up for 10 different Arctic regions. In all regions except for the Sea of Okhotsk, which shows a very slight and statistically insignificant positive trend (O.4 days/decade), trends in melt onset are negative, i.e. towards earlier melt. The trends range from -1.0day/decade for the Bering Sea to -7.3 days/decade for the East Greenland Sea. Except for the Sea of Okhotsk all areas also show a trend towards later autumn freeze onset. The Chukchi/Beaufort Seas and Laptev/East Siberian Seas observe the strongest trends with 7 days/decade. For the entire Arctic, the melt season length has increased by about 20 days over the last 30 years. Largest trends of over 1O days/decade are seen for Hudson Bay, the East Greenland Sea the Laptev/East Siberian Seas, and the Chukchi/Beaufort Seas. Those trends are statistically significant a1 the 99% level.

  2. Impact of Site Elevation on Mg Smelter Design

    Science.gov (United States)

    Baker, Phillip W.

    Site elevation has many surprising and significant impacts on the engineering design of metallurgical plant of all types. Electrolytic magnesium smelters maybe built at high elevation for a variety of reasons including availability of raw material, energy or electric power. Because of the unit processes they typically involve, Mg smelters can be extensively impacted by site elevation. In this paper, generic examples of the design changes required to adapt a smelter originally designed for sea level to operate at 2700 m are presented. While the examples are drawn from a magnesium plant design case, these changes are generically applicable to all industrial plants utilizing similar unit processes irrespective of product.

  3. Sea Ice

    Science.gov (United States)

    Perovich, D.; Gerland, S.; Hendricks, S.; Meier, Walter N.; Nicolaus, M.; Richter-Menge, J.; Tschudi, M.

    2013-01-01

    During 2013, Arctic sea ice extent remained well below normal, but the September 2013 minimum extent was substantially higher than the record-breaking minimum in 2012. Nonetheless, the minimum was still much lower than normal and the long-term trend Arctic September extent is -13.7 per decade relative to the 1981-2010 average. The less extreme conditions this year compared to 2012 were due to cooler temperatures and wind patterns that favored retention of ice through the summer. Sea ice thickness and volume remained near record-low levels, though indications are of slightly thicker ice compared to the record low of 2012.

  4. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Charleston WFO (Georgia)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  5. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: San Diego (CA) WFO

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  6. NOAA Coastal Services Center Coastal Inundation Digital Elevation Model: Philadelphia WFO - Pennsylvania

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Coastal Services Center's Sea Level...

  7. Temperature, salinity, oxygen and fluorescence profiles collected by CTD from the Norseman II in Bering Strait from 2013-07-04 to 2013-07-10 (NCEI Accession 0136939)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archive is of data from 150 CTD casts taken during the 2013 Norseman II cruise to the Bering Strait. For positions, see file headers or the cruise report...

  8. Temperature profiles from MBT casts from the BERING STRAIT from Ocean Weather Station V (OWS-V) in the North Pacific Ocean from 1958-11-30 to 1958-12-30 (NODC Accession 5800073)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bathythermograph data were collected from the BERING STRAIT within a 1-mile radius of Ocean Weather Station V (3400N 16400E) and in transit. Data were collected by...

  9. Temperature, salinity, velocity including ADCP ice tracking, and bottom pressure collected by Bering Strait Moorings A1W, A1, A1E from 2010-08-03 to 2012-08-25 (NCEI Accession 0138174)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is an archive of data from US moorings deployed in the Russian Channel of the Bering Strait from summer 2010 to summer 2012. The deployments were designed to be...

  10. Temperature profile data from Mechanical Bathythermograph (MBT) casts from the BERING STRAIT, STRANGER, and other platforms in the North Pacific, Coastal Equatorial Pacific, and other locations from 1945 to 1968 (NODC Accession 0000507)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature profiles were collected from Mechanical Bathythermograph (MBT) casts from the BERING STRAIT, STRANGER, and other platforms. Data were collected from 02...

  11. Temperature, salinity, velocity including ADCP ice tracking, and bottom pressure collected from moored buoys in Bering Strait from 2011-07-14 to 2013-07-05 (NCEI Accession 0138173)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is an archive of data from moorings deployed in the US waters of the Bering Strait from summer 2011 to summer 2013 (with mooring servicing in summer 2012). For...

  12. Temperature, salinity, velocity including ADCP ice tracking, and bottom pressure collected by Bering Strait Moorings A2W, A2, A4W, A4, A3 from 2010-08-03 to 2011-07-14 (NCEI Accession 0138583)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is an archive of data from US moorings deployed in the Bering Strait from summer 2010 to summer 2011. Moorings were also deployed for this period in Russian...

  13. Sea level change

    Digital Repository Service at National Institute of Oceanography (India)

    Church, J.A.; Clark, P.U.; Cazenave, A.; Gregory, J.M.; Jevrejeva, S.; Levermann, A.; Merrifield, M.A.; Milne, G.A.; Nerem, R.S.; Nunn, P.D.; Payne, A.J.; Pfeffer, W.T.; Stammer, D.; Unnikrishnan, A.S.

    This chapter considers changes in global mean sea level, regional sea level, sea level extremes, and waves. Confidence in projections of global mean sea level rise has increased since the Fourth Assessment Report (AR4) because of the improved...

  14. National Elevation Dataset

    Science.gov (United States)

    ,

    2002-01-01

    The National Elevation Dataset (NED) is a new raster product assembled by the U.S. Geological Survey. NED is designed to provide National elevation data in a seamless form with a consistent datum, elevation unit, and projection. Data corrections were made in the NED assembly process to minimize artifacts, perform edge matching, and fill sliver areas of missing data. NED has a resolution of one arc-second (approximately 30 meters) for the conterminous United States, Hawaii, Puerto Rico and the island territories and a resolution of two arc-seconds for Alaska. NED data sources have a variety of elevation units, horizontal datums, and map projections. In the NED assembly process the elevation values are converted to decimal meters as a consistent unit of measure, NAD83 is consistently used as horizontal datum, and all the data are recast in a geographic projection. Older DEM's produced by methods that are now obsolete have been filtered during the NED assembly process to minimize artifacts that are commonly found in data produced by these methods. Artifact removal greatly improves the quality of the slope, shaded-relief, and synthetic drainage information that can be derived from the elevation data. Figure 2 illustrates the results of this artifact removal filtering. NED processing also includes steps to adjust values where adjacent DEM's do not match well, and to fill sliver areas of missing data between DEM's. These processing steps ensure that NED has no void areas and artificial discontinuities have been minimized. The artifact removal filtering process does not eliminate all of the artifacts. In areas where the only available DEM is produced by older methods, then "striping" may still occur.

  15. Evidence of high-elevation amplification versus Arctic amplification.

    Science.gov (United States)

    Wang, Qixiang; Fan, Xiaohui; Wang, Mengben

    2016-01-12

    Elevation-dependent warming in high-elevation regions and Arctic amplification are of tremendous interest to many scientists who are engaged in studies in climate change. Here, using annual mean temperatures from 2781 global stations for the 1961-2010 period, we find that the warming for the world's high-elevation stations (>500 m above sea level) is clearly stronger than their low-elevation counterparts; and the high-elevation amplification consists of not only an altitudinal amplification but also a latitudinal amplification. The warming for the high-elevation stations is linearly proportional to the temperature lapse rates along altitudinal and latitudinal gradients, as a result of the functional shape of Stefan-Boltzmann law in both vertical and latitudinal directions. In contrast, neither altitudinal amplification nor latitudinal amplification is found within the Arctic region despite its greater warming than lower latitudes. Further analysis shows that the Arctic amplification is an integrated part of the latitudinal amplification trend for the low-elevation stations (≤500 m above sea level) across the entire low- to high-latitude Northern Hemisphere, also a result of the mathematical shape of Stefan-Boltzmann law but only in latitudinal direction.

  16. Topobathymetric elevation model development using a new methodology: Coastal National Elevation Database

    Science.gov (United States)

    Danielson, Jeffrey J.; Poppenga, Sandra K.; Brock, John C.; Evans, Gayla A.; Tyler, Dean; Gesch, Dean B.; Thatcher, Cindy A.; Barras, John

    2016-01-01

    During the coming decades, coastlines will respond to widely predicted sea-level rise, storm surge, and coastalinundation flooding from disastrous events. Because physical processes in coastal environments are controlled by the geomorphology of over-the-land topography and underwater bathymetry, many applications of geospatial data in coastal environments require detailed knowledge of the near-shore topography and bathymetry. In this paper, an updated methodology used by the U.S. Geological Survey Coastal National Elevation Database (CoNED) Applications Project is presented for developing coastal topobathymetric elevation models (TBDEMs) from multiple topographic data sources with adjacent intertidal topobathymetric and offshore bathymetric sources to generate seamlessly integrated TBDEMs. This repeatable, updatable, and logically consistent methodology assimilates topographic data (land elevation) and bathymetry (water depth) into a seamless coastal elevation model. Within the overarching framework, vertical datum transformations are standardized in a workflow that interweaves spatially consistent interpolation (gridding) techniques with a land/water boundary mask delineation approach. Output gridded raster TBDEMs are stacked into a file storage system of mosaic datasets within an Esri ArcGIS geodatabase for efficient updating while maintaining current and updated spatially referenced metadata. Topobathymetric data provide a required seamless elevation product for several science application studies, such as shoreline delineation, coastal inundation mapping, sediment-transport, sea-level rise, storm surge models, and tsunami impact assessment. These detailed coastal elevation data are critical to depict regions prone to climate change impacts and are essential to planners and managers responsible for mitigating the associated risks and costs to both human communities and ecosystems. The CoNED methodology approach has been used to construct integrated TBDEM models

  17. Estimating Coastal Digital Elevation Model (DEM) Uncertainty

    Science.gov (United States)

    Amante, C.; Mesick, S.

    2017-12-01

    Integrated bathymetric-topographic digital elevation models (DEMs) are representations of the Earth's solid surface and are fundamental to the modeling of coastal processes, including tsunami, storm surge, and sea-level rise inundation. Deviations in elevation values from the actual seabed or land surface constitute errors in DEMs, which originate from numerous sources, including: (i) the source elevation measurements (e.g., multibeam sonar, lidar), (ii) the interpolative gridding technique (e.g., spline, kriging) used to estimate elevations in areas unconstrained by source measurements, and (iii) the datum transformation used to convert bathymetric and topographic data to common vertical reference systems. The magnitude and spatial distribution of the errors from these sources are typically unknown, and the lack of knowledge regarding these errors represents the vertical uncertainty in the DEM. The National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI) has developed DEMs for more than 200 coastal communities. This study presents a methodology developed at NOAA NCEI to derive accompanying uncertainty surfaces that estimate DEM errors at the individual cell-level. The development of high-resolution (1/9th arc-second), integrated bathymetric-topographic DEMs along the southwest coast of Florida serves as the case study for deriving uncertainty surfaces. The estimated uncertainty can then be propagated into the modeling of coastal processes that utilize DEMs. Incorporating the uncertainty produces more reliable modeling results, and in turn, better-informed coastal management decisions.

  18. A new bed elevation dataset for Greenland

    Directory of Open Access Journals (Sweden)

    J. L. Bamber

    2013-03-01

    Full Text Available We present a new bed elevation dataset for Greenland derived from a combination of multiple airborne ice thickness surveys undertaken between the 1970s and 2012. Around 420 000 line kilometres of airborne data were used, with roughly 70% of this having been collected since the year 2000, when the last comprehensive compilation was undertaken. The airborne data were combined with satellite-derived elevations for non-glaciated terrain to produce a consistent bed digital elevation model (DEM over the entire island including across the glaciated–ice free boundary. The DEM was extended to the continental margin with the aid of bathymetric data, primarily from a compilation for the Arctic. Ice thickness was determined where an ice shelf exists from a combination of surface elevation and radar soundings. The across-track spacing between flight lines warranted interpolation at 1 km postings for significant sectors of the ice sheet. Grids of ice surface elevation, error estimates for the DEM, ice thickness and data sampling density were also produced alongside a mask of land/ocean/grounded ice/floating ice. Errors in bed elevation range from a minimum of ±10 m to about ±300 m, as a function of distance from an observation and local topographic variability. A comparison with the compilation published in 2001 highlights the improvement in resolution afforded by the new datasets, particularly along the ice sheet margin, where ice velocity is highest and changes in ice dynamics most marked. We estimate that the volume of ice included in our land-ice mask would raise mean sea level by 7.36 m, excluding any solid earth effects that would take place during ice sheet decay.

  19. What is going on up there? - The Chukchi Sea Ecosystem Mooring

    Science.gov (United States)

    Janzen, C.; McCammon, M.; Danielson, S. L.; Winsor, P.; Hopcroft, R. R.; Lalande, C.; Stafford, K.; Hauri, C.; McDonnell, A. M. P.

    2016-02-01

    As Arctic regions are projected to strongly reflect the impacts of a changing climate, an effort is underway to make sustained, year-round measurements of concurrent physical and biogeochemical parameters in the Arctic. Deploying highly instrumented year-round moorings in the water is no simple feat, given harsh Arctic conditions that include the presence of sea ice and deep ice keels during much of the year. Enter the late-breaking ecosystem mooring located in the northeast Chukchi Sea. This mooring complements established biophysical moorings elsewhere in the northern Bering and Chukchi seas, including those maintained by NOAA-PMEL (M8), UW-APL (Bering Strait) and JAMSTEC moorings. (southern Chukchi and Barrow Canyon). The mooring described here is located on the southern flank of Hanna Shoal and provides a multi-disciplinary approach to year-round observations within a biological hotspot. The Chukchi Ecosystem Mooring is equipped with a sensor suite aimed to monitor and document the state of ocean acidification, nutrient and carbon cycles, particles, waves, currents and physical properties, and even passive and active acoustic monitoring for zooplankton, fish, and marine mammals. Having the simultaneous interdisciplinary measurements provides data valuable to an ecosystem-based approach to research and resource management. The fully outfitted observatory is providing an unprecedented view into the mechanistic workings of the Chukchi Shelf Ecosystem. The first mooring was deployed in September 2014 and recovered in August 2015. The August 2015 deployment consisted of three moorings, each with incremental sensor packages to complete the ecosystem sensor suite. The mooring construction and instrumentation are described in detail, including introduction to the advances in sensor technologies that enable such deployments. Year one data recovery summaries and plots are provided to demonstrate the capabilities.

  20. Interaktive tavler - interaktive elever

    DEFF Research Database (Denmark)

    Reusch, Charlotte F.; Otzen, Elsebeth

    Abstract, Poster-præsentation 13.-14. juni 2012, Pilotprojekt: Interaktive tavler – interaktive elever Lektor, cand. pæd., Elsebeth Otzen og Lektor, cand. mag., Charlotte Reusch, Institut for Skole og Læring, Læreruddannelsen, Professionshøjskolen Metropol, København Hvordan motiverer en interaktiv...... tavle lærere og elever? Hvad sker der mellem elev, stof og lærer, når læreren bliver i stand til at billedliggøre og dynamisere sine oplæg på tavlen? Bliver læreroplæg prioriteret? Bliver eleverne aktive, eller ender den interaktive tavle med blot at understøtte lærerens envejskommunikation til klassen......? Og hvad sker der mellem eleverne? Disse spørgsmål var igangsættende for arbejdet med pilotprojektet Interaktive tavler – interaktive elever, som blev afviklet i skoleåret 2010-2011. Projektet blev udført af en tværfaglig gruppe, bestående af lektorer i matematik, biologi og dansk i læreruddannelsen...