Plastic pollution is globally recognised as a threat to marine ecosystems, habitats, and wildlife, and it has now reached remote locations such as the Arctic Ocean. Nevertheless, the distribution of microplastics in the Eurasian Arctic is particularly underreported. Here we present analyses of 60 subsurface pump water samples and 48 surface neuston net samples from the Eurasian Arctic with the goal to quantify and classify microplastics in relation to oceanographic conditions. In our study area, we found on average 0.004 items of microplastics per m³ in the surface samples, and 0.8 items per m³ in the subsurface samples. Microplastic characteristics differ significantly between Atlantic surface water, Polar surface water and discharge plumes of the Great Siberian Rivers, allowing identification of two sources of microplastic pollution (p < 0.05 for surface area, morphology, and polymer types). The highest weight concentration of microplastics was observed within surface waters of Atlantic origin. Siberian river discharge was identified as the second largest source. We conclude that these water masses govern the distribution of microplastics in the Eurasian Arctic. The microplastics properties (i.e. abundance, polymer type, size, weight concentrations) can be used for identification of the water masses.

Expanding human activities alongside climate change, the introduction of invasive species and water contamination pose multiple threats to the unique marine ecosystems of the Pechora Sea in the Russian Arctic. Baseline data on biodiversity and responses to environmental change are urgently needed. Benthic decapod crustaceans are globally distributed and play an important role in fisheries, yet their roles in food webs are less understood. In this study, we used an integrated approach combining stomach content analysis and stable isotope analyses (δ¹³C and δ¹⁵N) to examine the trophic niches of three decapod species in the Pechora Sea including the invasive snow crabChionoecetes opilioand two species of native decapods, the spider crabHyas araneusand the hermit crabPagurus pubescens. Stomach contents of 75 decapods were analysed (C. opilion = 23;H. araneusn = 9;P. pubescensn = 43), and 20 categories of prey items were identified with the most frequently occurring prey items being bivalve molluscs (Ciliatocardium ciliatum,Ennucula tenuis,Macoma calcarea),polychaetes, crustaceans and plant debris. Bayesian ellipse analyses of stable isotope signatures (n = 40) revealed thatC. opiliodisplays an overlapping trophic niche with the two native decapods, providing direct evidence that the invader likely competes for food resources with bothH. araneusandP. pubescens. As such, the presence of this invasive species could hold important consequences for trophic interactions, benthic ecosystem functioning and biodiversity. Microplastics were also found to be a likely stressor on this ecosystem, as 28% of all stomachs contained digested microplastics among other items. Long-term studies of benthic ecosystem structure and functioning are now needed to more fully understand the extent to which this new competitor may alter the future biodiversity of the Pechora Sea alongside the additional stressor of digested plastics.

The Atlantic walrus, Odobenus rosmarus rosmarus, forms a herd of nearly 4,000 heads in the Pechora Sea (south‐eastern Barents Sea). The Near Threatened status of O. rosmarus rosmarus and the relative isolation of the Pechora Sea population, as well as the potential impacts of human activities in the area, make it important to characterize key habitats, including feeding grounds, in order to protect the species. The aim of the present study was to integrate multiple sources of environmental and biological data collected by satellite telemetry, remotely operated vehicle (ROV), and benthic grab sampling to examine the distribution and diversity of benthic foraging resources used by walrus in the Pechora Sea. Analysis of satellite telemetry data from seven males tagged on Vaigach Island helped to identify areas of high use by walruses near haulout sites on Matveev and Vaigach islands, and in between. Field data were collected from those feeding grounds in July 2016 using ROV video recordings and bottom grab sampling. Analysis of 19 grab stations revealed a heterogeneous macrobenthic community of 133 taxa with a mean biomass of 147.11 ± 7.35 g/m². Bivalve molluscs, particularly Astarte borealis, Astarte montagui, and Ciliatocardium ciliatum, dominated the overall macrobenthic biomass, making up two‐thirds of the total. Analysis of 16 ROV video transects showed high occurrences of mobile benthic decapods (3.03 ± 2.74 ind./min) and provided the first direct evidence that areas actively used by walrus in the Pechora Sea overlap with the distribution of the non‐native omnivorous snow crab, Chionoecetes opilio. Integrating multiple data sources provides an early foundation for the kinds of ecosystem‐based approaches needed to improve Pechora Sea resource management and to underpin Russia’s nascent marine spatial planning initiatives. Factors that need to be considered in marine spatial planning include impacts on benthic feeding grounds from offshore oil and gas development and the spread of the snow crab.

Microplastics are pervasive in marine environments, posing potential risks to aquatic life and human health. This study investigates the trophic transfer of microplastics in marine invertebrates, focusing on the predator Asterias rubens and the filter-feeder Mytilus edulis. Conducted at the White Sea Biological Station, the experiment used polyethylene microspheres (40-48 μm) to trace microplastic ingestion and translocation within these species. Findings demonstrated that microplastics were not only ingested from water but were also transferred through predation from mussels to starfish, providing evidence of trophic transfer among some invertebrate species. Microplastics were detected in both control and experimental groups; however, ingestion rates were markedly higher in experimental conditions. The study introduces a trophic transfer coefficient of 0.36 from mussels to starfish, highlighting the need for further studies to refine microplastic analysis methods in marine settings and explore the ecological impacts on marine species.

The Franz Josef Land population of the Atlantic walrus (Odobenus rosmarus rosmarus) remains one of the least studied. Here, 26 walruses were tagged with satellite‐linked radio transmitters in Franz Josef Land archipelago and Victoria Island in summer‐autumn 2020 and 2021 to assess movements patterns and area utilization. In addition, 65 grab samples were taken to evaluate macrobenthic foraging resources. The mean duration of data records was 53 ± 27 days. The walruses traveled on average 29 ± 13.5 km/day with a mean speed of 1.2 ± 0.6 km/hr. The travel speed and distance were statistically different for male, female, and immature walruses. The individuals tagged on Victoria Island remained in the vicinity of the island, while walruses tagged within the Franz Josef Land archipelago moved between the islands, utilizing the entire area for foraging trips. One walrus migrated from Franz Josef Land to Novaya Zemlya in late November, providing evidence of connectivity with the Kara‐Barents Sea population. The area was characterized by high average biomass of macrobenthos. Bivalve mollusks,Hiatella arctica, were dominating macrobenthic biomass, likely being the main foraging resource for the walruses. Further observations are needed to better understand winter behaviors of Franz Josef Land walruses and possible impacts of climate change on movement patterns.