There is a lack of knowledge regarding the modern status of intertidal bryozoan communities in the coastal Barents Sea. Here, we studied species composition, richness, and biomass of bryozoans in Yarnyshnaya and Dalnezelenetskaya Bays, both located in the eastern part of the Kola Peninsula (Barents Sea), in summer. Species composition and biodiversity were consistent with previous research but the record of the ctenostome bryozoan Walkeriauva is the first for the region indicating eastward range expansion of this species associated with climate forcing in the Arctic. Mean biomass was relatively low accounting for 2.25 ± 0.95 g·m⁻². The most common species were Eucratea loricata, Harmeria scutulata, Crisia eburnea, and Cribrilina cryptooecium averaging 96% of the total biomass. Cluster analysis delineated two distinct groups of stations, one with true marine conditions and another with brackish water conditions. Redundancy analysis revealed that bryozoan diversity was strongly associated with salinity fluctuations being extremely low at brackish water sites. In contrast, water temperature was found to be a significant contributor to biomass with the lowest values found at warmer waters probably owing to the predominance of Boreo-Arctic species which prefer lower-temperatures. Other hydrological variables (dissolved organic matter, silicates, and oxygen) were consistent with usual summer values and had no significant effects on the bryozoan assemblages. Our study provides a reference point for further biodiversity studies in changing marine ecosystems of the Arctic region.

In the marine environment, bacteria and viruses play a significant role in carbon fluxes, remineralization processes, and the infection of various organisms. We performed a survey in the northeastern Barents Sea, a region adjacent to the Arctic Ocean, to investigate spatial patterns of microbial plankton, after the main productive period, in October 2020. Two main water masses occurred in the study region—colder Arctic Water and warmer Barents Sea Water, representing transformed Atlantic Water. Multivariate analyses detected patchiness in the horizontal distribution of bacteria and viruses, and their abundances showed no clear association with the water masses. There was an obvious vertical pattern in microbial concentration, with the highest estimates in the upper layers. Surface viral and bacterial abundance varied in a wide range (2.20 × 10⁵–10.7 × 10⁵ cells·mL⁻¹ and 0.86 × 10⁶–14.98 × 10⁶ particles·mL⁻¹, respectively) and were correlated with each other. Bacterioplankton was dominated by small-sized cells (<2 μm, 0.04–0.06 µm³), and the average volume of bacterial cells tended to increase toward the seafloor. The ratio of viral to bacterial abundance (VBR) was 11 ± 1 and did not differ between water masses and depth layers. VBR were higher, compared to summer values, suggesting a strong impact of viruses on bacterioplankton, after the main productive season. Redundancy and correlation analyses showed that inorganic nutrients (nitrate and phosphate) and organic carbon from zooplankton were most responsible for the total variability in the microbial parameters. Water temperature and salinity, also, had a measurable impact, but their influence was lower. Bacterial abundance was lower than in other seasons and regions of the Barents Sea, while viral abundance was comparable, suggesting a stronger viral impact on Arctic marine bacteria in the autumn season.

In spring 2016, the thermohaline characteristics of water masses and the distribution of chlorophyll-a concentration in the pelagic zone of the eastern part of the Barents Sea were studied. For the first time, in the conditions of an abnormally warm year and the absence of ice cover, a complex of hydrobiological works was carried out on a section crossing the Barents Sea from south to north along the western coast of the Novaya Zemlya archipelago. High concentrations of chlorophyll-a > 1 ˂ 6 mg/m³ at all stations of the transect indicate a stage of spring bloom in the successional cycle of microalgae. Significant differences in the content of chlorophyll-a in waters of various origins were revealed. The highest concentrations of chlorophyll-a corresponded to Arctic surface water (5.56 mg/m³). Slightly lower values were observed in the transformed Atlantic waters of the Novozemelskoe and Kolguevo–Pechorskoe currents (3.53 ± 0.97–3.71 ± 1.04 mg/m³), and the lowest was in the Barents waters (1.24 ± 0.84–1.45 ± 1.13 mg/m³).

The state of bacterioplankton was investigated in the northeastern Barents Sea in the autumn period for the first time. The warm transformed Atlantic water and cold Arctic water, as well as the intermediate and bottom waters were delineated in the study area. Small amounts of nutrients and oxygen were recorded in the upper water layer, while the maximum values of the nutrient concentrations were in the bottom layer. The bacterial abundance varied from 220 to 1068 thousands cells/ml, biomass varied from 2.7 to 12.5 mg С/m³, and the mean volume of bacterial cells varied from 0.020 to 0.136 μm³. The horizontal distribution of bacterioplankton demonstrated patchiness, while there was a clear vertical pattern with a decrease of the total bacterial abundance and an increase of the mean bacterial size with depth. Small single cells dominated in the bacterioplankton. The total bacterial abundance and biomass of the bacterioplankton, as well as the number of some bacterial size groups, negatively correlated with the concentration of nutrients (nitrates, phosphates, and silicates) and salinity. The abundance and biomass of the bacteria showed a weak tendency to increase with increasing water temperature and surface chlorophyll a content. A comparison of the obtained data with other Arctic regions and other seasons has been made. The factors determining the distribution patterns of marine bacteria in the Arctic in the autumn are discussed.

In the period from January 2, 2018 to December 30, 2022, a comprehensive study of solid atmospheric precipitation was carried out in Murmansk and its environs. Data were obtained on the concentration in freshly fallen snow of solid insoluble particles (9.19±0.51 mg/l) and their components: heavy metals (zinc – 60.1±9.8 ng/g, copper – 11.0±2.6 ng/g, lead – 3.28±0.18 ng/g, cadmium – 0.859±0.096 ng/g), nutrients (nitrates – 79±11 µg-at/l, nitrites – 1.02±0.14 µg-at/l, phosphates – 4.64±0.67 µg-at/l, silicates – 25±5 µg-at/l) and organic matter (21.2±2.2 mg/l), as well as the amount of polymer particles (fragments – 7766±1401 particles per liter, micro-fibers – 638±134 threads per liter, macro-fibers – 29±4 threads per liter). The relationship between the number of insoluble particles and the direction of air masses inflow was revealed. Air masses coming from the Barents Sea brought solid precipitation with less insoluble aerosols (including heavy metals, polymer particles and organic matter) than air masses coming from the continent. The amount of biogenic elements in solid atmospheric precipitation does not depend on the direction of inflow of air masses.

This study aimed to confirm the hypothesis of a floristic identity between the southeastern Barents Sea and the southwestern Kara Sea. We conducted integrated studies of pelagic microalgae communities including microscope cell counting and taxonomical identification as well as photosynthetic pigments determination and defining of hydrological and hydrochemical characteristics during a cruise in late August and the first half of September 2020. As far as we are concerned, no such observations had been carried out in this region at this time of the year before. During our observations, 35 species were identified, 14 (40%) of which were present in both water bodies. The communities of both regions were in a state corresponding to the autumn stage of the annual succession cycle. In the southeastern Barents Sea, the mean abundance of organisms in the water column varied from 10.650 to 41.840 cells per liter with a biomass of 71.04 to 300.55 µg/L. In the southwestern Kara Sea, these values were 3.510–28.420 cell/L and 16.31–66.96 µg/L, respectively. In general, the results of a comparative analysis suggest that the pelagic algal communities in the regions under comparison, despite the difference in hydrological parameters, demonstrate similar qualitative and quantitative characteristics and thus may belong to the same phytogeographic region.