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 crab Chionoecetes opilio and two species of native decapods, the spider crab Hyas araneus and the hermit crab Pagurus 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 that C. opilio displays an overlapping trophic niche with the two native decapods, providing direct evidence that the invader likely competes for food resources with both H. araneus and P. 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.

No abstract

Macrozoobenthic communities provide vital ecosystem services including habitats and foraging resources for other species in all marine ecosystems. Although macrozoobenthos of deeper parts of the �echora �ea ��� �ar� macrozoobenthos of deeper parts of the �echora �ea ��� �ar� ents �ea) have been studied in more detail, there is a lack of research in shallow waters of the �echora �ay. The study area lies within the Nenetsky �tate Nature Reserve, established in 1997, to protect important breeding and moulting grounds of waterfowl. Macrozoobenthos provide key foraging resources for waterfowl in the nature reserve, however, there is a mismatch between ornithological and macrobenthic data. �ight stations were studied along the Russky Zavorot �eninsula in the �echora �ay on a depth of 1.1-1.8 m within the near�shore zone of the Nenetsky �tate Nature Reserve in August 2016. A monodominant community of Limecola balthica with a biomass of 21.31 ± 0.32 g/m 2 and 14 species in total was recorded across the area. The dominant species of the community correspond to those in the community of L. balthica recently described from the central estuarine part of the �echora estuary. A low biomass and poor species richness in the L. balthica community support the earlier published results for the northern part of the bay and indicate the dependence of the community charac� teristics on environmental factors. The paucity of macrozoobenthos in the area is likely attributed to extreme environmental conditions including the following: �1) the water column freezes to the bottom during winter in the shallows of the Pechora estuary or (2) the freshwater flow spreads under the ice, severely impacting salinity. Hence the community is comprised of eurythermal and euryhaline forms and is reduced in biomass. It is unlikely that the shallows of the Russky Zavorot �eninsula play an important role as feeding grounds for benthic preda� tors since a low in biomass barren community of a burrowing mollusc L. balthica does not provide enough forag� ing resources to feed stocks of waterfowl. The L. balthica�community could be used as an indicator of climate changes in the future-it is predicted that a reduction in sea ice volume will improve conditions for growth of L. balthica and may therefore lead to an increased body size and biomass of bivalves in the shallows.

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.

No abstract

Biofouling of artificial substrates is a well-known phenomenon that can negatively impact offshore industry operations as well as data collection in the ocean. Fouling communities worldwide have mostly been studied within the top 50 m of the ocean surface, while biofouling below this depth remains largely underreported. Existing methods used to study biofouling are labor intensive and expensive when applied to the deep sea. Here, we propose a simple and cost-effective modification of traditional methods for studying biofouling by mounting test plates on autonomous seafloor equipment and preserving them in ethanol upon retrieval for transport to the laboratory. This method can greatly advance our understanding of biofouling processes in the deeper ocean, including fouling community biodiversity, recruitment, and seasonality. We present two case studies from the Laptev Sea and the Sea of Okhotsk in support of this method. In the first study, we looked at fouling communities on the surfaces of ocean-bottom seismometers deployed for one year in the 36–350 m depth range. In the second study, we tested metal and plexiglass (poly(methyl methacrylate) plates mounted on autonomous bottom stations and found evidence of both micro- and macrofouling after three months of deployment. Our results demonstrate that various autonomous seafloor equipment can be used as supporting platforms for biofouling studies.

The geographic settings and interests of diverse groups of rights- and stakeholders figure prominently in the need for internationally coordinated Arctic observing systems. Global and regional observing systems exist to coordinate observations across sectors and national boundaries, leveraging limited resources into widely available observational data and information products. Observing system design and coordination approaches developed for more focused networks at mid- and low latitudes are not necessarily directly applicable in more complex Arctic settings. Requirements for the latter are more demanding because of a greater need for cross-disciplinary and cross-sectoral prioritization and refinement from the local to the pan-Arctic scale, in order to maximize the use of resources in challenging environmental settings. Consideration of Arctic Indigenous Peoples’s observing priorities and needs has emerged as a core tenet of governance and coordination frameworks. We evaluate several different types of observing systems relative to the needs of the Arctic observing community and information users to identify the strengths and weaknesses of each framework. A typology of three approaches emerges from this assessment: “essential variable,” “station model,” and “central question.” We define and assess, against the requirements of Arctic settings, the concept of shared Arctic variables (SAVs) emerging from the Arctic Observing Summit 2020 and prior work by the Sustaining Arctic Observing Networks Road Mapping Task Force. SAVs represent measurable phenomena or processes that are important enough to multiple communities and sectors to make the effort to coordinate observation efforts worthwhile. SAVs align with essential variables as defined, for example, by global observing frameworks, in that they guide coordinated observations across processes that are of interest to multiple sectors. SAVs are responsive to the information needs of Arctic Indigenous Peoples and draw on their capacity to codesign and comanage observing efforts. SAVs are also tailored to accommodate the logistical challenges of Arctic operations and address unique aspects of the Arctic environment, such as the central role of the cryosphere. Specific examples illustrate the flexibility of the SAV framework in reconciling different observational approaches and standards such that the strengths of global and regional observing programs can be adapted to the complex Arctic environment.