Barents Sea Research Articles

The Many (De)colonial Lives of Kāpena George Gilley

This article provides the first full biographical account of history’s only known Native Hawaiian whaling captain, George Gilley, whose life story ranges across the entire North Pacific, throughout the Bering Sea, and into the Arctic Circle. It adds to a growing body of work on Indigenous participation in colonial institutions, including Pacific commercial whaling, and makes a case for using relevant Indigenous epistemologies and methods to locate Native agency within the largely non-Native sources born of those institutions. Gilley’s mo‘olelo (story/history) specifically fits into the burgeoning field of Native Hawaiian biography, which, it is argued, should expand to consider historic Hawaiians who left few written records. The article demonstrates a model for achieving this expansion, by treating Gilley’s hybridized, (de)colonial mobility and embodied, inherited knowledge as legible evidence of his sovereignty within the Euro-American economic, racial, and nationalistic structures that nineteenth-century whaling purveyed throughout the Pacific.

Intercomparisons and Evaluations of Satellite-Derived Arctic Sea Ice Thickness Products

Currently, Arctic sea ice thickness (SIT) data with extensive spatiotemporal coverage primarily comes from satellite observations, including CryoSat-2, Soil Moisture and Ocean Salinity (SMOS), and the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2). The studies of the intercomparison and evaluation of multi-source satellite products in recent years are limited. In this study, three latest version products of ICESat-2, CryoSat-2, and CS2SMOS (a merged product of CryoSat-2 and SMOS) were examined from October to April, between 2018 and 2022. Three types of observation including airborne data from the Operation IceBridge (OIB) and IceBird, and in situ data from Beaufort Gyre Exploration Project (BGEP) are selected as the reference in the evaluation. The intercomparison results show that the mean SIT is generally largest in ICESat-2, second largest in CryoSat-2, and smallest in CS2SMOS. The SIT in CryoSat-2 is closer to the SIT in ICESat-2. The thickness displayed by the three satellite products starts to increase at different freezing months, varying between October and November. The three satellite products demonstrated the strongest agreements in SIT in the Beaufort Sea and Central Arctic regions, and exhibited the most distinct differences in the Barents Sea. In the evaluation with OIB data, three satellite-derived SIT were generally underestimated and CS2SMOS demonstrates the closest match. The evaluation using IceBird data indicates an underestimation for all satellites, with CryoSat-2 showing the best agreement. In the assessment with BGEP data, ICESat-2 displayed a more pronounced degree of overestimation or underestimation compared to the other two satellites, and CS2SMOS exhibited the optimal agreement. Based on the comprehensive consideration, CS2SMOS demonstrated the best performance with the airborne and in situ observational data, followed by CryoSat-2 and ICESat-2. The intercomparison and evaluation results of satellite products can contribute to a further understanding of the accuracies and uncertainties of the latest version SIT retrieval and the appropriate selection and utilization of satellite products.

Quantifying zoobenthic blue carbon storage across habitats within the Arctic’s Barents Sea

IntroductionThe Arctic sea ice extent in September (when it is at its lowest) has declined 13% Q10 per decade, and the Arctic Ocean is becoming a more Atlantic-influenced system. Rapid climate-forced changes are taking place in many high-latitude marine ecosystems. The Barents Sea is one such high-latitude shelf ecosystem, between approximately 70° and 80°N in the Norwegian Arctic. The purpose of the current study was to estimate zoobenthic blue carbon across multiple habitats within the Barents Sea (trough, basin, shelf, and shallows), potentially providing values to aid ecosystem-based management of these areas under future climate change scenarios.MethodWe tested this by capture and analysis of 947 high-resolution (each 405.7 × 340.6 mm, 12 MB, 5 megapixels) seabed images at 17 sites with latitudinal cline, linked to a collection of corresponding oceanographic data. Biotas within these images were identified to one of the 14 functional groups and the density was calculated. Mean stored carbon per individual was assigned by ash mass (AM) and ash-free dry mass (AFDM) of individuals caught within Agassiz trawl deployments at the same sites.ResultsTrough sites, except for one site (B16), have a low quantity of zoobenthic blue carbon compared with the shallow, shelf, and basin habitats.DiscussionThe results of a previous study focused entirely on trough habitats and are therefore difficult to scale up as the basis for a meaningful estimate of across-habitat zoobenthic blue carbon in the Barents Sea. Compared with the trough and the basin, the shelf and shallow habitats of the Barents Sea are also subjected to more trawling events through demersal fisheries and showed higher zoobenthic blue carbon stock values.

Two new species of Callophyllis (Rhodophyta, Kallymeniaceae) from the Russian Pacific coast

ABSTRACT Seven species of Callophyllis have been known off the Pacific coast of Russia; hovewer, molecular data have been obtained only for three species. In this study we re-examined the genus along the Russian Pacific coast using a comparative morphological study and molecular analyses based on rbcL and nrLSU. Five genetic species were identified on the Russian coast based on phylogenetics and species delimitation (ASAP and p-distance) analyses; while C. beringensis, C. papulosa and C. platyna were outscore of the analyses. The results of the molecular analyses uncovered one undescribed species, which we named C. selivanovae sp. nov. The divergence between this species and other species of the genus varied from 1.16% to 5.66%, while intraspecific divergence in the genus was in a range of 0.00%–0.22%. In phylogenetic trees C. selivanovae was recognized as sister to a diverse clade including C. thompsonii, C. beringensis, C. violacea, C. flabellulata and C. variegata from the Pacific coast of Canada. Callophyllis selivanovae from the southeastern coast of Kamchatka is morphologically close to C. beringensis, described from St. Paul Island (Bering Sea); the two species differ in features of branching, shape and size of the terminal branches. We propose a new name, C. perestenkoae sp. nov., for the algae previously listed in the Russian flora as ‘C. flabellata’. Pacific specimens assigned to C. perestenkoae differ from C. flabellata from the type locality (Atlantic, France) in having irregular branching, thicker apical branches, and smaller cystocarps. We also filled in the gaps in the description of C. radula for which procarp and tetrasporangia are described herein for the first time.

Exploring the Potential of Sentinel-1 Ocean Wind Field Product for Near-Surface Offshore Wind Assessment in the Norwegian Arctic

The exploitation of offshore wind resources is a crucial step towards a clean energy future. It requires an advanced approach for high-resolution wind resource evaluations. We explored the suitability of the Sentinel-1 Level-2 OCN ocean wind field (OWI) product for offshore wind resource assessments. The SAR data were compared to in situ observations and three reanalysis products: the global reanalysis ERA5 and two regional reanalyses CARRA and NORA3. This case study matches 238 scenes from 2022 for the Goliat station, an oil platform located 85 km northwest of Hammerfest in the Barents Sea, where a new offshore wind park has been proposed. The analysis showed that despite their unique limitations in spatial and temporal resolutions, all data sources have similar statistical properties (RMSE, correlation coefficient, and standard deviation). The Weibull parameters characterizing the wind speed distributions showed strong similarities between the Sentinel-1 and all reanalysis data. The Weibull parameters of the in situ measurements showed an underestimation of wind speed compared to all other sources. Comparing the full reanalysis datasets with the subsets matching the SAR scenes, only slight changes in Weibull parameters were found, indicating that, despite its low temporal resolution, the Sentinel-1 Level 2 OWI product can compete with the more commonly used reanalysis products in the estimation of offshore wind resources. Its high spatial resolution, which is unmatched by other methods, renders it especially valuable in offshore areas close to complex coastlines and in resolving weather events at a smaller scale.

Pristine biomarker compositions recovered from biodegraded oil samples using MSSV-Hy

Oil-source and oil-oil correlations are challenging when the primary chemical composition of petroleum was altered or destroyed by biodegradation. Biomarkers that are bound to macromolecular matrices rather than being in a free form are largely protected from alteration and may therefore offer a solution to the challenges. Using Microscale Sealed Vessel Catalytic Hydrogenation (MSSV-Hy), the bound biomarkers of two North Sea and two Barents Sea oil samples, with varying levels of biodegradation, were released from their respective asphaltenes. Despite biodegradation having changed the relative concentrations of steranes (C27–C30 steranes) and hopanes (C29–C30 hopanes) in the free biomarker fraction to varying degrees, the asphaltene-bound biomarkers were protected and show pristine ratios unaffected by biodegradation, e.g., the relative content of C27–C29 steranes, the C30/C29 sterane ratio, and the C29/C30 hopane ratio. Empirical calibration then allows these bound biomarkers to be converted into regular biomarker ratios. The MSSV-Hy technique has been shown to be an efficient and effective tool for releasing asphaltene-bound biomarkers from biodegraded oil and revealing genetic information when free biomarkers are altered by biodegradation.

Using the tectophase conceptual model to assess late Triassic–Early Jurassic far-field tectonism across the South-central Barents Sea shelf

The Upper Triassic–Lower Jurassic succession of the Barents Sea Shelf (BSS) represents one of Europe’s most prolific and strategic petroleum systems. This succession reflects various depositional environments and tectonostratigraphic events. Even though these strata are considered largely well-understood, connections with far-field stresses triggered by regional tectonics remain a subject of investigation. This study presents new interpretations that focus on relationships between the stratigraphic succession across the south-central BSS and Triassic–Jurassic Novaya Zemlya compressional tectonics. By applying the “tectophase model,” developed in the Appalachian Basin, to analyze this succession, the presence of foreland-basin depozones and associated far-field processes related to compressional tectonics in an adjacent orogen are suggested. This model addresses unconformity development, lithostratigraphic succession, and reactivation of structures. Use of this model suggests far-field tectonostratigraphic responses during two episodes of Novaya Zemlya tectonism, reflected in the coeval BSS stratigraphy. Overall, this tectonostratigraphic study aligns with other research suggesting a Late Triassic inception for Novaya Zemlya compressional tectonism, which influenced larger parts of the BSS through extensive clastic sedimentation, far-field structural reactivation, and flexural responses to deformational loading triggered by tectonics.

Fatty Acids in the Eggs of Red King Crabs from the Barents Sea.

The red king crab, Paralithodes camtschaticus, was introduced into the Barents Sea where, after a period of 30 years of adaptation, it has established a new population. This population has been commercially exploited over the past two decades, supporting profitable fisheries in both Russia and Norway. Biochemical studies aimed at assessing fatty acid profiles have been conducted, focusing primarily on the edible parts of red king crabs. Only recently have by-products been included in this research. Capture of female red king crabs is prohibited in Russia but is allowed in Norway. The fatty acids of the egg masses carried by these females have not yet been studied. To fill this knowledge gap, we assayed the fatty acid composition of eggs using gas-liquid chromatography. Our results showed a predominance of polyunsaturated fatty acids, while the concentrations of saturated and monounsaturated fatty acids were similar. Multivariate comparisons showed no significant differences in fatty acid profiles in terms of egg developmental stage (nauplius vs. metanauplius), habitat conditions (soft vs. hard bottoms), female size class, or number of autotomized limbs. However, individual comparisons showed some differences in fatty acids, the most important being the lower content of docosahexaenoic acid in eggs at the metanauplius stage compared to eggs at the nauplius stage, which is likely due to its essential role in the development of red king crab embryos. The total fatty acid content (53.94 mg g-1) was 2-87 times higher in eggs than in other red king crab tissues, confirming the critical role that fatty acids play in maintaining physiological processes during vitellogenesis. The high content of essential fatty acids and an optimal omega-3-to-omega-6 ratio (4.9) suggest that red king crab eggs are a good product for a healthy diet and a valuable source for extracting essential fatty acids.

First Record of Sarsia tubulosa (M. Sars, 1835) (Cnidaria, Hydrozoa) on Red King Crabs in the Coastal Barents Sea

Sarsia tubulosa (M. Sars, 1835), a colonial hydrozoan of the family Corynidae, is common in the Barents Sea. This study provides new evidence that the species acts as an epibiont of the red king crab Paralithodes camtschaticus, a non-indigenous but remarkably abundant decapod crustacean of immense commercial value in the coastal regions of the sea. This finding adds to the current collection of identified epibionts on the red king crab and highlights the prospect of ongoing symbiotic relationships between the crab and the regional fauna. We also provide photographic evidence of S. tubulosa colonies and a comparative morphological evaluation with another closely related corynid, Coryne hincksi Bonnevie, 1898, previously found on the red king crab. The main differences between these two species are the location of the gonophores (reproductive organs) on the hydranths and the final stage of their development: in the form of free-floating medusae (S. tubulosa) or remaining sessile as sporosacs (C. hincksi). Other distinguishing features include variations in hydranth morphology, number and arrangement of tentacles, and structural development of gonophores.

Mercury content in commercial crustaceans of the Barents Sea

This study aims to identify the total mercury content in the muscle and hepatopancreas of the main commercial crustaceans from the Barents Sea.The material for this study was the samples of red king crab Paralithodes camtschaticus and northern shrimp Pandalus borealis caught during the research cruises conducted by “PINRO” from 2012 to 2022. This study examines the samples of muscle collected from crustaceans, as well as the samples of hepatopancreas collected from the red king crab.Novelty: This study involves abundant data that was used to make the first comparative analysis of the Hg concentration in red king crab and northern shrimp. A significant similarity in the levels of Hg content in the muscle of shrimp and crab at the mean level was shown. The paper provides maps of average Hg content in the studied species for the entire Barents Sea.Methods used: the total mercury content in the samples was estimated by flameless atomic absorption spectroscopy analysis using Shimadzu Cold Vapor Atomic Absorption Spectrophotometer (Japan). Statistical data processing and charting were done using MS Excel and application software package of Statistica 13.Results: The paper shows that the average concentration of Hg in the muscle and hepatopancreas of the studied hydrobionts did not exceed 0.2 mg/kg of wet weight that is the acceptable concentration established by sanitary standards. The content of Hg in the red king crab’ hepatopancreas was about 2 times higher than in the muscle. The paper makes an assumption on the species-specifity of Hg content in the red king crab’ muscle. The Hg content in the muscle of P. borealis is strongly related to its fattiness. The paper suggests calculated background levels of the total Hg concentration in the muscle of P. camtschaticus and P. borealis from the Barents Sea.Practical relevance: The results obtained were used to establish the safety compliance of commercial crustaceans with the requirements adopted in Russia.

Ascophyllum nodosum (Linnaeus) Le Jolis from Arctic: Its Biochemical Composition, Antiradical Potential, and Human Health Risk.

Ascophyllum nodosum is a brown seaweed common in Arctic tidal waters. We have collected A. nodosum samples from the Barents Sea (BS), Irminger Sea (IS), and Norwegian Sea (NS) in different reproductive stages and have evaluated their biochemical composition, radical scavenging potential, and health risks. The total content of dominating carbohydrates (fucoidan, mannitol, alginate, and laminaran) ranged from 347 mg/g DW in NS to 528 mg/g DW in BS. The proportion of two main structural monosaccharides of fucoidan (fucose and xylose) differed significantly between the seas and reproductive phase, reaching a maximum at the fertile phase in the BS sample. Polyphenols and flavonoids totals were highest in NS A. nodosum samples and increased on average in the following order: BS < IS < NS. A positive correlation of free radical scavenging activity for seaweed extracts with polyphenols content was observed. The concentration of elements in A. nodosum from the Arctic seas region was in the following order: Ca > Mg > Sr > Fe > Al > Zn > As total > Rb > Mn > Ba > Cu > Co. Seaweeds from BS had the lowest metal pollution index (MPI) of 38.4. A. nodosum from IS had the highest MPI of 83. According to the calculated target hazard quotient (THQ) and hazard index (HI) values, Arctic A. nodosum samples pose no carcinogenic risk to adult and child health and are safe for regular consumption. Our results suggest that the Arctic A. nodosum has a remarkable potential for food and pharmaceutical industries as an underestimated source of polysaccharides, polyphenols, and flavonoids.

Estimating of the maximum life expectancy and natural mortality of the red king crab on the example of the Barents Sea population

The purpose of the study is to establish the maximum life span (tmax) and natural mortality (M) in commercial Lithodidae using the example of the red king crab Paralithodes camtschaticus.Material and methods — after the introduction of P. camtschaticus into the Barents Sea in 1969, the dynamics of the maximum carapace width (CWmax) from the first crab catches in 1974 to 2022 was considered. The data of the authors’ own observations and the results of studies from the open press were used.Results. The retrospective dynamics of the maximum size of crabs for older ages for 1974–2022 is presented. The maximum sizes were established: in males CWmax 280–312 and 298 mm was in 2002 and 2003, and in females CWmax 210–220 mm in 1995, 1998 and in a later period.New data. Based on the fifty-year dynamics of CWmax, it was suggested that after the end of the acclimatization of P. camtschaticus in 1969, the first generation of local juveniles appeared in the area of introduction in the early 1970s; in the absence of fishing, these juveniles were able to freely reach the maximum historical size and maximum age. Males caught in 2002–2003 with CWmax 280–312 mm, could have been 30–33 years old (mean 31 years), and the age of females in 1995 with CWmax 210 mm was 20–25 years (mean 23 years). This age limit of crabs allows us to establish a natural mortality according to the formula М=3/tmax for crabs with CW ≥70–90 mm, when their natural elimination is minimal. In this case, the decrease in M in males will be 10% per year, and in females 13%.Practical significance. To estimate the commercial stock of P. camtschaticus, the values of natural mortality used today are 1.8–2.3 times higher than M established by tmax for this species in the Barents Sea. The use of a double overestimated value of M in model calculations leads to a decrease in the commercial stock of crab and, as a consequence, to a decrease in its total allowable catch.

To the assessment of green sea urchin stocks in the coastal zone of the Barents Sea

The purpose of the work is to assessment the state of stocks of the green sea urchin (Strongylocentrotus droebachiensis) in the coastal zone of the Barents Sea.Methods used — to achieve the set goal, standard methods for collecting hydrobiological material and calculating the abundance and biomass of hydrobionts were used.Novelty — the data obtained as a result of the research made it possible to update information on the state of the green sea urchin stocks on the coasts of Western and Eastern Murman.Results — the total and commercial reserves of sea urchin were determined on an area of 2812 thousand m2. The total stock of sea urchins was 3.58 thousand tons, the commercial one — 2.17 thousand tons. The total density of urchins in the studied water area was 32 specimens/m², the commercial one — 10.3 specimens/m². The most promising areas for fishing have been identified.Practical significance — thanks to the use of the research results, adding them to materials from other sources, it will be possible to more accurately predict the volumes and timing of fishing. Mining companies will receive more complete information about promising fishing areas and possible catch volumes.

To the History of Reindeer and Reindeer Husbandry in Eastern Fennoscandia

The hypotheses of the reindeer appearance in Eastern Fennoscandia are discussed. Probably, reindeer appeared in the south of the Scandinavian Peninsula and then moved along the coast of the Norwegian Sea. Further, it dispersed along the Barents Sea to the north of Finland and to the northwest of the Kola Peninsula. The occupancy of the central and northeastern parts of the Kola Peninsula, apparently, took place along the mainland of the peninsula, fi rst in the southern and then in the eastern direction. Forest reindeer entered Eastern Fennoscandia 8–9 thousand years ago: fi rst in central Karelia, much later in Finland, and, possibly, to the south of the Kola Peninsula (Siivonen, 1979; Rankama, Ukkonen, 2001). Currently, Eastern Fennoscandia is inhabited by three subspecies of reindeer: European tundra deer (Rangifer tarandus tarandus (L.)), forest reindeer (Rangifer tarandus fennicus Lönnb.), and Siberian tundra reindeer (Rangifer tarandus sibiricus (L.)) appeared here in 1887 with the arrival of reindeer herders from the Bolshezemelskaya tundra. The existence of wild reindeer in Fennoscandia is closely related to domestic reindeer husbandry. Reindeer husbandry severely limited the distribution of the wild form, and as a result, the European tundra reindeer survived in Fennoscandia in the form of geographically isolated pockets of various sizes only in Norway and on the Kola Peninsula. Genetic studies have shown that, despite the longterm coexistence of the domesticated tundra reindeer and the native wild form in the eastern part of the Kola Peninsula, the wild reindeer preserved his genetic uniqueness. To the south, in Karelia, the main tasks now should be the protection and restoration of wild forest reindeer

Sea Ice and Cloud Processes Mediating Compensation between Atmospheric and Oceanic Meridional Heat Transports across the CMIP6 Preindustrial Control Experiment

Abstract Bjerknes compensation (BJC) refers to the anticorrelation observed between atmospheric and oceanic heat transport (AHT/OHT) variability, particularly on decadal to longer time scales that may be important to the predictability of the climate system. This study investigates the spread in BJC across fully coupled simulations of phase 6 of the Coupled Model Intercomparison Project (CMIP6) and critical processes (particularly related to sea ice and clouds) that may contribute to that spread. BJC on decadal to longer time scales is confirmed across all the simulations evaluated, and it is strongest in the Northern Hemisphere (NH) between 60° and 70°N. At these latitudes, BJC appears to be primarily driven by the exchange of turbulent fluxes (sensible and latent) in the Greenland, Iceland, and Barents Seas. Metrics to break down how sea ice and clouds uniquely modify the radiative balance of the polar atmosphere during anomalous OHT events are presented. These metrics quantify the impacts of sea ice and clouds on surface and top of atmosphere (latent, sensible, longwave, and shortwave radiative) energy fluxes. Cloud responses tend to counter the clear sky impacts over the Marginal Ice Zone (MIZ). It is further shown that the degree of BJC present in a simulation at high latitudes is heavily influenced by the sensitivity of the sea ice to OHT, which is most influential over the MIZ. These results are qualitatively robust across models and explain the intermodel spread in NH BJC in the preindustrial control experiment.

The behaviour of aluminium, manganese, iron, cobalt, and lead in the subarctic Pacific Ocean: boundary scavenging and temporal changes

AbstractAluminium (Al), manganese (Mn), iron (Fe), cobalt (Co), and lead (Pb) are trace metals that exhibit significant scavenging tendencies in the oceans. This study presents the full-depth distributions of the dissolved (d) and labile particulate (lp) fractions of these five elements in the subarctic Pacific Ocean, obtained during the GEOTRACES Japan KH-17-3 cruise. Along the 145° W meridional transect, the d and lp species of Al, Mn, Fe, and Co reflected fluvial supply from Alaska and benthic input from the continental shelf. We estimated that the boundary-scavenging zone has a width of approximately 250 km off Alaska. Along the 47° N zonal transect (GEOTRACES GP02 Line), we found input of trace metals from the Okhotsk and Bering Seas in the west, contrasting to the limited input of trace metals due to boundary scavenging in the east. The hydrothermal activity of the Juan de Fuca Ridge influenced the distribution of deep-water trace metals at the easternmost station, CL-21. Temporal change in the vertical profiles of dPb in the middle of the subarctic gyre highlighted a decline in anthropogenic Pb emissions from 2005 to 2017. Temporal change of the vertical profiles of Al, Mn, and Fe at 47° N, 160° E from 2011 to 2017 indicates the influence of the Great East Japan Earthquake. In particular, lp trace metals were brought by tsunami and ocean circulation in 2011, and decreased over time through scavenging.

Are state-space stock assessment model confidence intervals accurate? Case studies with SAM and Barents Sea stocks

Our main contribution is to examine the reliability of confidence intervals using the SAM state-space fish stock assessment model used for the assessment of many stocks by the International Council for the Exploration of the Seas. We focus on frequentist statistical inferences and more specifically on inference conditioned on specific values of the state-space model random effects drawn from their process distribution. This is somewhat consistent with simulation self-test procedures that are commonly used to examine the reliability of state-space assessment model results. However, recent research has indicated that some estimation bias may be expected in the conditional setting. Hence, we also investigate recently proposed bias corrected confidence intervals appropriate for the conditional inference setting. The SAM simulation coverage probabilities of 95% confidence intervals for SSB and Fbar were usually slightly larger than 95%, but in a small number of years these coverage probabilities could be much smaller than 95%. The bias corrected confidence intervals were more reliable. When averaged over years, the SAM and bias corrected confidence interval coverage probabilities were similar for the Northeast Artic cod and saithe case studies, but the bias corrected confidence intervals performed much better overall for the haddock case study.

A FEM Flow Impact Acoustic Model Applied to Rapid Computation of Ocean-Acoustic Remote Sensing in Mesoscale Eddy Seas

Mesoscale eddies have an impact on the marine environment mainly in two areas, namely, currents and changes in the sound velocity gradient due to temperature and salt stirring. The traditional underwater-related remote sensing acoustic remote sensing model is capable of analyzing the acoustic field under the change in sound velocity gradient, but it is not capable of analyzing the acoustic field under the influence of ocean currents. In order to more effectively analyze the changes in the acoustic field caused by mesoscale eddies, this paper proposes a FEM flow impact model applied to the rapid computation of acoustic remote sensing of mesoscale eddies in the sea area. The algorithm first performs a grid optimization of the sea area model based on vertical sound velocity variations and completes the classification of sound velocity layer junctions. At the same time, we construct the sound velocity gradient environment affected by the mesoscale eddy and then simplify the fluid flow in the mesoscale eddy into a non-viscous and non-rotating velocity potential, and then participate in the solution of the three-dimensional spatial fluctuation equations in the form of time-harmonic in the frequency domain, from which we can obtain the truncated sound pressure as well as the propagation loss, and quickly and completely characterize the acoustic remote sensing of the sea area of the mesoscale eddy. The paper verifies the effectiveness of the algorithm through SW06-contained flow experiments and further proposes an optimization formula for sound velocity inversion. We analyze this using measured data of mesoscale eddy fields in the Bering Sea waters during 2022 and find that eddies have a greater effect on the propagation of the acoustic field along their flow direction.

Size-fractioned zooplankton biomass in the Barents Sea: macroecological patterns across biogeography, climate, and varying ecosystem state (1989-2020)

The zooplankton community in the Barents Sea was monitored during autumn cruises from 1989-2020, with biomass determined as the depth-integrated dry weight (g m-2) of 3 size fractions (&gt;2 mm, 1-2 mm, &lt;1 mm). A large data set of 4543 sampling stations encompassing a subdivision of the Barents Sea was spatially averaged into 15 polygons based on topography. The resulting data set is used to describe relationships between the biomass of size fractions as expressions of the size structure of the zooplankton communities. Each of the 3 size fractions was positively related to the total zooplankton biomass (sum of fractions). The medium size fraction, which contained on average 48% of the total biomass, showed a strong linear correlation with total biomass (R2 ≈ 0.8). The medium fraction contained the older copepodite stages of Calanus species (C. finmarchicus and C. glacialis), which are dominant species interpreted to drive the overall changes in zooplankton biomass. The biomass of the small size fraction decreased with decreasing total biomass, but less so than the medium fraction. Thus, the small/medium biomass ratio increased as the total biomass decreased. This trend was most pronounced for shallow and central polygons, which coincide with the core feeding area of the large Barents Sea stock of capelin Mallotus villosus. The change in the small/medium biomass ratio is interpreted to reflect a shift from Calanus to smaller zooplankton in response to predation by capelin and other planktivorous predators, and possibly also by warming due to climate change.

Amino Acid Composition in Different Tissues of Iceland Scallop from the Barents Sea.

The Iceland scallop from the Barents Sea is a commercially important species with promising aquaculture potential, but information on the biochemical properties of its tissues is limited. Our analysis of the adductor muscle, gonad, and mantle of this bivalve mollusk from coastal waters provided insight into its amino acid composition. Biochemical analysis revealed predominant levels of glycine (11.8, 11.5, and 9.6 mg g-1, respectively) and arginine (11.2, 8.3, and 5.8 mg g-1, respectively). While multivariate comparisons did not reveal significant differences in amino acid composition between the tissues, single comparisons showed significantly higher levels of arginine and leucine in the adductor muscle compared to those of the mantle. The abundant presence of glycine and arginine underscores their importance in maintaining basic physiological processes, consistent with other scallop species. Redundancy analysis identified water depth and scallop gonad index as influential factors shaping the amino acid profile in the adductor muscle. In the case of the mantle, water temperature emerged as the main driver of amino acid content. Our results confirm the richness of essential amino acids in scallop by-products and highlight their potential for human consumption, production of feed ingredients for farmed animals, and nutraceuticals.