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Indoor concentrations of black carbon (BC) were measured when wood was burned for traditional cultural activities in a study in a Cree community located in subarctic Canada. The study also included an intervention using a propane-fuelled heater to mitigate in situ BC. Mass concentrations of BC were measured in a game-smoking tent for 39 days and in hunting cabins on the west coast of James Bay, Canada, for 8 days. Five-minute averaged BC mass concentration (N = 12,319) data were recorded and assessed using optimised noise-reduction averaging. Mean BC mass concentrations were lower in hunting cabins (mean = 8.25 micrograms per cubic metre (µg m−3)) and higher in the game-smoking tent (mean = 15.46 µg m−3). However, excessive BC peaks were recorded in the game-smoking tent (maximum = 3076.71 µg m−3) when the fire was stoked or loaded. The intervention with the propane heater in a hunting cabin yielded a 90% reduction in measured BC mass concentrations. We do not presume that exposure to BC is of concern in hunting cabins with appropriate wood-burning appliances that are well-sealed and vent outside. In game-smoking tents, we advise that persons take intermittent breaks outside of the tent for fresh air.

We report the human-assisted spread of Senecio pseudoarnica, native to the northern coasts of North America and the Far East, to arctic and subarctic regions of Europe. Our findings indicate that the species, imported as a decorative plant, is currently rapidly spreading along coastal areas of Iceland and Norway. An exponential model comprehensively explained the increase in the number of known localities. Close climate matching between the native and non-native ranges (shown by our preliminary analyses), as well as practically exact environmental matching, are the main factors that facilitate the process of naturalisation and invasion. S. pesudoarnica is one of the very few species invading these arctic and subarctic regions.

For Inuit in the subarctic transition zone of northeastern Canada, an intimate knowledge of the environment and local biodiversity is crucial for successful traditional activities. This study examines what kinds of landscape features and habitats Inuit of Nunatsiavut recognize and name. During interviews, community members (mostly Elders) were shown photographs from the region and were asked to describe and name salient types of places in Labrador Inuttitut. The most frequently reported geographical units dealt with the region’s topography (e.g., mountain, island, flat-place), hydrology (e.g., river, bay), and superficial characteristics (e.g., bedrock, permanent snow patch). Ecological considerations were also prominent, such as plant associations and animal habitats (e.g., shrubby-place, wetland, caribou-return-to-place). Areas were often characterized by a dominant species or substrate type, being named using the plural form of the species and (or)substrate (e.g., “napâttuk” meaning ‘tree’ and “napâttuit” meaning ‘forest’ or “siugak” meaning ‘sand’ and “siugalak” meaning ‘sandy-area’). Some types of places reported by Inuit were significant mainly for traditional activities (e.g., berry-patch, seal-place, dry-wood-place, danger-place), aiding navigation and resource finding. Integrating Inuit conceptions of ecosystems and their component landscape units with those of contemporary science can improve our understanding of subarctic ecology, benefit climate change adaptation strategies, and Inuit language as well as culture conservation initiatives.

In many northern ecosystems, mosses account for an important component of the plant community. Further, mosses host nitrogen (N2)-fixing bacteria that have been shown to contribute a large part of ‘new‘ N in pristine ecosystems. This study aimed to assess direct and indirect effects of warming on moss-associated N2 fixation. We assessed how N2 fixation activity at ecosystem- and at moss species-level is affected by direct (warming) and indirect (vegetation shift) climate change using two long-term field manipulation experiments in a subarctic birch forest combined with mesocosm studies from a close-by heath. We linked the abundance of ground covering mosses to N2 fixation activity and assessed the temperature sensitivity of N2 fixation in two common feather mosses, Hylocomium splendens and Pleurozium schreberi. Our study shows a steep decline in moss ground cover as well as in associated N2 fixation in response to 10 years of manipulated field-warming, whereas a shift in dominant shrub species did not impact moss cover or N2 fixation activity. Interestingly, the moss H. splendens was more sensitive than P. schreberi to warming both in terms of cover and N2 fixation activity. Our study shows that warming affects moss-associated N2 fixation activity negatively - both indirectly via a decline in moss cover and directly by reducing N2 fixation activity. This suggests lower N input via moss-associated N2 fixation in a future climate, which will consequently affect nutrient turnover and ecosystem productivity.

Satellite remote sensing is a popular approach for identifying vegetation change in northern environments; however, disentangling ecological processes causing variability in spectral indices remains a challenge. Here, we aim to determine how shrub characteristics differ between low and rapidly greening areas near Nain, Nunatsiavut, Canada. Using a cross-scale approach, we combined remotely sensed spectral greening trends (Normalized Difference Vegetation Index; Landsat Collection 1, 1985–2018) with shrub dynamics derived from ring-widths of green alder (Alnus alnobetula (Ehrh.) K. Koch) and dwarf birch (Betula glandulosa Michx.). Differentiation of spectral greening classes appears to be driven by the distribution of shrub species. Alder were taller, grew faster, had more recent stem initiation than dwarf birch, and were dominant in rapid greening subplots. In low greening subplots, alder were co-dominant with dwarf birch, whose dominant stems initiated more gradually, were shorter, and had lower rates of vertical growth. The radial growth of both shrub species was favoured by warm winter temperatures and precipitation, whereas rapid greening alder was also favoured by warm summer temperatures. Further shrub growth will likely be enhanced under continued climate warming if moisture does not become limiting. This research demonstrates the importance of species identity in determining rates of spectral greening in northern environments.

The subarctic NE Pacific is comprised of several oceanographic regimes, in which regional variability in sea surface temperature (SST), satellite chlorophyll a, and crustacean zooplankton biomass influence the production rates of crustacean zooplankton. Traditional methods for estimating zooplankton production rates are labour/time intensive and restricted to select copepod species. A practical field alternative is the ‘chitobiase method’, which yields community-level biomass production rates (BPR) analogous to traditional moulting rate methods. BPR was measured along the west coast of Vancouver Island and in the subarctic NE Pacific during 2005, 2009–2011, and 2015–2018. Generalized additive modelling identified SST and the developing crustacean zooplankton biomass as key drivers of BPR variability. BPR varied positively with the proportion of developing copepod biomass relative to that of non-copepod crustacean zooplankton biomass. Our analysis indicates that BPR variation is associated with zooplankton community composition, but that high zooplankton biomass is not necessarily predictive of high BPR. Specifically, higher BPR is associated with a higher relative biomass of large-bodied, cold-water indicator species, and a lower biomass of non-copepod crustaceans.

This study compares inter-annual dynamics of the two biomass dominant copepods in the Iceland Sea, the North Atlantic species Calanus finmarchicus and the Arctic C. hyperboreus, in an era of relatively low temperatures in the beginning of the study period (1990-1995) and higher temperatures thereafter. Samples were collected annually in May along a cross-shore transect of eight stations. The long-term variability in abundance of the two Calanus species was analysed in relation to hydrography, nutrients and phytoplankton dynamics, and large-scale climatic changes in the North Atlantic Ocean. Sea surface temperatures showed an increasing trend from the beginning to the end of the time series for all stations. From the end of the 1990s, C. finmarchicusshowed an increasing trend at the outermost station, whereas C. hyperboreus generally showed a decreasing trend along the whole transect from the mid-2000s. For both species, temperature was the single most important environmental factor explaining variance in abundance, however with opposite effects for the Arctic (C. hyperboreus) and the Atlantic (C. finmarchicus) species. It is hypothesized that warming north of Iceland may lead to increase of C. finmarchicus abundance through increased recruitment and advection, and decreased C. hyperboreus abundance. The change in species composition may in turn influence upper trophic levels, e.g. the capelin, the region’s main planktivorous fish.

Arctic grayling (Thymallus arcticus) is an iconic fish species that is present across the remote subarctic Barrenlands, yet our lack of understanding of their distributional patterns constrains predictions of anthropogenic effects on Barrenland populations. These adfluvial fish rely on seasonal lake-stream connections to migrate, spawn, and rear. We address knowledge gaps on what Barrenland stream attributes are suitable for rearing young-of-year Arctic grayling. Visual surveys of young-of-year Arctic grayling were conducted in 48 streams near Baker Lake, Nunavut, Canada. Occupancy modeling was used to relate stream habitat and landscape variables to fish presence/absence. The best predictors of occupancy were total area of contributing upstream lakes and landcover (upland/lowland); stream basins with larger contributing upstream lake area and more lowland cover were more likely to be occupied. Results suggest that occupancy reflects reliability of stream connectivity throughout the open water season and across years. The occupancy model developed here can adequately predict stream suitability for young-of-year Arctic grayling using lake area and land classification data that are remotely accessed. This may lessen the considerable financial and logistical constraints of conducting field research on Arctic grayling in the vast Barrenlands and facilitate more directed field programs to inform conservation and mitigation plans.

Cercarial activity and survival are crucial traits for the transmission of trematodes. Temperature is particularly important, as faster depletion of limited cercarial energy reserves occurs at high temperatures. Seasonal climate conditions in high latitude regions may be challenging to complete trematode life cycle during the 6-month ice-free period, but temperature effects on the activity and survival of freshwater cercariae have not been previously identified. After experimentally simulating natural subarctic conditions during warmer and colder months (13 and 6°C), a statistical approach identifying changes in the tendency of cercarial activity loss and mortality data was used to detect differences in three trematode genera, represented by four taxa (Diplostomum spp., Apatemon spp., small- and large-sized Plagiorchis spp.). A strong temperature-dependent response was identified in both activity loss and mortality in all taxa, with Diplostomum spp. cercariae showing the most gradual changes compared to other taxa. Furthermore, whilst activity loss and mortality dynamics could not be divided into ‘fish- vs invertebrate-infecting cercariae’ groups, the detected taxa-specific responses in relation to life-history traits indicate the swimming behaviour of cercariae and energy allocation among larvae individuals as the main drivers. Cercariae exploit the short transmission window that allows a stable continuance of trematodes’ life cycles in high-latitude freshwater ecosystems.

The goal is to conduct a comparative analysis of the characteristics of blood counts of pregnant women with HIV living in the subarctic climatic zone of the Khanty-Mansiysk District, as predictors of a systemic inflammatory reaction on the background of infection and pregnancy complicated by preterm delivery.Material and methods. A retrospective analysis of 78 stories of pregnant women with HIV (main group II) was carried out, in 2016–2018. observed in one antenatal clinic in the city of Surgut. Control group (I) comprised 20 histories of pregnant women without HIV. Clinical-anamnestic and blood parameters were compared, including indicators of T-helpers, T-suppressors and viral load, leukocyte intoxication indices, hemoglobin, erythrocytes and platelets by trimesters of pregnancy. The material was processed using the Statistica-10 software system. The critical level of statistical significance was taken at pResults. A comparative analysis of blood counts of pregnant women living in the subarctic region showed a relationship between the preterm labor of patients with HIV with a progressive decrease in the T-cell level of immunity, an increase in the level of lymphocytes and leukocyte blood indices, a decrease of hemoglobin, erythrocytes, platelets, against the background of persisting viral load for the remainder of pregnancy. A decrease of T-lymphocyte counts indicates the development of a systemic inflammatory response on the background of HIV infection, depletion of the immune defense organs and the progression of the disease, while a low level of CD4 lymphocytes stimulates the activation of granulocytes in the blood and indicates further depletion of T-lymphocytes. Activation of a systemic inflammatory response that promotes the release of inflammatory mediators and prostaglandins and, with a high probability, underlies the mechanisms of rejection of the fetus and placenta and the spontaneous preterm labor. The comorbid background of pregnant women with HIV and preterm labor is associated with low adherence to HAART therapy and high detectable viral load throughout gestation.

We assess the quality of regional and global ozone reanalysis data for vegetation modeling and ozone (O3) risk mapping over subarctic Europe where monitoring is sparse. Reanalysis data can be subject to systematic errors originating from, for example, quality of assimilated data, distribution and strength of precursor sources, incomprehensive atmospheric chemistry or land–atmosphere exchange, and spatiotemporal resolution. Here, we evaluate two selected global products and one regional ozone reanalysis product. Our analysis suggests that global reanalysis products do not reproduce observed ground-level ozone well in the subarctic region. Only the Copernicus Atmosphere Monitoring Service Regional Air Quality (CAMSRAQ) reanalysis ensemble sufficiently captures the observed seasonal cycle. We also compute the root mean square error (RMSE) by season. The RMSE variation between (2.6–6.6) ppb suggests inherent challenges even for the best reanalysis product (CAMSRAQ). O3 concentrations in the subarctic region are systematically underestimated by (2–6) ppb compared to the ground-level background ozone concentrations derived from observations. Spatial patterns indicate a systematical underestimation of ozone abundance by the global reanalysis products on the west coast of northern Fennoscandia. Furthermore, we explore the suitability of CAMSRAQ for gap-filling at one site in northern Norway with a long-term record but not belonging to the observational network. We devise a reconstruction method based on Reynolds decomposition and adhere to recommendations by the United Nations Economic Commission for Europe (UNECE) Long-Range Transboundary Air Pollution (LRTAP) convention. The thus reconstructed data for 2 weeks in July 2018 are compared with CAMSRAQ evaluated at the nearest-neighbor grid point. Our reconstruction method's performance (76 % accuracy) is comparable with CAMSRAQ (80 % accuracy), but diurnal extremes are underestimated by both.

Climate change impacts are pronounced at high latitudes, where warming, reduced sea-ice-cover, and ocean acidification affect marine ecosystems. We review climate change impacts on two major gateways into the Arctic: the Bering and Chukchi seas in the Pacific and the Barents Sea and Fram Strait in the Atlantic. We present scenarios of how changes in the physical environment and prey resources may affect commercial fish populations and fisheries in these high-latitude systems to help managers and stakeholders think about possible futures. Predicted impacts include shifts in the spatial distribution of boreal species, a shift from larger, lipid-rich zooplankton to smaller, less nutritious prey, with detrimental effects on fishes that depend on high-lipid prey for overwinter survival, shifts from benthic- to pelagic-dominated food webs with implications for upper trophic levels, and reduced survival of commercially important shellfish in waters that are increasingly acidic. Predicted changes are expected to result in disruptions to existing fisheries, the emergence of new fisheries, new challenges for managing transboundary stocks, and possible conflicts among resource users. Some impacts may be irreversible, more severe, or occur more frequently under anthropogenic climate change than impacts associated with natural variability, posing additional management challenges.

Alaska Wild Rhubarb (Koenigia alaskana var. glabrescens; Polygonaceae) is a native Arctic, subarctic, and alpine plant of northwestern North America. Although the plant has some economic and ecological importance, its biology is poorly known. At 11 sites in the northeast corner of its range in Northwest Territories, we found that 87% of its floral visitors were flies, mostly Syrphidae, a diverse family known to be important pollinators. Insects visiting consecutive flowers on different plants and, thus, likely effecting pollination were also flies (78.6%) and also mostly Syrphidae (72.7%) followed by Hymenoptera (20%). Although syrphids were the dominant potential pollinators at most sites, there was some variation among sites. Our results provide quantitative support for pollinator diversity and the major role of Syrphidae in pollination of Alaska Wild Rhubarb. We suggest that pollination is not a limiting factor in this plant’s spread, nor its rare and local occurrence and restricted distribution, because the majority of its pollinators are widespread.

Recent studies on marine heat waves describe water temperature anomalies causing changes in food web structure, bloom dynamics, biodiversity loss, and increased plant and animal mortality. However, little information is available on how water temperature anomalies impact prokaryotes (bacteria and archaea) inhabiting ocean waters. This is a nontrivial omission given their integral roles in driving major biogeochemical fluxes that influence ocean productivity and the climate system. Here we present a time-resolved study on the impact of a large-scale warm water surface anomaly in the northeast subarctic Pacific Ocean, colloquially known as the Blob, on prokaryotic community compositions. Multivariate statistical analyses identified significant depth- and season-dependent trends that were accentuated during the Blob. Moreover, network and indicator analyses identified shifts in specific prokaryotic assemblages from typically particle-associated before the Blob to taxa considered free-living and chemoautotrophic during the Blob, with potential implications for primary production and organic carbon conversion and export., Traving et al. use small subunit ribosomal RNA gene sequencing to examine spatial and temporal trends in bacterial and archaeal community structure during a large marine warm water surface anomaly, the Blob. Their findings suggest that community structure shifted during the Blob, with taxa considered free-living and chemoautotrophic prevailing under these unusual conditions.

The mechanism that controls particulate organic carbon (POC) flux in the deep sea differs depending on the season and sea. The POC produced in the western subarctic North Pacific are known to be transported to the deep sea efficiently, but the direct relationship between the POC flux and physical processes is still unclear. In this study, we evaluated the effect of mesoscale eddies on POC flux in the western subarctic North Pacific. The seasonal and interannual variabilities of POC flux were investigated using data from a time-series sediment trap deployed at 4810 m at station K2 (47°N, 160°E) from 2005 to 2018. POC flux was high during May–November, appearing to reflect spring and fall blooms at the ocean surface. POC flux also showed interannual variability, with twelve peaks that were mostly affected by enhanced bloom just before the peak. Nine peaks of the twelve peaks were affected by mesoscale eddies, which enhanced bloom around K2 by extending the area with a high chlorophyll-a concentration along the coastal region into the offshore region, suggesting that mesoscale eddies strongly impact the interannual variability of POC flux at K2.

Concrete creep and shrinkage at cold temperatures are less significant than those at room temperature. For the structures exposed to subarctic weather, in situ creep and shrinkage strains are important factors in design process, such as estimating pre-stress losses, since ambient temperature and relative humidity change in a wide range. In the present study, the in situ creep and shrinkage strains were measured from high strength concrete specimens loaded in a concrete creep frame exposed to subarctic weather for 332 days. The measured creep strain was 23–30% of creep strain from specimens at room temperature. Also, the shrinkage strain was 67% of the shrinkage strain measured at room temperature. The comparison showed that the creep and shrinkage strains in real subarctic weather were larger than strains at a sustained cold temperature, but they were substantially smaller than strains at room temperature. The measured strains were compared with predicted values from widely used creep and shrinkage models. The AASHTO-LRFD model and the CEB MC90-99 model matched well with test results.

—In recent years, the supra-long Yamal tree-ring chronology has been significantly extended and became much more reliable. This article characterizes the sample wood used to build the longest absolutely dated Siberian Larch tree-ring chronology of the Subarctic area, i.e. from 6748 BC to 2019 AD, for a total continuous period of 8768 years. The ecological value of the temporal and spatial distribution of the dated trees are presented, and their potential use for application in various field of natural sciences and humanities are discussed.

Based on the analysis of oceanographic survey materials and sea surface temperature satellite observations, the conditions of formation and characteristics of the anticyclonic eddy located in the region of the South Kuril Islands in the spring of 1999 were studied. It was shown that it separated from the subarctic front as result of its interaction with the Oyashio current stream in the second half of March and ceased to exist in mid-June, which is also confirmed by observations of the concentration of chlorophyll-a. In contrast the eddies formed as a result of meandering of the warm Kuroshio and Tsugaru currents, the eddy core, located at depths of 150–300 m, was characterized by lower values of temperature and salinity (4°–4.6°С and 33.55–33.65 е.п.с.) and low current velocities ( about 10 cm/s). The eddy was rather weakly distinguished in the density field both on horizontal and vertical distributions, as well as according to satellite altimetry data.

Rapid changes in the hydrological and temperature regimes over the past decades at the northern latitudes enhance significantly permafrost degradation accelerating carbon release, increase the frequency of drought events and extensive wildfires. However, the mechanisms and dynamics driving drought events and their influence on Siberian forests are currently the subject of numerous research activities. Newly developed and annually resolved stable carbon and oxygen isotope chronologies of larch tree-ring cellulose (δ13Ccell and δ18Ocell) for the period 516–2009 CE allowed the reconstruction of July precipitation and Arctic Oscillation (AO) in May, respectively. Unprecedented drought events occurred towards twentieth–twenty-first centuries as indicated by the July precipitation reconstruction. Positive AO phases in May were most pronounced during the second part of the first millennium, but also increased in frequency in the modern period of the twentieth–twenty-first centuries. Negative AO phases are associated with cold anomalies and show a remarkable decrease in the nineteenth century caused by a series of major volcanic eruptions. Our findings help explaining the increased frequency of Siberian forest fires over the past decades in Central Siberia consistent with a reduction of summer precipitation, triggered by a positive phase of the Arctic Oscillation in May.

We discuss the results of gravimetric and satellite geodetic measurements at the Zapolyarnoye and Yamburgskoye gas and oil deposits in Transpolar Western Siberia in subarctic zone of Yamal-Nenets autonomous okrug. The development of mineral deposits and large number of pipelines require monitoring of recent motions of the Earth’s surface. Displacements and other phenomenon were studied by satellite geodesy and absolute gravimetry. It is now possible to obtain the kinematic parameters (rates of subsidence and horizontal motion) and addition information on fluid motion into the layers of the deposits. The ground displacements rate in different short periods recorded at large man-made objects are shown. Rates for hydroobjects are estimated at 5 mm/yr. The gravimetry and satellite geodesy results obtained at the Zapolyarnoye deposit in the northern part of Western Siberia were analyzed. Subsidence rates of 21–23 mm/yr were estimated. An increase in gravity of up to 7 µGal were recorded at the deposits (2006–2008). In this case, the increased gravity is related to surface subsidence (with a normal vertical gradient). Subsidence rates of 16–21 mm/yr were estimated at the Yamburgskoye field. This result is consistent with the rates at Zapolyarnoye. The horizontal rates and orientation differed at different deposits.

We present the longest tree-ring chronology to date in northeastern North America (2233 years; 227 BCE – 2005 CE), resulting from several research projects conducted at the subarctic treeline in no...

Climate change increases the insect abundance, especially in Arctic ecosystems. Insect herbivory also significantly increases plant emissions of volatile organic compounds (VOCs), which are highly reactive in the atmosphere and play a crucial role in atmospheric chemistry and physics. However, it is unclear how the effects of insect herbivory on VOC emissions interact with climatic changes, such as warming and increased cloudiness. We assessed how experimental manipulations of temperature and light availability in subarctic tundra, that had been maintained for 30 years at the time of the measurements, affect the VOC emissions from a widespread dwarf birch (Betula nana) when subjected to herbivory by local geometrid moth larvae, the autumnal moth (Epirrita autumnata) and the winter moth (Operophtera brumata). Warming and insect herbivory on B. nana stimulated VOC emission rates and altered the VOC blend. The herbivory‐induced increase in sesquiterpene and homoterpene emissions were climate‐treatment‐dependent. Many herbivory‐associated VOCs were more strongly induced in the shading treatment than in other treatments. We showed generally enhanced tundra VOC emissions upon insect herbivory and synergistic effects on the emissions of some VOC groups in a changing climate, which can have positive feedbacks on cloud formation. Furthermore, the acclimation of plants to long‐term climate treatments affects VOC emissions and strongly interacts with plant responses to herbivory. Such acclimation complicates predictions of how climate change, together with interacting biotic stresses, affects VOC emissions in the high latitudes., Climate change increases the insect abundance, especially in arctic ecosystems. Insect herbivory also significantly increases plant emissions of volatile organic compounds (VOCs), which are highly reactive in the atmosphere and play a crucial role in atmospheric chemistry and physics. We showed generally enhanced tundra VOC emissions upon insect herbivory and synergistic effects on the emissions of some VOC groups in a changing climate, which can have positive feedbacks on cloud formation.

Species and community-level responses to warming are well documented, with plants and invertebrates known to alter their range, phenology or composition as temperature increases. The effects of warming on biotic interactions are less clearly understood, but can have consequences that cascade through ecological networks. Here, we used a natural soil temperature gradient of 5–35°C in the Hengill geothermal valley, Iceland, to investigate the effects of temperature on plant community composition and plant–invertebrate interactions. We quantified the level of invertebrate herbivory on the plant community across the temperature gradient and the interactive effects of temperature, plant phenology (i.e. development stage) and vegetation community composition on the probability of herbivory for three ubiquitous plant species, Cardamine pratensis, Cerastium fontanum and Viola palustris. We found that the percentage cover of graminoids and forbs increased, while the amount of litter decreased, with increasing soil temperature. Invertebrate herbivory also increased with soil temperature at the plant community level, but this was underpinned by different effects of temperature on herbivory for individual plant species, mediated by the seasonal development of plants and the composition of the surrounding vegetation. This illustrates the importance of considering the development stage of organisms in climate change research given the variable effects of temperature on susceptibility to herbivory at different ontogenetic stages.

Distribution and abundance of myctophid fish species in the upper epipelagic layer are analyzed based on results of surveys in the Gulf of Alaska in winters of 2019 and 2020. A common myctophid community driven by blue lanternfish Tarletonbeania crenularis was revealed that occupied likely the entire eastern part of the Subarctic Front zone eastward from 150ºW. Abundance and biomass of four mass myctophid species were generally comparable between the northeastern and northwestern Pacific. Small-sized juveniles prevailed among northern lampfish Stenobrachius leucopsarus, which were likely transported by the Subarctic Current and could be recruited to the Bering Sea stock. Patterns of daily vertical migrations are discussed for the mass myctophid species. New observations confirm general understandings on the myctophid species input to functioning of fish community.

Abstract The taxonomic structure, typology, species richness, and total abundance of bentic and littoral macroinvertebrate communities from small lakes of the Arctic and Subarctic zones are considered on the basis of original data from three northern Palearctic regions (the foot of the Putorana Plateau, Kolguev Island, and Western Svalbard Island). A comparative analysis of the communities of these regions has been carried out. The features of High Arctic insular, Low Arctic, subarctic, and boreal lake communities are discussed using a large volume of literature data. The complex pattern of changes in the total benthos biomass of small lakes has been revealed: it decreases in the subarctic taiga, increases in the hypoarctic tundra, and decreases again in the High Arctic.

The composition and concentrations of steroids, acyclic and cyclic terpenoids, n-alkanes, fatty acids, alkanones, and polysubstituted phenols in peats from ten deposits located within the continental part of the Nenets autonomous okrug and Mezen, Primorskii, and Onega districts of Arkhangelsk oblast and from three deposits on islands in the White Sea (Nemetskii Kuzov) and the Barents Sea (Kolguev and Bol’shoi Tsinkovyi) were studied. Changes in the composition of lipids within individual deposits and in regions were shown: an increase in the concentration of pentacyclic terpenoids with the depth of peat occurrence in most of the deposits and the appearance of aromatized steroids in the lower parts of deposits, a decrease in the concentration of acyclic diterpenoids in northern and eastern directions, and a significant decrease in the concentrations of all identified groups of lipids in peat in the Subarctic. Promising areas characterized by the presence of peat with increased concentrations of biologically active components were revealed.

The article presents a study of the hydrological regime of the Lena and Mackenzie rivers, flowing in the zone of permafrost rocks of different types. Features typical of river mouths in subarctic zone are identified. Sediment transport in both deltas and the export of material into the Laptev and Beaufort seas is studied. Permafrost rock characteristics are given and their changes under the current rise of air temperature are discussed. The possible effect of permafrost rock thawing under climate warming on water and sediment runoff in arctic deltas is discussed.

This review is devoted to mesoscale anticyclonic eddies of the Japan, Kuril–Kamchatka, and Aleutian deepwater trenches in the northwestern part of the Pacific Ocean. These eddies play an important role in water circulation in the Western Subarctic Gyre and have a significant impact on the weather, climate, and bioproductivity in the region. The review presents information about trench eddies, including a discussion of the formation, stagnation, motion, deformation, and decay of trench eddies. Using Lagrangian methodology, a complete census of these eddies in the altimetric era was carried out starting from January 1, 1993. Their evolution and origin are studied using Lagrangian maps of various indicators of water motion, which allow identifying eddies, as well as tracking their trajectories and important events in life: birth, capture, and release of water; merging with other vortices and splitting; erosion; and decay. The vertical structure and hydrological characteristics derived from ship surveys and profiles of Argo drifting buoys are discussed and analyzed.

Early studies (1976–1982) of the Drizzle Lake Ecological Reserve on Haida Gwaii, British Columbia focussed on the endemic Giant Threespine Stickleback (Gasterosteus aculeatus) and their predators. These surveys showed daily visits to the small lake (110 ha) by up to 59 adult non-breeding Common Loon (Gavia immer), an important stickleback predator and up to 19 breeding and non-breeding adult Red-throated Loon (Gavia stellata), which leave daily to forage in nearby marine waters. We continued loon surveys for 17 additional years (1983–1989, 2011–2020) and found that aggregations of non-breeding Common Loons occurred annually on the lake during July with maximum daily numbers of 78–83 individuals in 1987, 2018, and 2020 and a large increase from 2011 to 2020. We did not detect any relationship of these differences with the Pacific Decadal Oscillation but a significant inverse correlation with average wind speed. Average yearly numbers of Red-throated Loons declined by 50% from 1976 to 1989 and have remained low, with lowest numbers (

The influence of snow cover on the dynamics of soil temperature in the modern climatic conditions of the Eurasian Subarctic was investigated through a quantitative assessment of the features of the seasonal and long-term variation of parameters. Seasonal and long-term values of soil temperature for stable snow period decrease from west to east: a decrease of snow thickness and air temperature from west to east of Eurasia leads to a weakening of the heat-insulating properties of the snow cover with a significant decrease in regional air temperatures. With the emergence of a stable snow cover, the soil temperature seasonal and long-term standard deviation sharply decreases compared to the autumn and spring periods. With the appearance of snow cover, the soil temperature standard deviation drops sharply compared to the autumn and spring periods. An exception is the northeast of Siberia: here, a relatively small thickness of snow determines a noticeable dependence of the course of soil temperature on the dynamics of surface air temperature. There are no significant long-term trends in soil temperature due to its low variability during winter period. Analysis of the course of the studied characteristics anomalies showed an insignificant and non-systematic number of their coincidences. Currently, we have not found similar research results for large regions. The revealed patterns can be used in the analysis of the results of monitoring the state of the land surface, in the development of remote sensing algorithms, in the refinement of predictive scenarios of environmental changes.

Climate change is projected to cause increased inflow of terrestrial dissolved organic matter to coastal areas in northerly regions. Estuarine bacterial community will thereby receive larger loads of organic matter and inorganic nutrients available for microbial metabolism. The composition of the bacterial community and its ecological functions may thus be affected. We studied the responses of bacterial community to inflow of terrestrial dissolved organic matter in a subarctic estuary in the northern Baltic Sea, using a 16S rRNA gene metabarcoding approach. Betaproteobacteria dominated during the spring river flush, constituting similar to 60% of the bacterial community. Bacterial diversity increased as the runoff decreased during summer, when Verrucomicrobia, Betaproteobacteria, Bacteroidetes, Gammaproteobacteria and Planctomycetes dominated the community. Network analysis revealed that a larger number of associations between bacterial populations occurred during the summer than in spring. Betaproteobacteria and Bacteroidetes populations appeared to display similar correlations to environmental factors. In spring, freshly discharged organic matter favoured specialists, while in summer a mix of autochthonous and terrestrial organic matter promoted the development of generalists. Our study indicates that increased inflows of terrestrial organic matter-loaded freshwater to coastal areas would promote specialist bacteria, which in turn might enhance the transformation of terrestrial organic matter in estuarine environments.