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Seabirds constitute an important link between marine and terrestrial ecosystems, one of its manifestations being the transport of organic matter from the sea to breeding grounds. The main aim of our study was to determine the impact of gregarious and planktivorous little auks on the quantity and chemistry of soil organic matter along the western coast of Spitsbergen, Svalbard archipelago. Samples from the vicinity of four breeding colonies and respective controls were investigated using the elemental analyzers as well as the Fourier transform infrared spectrometer with attenuated total reflection module. The results clearly indicate that soils affected by little auks are characterized by significantly higher content of soil organic carbon, total nitrogen, water-extractable organic carbon, and water-extractable total nitrogen in comparison with those unaffected by the birds. The size of the local population of little auks appears to be the crucial factor here. The chemistry of soil organic matter in soils affected by little auks is significantly different from that in soils unaffected by the birds. This is associated with fertilization of soils via guano deposition as well as differences in the quantity and quality of vegetation cover related to aforementioned process. [ABSTRACT FROM AUTHOR]

An analysis of a suite of climatological indices was undertaken on the basis of long-term (1979-2019) climatological data from the Polish Polar Station in Hornsund, SW Spitsbergen. It was followed by an attempt to assess the scale of their impact on the local environment. The temperature and precipitation indices were based on percentiles of the variables calculated for a population of daily values from the climate normals for 1981-2010. A greater share of both cyclonic and anticyclonic circulations from the S and SW sectors, forcing the advection of warm air masses from the south, was decisive for the trends of change in comparison with the long-term mean. Both extreme precipitation and drought events depend on the 500 hPa geopotential height and precipitable water anomalies, determined by the baric field over the North Atlantic. Climate changes impact on the dynamics of local geoecosystems by causing faster glacier ablation and retreat, permafrost degradation, intensification of the hydrological cycle in glaciated and unglaciated catchments, and changes in the condition and growth of tundra vegetation. [ABSTRACT FROM AUTHOR]

Progressing climate changes and declining ice cover (glacial) are accompanied by an increase in the length of paraglacial coasts. Therefore, issues related to the development and transformation of such areas attract increasing interest. No complex classification of paraglacial coasts has been presented so far. The main aim of this study was the determination of the mutual relations and evolution of paraglacial coasts in a systemic approach (paraglacial, proglacial, periglacial) based on the example of Recherchefjorden (Svalbard). Classification of coasts based on geomorphological mapping of the coasts of Recherchefjorden has been developed in terms of the lithology of sediments, genetic origins of hinterland, morphology, and morphodynamics. Analyses of field data and archival materials permitted the preparation of a model of the evolution of six main groups of coasts. Three groups were designated, characteristic of each of the glacial and paraglacial, and periglacial landscape and conditions causing transitions between particular types of coasts were determined. Due to the comprehensive and universal characteristics used in the development of the scheme and the representative landscapes of the Recherchefjorden region, the classification of High Arctic rock coasts presented here is readily transferable to other regions, potentially facilitating future research, management, and modeling of paraglacial areas. [ABSTRACT FROM AUTHOR]

In 1953, the Canadian government relocated Inuit from northern Quebec and Baffin Island to the High Arctic. Some secondary accounts identify sovereignty worries as the government's key motive, arguing that for decades, Ottawa bureaucrats had seen Inuit resettlement on uninhabited islands as an effective way to bolster Canada's territorial claim. Others deny that sovereignty played any significant role. Writers in the latter group insist that a longstanding concern for Inuit welfare was the real reason for the 1953 move. This article offers a third explanation. It demonstrates that in the 1920s, civil servants opposed relocations, while the Hudson's Bay Company favoured them. In the 1930s, some relocations by the company were allowed, but during the next decade Ottawa again imposed restrictions. Then in 1949 the northern fur economy collapsed, and the need for government relief increased. Between 1949 and 1953, bureaucrats became preoccupied with the perceived need to ensure that in future Inuit would follow southern ideals of personal thrift, saving enough to carry them through hard times. The major aim of the resettlement was to place a test group in an isolated location where government representatives could control the use of their income and impose approved patterns of economic behaviour. [ABSTRACT FROM AUTHOR]

Ice‐wedge ice is the most widespread type of massive ice found in the continuous permafrost zone. Polygonal networks of ice‐wedges drive environmental changes and feedback that will likely be exacerbated with future climate change. Recent decadal‐scale observations have shown that ice‐wedges are degrading rapidly within the entire Circum‐Arctic Region but observations of feedback associated with ground temperature regimes are still lacking in many areas. We present over a year's worth of field observations from an area with cold (−16.5°C), thick (>500 m) continuous permafrost and a mean annual air temperature of −19.7°C in the Canadian high Arctic. Topographic surveys, thaw depths, vegetation cover, soil moisture, and annual shallow (12 cm) ground temperature measurements were collected for seven ice‐wedge troughs and two polygon centers in a high‐centered polygon system. We show that geomorphic changes caused by ice‐wedge degradation generate new responses in soil moisture, vegetation cover, and snow distribution that create a mosaic of ground temperatures that range by 5.1°C for mean annual, 2.5°C in summer, and 15.2°C in winter between polygon‐centers and ice‐wedge troughs. Our results show that snow redistribution due to wind induces the cooling of polygon centers, thus promoting new thermal contraction cracking and ice‐wedge formation. We provide an example based on high‐resolution remote sensing data on how these ice‐wedge trough densities vary spatially in our study area. Capturing these fine scale geomorphic differences and resulting ground temperatures will be critical to accurately assess future changes of these common Arctic landscapes. Key Points: Ice‐wedge degradation drives geomorphic changes that impact surficial conditions and shallow ground temperatures in polygon centers and troughsCapturing microtopographic thermal regime impacts is crucial to accurately model permafrost dynamics spatially and estimate future changesIce‐wedge degradation promotes cooling of high centered polygon ground temperatures that likely initiates ice‐wedge polygon subdivision [ABSTRACT FROM AUTHOR]

The Franklin expedition disappeared in the High Arctic in the 1840s, looking for the North-West Passage. After a long search, contacts with local Inuit revealed they had all perished. Could the Inuit have saved Franklin's crews? The experience of John and James Ross is instructive. A decade earlier they led a smaller party to an Arctic region near where Franklin's crews landed. They made friends with an Inuit community and learnt useful skills in clothing, diet, shelter and transport. This enabled them to survive four Arctic winters and come home safely. But the Franklin expedition was poorly placed to benefit from Inuit contact. They were too numerous and had no interpreters. Trapped in the ice, they did not seek out Inuit villages. Leaving the ships, they turned towards a desert region and abandoned useful equipment. The wrecks of Erebus and Terror were only discovered in 2014 and 2016, again thanks to Inuit guidance. Britain has transferred the wrecks and their contents to Canada. They will be jointly held by the government and the Inuit people, whose contribution to the Franklin story is finally being recognized. [ABSTRACT FROM AUTHOR]

Proglacial environments are ideal for studying the development of soils through the changes of rocks exposed by glacier retreat to weathering and microbial processes. Carbon (C) and nitrogen (N) contents as well as soil pH and soil elemental compositions are thought to be dominant factors structuring the bacterial, archaeal and fungal communities in the early stages of soil ecosystem formation. However, the functional linkages between C and N contents, soil composition and microbial community structures remain poorly understood. Here, we describe a multivariate analysis of geochemical properties and associated microbial community structures between a moraine and a glaciofluvial outwash in the proglacial area of a High Arctic glacier (Longyearbreen, Svalbard). Our results reveal distinct differences in developmental stages and heterogeneity between the moraine and the glaciofluvial outwash. We observed significant relationships between C and N contents, δ 13Corg and δ 15N isotopic ratios, weathering and microbial abundance and community structures. We suggest that the observed differences in microbial and geochemical parameters between the moraine and the glaciofluvial outwash are primarily a result of geomorphological variations of the proglacial terrain. [ABSTRACT FROM AUTHOR]

Mount St. Helens (MSH) lies in the forearc of the Cascades where conditions should be too cold for volcanism. To better understand thermal conditions and magma pathways beneath MSH, data from a dense broadband array are used to produce high‐resolution tomographic images of the crust and upper mantle. Rayleigh‐wave phase‐velocity maps and three‐dimensional images of shear velocity (Vs), generated from ambient noise and earthquake surface waves, show that west of MSH the middle‐lower crust is anomalously fast (3.95 ± 0.1 km/s), overlying an anomalously slow uppermost mantle (4.0–4.2 km/s). This combination renders the forearc Moho weak to invisible, with crustal velocity variations being a primary cause; fast crust is necessary to explain the absent Moho. Comparison with predicted rock velocities indicates that the fast crust likely consists of gabbros and basalts of the Siletzia terrane, an accreted oceanic plateau. East of MSH where magmatism is abundant, middle‐lower crust Vs is low (3.45–3.6 km/s), consistent with hot and potentially partly molten crust of more intermediate to felsic composition. This crust overlies mantle with more typical wave speeds, producing a strong Moho. The sharp boundary in crust and mantle Vs within a few kilometers of the MSH edifice correlates with a sharp boundary from low heat flow in the forearc to high arc heat flow and demonstrates that the crustal terrane boundary here couples with thermal structure to focus lateral melt transport from the lower crust westward to arc volcanoes. Key Points: High wave speeds in the forearc crust of Cascadia help explain the absent Moho that is commonly ascribed to mantle hydrationLower‐crustal magma storage appears offset from the Mount St. Helens edifice, which is offset west of the main arc lineCrustal structure plays a critical role in the location of volcanism and helps explain the unusual trenchward location of Mount St. Helens [ABSTRACT FROM AUTHOR]

In this study, we present a bottomside model representation to be used by the Empirical Canadian High Arctic Ionospheric Model (E‐CHAIM). This model features a new approach to modeling the bottomside electron density; namely, instead of modelling electron density directly, E‐CHAIM models the altitude profile of the scale thickness of a single bottomside layer. In this approach, the curvature in the bottomside associated with the E region and F1 layer is represented in the scale thickness domain as a peak function centered at the layer peak altitude. The use of this approach ensures the production of explicitly doubly differentiable bottomside electron density profiles and directly avoids issues known to exist within current standards, such as the International Reference Ionosphere (IRI), which has discontinuities in space, time, and in the vertical electron density gradient. In terms of performance, after removing the impacts of hmF2 and NmF2, the new E‐CHAIM profile function generally performs comparably to the IRI, with bottomside TEC from both models within 2.0 TECU (1 TECU = 1016 e/m3) of observations. More specifically, the E‐CHAIM bottomside is demonstrated to outperform the IRI bottomside function in the F region during low solar activity periods with respect to incoherent scatter radar observations. At high latitudes, E‐CHAIM tends to outperform the IRI during winter months by between 10% and 40% of NmF2 while being outperformed by the IRI by between 10% and 25% of NmF2 during summer periods, mainly during the daytime at high solar activity. Key Points: A bottomside function for the Empirical Canadian High Arctic Ionospheric Model (E‐CHAIM) is presentedThe IRI demonstrates electron density discontinuities in space, time, and in its vertical gradientsThe E‐CHAIM bottomside function performs comparably to the IRIs while avoiding the need for discontinuous behavior and ensuring continuous derivatives [ABSTRACT FROM AUTHOR]

Background: The McGill Arctic Research Station (MARS) runway on Axel Heiberg Island, Nunavut has been subject to intense compaction from aircrafts since the 1960's, causing alterations to the landscape across time and space. This study investigated the thermal, hydrological and physical responses of repeated aircraft compaction of the runway to characterize its vulnerability to land use, and the effects of long-term and repeated compaction. Methods: In late July and early August 2018, the island's summer thaw season, topographic, soil, hydrological and frost table data were collected along four transects across the MARS runway. Results: Topography and effective porosity differences caused by compaction were found to affect soil moisture contents, leading to the observed differential frost heaving and insulation properties of soil across the runway. Soil was found to be mostly silt on and off disturbed areas, indicating that compaction does not affect grain-size but rather pore space and soil bulk density. The frost table mapping suggested statistically significant variations in depth of the frost table across undisturbed, disturbed, and indirectly disturbed areas, showing that compression from aircrafts has both direct and indirect spatial impacts on the hydrogeomorphic system. Furthermore, this research examined possible solutions to mitigate thaw consolidation of the runway. Limitations: The method of probing used to determine frost table depths introduced significant error to the data. Probing discrepancies arose between people probing and between sampling days, as techniques differed and/or improved. Future studies should consider using electrical resistance tomography to map the frost table, as this would eliminate inconsistencies. Furthermore, white pore size distributions were inferred based on grain-size and extent of compaction, subsequent studies should consider a quantitative approach to pore space analysis. Conclusion: This study suggests that aircraft travel to the remote McGill Arctic Research Station causes spatially and temporally significant changes in the local hydrogeomorphology, especially in fine-grained and wet, frost-susceptible soils. Thaw consolidation, which results indicate is caused by the direct and indirect effects of soil compaction, compromises the prolonged use of the runway. [ABSTRACT FROM AUTHOR]

The vertical distribution of black carbon (BC) particles in the Arctic atmosphere is one of the key parameters controlling their radiative forcing and thus role in Arctic climate change. This work investigates the presence and properties of these light-absorbing aerosols over the High Canadian Arctic (>70 ∘ N). Airborne campaigns were performed as part of the NETCARE project (Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments) and provided insights into the variability of the vertical distributions of BC particles in summer 2014 and spring 2015. The observation periods covered evolutions of cyclonic disturbances at the polar front, which favoured the transport of air pollution into the High Canadian Arctic, as otherwise this boundary between the air masses largely impedes entrainment of pollution from lower latitudes. A total of 48 vertical profiles of refractory BC (rBC) mass concentration and particle size, extending from 0.1 to 5.5 km altitude were obtained with a Single-Particle Soot Photometer (SP2). Generally, the rBC mass concentration decreased from spring to summer by a factor of 10. Such depletion was associated with a decrease in the mean rBC particle diameter, from approximately 200 to 130 nm at low altitude. Due to the very low number fraction, rBC particles did not substantially contribute to the total aerosol population in summer. The analysis of profiles with potential temperature as vertical coordinate revealed characteristic variability patterns within specific levels of the cold and stably stratified, dome-like, atmosphere over the polar region. The associated history of transport trajectories into each of these levels showed that the variability was induced by changing rates and efficiencies of rBC import. Generally, the source areas affecting the polar dome extended southward with increasing potential temperature (i.e. altitude) level in the dome. While the lower dome was mostly only influenced by low-level transport from sources within the cold central and marginal Arctic, for the mid-dome and upper dome during spring it was found that a cold air outbreak over eastern Europe caused intensified northward transport of air from a corridor over western Russia to central Asia. This sector was affected by emissions from gas flaring, industrial activity and wildfires. The development of transport caused rBC concentrations in the second lowest level to gradually increase from 32 to 49 ng m -3. In the third level this caused the initially low rBC concentration to increase from <15 to 150 ng m -3. A shift in rBC mass-mean diameter, from above 200 nm in the lower polar dome dominated by low-level transport to <190 nm at higher levels, may indicate that rBC was affected by wet removal mechanisms preferential to larger particle diameters when lifting processes were involved during transport. The summer polar dome had limited exchange with the mid-latitudes. Air pollution was supplied from sources within the marginal Arctic as well as by long-range transport, but in both cases rBC was largely depleted in absolute and relative concentrations. Near the surface, rBC concentrations were <2 ng m -3 , while concentrations increased to <10 ng m -3 towards the upper boundary of the polar dome. The mass mean particle diameter of 132 nm was smaller than in spring; nonetheless the summer mean mass size distribution resembled the spring distribution from higher levels, with depletion of particles >300 nm. Our work provides vertical, spatial and seasonal information of rBC characteristics in the polar dome over the High Canadian Arctic, offering a more extensive dataset for evaluation of chemical transport models and for radiative forcing assessments than those obtained before by other Arctic aircraft campaigns. [ABSTRACT FROM AUTHOR]

Abstract Well-preserved beetle elytra from the fossil and subfossil record are used by palaeoclimatologists to estimate past temperatures. Beetle-derived estimates of temperature across the Pliocene Arctic are consistently lower than those derived from other palaeoclimate proxies. Here we test if that pattern is attributable to either the modern dataset or specific mutual climatic range method (MCRM). We used a global dataset of observations (Global Biodiversity Information Facility) for modern beetles as opposed to a North American regional dataset, and a consistent MCRM for comparison to vegetation-derived estimates, termed CRACLE (Climate Reconstruction Analysis using Coexistence Likelihood Estimation), rather than different MCRM methods for each analysis. Beetle-derived estimates from one site, Beaver Pond, are consistently much lower than the vegetation-derived estimates, stable isotope results from flora and fauna, and summer temperatures from bacterial tetraethers. The reanalysis of beetle data produced a small reduction in proxy estimate mismatch overall. We found good agreement among proxy estimates of maximum temperature of the warmest month for two of the three sites in the Canadian Arctic, but increasingly poorer agreement for warmest quarter, coldest quarter and minimum temperature of the coldest month. This pattern may be due to beetles' avoidance mechanisms and a climate space different from modern calibration sets during the Pliocene. Beetle derived temperature estimates, especially cold season, should be interpreted with caution when reconstructing palaeoclimates. Highlights • Beetle-derived estimates of Pliocene Arctic winter temperature appear cold-biased. • Global dataset and consistent method improved warm season estimate mismatch. • Cold season temperature mismatch persists. [ABSTRACT FROM AUTHOR]

Slopes in and around Thomas Lee Inlet (Devon Island, Nunavut, Canada) are eroded by means of gullying, yet the driving factors, such as the nature of the substrate and availability of different sources for water, influencing gully morphology remain poorly understood. Here we investigate the factors that contribute to gully formation using a combination of satellite mapping, field observations and statistical analysis of morphological data. In total, 161 gullies were mapped within the 126 km2 study area. Factors linked to gullies, such as the nature of its substrate and the presence of glaciers, were integrated into a spatial geodatabase. A Factor Analysis of Mixed Data performed on the geodatabase was used to discriminate which factors may influence gully geometry. Our results show that the type of geological formation has a strong impact on gully slope. In addition, supplemental sources of water are often found near alcoves of the steep, longer and mature gullies, and levees often form in their aprons. Immature debris flow‐like gullies were dryer and found on short and variable (from steep to gentle) slopes. This detailed study of the rocky and arid Thomas Lee Inlet plateaus and slopes provides the first insight into gullied slopes as a hydrological component connecting upland units to downslope in this area. [ABSTRACT FROM AUTHOR]

Based on lake sediment data, archaeological findings, and historical records, we describe rapid transformations, resilience and resistance in societies and ecosystems, and their interactions in the past in the North Water area related to changes in climate and historical events. Examples are the formation of the polynya itself and the early arrival of people, ca. 4500 years ago, and later major human immigrations (different societies, cultural encounters, or abandonment) from other regions in the Arctic. While the early immigrations had relatively modest and localised effect on the ecosystem, the later-incoming culture in the early thirteenth century was marked by extensive migrations into and out of the area and abrupt shifts in hunting technologies. This has had long-lasting consequences for the local lake ecosystems. Large natural transformations in the ecosystems have also occurred over relatively short time periods related to changes in the polynya. Finally, we discuss the future perspectives for the North Water area given the many threats, but also opportunities. [ABSTRACT FROM AUTHOR]

Regional warming has caused permafrost thermokarst and disturbances, such as active layer detachments (ALDs), which may alter carbon feedback in Arctic ecosystems. However, it is currently unclear how these disturbances alter DOM biogeochemistry in rivers and ponds in Arctic ecosystems. Water samples from the main river channel, ALD-disturbed/undisturbed tributaries, and disturbed/undisturbed ponds within a catchment in the Canadian High Arctic were collected and analyzed using carbon isotopes and spectroscopic methods. Both river and pond samples had large variations in dissolved organic carbon (DOC) concentrations. Ponds, particularly ALD-disturbed ponds, had much older 14C DOC ages than rivers. Results from δ13C and absorption and fluorescence analyses indicate higher autochthonous contributions in ponds than rivers and increasing autochthonous contributions from upper to lower reaches of the main channel. The disturbed samples had less carbohydrates but more carboxyl-rich alicyclic molecules in 1H nuclear magnetic resonance spectra than undisturbed samples. These ALD-impacted samples also contained less terrestrial-humic-like but more oxidized-quinone-like components in the fluorescence spectra. Interestingly, the disturbed pond DOM displayed the greatest DOM oxidation with ALDs compared to undisturbed areas. Compared to Arctic rivers, small Arctic ponds have DOM predominantly from permafrost and microbial sources and may have a disproportionally stronger positive feedback on climate warming. [ABSTRACT FROM AUTHOR]

An ice core of 15.5 m retrieved from Agassiz Ice Cap (Nunavut, Canada) in April 2009 was analyzed for perchlorate to obtain a temporal trend in the recent decades and to better understand the factors affecting High Arctic deposition. The continuous record dated from 1936 to 2007, covers the periods prior to and during the major atmospheric releases of organic chlorine species that affected the stratospheric ozone levels. Concentrations and yearly fluxes of perchlorate and chloride showed a significant correlation for the 1940-1959 period, suggesting a predominant tropospheric formation by lightning. While concentration of chloride remained unchanged from 1940s until 2009, elevated levels of perchlorate were observed after 1979. A lack of significant increases in either sulfate or chloride between 1980 and 2001 suggests that the effect of volcanic activities on the perchlorate at the study site during this period could be insignificant. Therefore, the elevated perchlorate in the ice could most likely be attributed to anthropogenic activities that influenced perchlorate sources and formation mechanisms after 1979. Our results show that anthropogenic contribution could be responsible for 66% of perchlorate found in the ice. Although with some differences in trends and amounts, deposition rate found in this study is similar to those observed at Devon Island (Nunavut, Canada), Eclipse Icefield (Yukon, Canada) and Summit Station (Greenland). Methyl chloroform, a chlorinated solvent largely used after 1976, peaked in the atmosphere in 1990 and has a much shorter atmospheric life than chlorofluorocarbons (CFCs). This study proposes methyl chloroform (CH3CCl3) as the significant anthropogenic source of perchlorate in the Canadian High Arctic between 1980 and 2000, with HCFC-141b (Cl2FC-CH3), a relatively short-lived CFC probably responsible for a slower decrease in perchlorate deposition after the late 1990s. The presence of aerosols in the stratosphere appears to suppress perchlorate production after 1974. As both methyl chloroform and HCFC-141b had no new significant emissions after 2003, deposition of perchlorate in High Arctic is expected to remain at pre-1980 levels. [ABSTRACT FROM AUTHOR]

Arctic landscapes undergo seasonal and long-term changes as the active layer thaws and freezes, which can result in localized or irregular subsidence leading to the formation of thermokarst terrain. Differential Interferometric Synthetic Aperture Radar (DInSAR) is a technique capable of measuring ground surface displacements resulting from thawing permafrost at centimetre precision and is quickly gaining acceptance as a means of measuring ground displacement in permafrost regions. Using RADARSAT-2 stacked DInSAR data from 2013 and 2015 we determined the magnitude and patterns of land surface change in a continuous permafrost environment. At our study site situated in the Canadian High Arctic, DInSAR seasonal ground displacement patterns were consistent with field observations of permafrost degradation. As expected, many DInSAR values are close to the detection threshold (i.e., 1 cm) and therefore do not indicate significant change; however, DInSAR seasonal ground displacement patterns aligned well with climatological and soil conditions and offer geomorphological insight into subsurface processes in permafrost environments. While our dataset is limited to two years of data representing a three-year time period, the displacements derived from DInSAR provide insight into permafrost change in a High Arctic environment and demonstrate that DInSAR is an applicable tool for understanding environmental change in remote permafrost regions. [ABSTRACT FROM AUTHOR]

Aim The presence of refugia in the Canadian High Arctic has been subject to debate for decades. We investigated the potential existence of Arctic refugia during the Pleistocene for a large mammal species in the Canadian Archipelago because if these refugia were present, reconsideration of the evolutionary histories of North American fauna and flora beyond the major refugia of Beringia and south of the Laurentide and Cordilleran Ice Sheets would be required. Peary caribou ( Rangifer tarandus pearyi), identified as a subspecies based on morphological characteristics, inhabits the Canadian Arctic Islands and Boothia Peninsula. Previous studies demonstrated incomplete lineage sorting of mitochondrial DNA interpreted as a Beringian origin but were based on small sample sizes. Location Canadian Arctic. Major taxa studied Mammals: caribou ( Rangifer tarandus). Methods We used two molecular markers (microsatellites and mitochondrial DNA) and approximate Bayesian computations ( ABC) testing the hypotheses of colonization out of Beringia into the Arctic Islands following the Last Glacial Maximum ( LGM) or a divergence from Beringia significantly before the end of the LGM within a different refugium. Results The coalescent-based analyses rejected a recent Beringian origin with subsequent colonization, instead supporting a divergence of Peary caribou from Beringia ~100,000 years ago linking it to the last interglacial/early Wisconsin Glacial Stage (125,000-75,000 years ago). Admixture on Banks Island with Beringian-derived barren-ground caribou is indicative of post-Pleistocene secondary contact; further supporting a divergent history of Peary caribou within a separated Arctic refugium. Main conclusions Our results offer support for the existence of an Arctic refugium for large mammal species and add to the increasing evidence of such refugia in North America. This has significant implications on understanding the evolution and conservation of Arctic species, particularly in light of sensitivities and adaptive potential to a rapidly changing climate. [ABSTRACT FROM AUTHOR]

Several regions in the High Arctic still lingered poorly explored for a variety of mineralization types because of harsh climate environments and remoteness. Inglefield Land is an ice-free region in northwest Greenland that contains copper-gold mineralization associated with hydrothermal alteration mineral assemblages. In this study, Landsat-8, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), and WorldView-3 multispectral remote sensing data were used for hydrothermal alteration mapping and mineral prospecting in the Inglefield Land at regional, local, and district scales. Directed principal components analysis (DPCA) technique was applied to map iron oxide/hydroxide, Al/Fe-OH, Mg-Fe-OH minerals, silicification (Si-OH), and SiO2 mineral groups using specialized band ratios of the multispectral datasets. For extracting reference spectra directly from the Landsat-8, ASTER, and WorldView-3 (WV-3) images to generate fraction images of end-member minerals, the automated spectral hourglass (ASH) approach was implemented. Linear spectral unmixing (LSU) algorithm was thereafter used to produce a mineral map of fractional images. Furthermore, adaptive coherence estimator (ACE) algorithm was applied to visible and near-infrared and shortwave infrared (VINR + SWIR) bands of ASTER using laboratory reflectance spectra extracted from the USGS spectral library for verifying the presence of mineral spectral signatures. Results indicate that the boundaries between the Franklinian sedimentary successions and the Etah metamorphic and meta-igneous complex, the orthogneiss in the northeastern part of the Cu-Au mineralization belt adjacent to Dallas Bugt, and the southern part of the Cu-Au mineralization belt nearby Marshall Bugt show high content of iron oxides/hydroxides and Si-OH/SiO2 mineral groups, which warrant high potential for Cu-Au prospecting. A high spatial distribution of hematite/jarosite, chalcedony/opal, and chlorite/epidote/biotite were identified with the documented Cu-Au occurrences in central and southwestern sectors of the Cu-Au mineralization belt. The calculation of confusion matrix and Kappa Coefficient proved appropriate overall accuracy and good rate of agreement for alteration mineral mapping. This investigation accomplished the application of multispectral/multi-sensor satellite imagery as a valuable and economical tool for reconnaissance stages of systematic mineral exploration projects in remote and inaccessible metallogenic provinces around the world, particularly in the High Arctic regions.

Advances in paleoclimatology from the Arctic have provided insights into long-term climate conditions. However, while past annual and summer temperature have received considerable research attention, comparatively little is known about winter paleoclimate. Arctic winter is of special interest as it is the season with the highest sensitivity to climate change, and because it differs substantially from summer and annual measures. Therefore, information about past changes in winter climate is key to improve our knowledge of past forced climate variability and to reduce uncertainty in climate projections. In this context, Arctic lakes with snowmelt-fed catchments are excellent potential winter climate archives. They respond strongly to snowmelt-induced runoff, and indirectly to winter temperature and snowfall conditions. To date, only a few well-calibrated lake sediment records exist, which appear to reflect site-specific responses with differing reconstructions. This limits the possibility to resolve large-scale winter climate change prior the instrumental period. Here, we present a well-calibrated quantitative temperature and snowfall record for the extended winter season (November through March; NDJFM) from Chevalier Bay (Melville Island, NWT, Canadian Arctic) back to CE 1670. The coastal embayment has a large catchment influenced by nival terrestrial processes, which leads to high sedimentation rates and annual sedimentary structures (varves). Using detailed microstratigraphic analysis from two sediment cores and supported by μ-XRF data, we separated the nival sedimentary units (spring snowmelt) from the rainfall units (summer) and identified subaqueous slumps. Statistical correlation analysis between the proxy data and monthly climate variables reveals that the thickness of the nival units can be used to predict winter temperature (r = 0.71, p c < 0.01, 5-yr filter) and snowfall (r = 0.65, p c < 0.01, 5-yr filter) for the western Canadian High Arctic over the last ca. 400 years. Results reveal a strong variability in winter temperature back to CE 1670 with the coldest decades reconstructed for the period CE 1800–1880, while the warmest decades and major trends are reconstructed for the period CE 1880–1930 (0.26°C/decade) and CE 1970–2010 (0.37°C/decade). Although the first aim of this study was to increase the paleoclimate data coverage for the winter season, the record from Chevalier Bay also holds great potential for more applied climate research such as data-model comparisons and proxy–data assimilation in climate model simulations. [ABSTRACT FROM AUTHOR]

The Microgastrinae (Hymenoptera: Braconidae) from ten islands of the Canadian Arctic Archipelago (CAA) and Greenland were studied based on 2,183 specimens deposited in collections. We report a total of 33 species in six genera, more than doubling the totals previously known. Most of the species (75.7%) have a distribution restricted to the Nearctic, with nine of those (27.3%) confirmed to be High Arctic endemics and another 10 species considered very likely to be High Arctic endemics as well - accounting for all of those, more than half of all species found are endemic to the region. The most diverse genera were Cotesia (10 species), Glyptapanteles (9 species), and Microplitis (7 species), representing 78.8% of the overall species diversity in the region. The six most frequently collected species comprised 84.7% of all examined specimens. The flight period for Microgastrinae in the High Arctic encompasses only two months, with activity peaking during the first half of July, when almost 40% of all available specimens were collected, and then plummeting in the first half to the end of August. Microgastrinae wasps from the High Arctic are currently known to parasitize eight species within four families of Lepidoptera: three species of Noctuidae, two each of Lymantridae and Nymphalidae and one species of Pterophoridae. However, that information is very preliminary, as only six of the 33 species of microgastrines currently have associated host data. An annotated checklist, including photographs for 24 of the 33 species, is provided, as well as a key to all Microgastrinae genera present in the region. [ABSTRACT FROM AUTHOR]

Moisture is critical for plant success in polar deserts but not by the obvious pathway of reduced water stress. We hypothesized that an indirect, nutrient-linked, pathway resulting from unique water/frozen soil interactions in polar deserts creates nutrient-rich patches critical for plant growth. These nutrient-rich patches (diapirs) form deep in High Arctic polar deserts soils from water accumulating at the permafrost freezing front and ultimately rising into the upper soil horizons through cryoturbated convective landforms (frost boils). To determine if diapirs provide an enhanced source of plant-available N for Salix arctica (Arctic willow), we characterized soil, root, stem, and leaf 15N natural abundance across 24 diapir and non-diapir frost boils in a High Arctic granitic semi-desert. When diapir horizons were available, S. arctica increased its subsurface (i.e., diapir) N uptake and plant root biomass doubled within diapir. Plant uptake of enriched 15N injected into organic rich soil patches was 2.5-fold greater in diapir than in non-diapir frost boils. S. arctica percent cover was often higher (7.3 ± 1.0 [mean ± SE]) on diapiric frost boils, compared to frost boils without diapirs (4.4 ± 0.7), potentially reflecting the additional 20% nitrogen available in the subsurface of diapiric frost boils. Selective N acquisition from diapirs is a mechanism by which soil moisture indirectly enhances plant growth. Our work suggests that diapirs may be one mechanism contributing to Arctic greening by shrub expansion. [ABSTRACT FROM AUTHOR]

Active layer detachments (ALDs) are permafrost disturbances associated with climate change and increased seasonal warming. Such perturbations result from thawing of the upper permafrost and downslope movement of the overlying thawed material, including the active layer. ALDs have the potential to impact soil microbial community composition and function in arctic soil ecosystems. Here we report an initial investigation of an ALD located at Cape Bounty on Melville Island in the Canadian High Arctic. We examined soil nutrient content as well as microbial community structure using denaturing gradient gel electrophoresis and sequencing. Soil from the disturbed site showed changes in microbial communities with strikingly different fungal community composition compared to soils from an adjacent undisturbed site. These community changes were correlated with enhanced levels of dissolved organic carbon, microbial carbon, total dissolved nitrogen, and microbial nitrogen. The Nitrososphaerales-an order of ammonia-oxidizing Archaea-were more abundant in the disturbed soil and may have been responsible for the altered nitrogen cycling that resulted in higher levels of total dissolved nitrogen there. The fungal communities at both sites were dominated by orders within the Ascomycota, a phylum of mainly hyphal fungi. Intriguingly however, they were more numerous in the undisturbed soil compared to the disturbed soil, suggesting that certain Ascomycota could not reestablish within six years of the ALD, and more generally that fungal hyphal networks may help to stabilize tundra surface soils against erosional losses. [ABSTRACT FROM AUTHOR]

Most permafrost is located in the Arctic, where frozen organic carbon makes it an important component of the global climate system. Despite the fact that the Arctic climate changes more rapidly than the rest of the globe, observational data density in the region is low. Permafrost thaw and carbon release to the atmosphere are a positive feedback mechanism that can exacerbate climate warming. This positive feedback functions via changing land-atmosphere energy and mass exchanges. There is thus a great need to understand links between the energy balance, which can vary rapidly over hourly to annual time scales, and permafrost, which changes slowly over long time periods. This understanding thus mandates long-term observational data sets. Such a data set is available from the Bayelva Site at Ny-Ålesund, Svalbard, where meteorology, energy balance components and subsurface observations have been made for the last 20 years. Additional data include a high resolution digital elevation model and a panchromatic image. This paper presents the data set produced so far, explains instrumentation, calibration, processing and data quality control, as well as the sources for various resulting data sets. The resulting data set is unique in the Arctic and serves a baseline for future studies. Since the data provide observations of temporally variable parameters that mitigate energy fluxes between permafrost and atmosphere, such as snow depth and soil moisture content, they are suitable for use in integrating, calibrating and testing permafrost as a component in Earth System Models. The data set also includes a high resolution digital elevation model that can be used together with the snow physical information for snow pack modeling. The presented data are available in the supplementary material for this paper and through the PANGAEA website (https://doi.pangaea.de/10.1594/PANGAEA.880120). [ABSTRACT FROM AUTHOR]

The Arctic has experienced substantial warming during the past century with models projecting continued warming accompanied by increases in summer precipitation for most regions. A key impact of increasing air surface temperatures is the deepening of the active layer, which is expected to alter hydrological processes and pathways. The aim of this study was to determine how one of the warmest and wettest summers in the past decade at a High Arctic watershed impacted water infiltration and storage in deeply thawed soil and solute concentrations in stream runoff during the thaw period. In June and July 2012 at the Cape Bounty Watershed Observatory, we combined active layer measurements with major ion concentrations and stable isotopes in surface waters to characterize the movement of different runoff sources: snowmelt, rainfall, and soil water. Results indicate that deep ground thaw enhanced the storage of infiltrated water following rainfall. Soil water from infiltrated rainfall flowed through the thawed transient layer and upper permafrost, which likely solubilized ions previously stored at depth. Subsequent rainfall events acted as a hydrological flushing mechanism, mobilizing solutes from the subsurface to the surface. This solute flushing substantially increased ion concentrations in stream runoff throughout mid to late July. Results further suggest the importance of rainfall and soil water as sources of runoff in a High Arctic catchment during mid to late summer as infiltrated snowmelt is drained from soil following baseflow. Although there was some evaporation of surface water, our study indicates that flushing from solute stores in the transient layer was the primary driver of increased ion concentrations in stream runoff and not evaporative concentration of surface water. With warmer and wetter summers projected for the Arctic, ion concentrations in runoff (especially in the late thaw season), will likely increase due to the deep storage and subsurface flow of infiltrated water and subsequent flushing of previously frozen solutes to the surface. [ABSTRACT FROM AUTHOR]

Climate-induced changes in vegetation phenology at northern latitudes are still poorly understood. Continued monitoring and research are therefore needed to improve the understanding of abiotic drivers. Here we used 14 years of time lapse imagery and climate data from high-Arctic Northeast Greenland to assess the seasonal response of a dwarf shrub heath, grassland, and fen, to inter-annual variation in snow-cover, soil moisture, and air and soil temperatures. A late snow melt and start of growing season is counterbalanced by a fast greenup and a tendency to higher peak greenness values. Snow water equivalents and soil moisture explained up to 77 % of growing season duration and senescence phase, highlighting that water availability is a prominent driver in the heath site, rather than temperatures. We found a significant advance in the start of spring by 10 days and in the end of fall by 11 days, resulting in an unchanged growing season length. Vegetation greenness, derived from the imagery, was correlated to primary productivity, showing that the imagery holds valuable information on vegetation productivity. [ABSTRACT FROM AUTHOR]

We report experimental results of near-surface winter temperatures along and adjacent to the channel bed of a High Arctic river on Melville Island, Canada. Temperature loggers 5 cm below the ground surface in areas where the terrain suggests varying snow accumulation patterns revealed that the maximum winter difference between air and near-surface temperatures ranged from 0 to +30°C during the winter of 2012-13, and that shallow near-surface freezing conditions were delayed for up to 21 days in some locations. Cooling to -10°C was delayed for up to 117 days. Modelled temperature at the top of permafrost indicates that permafrost at locations with thick snow can be up to 8°C warmer than those with thin snow. This thermal evidence for an ameliorated surface environment indicates the potential for substantial extended microbial and biogeochemical cycling during early winter. Rapid thaw of the bed during initiation of snowmelt in spring also indicates a high degree of hydrological connectivity. Therefore, snow-filled channels may contribute to biogeochemical and aquatic cycling in High Arctic rivers. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Many environmental factors affecting methane (CH 4 ) and nitrous oxide (N 2 O) fluxes have been investigated during the processes of carbon and nitrogen transformation in the boreal tundra. However, effects of sunlight on CH 4 and N 2 O fluxes and their budgets were neglected in the boreal tundra. Here, summertime CH 4 and N 2 O fluxes in the presence and total absence of sunlight were investigated at the six tundra sites (DM1-DM6) on Ny-Ålesund in the High Arctic. The mean CH 4 fluxes at the tundra sites ranged from − 4.7 to − 158.6 μg CH 4 m − 2 h − 1 in the presence of light, indicating that a large CH 4 sink occurred in the tundra soils. However, enhanced CH 4 emission in total absence of light occurred at all the tundra sites. The mean N 2 O fluxes ranged from 7.4 to 14.6 μg N 2 O m − 2 h − 1 in the presence of light, whereas in the absence of light all the tundra sites generally released less N 2 O, and even significant N 2 O uptake occurred there. Soil temperature, chamber temperature and soil moisture showed no significant correlations with tundra CH 4 and N 2 O flux. The presence of sunlight increased tundra CH 4 uptake by 114.2 μg CH 4 m − 2 h − 1 and N 2 O emission by 10.9 μg N 2 O m − 2 h − 1 compared with total absence of light. Overall our results showed that tundra ecosystem switched from CH 4 sink and N 2 O emission source in the presence of light to CH 4 emission source and N 2 O sink in the absence of light. Therefore sunlight had an important effect on CH 4 and N 2 O budgets in the High Arctic tundra. The exclusion of sunlight might overestimate CH 4 budgets, but underestimate N 2 O budgets in the Arctic tundra ecosystem. [ABSTRACT FROM AUTHOR]

Geological mapping and mineral exploration programs in the High Arctic have been naturally hindered by its remoteness and hostile climate conditions. The Franklinian Basin in North Greenland has a unique potential for exploration of world-class zinc deposits. In this research, multi-sensor remote sensing satellite data (e.g., Landsat-8, Phased Array L-band Synthetic Aperture Radar (PALSAR) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)) were used for exploring zinc in the trough sequences and shelf-platform carbonate of the Franklinian Basin. A series of robust image processing algorithms was implemented for detecting spatial distribution of pixels/sub-pixels related to key alteration mineral assemblages and structural features that may represent potential undiscovered Zn–Pb deposits. Fusion of Directed Principal Component Analysis (DPCA) and Independent Component Analysis (ICA) was applied to some selected Landsat-8 mineral indices for mapping gossan, clay-rich zones and dolomitization. Major lineaments, intersections, curvilinear structures and sedimentary formations were traced by the application of Feature-oriented Principal Components Selection (FPCS) to cross-polarized backscatter PALSAR ratio images. Mixture Tuned Matched Filtering (MTMF) algorithm was applied to ASTER VNIR/SWIR bands for sub-pixel detection and classification of hematite, goethite, jarosite, alunite, gypsum, chalcedony, kaolinite, muscovite, chlorite, epidote, calcite and dolomite in the prospective targets. Using the remote sensing data and approaches, several high potential zones characterized by distinct alteration mineral assemblages and structural fabrics were identified that could represent undiscovered Zn–Pb sulfide deposits in the study area. This research establishes a straightforward/cost-effective multi-sensor satellite-based remote sensing approach for reconnaissance stages of mineral exploration in hardly accessible parts of the High Arctic environments.

The effects of climate change are more acute in the Arctic than any other region, and as such, arctic tundra wildlife habitats are changing in ways that are not yet well understood. Remote sensing tools are capable of assessing dynamics in wildlife-habitat associations over a wide range of spatial scales and in a variety of ecosystems. As already well-established in other ecosystems, Light Detection and Ranging (LiDaR) technology has the potential to greatly expand our understanding of tundra wildlife-habitat associations because unlike the most commonly used spectral vegetation index - the Normalized Difference Vegetation Index (NDVI) - LiDaR directly quantifies three-dimensional (3-D) vegetation structure. Only recently has airborne laser scanning (ALS) technology evolved to having vertical resolution and point densities high enough to quantify small differences in vegetation structure, such as characterize arctic tundra ecosystems. Our objective was to employ ALS metrics, airborne spectral data (for NDVI), and Landsat 7 ETM + data (for snow cover) to determine the relative importance of a suite of ecological characteristics - considered at multiple spatial scales - on habitat use and reproductive success of two of the most common migratory songbird species breeding in northern Alaska. Our most important findings are that (1) combining ALS metrics, but not NDVI, with Landsat derived snow cover data provided useful information, revealing that while Gambel's white-crowned sparrows use breeding territories in areas with high canopy volume and large snow-free areas, Lapland longspurs will establish territories in areas with low canopy volume, small patches of snow-free tundra, and minimal surface wetness and; (2) while habitat characteristics were important determinants of habitat use for both species at the territory scale, those in the immediate vicinity of nest-sites were not important. Contrary to expectation, we also found that the reproductive success of both species was unaffected by variation in our hypothesized metrics of shelter and food availability (canopy volume, standard deviation of micro-terrain height) at both the nest-site or territory scales. Our study is the first arctic demonstration of how ALS yields novel insights into wildlife-habitat associations, suggesting it has great potential in other ecosystems with similarly small - yet often ecologically important - ranges in 3-D vegetation structure. [ABSTRACT FROM AUTHOR]

The at-sea distribution of top predators, seabirds and marine mammals, was determined in the high Arctic pack ice on board the icebreaker RV Polarstern in July to September 2014. In total, 1,620 transect counts were realised, lasting 30 min each. The five most numerous seabird species represented 74% of the total of 15,150 individuals registered: kittiwake Rissa tridactyla, fulmar Fulmarus glacialis, puffin Fratercula arctica, Ross’s gull Rhodostethia rosea, and little auk Alle alle. Eight cetacean species were tallied for a total of 330 individuals, mainly white-beaked dolphin Lagenorhynchus albirostris and fin whale Balaenoptera physalus. Five pinniped species were represented by a total of 55 individuals and the polar bear Ursus maritimus was represented by 12 individuals. Four main geographical zones were identified: from Tromsø to the outer marginal ice zone (OMIZ), the Arctic pack ice (close pack ice, CPI), the end of Lomonosov Ridge off Siberia, and the route off Siberia and northern Norway. Important differences were detected between zones, both in species composition and in individual abundance. Low numbers of species and high proportion of individuals for some of them can be considered to reflect very low biodiversity. Numbers encountered in zones 2 to 4 were very low in comparison with other European Arctic seas. The observed differences showed strong patterns. [ABSTRACT FROM AUTHOR]

The amount of biomass, carbon (C), and nitrogen (N) in vegetation and soil were measured at two spatial scales in the high Arctic. At the scale of proglacial landscape, the amount of C and N in aboveground and belowground parts of vegetation, surface litter, and soil were significantly affected by the habitat (moraines vs hummocks), the relative age of the terrain after the deglaciation, and/or the vegetation. At another scale, we focused on mudboils as an agent of local disturbance in the vegetation and soil of the glacier foreland. The biomass and the amount of C and N in aboveground vegetation, surface litter, biological soil crust, and soil were generally increased with the stage of mudboils' inactivation. Biomass, C, and N in aboveground vegetation and surface litter were generally greater at moraine than at hummock, whereas those in biological soil crust and soil were greater at hummock. Principal component analysis identified two pathways, xeric and mesic ones on moraines and hummocks, respectively, of C and N accumulation both at the two spatial scales. These results suggested that the C and N accumulation was not linearly related to the time since deglaciation and that moisture condition, vegetation, and mudboil activity were locally important. [ABSTRACT FROM AUTHOR]

DNA sequences offer powerful tools for describing the members and interactions of natural communities. In this study, we establish the to-date most comprehensive library of DNA barcodes for a terrestrial site, including all known macroscopic animals and vascular plants of an intensively studied area of the High Arctic, the Zackenberg Valley in Northeast Greenland. To demonstrate its utility, we apply the library to identify nearly 20 000 arthropod individuals from two Malaise traps, each operated for two summers. Drawing on this material, we estimate the coverage of previous morphology-based species inventories, derive a snapshot of faunal turnover in space and time and describe the abundance and phenology of species in the rapidly changing arctic environment. Overall, 403 terrestrial animal and 160 vascular plant species were recorded by morphology-based techniques. DNA barcodes ( CO1) offered high resolution in discriminating among the local animal taxa, with 92% of morphologically distinguishable taxa assigned to unique Barcode Index Numbers ( BINs) and 93% to monophyletic clusters. For vascular plants, resolution was lower, with 54% of species forming monophyletic clusters based on barcode regions rbcL a and ITS2. Malaise catches revealed 122 BINs not detected by previous sampling and DNA barcoding. The insect community was dominated by a few highly abundant taxa. Even closely related taxa differed in phenology, emphasizing the need for species-level resolution when describing ongoing shifts in arctic communities and ecosystems. The DNA barcode library now established for Zackenberg offers new scope for such explorations, and for the detailed dissection of interspecific interactions throughout the community. [ABSTRACT FROM AUTHOR]

Aquatic mosses are important primary producers in High-Arctic lakes, but little information is available on their contribution to the overall production in these lakes. In order to predict effects of climate change on whole-lake ecosystem characteristics, more knowledge is needed on the role of moss in primary production, the extent of nutrient limitation of moss primary production and whether moss serves as food resource for secondary producers. In this study, we conducted an in situ growth experiment of an aquatic moss in a High-Arctic lake in NE Greenland and used these data to determine annual net production of this moss in the whole lake. We also measured tissue-N and tissue-P in order to assess nutrient limitation of moss production, measured in situ decomposition rates by litter bag experiments over 1 year and assessed the role of moss as food source by analysing stable isotope N and C of relevant organism groups in the lake. Net primary production of moss was 1.3 gC m year and constituted 23 % of the total benthic primary production and 18 % of the total lake primary production. Stoichiometric assessments suggested N and P limitation of moss growth. On average, 15 % of the standing biomass was decomposed per year. Our results also indicate that moss is not directly used as food resource by herbivores, but the most abundant herbivore, Lepidurus arcticus, is feeding on the epiphytic biofilm on the moss. Moss biomass is instead incorporated into the microbial decomposer pathway. All together, the study shows that moss plays an important ecological role as primary producer in High-Arctic lakes and functions as substrate for periphytic biofilm that serves as food resource for important herbivore invertebrates. [ABSTRACT FROM AUTHOR]

The CO 2 efflux from representative tundra ecosystems in the high Arctic should be monitored in order to evaluate the potential future sensitivity of the carbon cycle to climate change. However, studies on the soil CO 2 efflux from them are still limited, especially deglaciated area due to the Arctic warming. The ecosystem in Ny-Ålesund, Svalbard, Norway (∼79°N) has gradually undergone substantial alterations due to deglaciation induced by climate change, where biological soil crusts (BSCs, mainly consisting of cyanobacteria, algae, lichen, and bryophytes, etc. on the soil surface) are widely formed in the glacier foreland and further developed especially in the later stages of primary succession. In this study, soil CO 2 efflux from partly or totally covered with black-colored BSCs (BSCs-B) was measured from 2007 to 2009 using portable dynamic chamber system. The objectives of this study were (i) to quantify the CO 2 efflux from the soil, (ii) to examine the controlling factors which affect the temporal and spatial variation of soil CO 2 efflux, (iii) to examine the contribution of BSCs-B to soil CO 2 efflux, and (iv) to estimate the relationship between soil CO 2 efflux and microbial activity to evaluate its role on the surface carbon budget at deglaciated area. It was found that the emission of soil CO 2 from BSCs-B was consistent through the long-term in situ measurement in the high arctic tundra. Soil CO 2 efflux ranged from 0.3 to 0.7 μmol m −2 s −1 with means of 0.56 (±0.07) μmol m −2 s −1 in 2007, 0.54 (±0.13) μmol m −2 s −1 in 2008, and 0.51 (±0.09) μmol m −2 s −1 in 2009. The soil temperature (Ts) explained 50–70% of the temporal variation of the soil CO 2 efflux when temperature ranged from 6 to 12 °C, whereas Ts is not controlling factor for spatial variation of soil CO 2 efflux considering the low coefficient of variation (CV). In the meanwhile, soil water content (SWC) was not a main controlling factor for temporal variation of soil CO 2 efflux. Even though CV of SWC was not low, spatial variation of SWC could not explain that of soil CO 2 efflux. The soil CO 2 efflux was spatially affected by BSCs-B coverage, amount of pebble, and the nearby vegetation distribution. All enzyme activities exhibited significantly higher values in BSCs-B than in mineral soil of BSCs ( p < 0.01). The activities of enzymes in BSCs-B generally exhibited positive correlations with the soil CO 2 efflux except for humic substances ( R 2 = 0.52). It can be concluded that the magnitude of the soil CO 2 efflux from BSCs-B is comparable to those from moss and vascular plants in the surface carbon budget. [ABSTRACT FROM AUTHOR]

Snow cover is one of the key factors controlling Arctic ecosystem functioning and productivity. In this study we assess the impact of strong interannual variability in snow accumulation during two subsequent years (2013-2014) on the land-atmosphere interactions and surface energy exchange in two high-Arctic tundra ecosystems (wet fen and dry heath) in Zackenberg, Northeast Greenland. We observed that record-low snow cover during the winter 2012/13 resulted in strong response of the heath ecosystem towards low evaporative capacity and substantial surface heat loss by sensible heat fluxes (H) during the subsequent snow melt period and growing season. Above-average snow accumulation during the winter 2013/14 promoted summertime ground heat fluxes (G) and latent heat fluxes (LE) at the cost of H. At the fen ecosystem a more muted response of LE, H and G was observed in response to the interannual variability in snow accumulation. Overall, the differences in flux partitioning and in the length of the snow melt periods and growing seasons during the two years had a strong impact on the total accumulation of the surface energy balance components. We suggest that in a changing climate with higher temperature and more precipitation the surface energy balance of this high-Arctic tundra ecosystem may experience a further increase in the interannual variability of energy accumulation, partitioning and redistribution. [ABSTRACT FROM AUTHOR]

Reconstructions of temperature and moisture regimes based on fossil leaves, combined with tree ring studies, detail the light regime, length of the growing season, and summer and winter temperatures of the Late Cretaceous Arctic. Such constraints have important implications for dinosaur feeding and reproductive behaviour, and the capacity to reside year-round in near-polar environments. At the highest palaeolatitudes where dinosaurs have been found (82–85 °N) winter darkness lasted for ~ 120 days and the spring and autumn twilight periods for ~ 15 days. A mostly cloud and mist-shrouded environment witnessed a mean annual temperature (MAT) of 6–7 °C, a warm month mean temperature (WMMT) of 14.5 ± 3.1 °C and a cold month mean temperature (CMMT) of −2 ± 3.9 °C. Growth rings in wood suggest summer temperatures frequently fell below + 10 °C. Winter temperatures as low as −10 °C were likely for short periods. Spring bud break in late February to early March and leaf fall in early October limited the time when fresh food was available in any quantity to not more than 6 months. The diversity of Arctic dinosaur body sizes implies a range of overwintering strategies but year-round residency requires reproduction. Burrowing and enclosed nest building no doubt facilitated overwintering for small animals, but for larger dinosaurs shelter was problematical. No dinosaur egg remains have yet been found as far north as 82° palaeolatitude, but they occur 6° further south in the Early Maastrichtian Kakanaut Formation, Northeastern Russia. Here the winter darkness was shorter (45 days), and the temperature regime warmer (MAT 10 °C, WMMT 19 °C, CMMT + 3 °C). The growing season (temperatures > 10 °C) was ~ 6.3 months and fresh food was available in quantity for slightly longer. These summer temperatures constrain the thermal regime of nest environments and suggest sophisticated nest management and possibly brooding strategies for the necessary rapid incubation and hatching before the onset of winter. [ABSTRACT FROM AUTHOR]

Low nitrogen availability in the high Arctic represents a major constraint for plant growth, which limits the tundra capacity for carbon retention and determines tundra vegetation types. The limited terrestrial nitrogen (N) pool in the tundra is augmented significantly by nesting seabirds, such as the planktivorous Little Auk (Alle alle). Therefore, N delivered by these birds may significantly influence the N cycling in the tundra locally and the carbon budget more globally. Moreover, should these birds experience substantial negative environmental pressure associated with climate change, this will adversely influence the tundra N-budget. Hence, assessment of bird-originated N-input to the tundra is important for understanding biological cycles in polar regions. This study analyzed the stable nitrogen composition of the three main N-sources in the High Arctic and in numerous plants that access different N-pools in ten tundra vegetation types in an experimental catchment in Hornsund (Svalbard). The percentage of the total tundra N-pool provided by birds, ranged from 0–21% in Patterned-ground tundra to 100% in Ornithocoprophilous tundra. The total N-pool utilized by tundra plants in the studied catchment was built in 36% by birds, 38% by atmospheric deposition, and 26% by atmospheric N2-fixation. The stable nitrogen isotope mixing mass balance, in contrast to direct methods that measure actual deposition, indicates the ratio between the actual N-loads acquired by plants from different N-sources. Our results enhance our understanding of the importance of different N-sources in the Arctic tundra and the used methodological approach can be applied elsewhere. [ABSTRACT FROM AUTHOR]

This study assessed the diversity and distribution of endophytic fungal communities associated with the leaves and stems of four vascular plant species in the High Arctic using 454 pyrosequencing with fungal-specific primers targeting the ITS region. Endophytic fungal communities showed high diversity. The 76,691 sequences obtained belonged to 250 operational taxonomic units (OTUs). Of these OTUs, 190 belonged to Ascomycota, 50 to Basidiomycota, 1 to Chytridiomycota, and 9 to unknown fungi. The dominant orders were Helotiales, Pleosporales, Capnodiales, and Tremellales, whereas the common known fungal genera were Cryptococcus, Rhizosphaera, Mycopappus, Melampsora, Tetracladium, Phaeosphaeria, Mrakia, Venturia, and Leptosphaeria. Both the climate and host-related factors might shape the fungal communities associated with the four Arctic plant species in this region. These results suggested the presence of an interesting endophytic fungal community and could improve our understanding of fungal evolution and ecology in the Arctic terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

Moss tundra that accumulates a thick peat layer is one of the most important ecosystems in the High Arctic, Svalbard. The importance of this ecosystem for carbon sequestration was estimated from the apparent rates of carbon accumulation based on the 14 C age and amount of peat in the active layer. The study site at Stuphallet, Brøgger Peninsula, northwestern Svalbard was covered with a thick peat layer dominated by moss species such as Calliergon richardsonii , Paludella squarrosa , Tomenthypnum nitens , and Warnstorfia exannulata . The average thickness of the active layer (brown moss and peat) was approximately 28 cm in 1 August 2011. The calibrated (cal) age of peat from the bottom of the active layer (20–30 cm below the peatland surface) ranged from 81 to 701 cal yr BP (median value of 2σ range). Based on the total carbon (4.5–9.2 kg C m −2 ), the apparent rate of carbon accumulation in the active layer was 9.0–19.2 (g C m −2 yr −1 ), which is similar to or greater than the net ecosystem production or net primary production reported for other vegetation types in this area. Our data suggest that moss tundra plays an important role in carbon sequestration in this area. [ABSTRACT FROM AUTHOR]

The Zhokhov site is one of the northern most archaeological sites in the world and a very ancient vestige of occupation of high latitudes by people, indicating that this territory was settled as early as about 8000 years ago. Investigation of the site began in 1989-1990 and then continued in 2000-2005. Here we consider the taphonomy, spatial distribution, species and age- and sex-related composition of the faunal remains from the Zhokhov site. These data allow conclusions regarding the subsistence strategy practiced by Zhokhov inhabitants, including the hunting tactics. This was a peculiar adaptation model based on reindeer and polar bear hunting in a 2:1 ratio. Reindeer hunting was all-seasonal, whereas polar bears were hunted mostly in winters at their dens. Mortality data for reindeer and polar bears depict the yearly subsistence cycle. The Zhokhov site is found to be a base camp occupied year-round with modest summer activities, while wintertime is characterised by intense polar bear hunting. Most reindeer were hunted in the fall. Subsistence strategy of the Zhokhov hunters was largely facilitated by the fact that at the time of occupation Zhokhov Island was still part of the coastal Siberian plain margin. [ABSTRACT FROM AUTHOR]

Abrupt shifts in sediment supply, relative sea level, permafrost regime, glacier state, snow cover and sea ice conditions associated with Holocene climate changes control processes operating on High Arctic coasts and make reconstructions of their past evolution a significant research challenge. This study attempts to describe the development of the coastal zone in southern Sassenfjorden, Svalbard, throughout the Holocene focusing on the styles of adjustment to major landscape changes. Five marine terraces (MT1-5) are identified and assessed. Spatial and chronological analysis suggests that the highest terrace, MT5, is pre-LGM (Last Glacial Maximum) and that MT4-3 underwent rapid uplift (151 and 11.4 mm/year, respectively) shortly prior to 11 061 ± 174 cal. yr BP and became fully terrestrial by 9100 years ago (as indicated by emergence rates) during the Holocene Thermal Maximum (HTM). Uplift rates for MT2-1 slowed to 5 and 2 mm/year, respectively, with suggested emergence between 7200 and 6800 cal. yr BP. A final 2 m uplift of the relict alluvial plain probably happened during the Medieval Warm Period (1200–950 cal. yr BP). Most recent coastal development (AD 1912–2012) is characterised by episodes of coastal erosion on the cliff and progradation of the Nøiselva delta. Interactions between sea ice, snow cover, permafrost, wind and wave regimes are assessed to understand their implications on future coastal development in a warming climate. [ABSTRACT FROM AUTHOR]

Terrestrial ecosystems are heterogeneous habitat mosaics of varying vegetation types that are differentially affected by climate change. Arctic plant communities, for example, are changing faster in moist habitats than in dry habitats and abiotic changes like snowmelt vary locally among habitats. Such differences between habitats may influence the effects of climate changes on animals and this could be especially true in low-mobility species. Suitable model systems to test this idea, however, are rare. We examined how proxies of reproductive success (body size, juvenile/female ratios) and sex ratios have changed in low-mobility crab spiders collected systematically over a 17-year period (1996-2012) from two distinct habitats (mesic and arid dwarf shrub heath) at Zackenberg in northeast Greenland. We identified all adults in the collection to confirm that they represented just one species ( Xysticus deichmanni Sørensen) based on morphology. This provided a unique opportunity to measure recruitment potential because we could assume that all juvenile crab spiders belonged to that species. We determined sex, stage, and size of all specimens ( n = 2,115). Body size variation was significantly related to the timing of snowmelt and differed significantly between the sexes and habitats with the spiders in the mesic habitat showing a stronger temporal response to later snowmelt. Juvenile/female ratios also differed significantly between habitats; as did the overall abundance of individuals. We found significant main effects of snowmelt and habitat on sex ratio with the proportion of females decreasing significantly in response to later snowmelt only in the mesic sites. Effects of climate change may be masked by habitat differences and have implications for future range changes of species at both small and large spatial extents. We recommend that local habitat differences are included in analyses of species responses to climate change. [ABSTRACT FROM AUTHOR]

In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biomagnification through food webs vary between neighboring lakes and are related to water chemistry variables and physical lake features. However, few studies have examined factors affecting the variable Hg concentrations in landlocked Arctic char ( Salvelinus alpinus ) or the biomagnification of Hg through their food webs. We estimated the food web structure of six high Arctic lakes near Resolute Bay, Nunavut, Canada, using stable carbon (δ 13 C) and nitrogen (δ 15 N) isotopes and measured Hg (total Hg (THg) in char, the only fish species, and methylmercury (MeHg) in chironomids and zooplankton) concentrations in biota collected in 2010 and 2011. Across lakes, δ 13 C showed that benthic carbon (chironomids) was the dominant food source for char. Regression models of log Hg versus δ 15 N (of char and benthic invertebrates) showed positive and significant slopes, indicting Hg biomagnification in all lakes, and higher slopes in some lakes than others. However, no principal components (PC) generated using all water chemistry data and physical characteristics of the lakes predicted the different slopes. The PC dominated by aqueous ions was a negative predictor of MeHg concentrations in chironomids, suggesting that water chemistry affects Hg bioavailability and MeHg concentrations in these lower-trophic-level organisms. Furthermore, regression intercepts were predicted by the PCs dominated by catchment area, aqueous ions, and MeHg. Weaker relationships were also found between THg in small char or MeHg in pelagic invertebrates and the PCs dominated by catchment area, and aqueous nitrate and MeHg. Results from these high Arctic lakes suggest that Hg biomagnification differs between systems and that their physical and chemical characteristics affect Hg concentrations in lower-trophic-level biota. [ABSTRACT FROM AUTHOR]

Per- and polyfluorinated alkyl substances (PFASs) enter Arctic lakes through long-range atmospheric transport and local contamination, but their behavior in aquatic food webs at high latitudes is poorly understood. This study compared the concentrations of perfluorocarboxylates, perfluorosulfonates, and fluorotelomer sulfonates (FTS) in biotic and abiotic samples from six high Arctic lakes near Resolute Bay, Nunavut, Canada. Two of these lakes are known to be locally contaminated by a small airport and Arctic char (Salvelinus alpinus) from these lakes had over 100 times higher total [PFAS] when compared to fish from neighboring lakes. Perfluorononanoate (PFOA) and perfluorooctanesulfonate (PFOS) dominated in char, benthic chironomids (their main prey), and sediments, while pelagic zooplankton and water were dominated by lower chain acids and perfluorodecanesulfonate (PFDS). This study also provides the first measures of perfluoroethylcyclohexanesulfonate (PFECHS) and FTS compounds in water, sediment, juvenile char, and benthic invertebrates from lakes in the high Arctic. Negative relationships between [PFAS] and 5 ,SN values (indicative of trophic position) within these food webs indicated no biomagnification. Overall, these results suggest that habitat use and local sources of contamination, but not trophic level, are important determinants of [PFAS] in biota from freshwater food webs in the Canadian Arctic. [ABSTRACT FROM AUTHOR]

Observation of Lg seismic waves at regional distances has long been considered indicative of continental crust that is 30–40 km thick. This study updates an earlier assessment of Lg propagation efficiency to characterize continental or non-continental crust and related structures across the Amerasia Basin and surrounding continental areas of the high Arctic. Recent refraction surveys and receiver function studies provide crustal thickness estimates of 18–41 km for comparison. Among 7000 candidate earthquake–station pairs considered, no classic Lg phases (0.14–2 Hz) are observed to cross the Amerasia Basin (Canada Basin, Alpha-Mendeleev Ridge) efficiently, but lower frequency (0.035–0.17 Hz) arrivals with group velocities intermediate between Lg and Sn (sometimes called early Lg) are observed along many ray paths crossing the basin. The characteristic frequencies of these observed arrivals match well with those of synthetic waves propagated within models with thinned or pinched continental crust, such as crust characteristic of the North Sea, and thus suggest that most parts of the Amerasia Basin have a crustal thickness intermediate between that typical of thin continental and oceanic crust. [ABSTRACT FROM AUTHOR]

The development of tourism is a significant aspect of the processes of modernity in the High Arctic. This article discusses the British art historian and mountaineer Sir William Martin Conway's two travelogues, The First Crossing of Spitsbergen (1897) and With Ski and Sledge over Arctic Glaciers (1898), in terms of a pioneering tourist approach to the archipelago of Svalbard. Unlike earlier yachting tourists, Conway described a journey into the uncharted interior of the main island, Spitsbergen. His books are therefore narrated as exploration accounts and following many of the demands of that genre, such as an emphasis on mapping, natural science and being the first. However, they may also be read as guidebooks for other discerning and undaunted British gentleman travellers. Inspired by the art critic John Ruskin's "science of aspects", which combined accurate scientific observations and practical knowledge with an imaginative and aesthetic response to the landscape, Conway attempts to give his readers a positive sense of the qualities of the Arctic. At the same time, he promotes Svalbard as an Arctic "Playground of Europe", where adventurous Alpinists in addition to climbing unknown mountains and glaciers could find fraternal domesticity far away from home around the hearth of the campfire. In this way Conway locates natural beauty, life and recreational opportunities where travellers before him had only described desolation and death. [ABSTRACT FROM AUTHOR]

Increased temperature and precipitation in Arctic regions have led to deeper thawing and structural instability in permafrost soil. The resulting localized disturbances, referred to as active layer detachments (ALDs), may transport organic matter (OM) to more biogeochemically active zones. To examine this further, solid state cross polarization magic angle spinning 13 C nuclear magnetic resonance (CPMAS NMR) and biomarker analysis were used to evaluate potential shifts in riverine sediment OM composition due to nearby ALDs within the Cape Bounty Arctic Watershed Observatory, Nunavut, Canada. In sedimentary OM near ALDs, NMR analysis revealed signals indicative of unaltered plant-derived material, likely derived from permafrost. Long chain acyclic aliphatic lipids, steroids, cutin, suberin and lignin occurred in the sediments, consistent with a dominance of plant-derived compounds, some of which may have originated from permafrost-derived OM released by ALDs. OM degradation proxies for sediments near ALDs revealed less alteration in acyclic aliphatic lipids, while constituents such as steroids, cutin, suberin and lignin were found at a relatively advanced stage of degradation. Phospholipid fatty acid analysis indicated that microbial activity was higher near ALDs than downstream but microbial substrate limitation was prevalent within disturbed regions. Our study suggests that, as these systems recover from disturbance, ALDs likely provide permafrost-derived OM to sedimentary environments. This source of OM, which is enriched in labile OM, may alter biogeochemical patterns and enhance microbial respiration within these ecosystems. [ABSTRACT FROM AUTHOR]

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