Search Results (195)

Wind energy is an important form of clean energy, and its rational utilization represents a crucial solution for mitigating the energy crisis and global warming. In this study, wind energy potential and its long-term changes in the South China Sea (SCS) are evaluated using ERA5 100 m wind data from 1944 to 2023, validated against ASCAT observations. High wind speeds and high wind power density (WPD) are concentrated southwest of Taiwan and southeast of Vietnam. Annual wind availability exceeds 6457 h across most regions, reaching up to 8283 h in optimal locations. WPD and capacity factor peak in winter (up to 2.4 × 10⁸ Wh·m⁻² and >50% capacity factor), with the most stable conditions occurring in the southwestern Taiwan Strait, southeast of the Pearl River Delta, and the Beibu Gulf. Empirical orthogonal function analysis reveals that the first mode of winter WPD accounts for 65.7% of the total variance, with a statistically significant increasing trend since 1990. The interannual variation in wind energy resources in the SCS during winter is controlled by the combined effects of sea surface temperature (SST) anomalies in the tropical Pacific and the Arctic Barents Sea. Specifically, in the years with strong wind anomalies in the SCS, mega-La Niña-type SST patterns in the tropical Pacific trigger anomalous cyclonic circulation in the SCS and the eastern Philippine Sea, while warm anomalies in the Arctic Barents Sea surface drive a wave-like structure of “anticyclone–cyclone–anticyclone” from Siberia to South China. The coupling of the two systems jointly promotes the strengthening of the South China Sea monsoon, leading to increased wind speeds and elevated WPD in the northern SCS. These findings provide a scientific basis for wind farm siting and long-term operational planning in the region. Full article

Rivers are a key pathway for the transport of plastics into the ocean. Studies of plastic pollution in Arctic rivers remain limited due to the inaccessibility of sampling sites and work in extreme weather conditions. This work presents the results of a three-year (2019–2021) survey of floating large microplastics (0.5–5 mm) and meso/macroplastics (>5 mm) in the Northern Dvina River, an actively navigated river that drains a densely populated region into the White Sea. Sampling was conducted during the ice-free periods (May–October) along a ∼3.5 km transect using a Neuston net, providing a multi-year dataset spanning three ice-free seasons. A critical methodological advancement was the calculation of plastic river–sea flux using the discharge of the sampled surface layer (upper 20 cm), which constitutes only ∼3% of the river’s total discharge, rather than the total discharge itself. Observed microplastic concentrations (average 0.003 items ${\mathrm{m}}^{-3}$) were low compared to many European rivers, and lower than those reported in the adjacent Barents and Kara Seas. Microplastic abundance was significantly lower during the high-water season than during the low-water season, which resulted in practically no seasonal variability in microplastic fluxes from the river to the White Sea (average 0.3 items ${\mathrm{s}}^{-1}$). A notable finding was that in some cases, meso/macroplastics outnumbered microplastics by item count, underscoring the river’s role as a significant source of larger plastic debris. A geospatial assessment of Arctic rivers’ pollution potential was performed, using socio-economic indicators such as near-delta population density and port activity. This study identified the Northern Dvina River as a major contributor of microplastics among the Arctic rivers. Full article

The effects of environmental factors on zooplankton within the marginal ice zone (MIZ) of the Barents Sea remain poorly understood. To address this knowledge gap, we investigated mesozooplankton communities across the central, northern, and northeastern regions in April 2016. Abundance and biomass ranged from 90 to 997 individuals m⁻³ and from 1.1 to 48.6 mg dry mass m⁻³ (0.3 to 13.6 g dry mass m⁻²), respectively. Oithona similis was the most abundant taxon, while calanoid copepods, including Calanus spp., Metridia longa, and Pseudocalanus spp., dominated total biomass. The spatial distribution of mesozooplankton communities was closely linked to the physical properties of water masses. Cluster analysis identified two distinct assemblages associated with Polar Front Water and Arctic Water. Redundancy analysis and generalized linear models identified temperature, mean salinity, mean chlorophyll a concentration, and sea ice concentration as significant predictors of abundance and biomass. The dominance of older life stages within major copepod taxa indicated a winter status for the mesozooplankton community. Regional and temporal comparisons of mesozooplankton biomass with prior May–June data from central and northwestern areas highlighted higher productivity in the northern and northeastern MIZ. This increase is potentially related to the warming trends observed in the Arctic since the 2000s. Our research provides novel insights into Arctic marine zooplankton assemblages and serves as a valuable baseline for future ecological monitoring and modeling of the Barents Sea ecosystem in the context of global climate change. Full article

Freshwater accumulation is one of the most striking observations in the Beaufort Gyre (BG) region in the Arctic Ocean. A 39-year simulation, using the validated high-resolution, geometrical-fitting, unstructured grid Finite-Volume Community Ocean Model for the Arctic Ocean, aimed to investigate the contributions of coastal currents and their interannual variability to this phenomenon. The model reasonably reproduced the interannual variability of freshwater content (FWC) in the BG region. Analysis revealed the constructive role of Ekman pumping in supplying FWC, while the lateral flux generally acts to remove FWC from the region. The disparity between Ekman pumping and lateral flux drives the interannual variability of total FWC, with accumulation occurring when the downward Ekman FWC flux surpasses the net outflow-induced lateral FWC flux. Since 2007, there has been a significant increase in downward Ekman pumping, accompanied by a rise in net outflow lateral flux, indicating heightened variability of FWC in the BG region. The model results suggested that the coastal flow over the Arctic continental shelf underwent dramatic changes, especially during summer, and these changes were partially due to increased freshwater and sea ice melting. Increased lateral FWC flux during summer has become a competitive source for unprecedented seasonal freshwater accumulation in the BG region. Flow intensification over the North American coast is influenced by increased freshwater runoff, including the Firth, Kobuk, and Mackenzie Rivers. Interannual FWC variation in the Beaufort Sea could be influenced by the changes in slope flow, with the water originating in part from the Barents and Kara Seas. Full article

Previous studies have reported the fatty acid composition of red king crab (Paralithodes camtschaticus) meat; however, no comparative analyses have simultaneously investigated raw (RM) and cooked meat (CM). This study addresses this gap by employing gas–liquid chromatography to analyze the fatty acid profiles of RM and CM from red king crabs from the coastal Barents Sea, Russia. Both products exhibited significant sex-specific differences, with females containing higher levels of fatty acids in their meat than males. Furthermore, males displayed greater dissimilarity between RM and CM compared to females. While nutritional indices were comparable between male and female RM and CM, the cooking process resulted in improved nutritional indices in CM relative to RM. Moreover, the red king crab meat exhibited superior nutritional indices compared to those reported for other, primarily southern, crab species, reflecting a higher polyunsaturated to saturated fatty acid ratio in both RM and CM. Comparisons with the existing literature revealed variability in red king crab meat fatty acid levels across geographical locations and years, suggesting that spatial variations in diet and temporal fluctuations in feeding habits may influence meat quality. Our findings confirm the high nutritional value of red king crab meat, a finding of relevance to both scientific and consumer audiences. Full article

Monitoring epibiotic communities on the invasive red king crab (Paralithodes camtschaticus) in the Barents Sea is crucial for understanding the co-adaptation between this species and the local benthic fauna. Red king crabs were collected during regular diving surveys conducted in the coastal Barents Sea in 2015, 2021, and 2022. A detailed examination revealed the presence of two amphipod species, Metopa pusilla and Crassicorophium bonellii, which were not previously documented as epibionts on this host. With these additions, the total number of epibiotic amphipods on Barents Sea red king crabs rises to nine species (versus two in the native Sea of Okhotsk). Amphipod colonization was skewed toward large males, likely reflecting their greater migratory behavior. The prevalence of Metopa pusilla ranged from 1.9% to 4.3%, with a mean intensity of one individual per infested crab; Crassicorophium bonellii exhibited prevalence of 4.7–14.3% and mean intensity of 1.3–3.3 individuals. The primary colonization sites were the carapace and limbs. Given the low infestation parameters and the epibionts’ localization away from critical structures like the gills and egg clutches, it is concluded that these amphipods pose a negligible risk to host health. Full article

Monitoring marine litter in the Arctic is crucial for environmental assessment, yet automated methods are needed to process large volumes of visual data. This study develops and compares two distinct machine learning approaches to automatically detect floating marine litter, birds, and other anomalies from ship-based optical imagery captured in the Barents and Kara seas. We evaluated a supervised Visual Object Detection (VOD) model (YOLOv11) against a self-supervised classification approach that combines a Momentum Contrast (MoCo) framework with a ResNet50 backbone and a CatBoost classifier. Both methods were trained and tested on a dataset of approximately 10,000 manually annotated sea surface images. Our findings reveal a significant performance trade-off between the two techniques. The YOLOv11 model excelled in detecting clearly visible objects like birds with an F1-score of 73%, compared to 67% for the classification method. However, for the primary and more challenging task of identifying marine litter, which demonstrates less clear visual representation in optical imagery, the self-supervised approach was substantially more effective, achieving a 40% F1-score, versus the 10% obtained for the VOD model. This study demonstrates that, while standard object detectors are effective for distinct objects, self-supervised learning strategies can offer a more robust solution for detecting less-defined targets like marine litter in complex sea-surface imagery. Full article

The introduced red king crab Paralithodes camtschaticus holds significant commercial value in the Barents Sea. This species is recognized as a host for a wide variety of symbiotic organisms, including polychaetes. In July 2015 and 2025, a total of 12 specimens of the marine terebellid polychaete Amphitrite cirrata were discovered inhabiting the gills of two red king crabs in Dalnezelenetskaya Bay, Barents Sea. This study represents the first documented occurrence of an association between these benthic species. Colonization of the red king crab by Amphitrite cirrata offers several advantages to the polychaetes by providing access to suitable feeding conditions, increased mobility, and protection from potential predators. However, this association poses disadvantages to the host crabs, as it results in tissue damage and an elevated concentration of sand particles within their gills. Full article

This review synthesizes current knowledge on the biology and ecology of the small cyclopoid copepod Oithona similis, a prevalent planktonic species in the Barents Sea, during the period of Arctic warming since the early 2000s. The region serves as an effective model system for examining the influence of different water masses on Arctic zooplankton dynamics. The highest abundances and biomass of Oithona similis are observed in Murmansk Coastal Waters (MCW) and Arctic Waters (ArW). Although its contribution to total zooplankton biomass is generally lower than that of higher copepod taxa, it can account for up to 27–35% seasonally and regionally. Ovigerous females are most abundant in Novaya Zemlya Waters (NZW) and ArW. Egg production rates exhibit a decreasing trend from south to north across the sea. Morphometric analyses reveal an increase in prosome length for both sexes, while relative antenna size diminishes from the south (MCW) to the north (ArW). The highest mortality rates occur during summer, coinciding with peak abundances of Oithona similis, its predators, and parasites, as well as increased interspecific competition. Based on morphological and reproductive parameters, three distinct populations are delineated within the Barents Sea: southern (MCW), central (Atlantic Water/Barents Sea Water), and northern/eastern (ArW/NZW), with respective life cycle durations of 11–12, 9–10, and 11 months, and typically one to two generations per year. The primary environmental drivers influencing population abundance, biomass, size, and reproduction are temperature and salinity, while chlorophyll a concentration predominantly affects mortality rates. Full article

GC-MS oxylipin profiling of brown and red algal thalli was performed. Brown algae (Fucus distichus and Alaria esculenta) were collected from the Barents Sea coastline nearby Teriberka, Murmansk region, Kola Peninsula, Russia, while other brown and red algae were sourced from the Pacific coast of the Russian Far East. Triols and δ-ketols (epoxyalcohol synthase products) were found in most brown and red algae. Several Heterokontophyta and Rhodophyta species possessed α-ketols (products of allene oxide synthase) and related vic-diols. Plasmodiophorols and ectocarpins (hydroperoxide bicyclase (HPB) products) were found only in brown algae from the Ectocarpales, Fucales, and Laminariales orders, not in brown algae from the Desmarestiales or Dictyotales orders, or in any red algae. Therefore, plasmodiophorol A and other HPB products could be used as chemotaxonomic markers for the classification of the separate orders of algae within Heterokontophyta. The in vitro incubations of F. distichus thalli with linoleic and α-linolenic acid resulted in the formation of α-ketols and the hydroperoxide bicyclase product, plasmodiophorol A. Full article

Amplified Arctic warming has led to a pervasive decline in sea ice cover over recent decades; yet, the pattern and governing mechanisms of sea ice concentration (SIC) state transitions remain unclear. This study reveals pronounced regional contrasts in mean-state SIC during the transition from 1979–2006 to 2007–2024, concurrent with a reduction in the sea ice extent over the same period. The September-mean sea ice in the 70° N–80° N Arctic belt retreated significantly from 1979–2006 to 2007–2024, while the Barents and Greenland Seas exhibited persistent ice loss in March. Enhanced ice-albedo feedback, together with concurrent rises in the 2 m air temperature and sea surface temperature, dominate these ice loss processes. Dynamical processes exert distinct regulatory roles in September and March. The strengthened Beaufort High induces sea ice convergence to partially offset the September thermodynamically driven ice loss, while the positive-phase Arctic Dipole in March amplifies the transpolar airflow and winds over the Greenland and Barents Seas and triggers rapid sea ice export and significant loss in these regions. These findings underscore the spatial heterogeneity of Arctic SIC transitions and highlight the complex interplay of thermodynamic and dynamic processes shaping them. Full article

This study builds on our prior research to refine the methodology for estimating marine primary production (PP) in the Barents Sea. It examines how abiotic factors—vertical mixing and horizontal advection—affect nutrient concentrations in the euphotic zone and subsequently influence PP. The analysis utilized salinity and nutrient data from the World Ocean Atlas (NCEI WOA). The δ¹⁸O parameter, used in conjunction with salinity, helped quantify the proportion of water from different origins. The results revealed a spatial heterogeneity in nutrient transport, identifying zones of both synchronous and asynchronous nutrient flows. Asynchronous flow was characterized by the removal of phosphorus and silicon alongside the influx of nitrogen. A significant correlation between these physical fluxes and PP was observed in the eastern part of the sea, where asynchronous flow prevails. Our calculations indicate that nitrogen influx increases PP by an average of 38% as high as 68%. The simultaneous fluxes of silicon and phosphorus showed no statistically significant effect. The study concludes that nitrogen is the primary limiting factor for PP in this region. Full article

During the 84th cruise of the R/V Akademik Mstislav Keldysh in August 2021, patterns of phytoplankton composition transformation were revealed along a northward gradient. The study involved three transects in the Fram Strait and adjacent Arctic waters: a southern transect (from the Barents Sea shelf to the Greenland shelf), a middle transect across the Fram Strait, and a northern transect along the ice edge. Ten species of diatoms and eleven of dinoflagellates were identified, and their ecological preferences were characterized by determining the minimum, maximum, mean, and median values for abundance, biomass, depth of the biomass maximum, salinity, temperature, and the concentrations and ratios of nitrogen, phosphorus, and silicon. Significant gradients in temperature, salinity, silicon, and nitrogen concentrations were recorded along the south–north direction in the study area. The phytoplankton community responds to these changing factors through restructuring. Dinoflagellates predominantly dominate the southern and middle transects, whereas large diatoms make a substantial contribution to the phytoplankton biomass in the northern transect. Diatom biomass is determined by nitrogen concentration. The dependence of dinoflagellate biomass on that of small flagellates confirms the importance of mixotrophic nutrition. A hypothesis is proposed that the most probable criterion for the selective selection of diatoms northward is the half-saturation constant for nitrogen uptake, while for dinoflagellates, it is temperature. Full article

The efficiency of the sorption–biological method for treatment of oil-polluted coastal substrates (soil and sand) of the Barents Sea under low temperature (10 °C) using the active hydrocarbon-oxidizing bacterial strain Rhodococcus erythropolis HO-KS22 was assessed in the laboratory. The highest rate of hydrocarbon degradation was in sand polluted with a low-density oil emulsion and in soil polluted with a medium-density oil emulsion. Sorption–biological treatment increased the rate of hydrocarbon degradation in sand by 3–4 times during the first month and enhanced the overall efficiency by 20% over a three-month period. The use of sorbents (granular activated carbon, thermally activated vermiculite and peat) both in sand and soil prevents secondary pollution of coastal ecosystems, since it significantly reduces the hydrocarbons’ desorption and their leaching by water. Rhodococcus erythropolis HO-KS22, in combination with sorbents, can be applied during the biological remediation of coastal sandy substrates following the initial removal of emergency oil spills. However, for biological treatment of oil-polluted soils of the Barents Sea coast, further selection of active strains of hydrocarbon-oxidizing bacteria resistant to low pH values and temperatures typical for this region is necessary. The use of microbiological preparations without taking into account the soil and climatic factors of the region may be ineffective, which will increase the cost of remediation of the territory without significantly improving its condition. Full article

Microbiological and biogeochemical investigation of the bottom sediments of semiclosed basins was carried out at the Kislaya Guba tidal power station (Barents Sea) and in Kanda Bay (White Sea). Suppressed tidal water mixing is known to affect the hydrological regime of isolated basins, resulting in the development of oxygen-free sediments. The upper sediments of the studied bays were shown to contain higher concentrations of sulfide and methane, with increased rates of sulfate reduction, methanogenesis, and methane oxidation. The relative abundance of truly marine microorganisms decreased, while microorganisms common in anoxic sediments of meromictic basins developed. The indicator microorganisms with increased relative abundance were archaea of the genera Methanoregula and Methanosaeta. Bacteria of the class Chlorobia, Chloroflexi of the family Anaerolineaceae, and Rhodoferax-related bacteria were indicators of the stagnant seawater. Members of the genus Woeseia were counter-indicators, occurring only in marine water. In our opinion, under reasonably regulated water exchange via the dams, the ecosystems of the Kanda and Kislaya Guba bays may retain the characteristics of marine bays. Otherwise, the studied bays may become stratified basins with anoxic near-bottom water, harboring microbial communities similar to those inhabiting meromictic basins. Full article