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EcoQS assessment of the marine intertidal zone based on its fauna is challenging because the assemblages have a low diversity and consist of stress tolerant species. The new approach we propose is to pool foraminiferal diversity (effective number of species exp(H' bc)) across the whole intertidal zone including the salt marsh and tidal flat. In seven fjordheads studied in northern Fennoscandia, polycyclic aromatic hydrocarbon (PAH) concentrations indicated low levels of pollution (EcoQS PAH Excellent to Moderate). Jadammina or Balticammina dominated the salt marsh, Elphidium albiumbilicatum, Elphidium williamsoni, Elphidium clavatum, and Buccella frigida occurred in the tidal flat. Ovammina opaca thrived in both belts. While foraminiferal test abnormalities are often proposed to measure pollution impacts, we did not detect any correlation with PAHs. EcoQS based on foraminiferal diversity (EcoQS foram Excellent to Good) matched EcoQS based on PAHs suggesting that pooled foraminiferal diversity reliably measures intertidal EcoQS. • New approach to assess EcoQS in intertidal zone inhabited by stress tolerant taxa. • PAH levels and pooled foraminiferal diversity give matching EcoQS estimates. • Sediment PAH concentrations unrelated to foraminiferal shell deformities. [ABSTRACT FROM AUTHOR]

Marine pollution by lost, abandoned or otherwise discarded fishing gear (ALDFG) often has negative impact on the ecosystem through plastic pollution and continuous capture of marine animals, so-called "ghost fishing". ALDFG in pot fisheries is associated with high ghost fishing risk. The snow crab (Chionoecetes opilio) pot fishery is conducted in harsh weather conditions increasing the risk of fishing gear loss. Due to plastic materials used in the pot construction, lost gear can most likely continue fishing for decades. This study presents a method to quantify ghost fishing efficiency relative to catch efficiency of actively fished pots. On average, the ghost fishing pots captured 8.29 % (confidence intervals: 4.33–13.73 %) target-sized snow crab compared to the actively fished pots, demonstrating that lost pots can continue fishing even when the bait is decayed. Given the large number of pots lost each year, the ghost fishing efficiency is a considerable challenge in this fishery. • Marine pollution by fishing gear can result in plastic pollution and ghost fishing. • Pot fisheries are associated with high ghost fishing risk. • The potential for pots to continue ghost fishing is unknown. • Ghost fishing pots retain 8 % target-sized snow crab compared to actively fished pots. • Ghost fishing is a considerable environmental and ecological challenge. [ABSTRACT FROM AUTHOR]

Offshore drilling operations result in the generation of drill cuttings and localized smothering of the benthic habitats. This study explores bacterial community changes in the in the upper layers of the seafloor resulting from an exploratory drilling operation at 1400 m water depth on the Barents Sea continental slope. Significant restructurings of the sediment microbiota were restricted to the sampling sites notably affected by the drilling waste discharge, i.e. at 30 m and 50 m distances from the drilling location, and to the upper 2 cm of the seafloor. Three bacterial groups, the orders Clostridiales and Desulfuromonadales and the class Mollicutes , were almost exclusively confined to the upper two centimeters at 30 m distance, thereby corroborating an observed increase in anaerobicity inflicted by the drilling waste deposition. The potential of these phylogenetic groups as microbial bioindicators of the spatial extent and persistence of drilling waste discharge should be further explored. [ABSTRACT FROM AUTHOR]

It has been proposed that the multiple pressures of fishing and petroleum activities impact fish stocks in synergy, as fishing-induced demographic changes in a stock may lead to increased sensitivity to detrimental effects of acute oil spills. High fishing pressure may erode the demographic structure of fish stocks, lead to less diverse spawning strategies, and more concentrated distributions of offspring in space and time. Hence an oil spill may potentially hit a larger fraction of a year-class of offspring. Such a link between demographic structure and egg distribution was recently demonstrated for the Northeast Arctic stock of Atlantic cod for years 1959–1993. We here estimate that this variation translates into a two-fold variation in the maximal proportion of cod eggs potentially exposed to a large oil spill. With this information it is possible to quantitatively account for demographic structure in prospective studies of population effects of possible oil spills. [ABSTRACT FROM AUTHOR]

Litter has been found in all marine environments and is accumulating in seabirds and mammals in the Nordic Seas. These ecosystems are under pressure from climatic change and fisheries while the human population is small. The marine landscapes in the area range from shallow fishing banks to deep-sea canyons. We present density, distribution and composition of litter from the first large-scale mapping of sea bed litter in arctic and subarctic waters. Litter was registered from 1778 video transects, of which 27% contained litter. The background density of litter in the Barents Sea and Norwegian Sea is 202 and 279 items/km 2 respectively, and highest densities were found close to coast and in canyons. Most of the litter originated from the fishing industry and plastic was the second most common litter. Background levels were comparable to European records and areas with most littering had higher densities than in Europe. [ABSTRACT FROM AUTHOR]

The concentrations and composition of hydrocarbons - HCs (aliphatic - AHCs and polycyclic aromatic hydrocarbons - PAHs) in the Barents and Kara Seas (cruises 80, 83 and 89 of the R/V «Akademik Mstislav Keldysh», August 2020, June 2021, September 2022 respectively) are analyzed in the paper. The concentrations of the HC dissolved and suspended forms were measured in the surface microlayer (SML, 100–1000 μm thick), melting ice and surface waters. Higher concentration of HCs in SML was found in suspended particulate matter (SPM). AHC concentration in SPM in the Barents Sea were lower (31–96, on average 68 μg/L) than in the Kara Sea in June 2021 (187–1051, 573 μg/L on average), where the studies were carried out in the early summer season. The concentrations of AHCs in the SPM in the SML of the Kara Sea were 3.6 times higher than in the dissolved form (127–217, on average 187 μg/L), and they were almost 15 times higher than those in the surface waters. The accumulation of organic compounds also occurs in ice, but to a lesser extent than in the SML. The composition of alkanes in SML and melting ice mainly indicates the slight influence of autochthonous processes shaping HCs. The average content of PAHs in SPM was also 4.8 times higher than that in the dissolved form. According to the markers, the influence of combustion products of marine fuel was traced in the composition of PAHs. In September 2022, AHC and PAH concentrations in the Kara Sea were lower than in June 2021: on average, 159 μg/L and 492 ng/L accordingly, that is due to a decrease in the content of SPM from an average of 1.89 to 1.21 mg/L. [Display omitted] • Hydrocarbons (HCs) accumulate in the surface microlayer. • The accumulation of hydrophobic AHCs and PAHs in SML occurs in a suspended form. • The HCs content in SML is influenced by the study season. • Anthropogenic oil HCs were not found in the open waters of the Barents and Kara seas. [ABSTRACT FROM AUTHOR]

The effects of oil spills on marine biological systems are of great concern, especially in regions with high biological production of harvested resources such as in the Northeastern Atlantic. The scientific studies of the impact of oil spills on fish stocks tend to ignore that spatial patterns of natural mortality may influence the magnitude of the impact over time. Here, we first illustrate how spatial variation in natural mortality may affect the population impact by considering a thought experiment. Second, we consider an empirically based example of Northeast Arctic cod to extend the concept to a realistic setting. Finally, we present a scenario-based investigation of how the degree of spatial variation in natural mortality affects the impact over a gradient of oil spill sizes. Including the effects of spatial variations in natural mortality tends to widen the impact distribution, hence increasing the probability of both high and low impact events. [ABSTRACT FROM AUTHOR]

This article is devoted to the study of the activity of technogenic 137Cs and 90Sr, as well as natural radionuclides 40K, 232Th and 226Ra in bottom sediments of the Kola coast of the Barents Sea, where a significant number of radiation objects are concentrated. In order to characterize and assess the accumulation of radioactivity in the bottom sediments, we studied the particle size distribution and some physicochemical parameters, such as the content of organic matter, carbonates and ash components. The average activities of natural radionuclides 226Ra, 232Th and 40K were 325.0, 25.1 and 466.7 Bq·kg−1, respectively. Levels of natural radionuclides in the coastal zone of the Kola Peninsula are within the range of marine sediments worldwide. Still, they are slightly higher than those observed in the central areas of the Barents Sea, most likely due to the formation of coastal bottom sediments as a result of the destruction of the natural radionuclide-enriched crystalline basement rocks that make up the Kola coast. The average activities of technogenic 90Sr and 137Cs in the bottom sediments of the Kola coast of the Barents Sea are 3.5 and 5.5 Bq·kg−1, respectively. The highest activities of 90Sr and 137Cs were found in the bays of the Kola coast, while they remain below detection limits in the open parts of the Barents Sea. Despite the presence of potential sources of radiation pollution in the coastal zone of the Barents Sea, we did not find any short-lived radionuclides in the bottom sediments, which indicates the absence of a significant influence of local sources on the transformation of the technogenic radiation background. The study of particle size distribution and physicochemical parameters showed that the accumulation of natural radionuclides is largely related to the content of organic matter and carbonates, while the accumulation of technogenic isotopes occurs in the composition of organic matter and the smallest fractions of bottom sediments. • Levels of natural and anthropogenic radionuclides in the bottom sediments from coastal area of the Barents Sea were analyzed. • Activities of technogenic radionuclides are low. • The highest activities of 90Sr and 137Cs were found in the bays. • The current influence of local radiation sources was not found. [ABSTRACT FROM AUTHOR]

Marine sediment is a significant sink for the global pollutant mercury. In a rapidly changing Arctic region, mercury (Hg) bioaccumulation in the marine ecosystem remains a prominent environmental issue. Here, we report surface sediment (0–2 cm) concentrations of Hg and other toxic elements of interest (Cr, Ni, Zn, Cu, As, Cd, Pb) in the northern Barents Sea and Eurasian Basin. We observed average Hg concentrations of 65 ± 23 ng/g with the highest concentration of 116 ng/g in the Eurasian Basin. Our calculated enrichment factors suggest low anthropogenic enrichment for mercury, chromium, nickel, and copper. Mercury and trace element geographic patterns are best explained by the origin and transportation of fine grain sediment towards the Eurasian Basin, with scavenging by both particulate organic carbon and metal oxides as significant delivery mechanisms. • Mercury concentration in surface sediment ranged from 21 to 116 ng/g • Higher concentrations of Co, Cu, Hg, Pb in Eurasian Basin • Metal distributions most likely reflect scavenging processes and redox conditions. • Normalized Hg positively correlated to Mn, Co, Cu, Pb [ABSTRACT FROM AUTHOR]

Highlights: [•] Livers of cod from the Barents Sea have been analysed for dioxins, PCBs and PBDEs. [•] The overall mean concentration of dioxins and DL-PCBs was 14.2ng TEQWHO-2005/kgww. [•] The concentrations of dioxins and DL-PCBs varied between 1.0 and 151ng TEQ/kgww. [•] 20% of the samples had concentrations higher than 20ng TEQ/kgww. [•] The highest concentrations of dioxins and PCB were found in samples from the east area of the Barents Sea. [Copyright &y& Elsevier]

Abstract: This study is one of several baseline studies that will provide basic and reliable information about the content of undesirable substances in important species of fish caught in Norwegian waters. Concentrations of metals in the muscle and liver of more than 800 Northeast Arctic cod caught at 32 sites in the Barents Sea are reported. The highest concentration of both mercury in the muscle and cadmium in the liver was found in cod caught in the western part of the Barents Sea, while the highest concentration of total arsenic was found in cod from the eastern part. The arsenic concentrations varied greatly among individual fish, ranging from 0.3 to 170mgkg−1 wet weight in the muscle. Such high levels of total arsenic have never previously been reported in any fish, and the primary factor for these high concentrations is likely to be the shrimp in the cod diet. [Copyright &y& Elsevier]

Abstract: This paper compares the ignitability of Troll B crude oil weathered under simulated Arctic conditions (0%, 50% and 90% ice cover). The experiments were performed in different scales at SINTEF’s laboratories in Trondheim, field research station on Svalbard and in broken ice (70–90% ice cover) in the Barents Sea. Samples from the weathering experiments were tested for ignitability using the same laboratory burning cell. The measured ignitability from the experiments in these different scales showed a good agreement for samples with similar weathering. The ice conditions clearly affected the weathering process, and 70% ice or more reduces the weathering and allows a longer time window for in situ burning. The results from the Barents Sea revealed that weathering and ignitability can vary within an oil slick. This field use of the burning cell demonstrated that it can be used as an operational tool to monitor the ignitability of oil spills. [Copyright &y& Elsevier]

Abstract: Environmental monitoring is performed on seafloor communities since these organisms are relatively stationary and integrate the environmental conditions over many years. Standard practices involve sampling by grab. Epifaunal taxa, often missed by grab sampling, are likely to have different ecological functions. We investigate how current environmental assessments represent the benthic community as a whole by comparing taxonomic and functional components sampled by grabs and epibenthic trawls. Faunal communities sampled by trawl (filtrating or predator, epifauna) and grab (infaunal, detrivore) differs widely by sampling distinct functional components, and these may be expected to respond to different human-induced stressors. Neither component appears to be a good surrogate for the community as a whole. We suggest a benthic monitoring by combining both techniques. Sustainable ecosystem functioning is intimately tied to the health of both components of the benthic community, and is recognized as an important goal by signatories of the Convention on Biological Diversity. [Copyright &y& Elsevier]

Abstract: A large-scale field experiment took place in the marginal ice zone in the Barents Sea in May 2009. Fresh oil (7000L) was released uncontained between the ice floes to study oil weathering and spreading in ice and surface water. A detailed monitoring of oil-in-water and ice interactions was performed throughout the six-day experiment. In addition, meteorological and oceanographic data were recorded for monitoring of the wind speed and direction, air temperature, currents and ice floe movements. The monitoring showed low concentrations of dissolved hydrocarbons and the predicted acute toxicity indicated that the acute toxicity was low. The ice field drifted nearly 80km during the experimental period, and although the oil drifted with the ice, it remained contained between the ice floes. [Copyright &y& Elsevier]

Abstract: The red king crab Paralithodes camtschaticus was introduced to the Barents Sea from the North Pacific in the 1960s. A previous study concluded that it may be indirectly responsible for increased transmission of Trypanosoma murmanense to cod Gadus morhua in the southern Barents Sea by promoting an increase in the population of the leech vector Johanssonia arctica. Eleven species of fish, totalling 681 individuals, caught in October 2002 along the coast of Finnmark, were examined for trypanosome infections. The aims were to investigate changes in levels of infection in cod since 1999–2001, and to extend the sampling to other fish species. Relatively high infection levels were found in cod, haddock Melanogrammus aeglefinus and long rough dab Hippoglossoides platessoides, while other species were lightly infected or uninfected. In cod, no significant geographical differences in levels of infection were found, but haddock were significantly more heavily infected in western Finnmark. [ABSTRACT FROM AUTHOR]

Abstract: A descriptive study of population structure, growth rates and shell morphometry was conducted on nine intertidal populations of the infaunal bivalve Cerastoderma edule in the Murmansk coast of the Barents Sea. Year-to-year population dynamics was analyzed during 2002–2006 on a tidal flat Dalniy Plaj (eastern Murmansk coast). The region constitutes the northern extremes of C. edule range where populations occupied the middle to low intertidal zone and were characterized by low densities. The distribution of age groups and unstable age structure across years in the cockle populations suggest irregular recruitment. Growth rates and shell morphometry showed little variation across the populations studied, and there were no gradient changes from the west to the east parts of Murmansk coast. [Copyright &y& Elsevier]

Abstract: Mytilus edulis and Chlamys islandica were exposed to nominal dispersed crude oil concentrations in the range 0.015–0.25mg/l for one month. Five biomarkers (enzymatic and cellular responses) were analysed together with bioaccumulation of PAHs at the end of exposure. In both species, PAH tissue residues reflected the exposure concentration measured in the water and lipophylicity determined the bioaccumulation levels. Oil caused biomarker responses in both species but more significant alterations in exposed C. islandica were observed. The relationships between exposure levels and enzymatic responses were apparently complex. The integrated biomarker response related against the exposure levels was U-shaped in both species and no correlation with total PAH body burden was found. For the monitoring of chronic offshore discharges, dose- and time-related events should be evaluated in the selection of biomarkers to apply. From this study, cellular damages appear more fitted than enzymatic responses, transient and more complex to interpret. [Copyright &y& Elsevier]

Abstract: Identifying patterns and drivers of natural variability in populations is necessary to gauge potential effects of climatic change and the expected increases in commercial activities in the Arctic on communities and ecosystems. We analyzed growth rates and shell geochemistry of the circumpolar Greenland smooth cockle, Serripes groenlandicus, from the southern Barents Sea over almost 70 years between 1882 and 1968. The datasets were calibrated via annually-deposited growth lines, and growth, stable isotope (δ18O, δ13C), and trace elemental (Mg, Sr, Ba, Mn) patterns were linked to environmental variations on weekly to decadal scales. Standardized growth indices revealed an oscillatory growth pattern with a multi-year periodicity, which was inversely related to the North Atlantic Oscillation Index (NAO), and positively related to local river discharge. Up to 60% of the annual variability in Ba/Ca could be explained by variations in river discharge at the site closest to the rivers, but the relationship disappeared at a more distant location. Patterns of δ18O, δ13C, and Sr/Ca together provide evidence that bivalve growth ceases at elevated temperatures during the fall and recommences at the coldest temperatures in the early spring, with the implication that food, rather than temperature, is the primary driver of bivalve growth. The multi-proxy approach of combining the annually integrated information from the growth results and higher resolution geochemical results yielded a robust interpretation of biophysical coupling in the region over temporal and spatial scales. We thus demonstrate that sclerochronological proxies can be useful retrospective analytical tools for establishing a baseline of ecosystem variability in assessing potential combined impacts of climatic change and increasing commercial activities on Arctic communities. [Copyright &y& Elsevier]

During a 2018 retrieval cruise for abandoned snow crab (Chionoecetes opilio) pots in the Barents Sea, approximately 8600 pots abandoned 1.5 years earlier were recovered. Forty-three percent of a subsample of 1000 pots contained snow crabs, with an average of three crabs per pot. Most of the crabs were alive (~98%) and dominated by large males. Pinch injuries and limb loss were common and tended to decline with increasing crab size. Reflex testing showed that the crabs were vital (i.e. the crabs moved their legs, chelipeds and maxillipeds when stimulated), which was supported by a relatively high meat content. However, energy reserves in the digestive glands (hepatopancreas reserves) were low, indicating overall energy deficiencies. Our results indicate considerable unaccounted mortality due to self-baiting, continued catch and cannibalism. The findings demonstrate that snow crab pots which are lost or abandoned in the Barents Sea fishery maintain huge potential for ghost-fishing impacts. • Retrieval programs are highly valuable for derelict fishing gear impact studies. • Evaluation of individual of crabs cues the dynamics of the ghost fishing cycle. • Self-baiting, continued catch and cannibalism are likely in lost snow crab pots. • Lost pots have huge potential for ghost fishing; mitigation measures are urgent. [ABSTRACT FROM AUTHOR]

Seals are high trophic level feeders that bioaccumulate many contaminants to a greater degree than most lower trophic level organisms. Their trophic status in the marine food web and wide-spread distribution make seals useful sentinels of arctic environmental change. The purpose of this investigation is to document the levels and bioaccumulation potential of radiocaesium in high latitude seal species for which data have not previously been available. The study was carried out on harp, ringed, and bearded seals caught north of the island archipelago of Svalbard (82°N) in 1999. The results are then compared with previous studies in order to elucidate factors responsible for bioaccumulation in Arctic seals. Concentrations of 137Cs were determined in muscle, liver and kidney samples from a total of 10 juvenile and one adult seal. The mean concentration in muscle samples for all animals was 0.23±0.045 Bq/kg f.w. 137Cs concentrations in both liver and kidney samples were near detection limits (≈0.2 Bq/kg f.w.). The results are consistent with previous studies indicating low levels of radiocaesium in Arctic seals in response to a long term trend of decreasing levels of 137Cs in the Barents Sea region. Bioconcentration factors (BCFs) estimated for seals from NE Svalbard are low, ranging from 34 to 130. Comparing these values with reported BCFs for Greenland seals from other sectors of the European Arctic, we suggest that the combination of physiological and ecological factors on radiocaesium bioaccumulation is comparable among different Arctic seal populations. The application of this work to Arctic monitoring and assessment programs is discussed. [Copyright &y& Elsevier]

Current knowledge of the distribution of sensitive seabirds is inadequate to safeguard seabird populations from impacts of oil spills in the Arctic. This gap is mainly driven by the fact that statistical models applied to survey data are coarse-scale and static with limited documentation of the distributional dynamics and patchiness of seabirds relevant to risk assessments related to oil spills. This paper describes a dynamic modelling framework solution for prediction of fine-scale densities and movements of seabirds in close-to-real time using fully integrated 3-D hydrodynamic models, dynamic habitat suitability models and agent-based models. The modelling framework has been developed and validated for the swimming migration of Brünnich's Guillemot Uria lomvia in the Barents Sea. The results document that the distributional dynamics of Brünnich's Guillemot and other seabird species to a large degree can be simulated with in-situ state variables and patterns reflecting the physical meteorology and oceanography and habitat suitability. • Oil risk assessments are impeded by static and coarse-scale models for seabirds. • Dynamic modelling frameworks can provide high-resolution information. • Solution integrates 3-D hydrodynamic, habitat suitability, and agent-based models. • Validated for the swimming migration of Brünnich's Guillemot in the Barents Sea [ABSTRACT FROM AUTHOR]

The spatial extent and persistence of bacterial change caused by deposition of water-based drill cuttings on the seafloor were explored by a community-wide approach. Ten centimeter sediment cores were sampled along transects extending from ≤15 m to 250 m from three nearby drilling sites in the southern Barents Sea. Eight months, 8 years and 15 years, respectively, had passed since the completion of the drillings. At locations heavily affected by drill cuttings, the two most recent sites showed distinct, corresponding deviances from native Barents Sea bacterial community profiles. Otherwise marginal groups, including Mollicutes and Clostridia, showed significant increases in relative abundance. Beyond 100 m from the boreholes the microbiotas appeared undisturbed, as they did at any distance from the 15-years old borehole. The extent of the biological distortion, as indicated by the present microbial study, agreed with previously published macrofaunal surveys at the same drilling sites. • Water-based drill cuttings affect seafloor bacterial community composition. • Bacterial community changes only observed within 100 m from the drilling site. • The bacterial perturbations may last for more than 8 years after drilling. • A few groups of bacteria, marginal in the native marine sediments, proliferated. [ABSTRACT FROM AUTHOR]

This study is focused on the analysis of microplastic concentrations in the surface waters of the White, Barents and Kara Seas. Sampling took place during the "Arctic Floating University 2018" expedition using a manta trawl. Particularly high concentrations of the microplastics were found off the west coast of Novaya Zemlya archipelago with a maximum in a highly productive region – Gusinaya bank. The microplastic distribution pattern in the Barents Sea correlates both with the oceanic circulation and the fishing activities. The results show the first recorded estimation of microplastic concentrations in the White Sea with the higher concentrations located in the area affected by the Severnaya Dvina River discharge. Relatively low concentrations of microplastics were found in the Kara Sea. • Concentrations of microplastics in regions of the Barents Sea reach subtropical area values. • Severnaya Dvina River possibly plays the main role in the transfer of microplastics to the White Sea. • Kara Sea remains relatively clean, being separated from the Atlantic water inflow. [ABSTRACT FROM AUTHOR]

The article is devoted to the study of the activity values of natural radionuclides 40K, 232Th and 226Ra and technogenic radionuclide 137Cs in the bottom sediments of the Barents Sea, which is distinguished from the rest of the Arctic seas by the fact that the largest number of radiation objects are concentrated here. The activity levels of natural radionuclides were within the range of activity values corresponding to marine sediments around the world. The highest radionuclide activities were found within the deepwater shelf of the Barents Sea. The current level of activity of the technogenic radionuclide 137Cs is low and does not exceed 6.5 Bq·kg−1. However, due to global climatic changes, the secondary source of radiation pollution of the sea may be the Novaya Zemlya ice sheet, in which huge quantities of technogenic radionuclides were deposited during atmospheric tests of the 1950s and 1960s. • Current natural and anthropogenic radionuclide activities in the bottom sediments from the Barents Sea were analyzed. • The current level of activity of the technogenic radionuclide 137Cs is low. • The highest radionuclide activities were found within the deepwater shelf. [ABSTRACT FROM AUTHOR]

We report the ratios of minor (K/Ca, Na/Ca, P/Ca, S/Ca) and trace elements (Al/Ca, Ba/Ca, Fe/Ca, Mn/Ca and Zn/Ca) in skeletons of five Arctic echinoderm species representing three classes: Asteroidea, Ophiuroidea, Crinoidea. We found that skeletons of Arctic echinoderms show a unique, species-specific trace element composition that may suggest that incorporation of elements into the skeleton is biologically controlled by the organism. On the other hand, the concentration of some minor elements in skeletal parts exhibit patterns that are consistent with elemental concentrations in seawater, indicating that formation of echinoderm skeletons is environmentally controlled. Seawater is the main source of ions and compounds needed for skeletal formation and maintaining similar concentrations most likely reduces the biological cost related to selective uptake of ions. Additionally, Al, Ba, Fe, Mg and Mn showed station specific variation in elemental concentration which again suggests that accumulation of metals can be shaped by environmental concentrations. • Skeletons of Arctic echinoderms show species-specific trace element composition. • Incorporation of elements into echinoderm skeleton can be controlled biologically. • Skeletal formation takes place in chemical equilibrium in ambient seawater. • Skeletal accumulation of metals can be shaped by their seawater concentrations. • Food may be a potential source of certain elements accumulated in skeletal tissue. [ABSTRACT FROM AUTHOR]

Using in situ data of 2014–2018, the summers Emiliania huxleyi blooms in the Barents Sea were studied. The blooms were recorded in the upper mixed layer in July and August every year, during which they spread to cover large areas and were associated with Atlantic waters. The E. huxleyi abundance revealed interannual variability, with the highest values (up to 12 × 106 cells/L) in July 2016. Bloom is characterized by a sharp seasonal thermocline, water surface temperature of about 7.14–11.7 °C, low silicate (0.45 ± 0.08 μM) and nitrogen (0.74 ± 0.16 μM) concentration, high phosphorus concentration (0.09 ± 0.01 μM) and nitrogen to phosphorus ratio significantly below the Redfield ratio. Data confirming the hypothesis of limiting the growth of diatoms by nitrogen concentration are presented. When E. huxleyi bloomed, its biomass exceeded 70% of the total phytoplankton biomass, species diversity was low, and diatoms were practically absent, and dinoflagellates were usually represented by large species. • In the Barents Sea, Emiliania huxleyi blooms were recorded in the summer every year from 2014 and 2018. • Low silicon and nitrogen concentrations and N:P ratios are the necessary conditions for the bloom. • Co-occurrence of large dinoflagellates but absence of diatoms is typical for these blooms. [ABSTRACT FROM AUTHOR]

The aim of this study is to identify the environmental impact of drill cuttings (DC) released around three wells drilled in 1992, 2000 and 2012 in the SW Barents Sea. Foraminiferal assemblages are studied in cores taken along transects <250 m from wells. Well E-1992 shows no impact of DC on foraminifera indicating that low amounts of released DC limit environmental impact. Impact at wells G-2000 and S-2012, is confined to <30 m, and attributable to smothering of fauna, resulting in low foraminiferal density. We therefore argue that previous monitoring studies, mainly focusing on samples collected >250 m from wellheads, might not capture the full impact of DC. In well G-2000, a recovery layer indicates partial recovery 15 years after DC releases. In well S-2012, no recovery is observed, 3 years after release. Released DC did not result in faunal composition changes. • Environmental impact of drill cuttings around wells in Barents Sea is investigated. • The environmental impact is confined to <30 m from the wellhead. • Main impact on foraminifera is attributed to smothering of fauna. • No changes in foraminiferal faunal composition due to drill cuttings are observed. • Partial environmental recovery is observed 15 years after release. [ABSTRACT FROM AUTHOR]

The recent intensification of energy resource exploration and human activities in the Barents Sea (BS) requires a more thorough assessment of the natural and anthropogenic impact of hydrocarbons on the environment. We analyzed a wide set of sensitive indicators, including hydrocarbon molecular markers and organic matter (OM) maturity parameters in the Holocene sediments from three regions of the BS: the Kola-Kanin Monocline (KKM), the Svalbard shelf, and the Shtokman gas-condensate field (GCF). An increase in pyrogenic polycyclic aromatic hydrocarbons toward the core surface traces the intensification of anthropogenic contamination in the KKM region during last century. An input of highly mature OM from the eroded coal rocks of Barentsburg were confirmed by comparison of biomarker distribution in sediments and coals. An increase in biogenic hopanes and hopenes content down-core, and a crude-oil stage of OM maturity in surface sediments of the Shtokman GCF attests to hydrocarbons migration from subsurface strata. • Recent sediments from Svalbard Shelf, Shtokman and Kola-Kanin Monocline areas studied • Significant variation in hydrocarbons genesis in the Barents Sea sediments detected • Svalbard sediments show the highest level of organic matter maturity. • In the Shtokman area, molecular marker distributions indicated hydrocarbon migration • Sediment PAH composition of Kola-Kanin Monocline suggested anthropogenic impact. [ABSTRACT FROM AUTHOR]

Evaluates environmental contamination and sources of polycyclic aromatic hydrocarbon compounds (PAH) polluting the White Sea in Russia. Concentration of PAH with six carbon in White Sea and Barent Sea; Role of aluminum smelter in polluting the White Sea; Similarity in composition of PAH compounds found in White Sea and Barents Sea.

The extent of environmental contamination and sources of polycyclic aromatic hydrocarbon (PAH) compounds to sediments of the White Sea are evaluated and compared with previously published results for adjacent Arctic Sea areas. Concentrations of two- to six-ring PAHs of molecular mass 128/278 including perylene and sediment characteristics areconsidered in this investigation. Mean Sigma PAH concentration was 61+/-34 ng/g dw (n=11) for all samples and 87+/-43 ng/g dw (n=6) for pelite-rich samples (>83% pelite). These concentrations are 2/3 times lower than were previously reported for the SE Barents Sea. Concentrations of Sigma PAH and Sigma CPAH in the central White Sea have increased by a factor of 2-5 over pre-industrial background levels based on 210Pb age-dating of one sediment core. Using principal component analysis (PCA), two common factors explained 87.5% of the total variance for the White Sea data. Factor 1 is associated with high-temperature combustion processes and is related to emissions from a local aluminium smelter. Factor 2 is associated mainly with the introduction of petrogenic PAH compounds and perylene into Dvina Bay via the Severnaya Dvina River. A comparison of the White Sea and SE Barents Sea data indicates that similarities exist in the composition of parent PAH compounds. However, based on a comparative analysis of parent PAH ratios and relative contents of alkyl-substituted homologues, acommon atmospheric source of anthropogenic pollutants can be ruled out. Further investigations are needed to determine whether sedimentary PAH signatures in areas of the Barents Sea that are in closer proximity to the White Sea are related to emissions from the aluminium smelter. [ABSTRACT FROM AUTHOR]

On data of the Barents Sea and some regions of the Kara, White, Norwegian and Greenland Seas transregional study, carried out in 1991-1992, concentrations of various contaminants in benthic algae and invertebrates are defined. According to the results of two-way ANOVA the conclusion about the absence of spatial variability in concentrations of POP, TM and K-40 in the investigated shelf biota is done. Concentrations of the analysed substances in organisms and the differences in contaminant bioaccumulation by plants and animals of various taxons are presented in a form of a table. In spite of the discrepant information about the background level of contamination, given by different authors, the obtained data to a greater degree corresponds to the idea of the background concentration of contaminants in biota, than testify to the man-induced pollution of the investigated area. [ABSTRACT FROM AUTHOR]

Bottom sediment was analysed, via grab, trawl and underwater photography in 1991-1992 in the Barents, White, Kara, Norwegian and Greenland Seas, and the large scale features of macrobenthos distribution aredescribed. The maps of alpha-diversity, biomass and trophic zone distribution on the investigated shelf are presented. Statistical assessment of the bottom community structure changes during the last 60-70 years for the Barents Sea area is presented. It is shown that on regional and transregional levels the researched communities are of natural undisturbed character and that the revealed changes may be both the result of natural processes or sampling errors. Local disturbances of benthos composition and structure, supposedly caused by man, are found to be rare not far from the Novaya Zemlya and Murman coasts. [ABSTRACT FROM AUTHOR]

Accumulation of the radionuclides 241Am, 110m Ag, 133Ba, 109Cd, 57Co-cobalamine, 60Co, 134Cs, 152Eu, 54Mn, 106Ru and 65Zn in the brown macroalga Fucus vesiculosus (L.) Phaeophyceae, was compared at 2 deg. C and 12 deg. C ina series of laboratory radiotracer experiments. Concentration factors in the thallus were temperature-dependent and significantly decreased at 2 deg. C for 110m Ag, 109Cd, 60Co, 54Mn and 65Zn (CF = 439, 51, 101, 92 and 162, respectively) but not for 241Am, 133Ba, 134Cs, 152Eu and organic 57Co (CF = 329, 210, 3.3, 470 and 214, respectively); hence, for these last isotopes concentration factors in this species derived from temperate latitude (12 deg. C) studies can probably be applied to radiological assessments made under Arctic conditions. Between 2 and 14 days of depuration, the radionuclides, except 133Ba and 134Cs, remained tightly bound to the alga. Our results suggest that: 1. temperature must be considered when modelling the radiological impact of radioactive waste dumping in the Arctic Seas; and 2. Fucus spp. wouldbe excellent bioindicators of radionuclide contamination and dispersion in the Barents and Kara Seas. [ABSTRACT FROM AUTHOR]