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The structure and productivity of planktonic microbial communities in the ecosystems of the Siberian Arctic seas are significantly dependent on freshwater input. During the study, we determined the spatial distribution of the abundance, biomass, and production of heterotrophic bacterioplankton in the Western Laptev Sea on the transect from the Khatanga River estuary to the continental slope and assessed the impact of river freshwater discharge. The influence of fresh water on bacterioplankton was restricted mainly to Khatanga Bay (KHAB) and the transitional zone (TZ) and was poorly recognized in the Western shelf (WS) and continental slope (CS) areas. The total bacterial abundance decreased from KHAB to the CS. Particle-attached bacteria constituted on average 63.0% of the total abundance of bacterioplankton in KHAB and 1.0% at the CS. Average bacterial production in the water column was highest in KHAB (10.3 mg C m−3 d−1), decreasing towards the CS (0.7 mg C m−3 d−1). In KHAB and TZ, bacteria were the main component of the planktonic community (44−55%). These results show that at the end of the growing season, bacterial processes prevailed over autotrophic ones and contributed largely to the total biological carbon flux in the coastal ecosystem of the Western Laptev Sea. [ABSTRACT FROM AUTHOR]

The study presents the results of the survey of beached litter on the two opposite shores of the Fields Peninsula (King George Island) conducted during the austral summer seasons of 2022 and 2023, as part of the 67th and 68th Russian Antarctic expeditions. Beaches situated on the coast of the Drake Passage were much more polluted compared to the beaches on the Maxwell Bay side. Plastic accounted for 86 % of all found items on the shores of the Drake Passage, with the majority of items related to fisheries or shipping. On the Maxwell Bay beaches, only 36 % of litter was plastic, with other categories like wood and metal dominating the total number. The average density of marine litter is 0.32 items/m (0.017 items/m2), comparable to other similar surveys conducted on Antarctic islands; however, this is at least 15–20 times lower than beach litter densities in the Arctic. • Antarctic beach litter density is at least 15–20 times lower than in the Arctic. • 86 % of marine litter on the Drake Passage side of the Fields Peninsula is plastic. • On the Maxwell Bay side of the Fields Peninsula wood is more prominent. • The majority of plastic items on the Fields Peninsula come from fisheries or shipping. • Several beaches are recommended for regular monitoring. [ABSTRACT FROM AUTHOR]

Atlantic Water is the main source of the heat and salt in the Arctic. On the way to the Arctic Ocean via the Nordic Seas, it interacts and mixes with other water masses which affects sea ice extent and deep water formation. The Atlantic Water heat transported into the Nordic Seas has a significant impact on the local climate and is investigated here along with its inter-annual variability using the ARMOR3D dataset, which is a collection of 3D monthly temperature, salinity and geostrophic velocities fields, derived from in situ and satellite data on a regular grid since 1993. The study region includes the eastern part of the Nordic seas, i.e., seven latitudinal transects from Svinoy section (65° N) to the northern part of the Fram Strait (78.8° N). The Atlantic Water heat advection decreases northwards, as a significant amount of heat is lost to the atmosphere and due to mixing with surrounding waters. As observed, the imbalance of heat fluxes in the upper layer leads to an increase in the upper ocean mean temperature over most of the study region. The correlations of the interannual variations of the advective heat fluxes rapidly drop from Svinoy to Jan Mayen sections and between Bear Island and Sorkapp sections. This is a result of a differential damping of periodicities (the 2-3 year and 5-6 year oscillations), as well as of different signs of the tendencies over the latest decades. The heat fluxes at all sections show a consistent change with meridional (C) and western (W) weather types, which is due to the different direction of the Ekman pumping associated with each of the weather types. A certain link to the NAO, AO and EA atmospheric indices is observed only at the southern sections. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to identify the features of hematological reactions in the inhabitants of the Arctic territory of the Kola Peninsula on a polar night and a polar day. Methods: The study included determining the hemogram, neutrograms, monocytograms, lymphocytograms, and phagocytic activity neutrophil granulocytes, enzyme immunoassay, flow cytometry. Results: It was established that during the polar night, there is an increase in the activity of migration of leukocytes from the marginal pool to the circulating pool, an increase in the intensity of phagocytosis by neutrophils, an increase in the concentrations of noradrenaline, cortisol, as well as an increase in hyperergic reactions involving immunoglobulin E and inhibitory processes due to an increase in interleukin‐10. Conclusion: A prolonged lack of sunlight causes a decrease in the reserve capacity for regulating homeostasis and forces the body to use proliferative reactions, which is reflected in the increase in stab neutrophils, large lymphocytes in the structure of the lymphocytogram and CD10+ lymphocytes. In winters, the frequency of neutropenia registration also increases to 13% of cases, the deficit of phagocytic activity of neutrophils; lymphopenia is recorded in 20% with T‐helper deficiency (37%). A part of the population probably has a relatively high degree of vulnerability to the action of natural environmental factors and is not able to completely restore the initial levels of the effectiveness of adaptation reactions in the summer. So at the end of the polar day in 8% of adults born in the north, neutropenia is recorded and in 21%—lymphopenia. [ABSTRACT FROM AUTHOR]

We analyze the problem of data availability and how this situation (which is very common in practice) is a limiting factor for doing quality control and data restoration of MetOcean fields. In order to support our claim, we analyzed the case of data availability in the Arctic Region, since it is true that climate historical archives have always been scarce in this area, due to the harsh climate conditions and logistic difficulties that involve the deployment of in-situ weather systems in the region. In addition to the problem of data scarcity, we also have the problem of inconsistent and missing observations. In this paper, we highlight this problem by the analysis of 125 hourly temperature and hourly wind speed time series, which have been all in common their spatial distribution and present an evaluation of those data in terms of quality and availability. We also discuss the way the presence of gaps in time series can condition the ability of estimating synthetic data and discuss possible solutions to overcome this problem in areas where no neighboring stations are available. [ABSTRACT FROM AUTHOR]

Growing anthropogenic activity in the Arctic, especially near regional municipal and transportation hubs, threatens coastal environments with significant changes and contamination. A detailed study of a wide set of organic-geochemical proxies in surface and subsurface sediments and soils around the typical urbanized Arctic area (Tromsø, Norway) was performed to investigate natural and anthropogenic input of hydrocarbons. The sites were located close to main areas of human activity and differed in the level of anthropogenic pressure: oil terminal, boat harbor and recreation beach zone in the city center, and a remote, conditionally-clean area. The samples from each site were collected along four subtidal – intertidal – supratidal transects. GC–MS data on the distribution of more than 110 compounds were obtained including n -alkanes, isoprenoids, terpanes, parent polycyclic aromatic hydrocarbons (PAHs), and alkyl PAHs. Organic matter embedded in a mineral matrix was more thermally mature than its fresh non-bound fraction. Biomarker distribution and diagnostic ratios attested to the predominantly local origin of near-shore organic matter formation (phytoplankton, algae, high foliar plants, grass). PAH composition revealed a significant input of pyrogenic components from liquid and solid fuel combustion to the surface coarse-grained sediments. Background bacterial activity was evidenced by the high content of biohopanes and hopenes in less polluted sediments and soils. The presence of an unresolved complex mixture and even n -alkanes in sediment profiles from the most polluted sites attested to the active biodegradation that, together with the erosion of the upper layers by tidal currents, reduces the toxic compound penetration deeper into the sediments. • Organic matter in intertidal deposits of the urbanized Arctic area was studied. • Organic matter bonded with the mineral matrix is of local origin and highly mature. • Variations in organic-geochemical proxies attest to recent human impact. • Contaminants accumulate predominantly in the surface coarse-grained sediments. • Biomarker composition evidences biodegradation process in polluted sites. [ABSTRACT FROM AUTHOR]

Belova, N.G.; Novikova, A.V.; Günther, F., and Shabanova, N.N., 2020. Spatiotemporal variability of coastal retreat rates at Western Yamal Peninsula, Russia, based on remotely sensed data. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 367–371. Coconut Creek (Florida), ISSN 0749-0208. The work aims at estimating coastal retreat at Western Yamal from 1972 to 2016, when significant climate change occurred in the Arctic. One fourth of the Kara Sea coasts are collapsing cliffs composed of permafrost, i.e. thermoabrasional coasts. Although these coasts are bounded by sea ice for most of the year, they retreat with rates comparable to those of temperate latitudes, but only during the short ice-free period. Permafrost cliffs are not only eroded by waves; they also get destroyed by melting of the ground ice bounding the sediments (thermo-denudation). Arctic coasts are sensitive to climate change, as rising summer air temperatures lead to deeper thawing of frozen sediments, and longer ice-free periods extend the time of the wave impact on the coast. At Western Yamal, in the area of Kharasavey gas condensate field, the average long-term coastal retreat rate is 1.3 m/yr (1972-2016) for 5.9 km of the coastline, reaching mean annual rates of 3 m/yr in some areas. The greatest retreat rates are typical for coastal segments composed of permafrost with high ice content. Based on the analysis of multitemporal aerial and space images, the coastal retreat rates for four time periods between 1972 and 2016 were estimated. The retreat rates were brought into context with data on sediment composition and type (grain size, ice content, presence of massive ice), reconstructed evolution of hydrometeorological parameters and the history of economic development of Kharasavey area. Unlike other Kara Sea sites of coastal dynamics' monitoring, the strongest coastal retreat rates at Kharasavey were observed earlier in 1977-1988, when the hydrometeorological stress was low, implying vulnerability of the coasts to significant anthropogenic impact at the beginning of the gas field development. [ABSTRACT FROM AUTHOR]

Coastal marine ecosystems in the Arctic are extremely vulnerable to human activities associated with oil and gas exploration, transportation and processing, and with industrial and urban development. The effects of complex pollutant mixtures interact with environmental factors. Here we assessed the effects of two anthropogenic and one natural factor on the reproduction, development and adult shell shape of the intertidal ovoviviparous gastropod Littorina saxatilis at 12 sites in the Barents and Norwegian Seas. The stressors studied were toxicity equivalency (TEQ) of the polycyclic aromatic hydrocarbons (PAH), the proximity of the site to urban/industrial locations as a proxy for urban pollution, and salinity. Total fecundity of the snails decreased at sites with low salinity but was not affected by PAH pollution. Allometric relationships of L. saxatilis shell shape varied between sites depending on the proximity of urban/industrial locations; the intrapopulation morphological disparity increased near urban sites. The frequency of abnormal embryos per brood and the incidence of females with abnormal embryos in the brood pouch increased at urban sites, especially under conditions of low salinity, but was unrelated to PAH pollution. Monte Carlo simulation showed that the registered embryotoxic effect of the proximity to urban/industrial locations was unlikely to result in a significant reduction of the population recruitment of L. saxatilis due to the high fecundity of these snails. Elucidation of the mechanisms of low sensitivity of L. saxatilis to PAHs in concentrations registered in our study and identification of the cause of embryotoxic effects associated with the proximity of urban/industrial locations are promising directions of further studies. Our results highlight the importance of considering multiple stressors when assessing anthropogenic impacts on coastal systems. We show that L. saxatilis can be an informative indicator of coastal urban pollution across its wide distribution range. • Effects of urban proximity, hydrocarbon pollution and salinity are described. • Reproduction, development and shape of Littorina saxatilis snails are used as a model. • Fecundity of L. saxatilis depends on salinity but not on PAH or urban proximity. • Frequency of abnormal embryos depends on salinity and urban proximity but not on PAH. • Adult shell shape morphological disparity is higher at urban sites. [ABSTRACT FROM AUTHOR]

Changes in the immune status and the content of blood transport components reflect adaptations in the human body in response to adverse factors, showcasing the organism's adaptive capabilities and functional state. In this study, we aimed to determine the features of the immune system and levels of transport components of the blood system in residents of the Arctic of the Russian Federation., Methods: The peripheral venous blood of 191 residents of the Arctic of the Russian Federation (Murmansk Oblast) aged 21-55 analyzed comprehensively. Blood was sampled from the ulnar vein on an empty stomach in the morning. The hemogram, phagocytic activity of neutrophils, lymphocyte content with CD3, CD4, CD8, CD10, CD19, CD16, CD71, CD25, HLA-DR and CD95 phenotypes, concentrations of cytokines: TNF-α, IFN-γ, IL-6, IL-10, extracellular receptor pool: sCD71, sCD62L, sApo-1/Fas, sFasL, circulating immune complexes (CIC) and blood transport components: haptoglobin (Hp), transferrin, IgM, IgG, IgA, IgE (immunoglobulins M, G, A and E) low-density lipoproteins (LDL), and high density lipoprotein (HDL) were evaluated. The results were analyzed using descriptive statistics and comparative, factorial, and regression analyses., Results: Residents of the Murmansk Oblast exhibit a high prevalence of erythrocytosis (62.3%), thrombocytosis (25.0%), leukocytosis (20.1%), and increased hemoglobin (Hb) concentrations (42.5%), coupled with a significantly decreased level of active phagocytes (47.6%). A significantly decreased level of lymphocytes with phenotypes CD3 (92.4%), CD4 (40.4%), CD71 (62.3%) was revealed, coupled with the activation of lymphocytes with phenotypes CD16 (50.1%), CD8 (37.5%), CD19 (15.9%) and increased concentrations of pro-inflammatory IFN-γ (47.9%), IL-6 (33.3%), and TNF-α (20.1%). Elevated levels of sCD71 (56.6%), sCD62L (32.1%), sApo-1/Fas (22.1%), sFasL (10.2%), and autoantibodies to double-stranded DNA (57.1%), RNA (10.4%), and oLDL (oxidized-modified LDL) (16.3%) were recorded in residents of the Murmansk Oblast. Arctic residents showed elevated concentrations of Hp (63.3%), IgM (63.9%), IgA (42.4%), IgE (18.8%), LDL (24.9%), and a decreased level of HDL (21.1%) owing to an ApoA-I ligand deficiency (58.1%). Elevated levels of Hp in the blood are associated with increased erythrocyte aggregation frequency, T-lymphocyte activation, and increased concentration of free receptors of the extracellular pool. Increased IgM and IgA levels in the blood are attributed to the need to bind components of the extracellular receptor pool sCD71, sCD62L, sApo-1/Fas, sFasL and are associated with decreased levels lymphocyte with CD8 and CD16 phenotypes. The humoral immune response in Arctic residents is triggered when the cellular component of immunity is under strain which compounded by ineffective clearance of metabolic byproducts owing to imbalanced LDL and HDL lipid transport complexes., Conclusions: The immune system of Arctic residents is characterized by excessive cytotoxic activity of lymphocytes and increased concentrations of pro-inflammatory cytokines, free forms of receptors of the extracellular pool, and autoantibodies. The change in the content of transport components of the blood system is directed at maintaining homeostasis by exhibiting antioxidant, anti-inflammatory, and immunoregulatory properties., (© 2024 Wiley Periodicals LLC.)

Background: Ancient DNA studies suggest that Late Pleistocene climatic changes had a significant effect on population dynamics in Arctic species. The Eurasian collared lemming (Dicrostonyx torquatus) is a keystone species in the Arctic ecosystem. Earlier studies have indicated that past climatic fluctuations were important drivers of past population dynamics in this species., Results: Here, we analysed 59 ancient and 54 modern mitogenomes from across Eurasia, along with one modern nuclear genome. Our results suggest population growth and genetic diversification during the early Late Pleistocene, implying that collared lemmings may have experienced a genetic bottleneck during the warm Eemian interglacial. Furthermore, we find multiple temporally structured mitogenome clades during the Late Pleistocene, consistent with earlier results suggesting a dynamic late glacial population history. Finally, we identify a population in northeastern Siberia that maintained genetic diversity and a constant population size at the end of the Pleistocene, suggesting suitable conditions for collared lemmings in this region during the increasing temperatures associated with the onset of the Holocene., Conclusions: This study highlights an influence of past warming, in particular the Eemian interglacial, on the evolutionary history of the collared lemming, along with spatiotemporal population structuring throughout the Late Pleistocene., (© 2022. The Author(s).)

The Arctic climate was warmer than today at the last interglacial and the Holocene thermal optimum. To reveal the impact of past climate-warming events on the demographic history of an Arctic specialist, we examined both mitochondrial and nuclear genomic variation in the collared lemming ( Dicrostonyx torquatus , Pallas), a keystone species in tundra communities, across its entire distribution in northern Eurasia. The ancestral phylogenetic position of the West Beringian group and divergence time estimates support the hypothesis of continental range contraction to a single refugial area located in West Beringia during high-magnitude warming of the last interglacial, followed by westward recolonization of northern Eurasia in the last glacial period. The West Beringian group harbors the highest mitogenome diversity and its inferred demography indicates a constantly large effective population size over the Late Pleistocene to Holocene. This suggests that northward forest expansion during recent warming of the Holocene thermal optimum did not affect the gene pool of the collared lemming in West Beringia but reduced genomic diversity and effective population size in all other regions of the Eurasian Arctic. Demographic inference from genomic diversity was corroborated by species distribution modeling showing reduction in species distribution during past climate warming. These conclusions are supported by recent paleoecological evidence suggesting smaller temperature increases and moderate northward forest advances in the extreme northeast of Eurasia during the Late Pleistocene-to-Holocene warming events. This study emphasizes the importance of West Beringia as a potential refugium for cold-adapted Arctic species under ongoing climate warming., Competing Interests: The authors declare no competing interest.

The recent intensification of energy resource exploration and human activities in the Barents Sea (BS) requires a more thorough assessment of the natural and anthropogenic impact of hydrocarbons on the environment. We analyzed a wide set of sensitive indicators, including hydrocarbon molecular markers and organic matter (OM) maturity parameters in the Holocene sediments from three regions of the BS: the Kola-Kanin Monocline (KKM), the Svalbard shelf, and the Shtokman gas-condensate field (GCF). An increase in pyrogenic polycyclic aromatic hydrocarbons toward the core surface traces the intensification of anthropogenic contamination in the KKM region during last century. An input of highly mature OM from the eroded coal rocks of Barentsburg were confirmed by comparison of biomarker distribution in sediments and coals. An increase in biogenic hopanes and hopenes content down-core, and a crude-oil stage of OM maturity in surface sediments of the Shtokman GCF attests to hydrocarbons migration from subsurface strata., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Hibernating arctic ground squirrels (Urocitellus parryii), overwintering in frozen soils, maintain large gradients between ambient temperature (T(a)) and body temperature (T(b)) by substantially increasing metabolic rate during torpor while maintaining a subzero T(b). We used quantitative reverse-transcription PCR (qRT-PCR) to determine how the expression of 56 metabolic genes was affected by season (active in summer vs hibernating), metabolic load during torpor (imposed by differences in T(a): +2 vs -10°C) and hibernation state (torpid vs after arousal). Compared with active ground squirrels sampled in summer, liver from hibernators showed increased expression of genes associated with fatty acid catabolism (CPT1A, FABP1 and ACAT1), ketogenesis (HMGCS2) and gluconeogenesis (PCK1) and decreased expression of genes associated with fatty acid synthesis (ACACB, SCD and ELOVL6), amino acid metabolism, the urea cycle (PAH, BCKDHA and OTC), glycolysis (PDK1 and PFKM) and lipid metabolism (ACAT2). Stage of hibernation (torpid vs aroused) had a much smaller effect, with only one gene associated with glycogen synthesis (GSY1) in liver showing consistent differences in expression levels between temperature treatments. Despite the more than eightfold increase in energetic demand associated with defending T(b) during torpor at a T(a) of -10 vs +2°C, transcript levels in liver and brown adipose tissue differed little. Our results are inconsistent with a hypothesized switch to use of non-lipid fuels when ambient temperatures drop below freezing.

Mammalian hibernation involves complex mechanisms of metabolic reprogramming and tissue protection. Previous gene expression studies of hibernation have mainly focused on changes at the mRNA level. Large scale proteomics studies on hibernation have lagged behind largely because of the lack of an adequate protein database specific for hibernating species. We constructed a ground squirrel protein database for protein identification and used a label-free shotgun proteomics approach to analyze protein expression throughout the torpor-arousal cycle during hibernation in arctic ground squirrels (Urocitellus parryii). We identified more than 3,000 unique proteins from livers of arctic ground squirrels. Among them, 517 proteins showed significant differential expression comparing animals sampled after at least 8 days of continuous torpor (late torpid), within 5 h of a spontaneous arousal episode (early aroused), and 1-2 months after hibernation had ended (non-hibernating). Consistent with changes at the mRNA level shown in a previous study on the same tissue samples, proteins involved in glycolysis and fatty acid synthesis were significantly underexpressed at the protein level in both late torpid and early aroused animals compared with non-hibernating animals, whereas proteins involved in fatty acid catabolism were significantly overexpressed. On the other hand, when we compared late torpid and early aroused animals, there were discrepancies between mRNA and protein levels for a large number of genes. Proteins involved in protein translation and degradation, mRNA processing, and oxidative phosphorylation were significantly overexpressed in early aroused animals compared with late torpid animals, whereas no significant changes at the mRNA levels between these stages had been observed. Our results suggest that there is substantial post-transcriptional regulation of proteins during torpor-arousal cycles of hibernation.