Arctic (Ecology)

The U.S. Geological Survey (USGS) Changing Arctic Ecosystems (CAE) initiative informs key resource management decisions for Arctic Alaska by providing scientific information on current and future ecosystem response to a changing climate. From 2010 to 2014, a key study area for the USGS CAE initiative has been the Arctic Coastal Plain of northern Alaska. This region has experienced rapid warming during the past 30 years, leading to the thawing of permafrost and changes to lake and river systems. These changes, and projections of continued change, have raised questions about effects on wildlife populations that rely on northern lake ecosystems, such as loons. Loons rely on freshwater lakes for nesting habitat and the fish and invertebrates inhabiting the lakes for food. Loons live within the National Petroleum Reserve-Alaska (NPR-A) on Alaska's northern coast, where oil and gas development is expected to increase. Research by the USGS examines how breeding loons use the Arctic lake ecosystem and the capacity of loons to adapt to future landscape change.

Arctic sea ice has changed dramatically, especially during the last decade and continued declines in extent and thickness are expected for the decades to come. Some ice-associated marine mammals are already showing distribution shifts, compromised body condition and declines in production/abundance in response to sea-ice declines. In contrast, temperate marine mammal species are showing northward expansions of their ranges, which are likely to cause competitive pressure on some endemic Arctic species, as well as putting them at greater risk of predation, disease and parasite infections. The negative impacts observed to date within Arctic marine mammal populations are expected to continue and perhaps escalate over the coming decade, with continued declines in seasonal coverage of sea ice. This situation presents a significant risk to marine biodiversity among endemic Arctic marine mammals.

It has been hypothesized that abundant heterotrophic ocean bacterioplankton in the SAR202 clade of the phylumChloroflexievolved specialized metabolism for the oxidation of organic compounds that are resistant to microbial degradation via common metabolic pathways. Expansions of paralogous enzymes were reported and implicated in hypothetical metabolism involving monooxygenase and dioxygenase enzymes. In the metabolic schemes proposed, the paralogs serve the purpose of diversifying the range of organic molecules that cells can utilize. To further explore this question, we reconstructed SAR202 single amplified genomes and metagenome-assembled genomes from locations around the world, including the deepest ocean trenches. In analyses of 122 SAR202 genomes that included six subclades spanning SAR202 diversity, we observed additional evidence of paralog expansions that correlated with evolutionary history, and further evidence of metabolic specialization. Consistent with previous reports, ...

The Arctic is among the most climatically sensitive environments on Earth, and the disappearance of multiyear sea-ice in the Arctic Ocean is predicted within decades. As apex predators, polar bears are sentinel species for addressing the impact of environmental variability on Arctic marine ecosystems. By integrating genomics, isotopic analysis, morphometrics, and ecological modelling, we investigate how Holocene environmental changes affected the evolutionary ecology of polar bears around Greenland. We show that throughout the last ∼11,000 years, Greenlandic polar bears have been heavily influenced by changes in sea-surface temperature (SST) and sea-ice cover. Most notable are major reductions in effective population size at the beginning of the Holocene and during the Holocene Thermal Maximum ∼6 kya, which coincide with increases in annual mean SST, reduction in sea-ice covers, declines in suitable habitat, and shifts in suitable habitat northwards. Furthermore, we show how individ...

Mr. Chairman, Members of the Committee, thank you for the opportunity to participate in today's Full Committee hearing on Climate Change Impacts. I am honored to testify before you today on behalf of an international team of 300 scientists, other experts, and elders and other insightful indigenous residents of the Arctic region who are preparing a comprehensive analysis of the impacts and consequences of climate variability and changes across the Arctic region, including the impacts induced by increases in UV radiation arising from depletion of stratospheric ozone in the region. I am Dr. Robert W. Corell, Chair of the Arctic Climate Impact Assessment (ACIA), which was established and charged to conduct the assessment by the Arctic Council 1 and the International Arctic Sciences Committee 2 . The Arctic Council is composed of senior officials from the eight Arctic countries (U.S. is represented by senior officials of the Department of State) and the leadership from six international indigenous peoples organizations of the Arctic region. The International Arctic Sciences Committee (IASC) was founded to encourage and facilitate cooperation in all aspects of Arctic research; the US is represented by an appointment made by the National Academy of Science. 1 The Arctic Council was established on September 19th, 1996 in Ottawa, Canada. A high level intergovernmental forum, the Council provides a mechanism to address the common concerns and challenges faced by the Arctic governments and the people of the Arctic.

She is a conservation scientist specialized in macroecology and biogeography, and is currently working to quantify vegetation shifts under climate change in extreme biomes such as the tundra and the savannah. Isla H. Myers-Smith is a Chancellor's Fellow and Senior Lecturer at the University of Edinburgh. Her research quantifies how global change alters plant communities and ecosystem processes, with a focus on the tundra biome.

The rapidly warming temperatures in high-latitude and alpine regions have the potential to alter the phenology of Arctic and alpine plants, affecting processes ranging from food webs to ecosystem trace gas fluxes. The International Tundra Experiment (ITEX) was initiated in 1990 to evaluate the effects of expected rapid changes in temperature on tundra plant phenology, growth and community changes using experimental warming. Here, we used the ITEX control data to test the phenological responses to background temperature variation across sites spanning latitudinal and moisture gradients. The dataset overall did not show an advance in phenology; instead, temperature variability during the years sampled and an absence of warming at some sites resulted in mixed responses. Phenological transitions of high Arctic plants clearly occurred at lower heat sum thresholds than those of low Arctic and alpine plants. However, sensitivity to temperature change was similar among plants from the diffe...

Given the current rate of Arctic warming, the associated ecological changes need to be put into a longer-term context of natural variability. Palaeolimnology offers tools to explore archives stored in the sediments of Arctic lakes and ponds. The interpretation of these archives requires a sound knowledge of the ecology and distribution of the sedimentary proxy organisms used. Here we explored the relationship between diatoms, a widely used proxy group of siliceous algae, and the environmental drivers defining their assemblages and diversity in 115 lakes and ponds in Greenland, a markedly understudied arctic region covering extensive climate and environmental gradients. The main environmental drivers of diatom communities were related to climate and lake ontogeny, including both measured and unmeasured (spatially structured) environmental variables. The lakes and ponds in the northern study regions showed a distinctive dominance of small benthic fragilarioid species, while diatom communities in the South(west) of Greenland were more varied, including many epiphytes, owing to the longer growing season and higher habitat diversity of these lakes and ponds. The newly established lakes in the Ilulissat region host markedly different communities compared to all other sites. Species diversity followed an overall clear latitudinal decline towards the North. Despite the large distances between our study regions, diatom dispersal appeared not to be limited. Based on our results, diatoms are an excellent proxy for climate-mediated lake ecosystem change in the Arctic and thus a valuable tool for climate reconstructions in the region. Particular consideration should be given to often unmeasured climate-related drivers, such as in-lake habitat availability, due to their apparent importance in defining Arctic diatom communities.

Collapsed permafrost block of coastal tundra on Alaska's Arctic Coast. Trends toward earlier dates of spring arrival on the Arctic coast (1974-2010) for three types of birds. J. Helmericks and USGS data. 2080s 2050s 2020s Present Flat-lobed lichen Cetraria nivalis, and Cladonia spp. Receding distribution of the barren ground shrew, a tundra specialist, as the tundra-boreal forest ecotone creeps northward. Present and future time frames based on preliminary USGS genetic and climate models.

The Arctic plays a fundamental role in the climate system and has shown significant climate change in recent decades, including the Arctic warming and decline of Arctic sea-ice extent and thickness. In contrast to the Arctic warming and reduction of Arctic sea ice, Europe, East Asia and North America have experienced anomalously cold conditions, with record snowfall during recent years. In this paper, we review current understanding of the sea-ice impacts on the Eurasian climate. Paleo, observational and modelling studies are covered to summarize several major themes, including: the variability of Arctic sea ice and its controls; the likely causes and apparent impacts of the Arctic sea-ice decline during the satellite era, as well as past and projected future impacts and trends; the links and feedback mechanisms between the Arctic sea ice and the Arctic Oscillation/North Atlantic Oscillation, the recent Eurasian cooling, winter atmospheric circulation, summer precipitation in East A...

This book - requested by S.J. Hawkins, the Editor of Excellence in Ecology, when John Smol was recognized with the International Ecology Institute Prize - is certainly one of the most modern and complete texts on the Canadian Arctic. The polar area like many other extreme environments that I studied during my scientific activity (e.g., Greenland, Antarctica, Svalbard archipelago, Finland Lapland and mountain ecosystems), has for years been subject to great alterations due to climate changes (“the big threat multiplier”), mine effluents, local and long-distance pollution. The book provides an excellent overview of how the arctic environment has developed during the last ca. 200 years and even before. The Arctic environment is transforming rapidly....

Key Words: Alaska, Aleutian Islands, Amatignak I., bird surveys, common eider, cormorant, Delarof Islands, Gareloi I., glaucous-winged gull, Kavalga I., Ogliuga I., pelagic cormorant, pigeon guillemot, red-faced cormorant, seabirds, Skagul I., Ulak I., ... US Fish and Wildlife ...

The Continuous Plankton Recorder survey has monitored plankton in the Northwest Atlantic at monthly intervals since 1962, with an interegnum between 1978 and 1990. In May 1999, large numbers of the Pacific diatom Neodenticula seminae were found in Continuous Plankton Recorder (CPR) samples in the Labrador Sea as the first record in the North Atlantic for more than 800 000 years. The event coincided with modifications in Arctic hydrography and circulation, increased flows of Pacific water into the Northwest Atlantic and in the previous year the exceptional occurrence of extensive ice-free water to the North of Canada. These observations indicate that N. seminae was carried in a pulse of Pacific water in 1998/early 1999 via the Canadian Arctic Archipelago and/or Fram Strait. The species occurred previously in the North Atlantic during the Pleistocene from $ 1.2 to $ 0.8 Ma as recorded in deep sea sediment cores. The reappearance of N. seminae in the North Atlantic is an indicator of the scale and speed of changes that are taking place in the Arctic and North Atlantic oceans as a consequence of regional climate warming. Because of the unusual nature of the event it appears that a threshold has been passed, marking a change in the circulation between the North Pacific and North Atlantic Oceans via the Arctic. Trans-Arctic migrations from the Pacific into the Atlantic are likely to occur increasingly over the next 100 years as Arctic ice continues to melt affecting Atlantic biodiversity and the biological pump with consequent feedbacks to the carbon cycle.

The Arctic is geologically and biogeographically young, and the origin of its seaweed flora has been widely debated. The Arctic littoral biogeographic region dates from the latest Tertiary and Pleistocene. Following the opening of Bering Strait, about 3.5 mya, the ''Great Trans-Arctic Biotic Interchange'' populated the Arctic with a fauna strongly dominated by species of North Pacific origin. The Thermogeographic Model (TM) demonstrates why climate and geography continued to support this pattern in the Pleistocene. Thus, Arctic and Atlantic subarctic species of seaweeds are likely to be evolutionarily ''based'' in the North Pacific, subarctic species are likely to be widespread in the warmer Arctic, and species of Atlantic Boreal or warmer origin are unlikely in the Arctic and Subarctic. Although Arctic seaweeds have been thought to have a greater affinity with the North Atlantic, we have reanalyzed the Arctic endemic algal flora, using the Thermogeographic Model and evolutionary trees based on molecular data, to demonstrate otherwise. There are 35 congeneric species of the six, abundant Arctic Rhodophyta that we treat in this paper; 32 of these species (91%) occur in the North Pacific, two species (6%) occur in the Boreal or warmer Atlantic Ocean, and a single species is panoceanic, but restricted to the Subarctic. Laminaria solidungula J. Agardh, a kelp Arctic ''endemic'' species, has 18 sister species. While only eleven (61%) occur in the North Pacific, this rapidly dispersing and evolving genus is a terminal member of a diverse family and order (Laminariales) widely accepted to have evolved in the North Pacific. Thus, both the physical ⁄ time-based TM and the dominant biogeographic pattern of relatives of Arctic macrophytes suggest strong compliance with the evidence of zoology, geology, and paleoclimatology that the Arctic marine flora is largely of Pacific origin.

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Background Maintaining gut health is a persistent and unresolved challenge in the poultry industry. Given the critical role of gut health in chicken performance and welfare, there is a pressing need to identify effective gut health intervention (GHI) strategies to ensure optimal outcomes in poultry farming. In

Unicellular eukaryotes are an integral part of many microbial ecosystems communities where they are known to interact with their surrounding prokaryotic community-either as predators or as a mutualistic habitat. Within the rumen, one of the most complex host-associated microbial habitats, ciliate protozoa represent the main micro-eukaryotes, accounting for up to 50% of the microbial biomass. Nonetheless, the extent of the ecological effect of protozoa on the microbial community and on the rumen metabolic output remains largely understudied. To assess the role of protozoa on the rumen ecosystem, we established an ex-vivo system in which distinct protozoa sub-communities were introduced to native rumen prokaryotic community. We show that the different protozoa communities exert a strong and differential impact on the composition of the prokaryotic community, as well as its function including methane production. Furthermore, the presence of protozoa increases prokaryotic diversity with a differential effect on specific bacterial populations such as Gammaproteobacteria, Prevotella and Spirochetes. Our results suggest that protozoa mitigate the effect of competitive exclusion between bacterial species, thereby contributing to the maintenance of prokaryotic diversity in the rumen. Our findings put forward the rumen protozoa populations as potentially important ecosystem engineers for future microbiome modulation strategies. .

The remains of a bird were discovered embedded in ice (Fig. 1) at the back of a cave (location: 80.3772˚N, −21.7476˚W) in Kronprins Christian Land, northeast Greenland (Fig. 2). The cave is formed in Ordovician-Silurian limestone and is located at an elevation of 510 m a.s.l., on the west wall of a 1-km-long north-south tributary valley of the larger Grottedalen valley. The cave is ca. 15 m in length and contains a 90° left-hand bend ca. 8 m from the entrance. The entrance is located in a cliff and measures ca. 6 m wide by ca. 5 m high, whilst the rear of the cave measures ca. 2 m wide by ca. 1 m high. The temperature at the rear of the cave was recorded as 2.8°C on 5 August 2015, using a Kestrel 4500 pocket weather meter. The nearest meteorological station is situated near the coast, ca. 205 km to the northeast at Station Nord (81.605˚N, −16.684 ˚W). The climate at the cave site is however expected to be more continental with warmer summers and colder winters than at Station Nord (Krinsley

Rapidly changing climate at high latitudes has triggered a search for bellwethers of ecological change there. If the initial signs of change can be identified, perhaps we can predict where these changes will lead. Large-bodied, terrestrial herbivores are potential candidates for bellwether taxa because of the key roles they play in some ecological communities. Here, we assembled historical, archaeological, and paleontological records of moose ( Alces alces (Linnaeus, 1758)) from the western Arctic and subarctic. The results showed that rather than having recently invaded tundra regions in response to post Little Ice Age warming, moose have inhabited river corridors several hundred kilometres north of the closed, boreal forest since they first colonized North America across the Bering Land Bridge ca. 14 000 years ago. The combination of high mobility, fluctuation-prone metapopulations, and reliance on early successional vegetation makes changes in the northern range limits of moose u...

Climate change is being experienced particularly intensely in the Arctic. Arctic average temperature has risen at almost twice the rate as that of the rest of the world in the past few decades. Widespread melting of glaciers and sea ice and rising permafrost temperatures present additional evidence of strong Arctic warming. These changes in the Arctic provide an early indication of the environmental and societal significance of global consequences. The Arctic also provides important natural resources to the rest of the world (such as oil, gas, and fish) that will be affected by climate change, and the melting of Arctic glaciers is one of the factors contributing to sea level rise around the globe. An acceleration of these climatic trends is projected to occur during this century, due to ongoing increases in concentrations of greenhouse gases in the Earth's atmosphere. These Arctic changes will, in turn, impact the planet as a whole.

The Arctic is a key part of the global climate system because the net positive energy input to the tropics must ultimately be resolved through substantial energy losses in high-latitude regions. The Arctic influences the global climate system through both positive and negative feedbacks that involve physical, ecological, and human systems of the Arctic. The balance of evidence suggests that positive feedbacks to global warming will likely dominate in the Arctic during the next 50 to 100 years. However, the negative feedbacks associated with changing the freshwater balance of the Arctic Ocean might abruptly launch the planet into another glacial period on longer timescales. In light of uncertainties and the vulnerabilities of the climate system to responses in the Arctic, it is important that we improve our understanding of how integrated regional changes in the Arctic will likely influence the evolution of the global climate system.

▪   The Arctic is a key part of the global climate system because the net positive energy input to the tropics must ultimately be resolved through substantial energy losses in high-latitude regions. The Arctic influences the global climate system through both positive and negative feedbacks that involve physical, ecological, and human systems of the Arctic. The balance of evidence suggests that positive feedbacks to global warming will likely dominate in the Arctic during the next 50 to 100 years. However, the negative feedbacks associated with changing the freshwater balance of the Arctic Ocean might abruptly launch the planet into another glacial period on longer timescales. In light of uncertainties and the vulnerabilities of the climate system to responses in the Arctic, it is important that we improve our understanding of how integrated regional changes in the Arctic will likely influence the evolution of the global climate system.

Arctic sea ice is rapidly declining in presence, thickness and extent. The consequences that this has for the overall biodiversity in Arctic marine ecosystems are poorly addressed. Especially the so-called sympagic meiofauna, the many tiny organisms living in sea ice, is rarely identified to species level. Here we present the first record of the hydrozoan Sympagohydra tuuli living in sea ice in the Svalbard fjords (European Arctic). Previously, this tiny ice-cnidarian has only been reported from sea ice of Barrow (Alaska), the Canadian Arctic and the central Arctic Ocean. In April 2015, two small hydrozoans were recorded in the landfast sea ice in Van Mijenfjorden (West Spitsbergen). Both of them were preserved in ethanol and one specimen was successfully identified with Sanger sequencing. DNA barcoding confirmed it to be the Protohydridae S. tuuli. Little is known about S. tuuli lifecycle, but its occurrence within the sea ice of seasonal ice-covered fjords in Western Svalbard with no sea-ice connection to the Arctic Ocean strengthens the theory about a sympago-benthic life strategy. We propose that S. tuuli has a pan-Arctic distribution and only spends parts of its life cycle in sea ice.

The gut microbiome provides vital functions for mammalian hosts, yet research on the variability and function of the microbiome across adult lifespans and multiple generations is limited in large mammalian carnivores. Here we use 16S rRNA gene and metagenomic sequencing to profile the taxonomic composition, genomic diversity, and metabolic function of the gut microbiome of 12 wild spotted hyenas (Crocuta crocuta) residing in the Masai Mara National Reserve, Kenya over a 23-year period spanning three generations. We determined the extent to which host factors predict variation in the gut microbiome and identify the core microbes present in the guts of hyenas. We also investigate novel genomic diversity in the mammalian gut by reporting the first metagenome-assembled genomes (MAGs) for hyenas. We found that gut microbiome taxonomic composition was highly variable across the two decades of sampling, but despite this, a core set of 14 bacterial genera and 19 amplicon sequence variants w...

This article focuses on the representations of Evenkis and their culture <em>national identity, economic and cultural development</em> in age of globalization, In Russia. The Evenki are an indigenous people of central and eastern Siberia, Mongolia, and Inner Mongolia.The Evenki have been under Russian and Chinese rule since their conquest during the 17th century by the Romanov and Qing dynasties respectively.In older Russian and Western ethno-graphic literature, the Evenki were formerly referred to by the term Tungus, which is derived from Tongus, the Yakut word for "Evenki."The article will use the various elements of critical study to highlight the interplay between the real, imaginary, and ideological development of this community. The article explores how visual datas of the Evenkis and the Evenki culture create the ideological structure of the nature of the Evenkis and replicate ethnic hierarchies in the Russian and Chinese region. The paper also tries to ...

Unprecedented and dramatic transformations are occurring in the Arctic in response to climate change, but academic, public, and political discourse has disproportionately focussed on the most visible and direct aspects of change, including sea ice melt, permafrost thaw, the fate of charismatic megafauna, and the expansion of fisheries. Such narratives disregard the importance of less visible and indirect processes and, in particular, miss the substantive contribution of the shelf seafloor in regulating nutrients and sequestering carbon. Here, we summarise the biogeochemical functioning of the Arctic shelf seafloor before considering how climate change and regional adjustments to human activities may alter its biogeochemical and ecological dynamics, including ecosystem function, carbon burial, or nutrient recycling. We highlight the importance of the Arctic benthic system in mitigating climatic and anthropogenic change and, with a focus on the Barents Sea, offer some observations and...

Did Beringian environments represent an ecological barrier to humans until less than 15 000 years ago or was access to the Americas controlled by the spatial–temporal distribution of North American ice sheets? Beringian environments varied with respect to climate and biota, especially in the two major areas of exposed continental shelf. The East Siberian Arctic Shelf (‘Great Arctic Plain’ (GAP)) supported a dry steppe-tundra biome inhabited by a diverse large-mammal community, while the southern Bering-Chukchi Platform (‘Bering Land Bridge’ (BLB)) supported mesic tundra and probably a lower large-mammal biomass. A human population with west Eurasian roots occupied the GAP before the Last Glacial Maximum (LGM) and may have accessed mid-latitude North America via an interior ice-free corridor. Re-opening of the corridor less than 14 000 years ago indicates that the primary ancestors of living First Peoples, who already had spread widely in the Americas at this time, probably dispersed...

Heat waves in the Arctic may strongly impact environment and local communities. Recently several indices have been proposed for monitoring environmental changes in the Arctic, but heat waves have not been addressed. By applying a structured approach for evaluating occurrences of periods with exceptionally high temperatures, this study demonstrates that in the last decades there was an increase of heat wave occurrences over the terrestrial Arctic. The increase is mainly over the Canadian Arctic Archipelago and Greenland that are surrounded by ocean undergoing a sea-ice melting trend, while the Eurasian Arctic shows no significant change in heat wave occurrence. Since 2002 the probability of experiencing heat waves in the Arctic has been similar or even higher than in the middle and low latitudes and heat waves have already started to increasingly threaten local vegetation, ecology, human health and economy.

Recent Arctic warming has major influences on biological communities, especially in freshwater environments. There is substantial evidence that lake ecosystems in the Canadian Arctic and Fennoscandia are undergoing changes that have been linked to human-induced climate warming during the past 150-100 years. However, only few data linking recent climatic changes with the changes in biological communities are available from the Russian Arctic. We investigated a short sediment core (bottom of the core dates to 1830 CE) from Lake Bolshoy Kharbey, the biggest lake of the Bol`shezemelskaya Tundra, western Russian Arctic, using chironomid, cladocera, diatom and palynological analyses. Variations in biological proxy were linked to regional meteorological data and compared with the available sub-recent palaeoecological and hydrobiological studies from the region. The overall change in species composition was the smallest for terrestrial vegetation (0.485 SD) followed by cladoceran communities (0.966 SD). Chironomid taxonomic turnover was 1.331 SD, and the greatest rate of change was observed in diatom assemblages (1.701 SD). Changes in biological communities demonstrated a correlation with meteorologically recorded climatic parameters (air temperature and precipitation). The strongest taxonomic shifts in biological communities took place in 1880 and 1980. Both dates can be linked with prominent and recent climatic events: 1880 can be related to the end of the Little Ice Age in the region and 1980 is the beginning of the modern accelerating warming.

Invertebrate herbivores depend on external temperature for growth and metabolism. Continued warming in tundra ecosystems is proposed to result in increased invertebrate herbivory. However, empirical data about how current levels of invertebrate herbivory vary across the Arctic is limited and generally restricted to a single host plant or a small group of species, so predicting future change remains challenging. We investigated large-scale patterns of invertebrate herbivory across the tundra biome at the community level and explored how these patterns are related to long-term climatic conditions and yearof-sampling weather, habitat characteristics and aboveground biomass production. Utilizing a standardized protocol, we collected samples from 92 plots nested within 20 tundra sites during summer 2015. We estimated the community-weighted biomass lost based on the total leaf area consumed by invertebrates for the most common plant species within each plot. Overall, invertebrate herbivory was prevalent at low intensities across the tundra, with estimates averaging 0.94% and ranging between 0.02% and 5.69% of plant biomass. Our results suggest that midsummer temperature influences the intensity of invertebrate herbivory at the community level, consistent with the hypothesis that climate warming should increase plant losses to invertebrates in the tundra. However, most of the observed variation in herbivory was associated with other site level characteristics, indicating that other local ecological factors also play an important role. More details about the local drivers of invertebrate herbivory are necessary to predict the consequences for rapidly changing tundra ecosystems.

Did Beringian environments represent an ecological barrier to humans until less than 15 000 years ago or was access to the Americas controlled by the spatial–temporal distribution of North American ice sheets? Beringian environments varied with respect to climate and biota, especially in the two major areas of exposed continental shelf. The East Siberian Arctic Shelf (‘Great Arctic Plain’ (GAP)) supported a dry steppe-tundra biome inhabited by a diverse large-mammal community, while the southern Bering-Chukchi Platform (‘Bering Land Bridge’ (BLB)) supported mesic tundra and probably a lower large-mammal biomass. A human population with west Eurasian roots occupied the GAP before the Last Glacial Maximum (LGM) and may have accessed mid-latitude North America via an interior ice-free corridor. Re-opening of the corridor less than 14 000 years ago indicates that the primary ancestors of living First Peoples, who already had spread widely in the Americas at this time, probably dispersed...

Phytoplankton blooms represent hotspots of primary production and lead to the formation of particulate organic matter composed of living and dead algal cells. These particles are characterized by steep chemical gradients, for instance in oxygen concentration, that provide diverse ecological niches for specifically adapted microbes to thrive. We analyzed cooccurrence networks based on 16S and 18S ribosomal RNA gene amplicon sequences obtained during a spring phytoplankton bloom in the North Sea. Particulate fractions larger than 10 µm size were collected at almost daily intervals between early March and late May in 2018. Metaproteomics was used to asses microbial protein expression at three selected time points during the sampling period. Cooccurrence networks identified two major modules representing bacteria cooccurring with diatoms and with dinoflagellates, respectively. Bacterial communities associated with these two algal lineages differed in composition, with diatoms being distinctly clustered with known sulfate-reducing Desulfobacterota as well as with potentially sulfur-oxidizing Ectothiorhodospiraceae. Metaproteomics confirmed expression of respective key enzymes in these taxa. Microbial sulfate reduction is known to occur in sinking particles at greater depths (marine snow), but is considered of lesser importance in the upper photic zone during phytoplankton blooms. However, our results suggest presence of sufficiently anoxic niches in diatom-derived particles, which could enable processes akin to cryptic sulfur cycling in oxygen minimum zones to take place also in the largely oxygen-rich photic zone during phytoplankton blooms. This illustrates the need to gain further insights into the functional roles of phytoplanktonassociated bacteria.

SummaryClimate change may influence the phenology of organisms unequally across trophic levels and thus lead to phenological mismatches between predators and prey. In cases where prey availability peaks before reproducing predators reach maximal prey demand, any negative fitness consequences would selectively favor resynchronization by earlier starts of the reproductive activities of the predators. At a study site in northeast Greenland, over a period of 17 years, the median emergence of the invertebrate prey of Sanderling Calidris alba advanced with 1.27 days per year. Yet, over the same period Sanderling did not advance hatching date. Thus, Sanderlings increasingly hatched after their prey was maximally abundant. Surprisingly, the phenological mismatches did not affect chick growth, but the interaction of the annual width and height of the peak in food abundance did. Chicks grew especially better in years when the food peak was broad. Sanderling clutches were most likely to be dep...

With the Arctic rapidly changing, the needs to observe, understand, and model the changes are essential. To support these needs, an annual cycle of observations of atmospheric properties, processes, and interactions were made while drifting with the sea ice across the central Arctic during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition from October 2019 to September 2020. An international team designed and implemented the comprehensive program to document and characterize all aspects of the Arctic atmospheric system in unprecedented detail, using a variety of approaches, and across multiple scales. These measurements were coordinated with other observational teams to explore cross-cutting and coupled interactions with the Arctic Ocean, sea ice, and ecosystem through a variety of physical and biogeochemical processes. This overview outlines the breadth and complexity of the atmospheric research program, which was organized into 4 subgro...

SummaryArchaea are responsible for methane production in the human gastrointestinal tract. Twenty percent of the Western populations exhale substantial amounts of this gas. The underlying principle determining high or low methane emission and its effect on human health was still not sufficiently understood.In this study, we analysed the gastrointestinal microbiome, archaeome, metagenome, metabolome, and eating behaviour of 100 healthy young adults. We correlated high levels of human methane emission (5-75 ppm) with a 1000-fold increase in Methanobrevibacter smithii. This archaeon co-occurred with a bacterial community specialised on dietary fibre degradation, which included members of the Ruminococcaceae and Christensenellaceae. Methane production was negatively affected by high vitamin B12 and fat intake of the subjects, and was positively associated with increased formate concentrations in the gut. Overall, methane emission is explained by dietary habits, host genetics, local meta...

This chapter discusses the issue of energy security within the broader framework of societal security in the Barents Region. As a 'master resource' (Strauss, Rupp and Love 2013, 11), energy penetrates and crosscuts all aspects of the broadly understood human security: economic, food, health, environmental, personal, community and political security dimensions and concerns (cf. UNDP 1994). However, societal aspects of energy security remain largely understudied and are often overlooked in energy-related debates and decisionmaking, including in the context of the Barents Region.

The Arctic-Barents Region is facing numerous pressures from a variety of sources, including the effect of environmental changes and extractive industrial developments. The threats arising out of these pressures result in human security challenges. This book analyses the formation, and promotion, of societal security within the context of the Arctic-Barents Region. It applies the human security framework, which has increasingly gained currency at the UN level since 1994 (UNDP), as a tool to provide answers to many questions that face the Barents population today. The study explores human security dimensions such as environmental security, economic security, health, food, water, energy, communities, political security and digital security in order to assess the current challenges that the Barents population experiences today or may encounter in the future. In doing so, the book develops a comprehensive analysis of vulnerabilities, challenges and needs in the Barents Region and provides recommendations for new strategies to tackle insecurity and improve the wellbeing of both indigenous and local communities. This book will be a valuable tool for academics, policy-makers and students interested in environmental and human security, sustainable development, environmental studies and the Arctic and Barents Region in particular.

The Arctic-Barents Region is facing numerous pressures from a variety of sources, including the effect of environmental changes and extractive industrial developments. The threats arising out of these pressures result in human security challenges. This book analyses the formation, and promotion, of societal security within the context of the Arctic-Barents Region. It applies the human security framework, which has increasingly gained currency at the UN level since 1994 (UNDP), as a tool to provide answers to many questions that face the Barents population today. The study explores human security dimensions such as environmental security, economic security, health, food, water, energy, communities, political security and digital security in order to assess the current challenges that the Barents population experiences today or may encounter in the future. In doing so, the book develops a comprehensive analysis of vulnerabilities, challenges and needs in the Barents Region and provide...

A 31-year-old woman, gravida 2 para 2, admitted due to acute abdominal pain and diarrhea at week 29 of her pregnancy was threatened with premature labor and acute enterocolitis; intravenous ritodrine hydrochloride was started. She showed bloody diarrhea and at 29 weeks and 2 days gestation, spontaneous labor began. Due to arm presentation, an emergency caesarean section was performed. On postoperative day 2, Shiga toxin 2 positive enterohaemorrhagic E. coli (EHEC) O157 was found. On postoperative day 4, thrombocytopenia, haemolytic uremic syndrome (HUS), and renal failure developed. After four plasma exchanges, her symptoms had improved and tested negative for O157 on day 10. For the health of the mother, we recommend inducing early delivery for a pregnancy presenting with bloody diarrhea and testing positive for EHEC O157 which may progress to Shiga toxin 2 infection.

Perennially frozen ground and sea ice are key constituents of permafrost coastal systems, and their presence is the primary difference between temperate and high-latitude coastal processes. These systems are some of the most rapidly changing landscapes on Earth and, in the Arctic, are representative of the challenges being faced at the intersection between natural and anthropogenic systems. Permafrost thaw, in combination with increasing sea level and decreasing sea-ice cover, exposes arctic coastal and nearshore areas to rapid environmental and social changes. Based on decadal timescales, observations in the Arctic indicate an increase in permafrost coastal bluff erosion and storm surge flooding of low-lying ice-rich permafrost terrain. However, circum-arctic observations remain limited and the factors responsible for the apparent increase in arctic coastal dynamics are poorly constrained. A better understanding of permafrost coastal systems and how they are responding to changes i...

, the staff and research commission of the Swiss National Park, BioGeoClimate Modelling Lab. We thank the innumerable field technicians, logistics teams, graduate and undergraduate assistants for help with data collection. Special thanks to the Tea Bag Index core-team. Finally, we thank parks, wildlife refuges, field stations and the local and Indigenous people for the opportunity to conduct research on their land.

Invertebrate herbivores depend on external temperature for growth and metabolism. Continued warming in tundra ecosystems is proposed to result in increased invertebrate herbivory. However, empirical data about how current levels of invertebrate herbivory vary across the Arctic is limited and generally restricted to a single host plant or a small group of species, so predicting future change remains challenging. We investigated large-scale patterns of invertebrate herbivory across the tundra biome at the community level and explored how these patterns are related to long-term climatic conditions and yearof-sampling weather, habitat characteristics and aboveground biomass production. Utilizing a standardized protocol, we collected samples from 92 plots nested within 20 tundra sites during summer 2015. We estimated the community-weighted biomass lost based on the total leaf area consumed by invertebrates for the most common plant species within each plot. Overall, invertebrate herbivory was prevalent at low intensities across the tundra, with estimates averaging 0.94% and ranging between 0.02% and 5.69% of plant biomass. Our results suggest that midsummer temperature influences the intensity of invertebrate herbivory at the community level, consistent with the hypothesis that climate warming should increase plant losses to invertebrates in the tundra. However, most of the observed variation in herbivory was associated with other site level characteristics, indicating that other local ecological factors also play an important role. More details about the local drivers of invertebrate herbivory are necessary to predict the consequences for rapidly changing tundra ecosystems.

Late Holocene climate and chemical change at high latitudes: case studies from contaminated sites in subarctic and arctic Canada Jennifer M. Galloway (1), Darryl Cooney (2), Carley Crann (2), Hendrik Falck (3), Dana Howell (4), Heather Jamieson (4), Andrew Macumber (2), Nawaf Nasser (2), Michael Palmer (5), R. Timothy Patterson (2), Michael Parsons (1), Helen M. Roe (6), Hamed Sanei (1), Christopher Spence (7), Drew Stavinga (4), and Graeme T. Swindles (8)

The interior of southern Baffin Island between 64˚N and 68˚N latitude is a mainly lowland area over 50 000 km 2 in extent, containing two large lakes (Amadjuak and Nettilling) and numerous smaller lakes and ponds. This area is important as summer range for caribou and a variety of birds, and there is evidence for a human presence as early as 3000 B.P. Field studies between 1984 and 1988 and the operation of climatic autostations from 1987 to 1995 revealed a warm summer climate and cold winters. There is a locally rich and diverse vegetation, including Betula glandulosa and other species that are indicative of the low arctic bioclimatic zone and mark the present northern limit of that zone in the eastern Canadian Arctic. Air photos and Landsat imagery were used to map vegetation beyond the field areas, leading to an estimate of 46% of the land area in continuous vegetation (tundra) of some type and 15% with shrub and heath elements. Palynology of sediment cores taken from Nettilling Lake permitted extrapolation from present bioclimatic conditions to 4750 years B.P. Betula and therefore elements of a low arctic vegetation association appear to have been present in the area during most of that period, indicating a local bioclimatic system that has been relatively stable under regional variations of climate.

Given the current threat of fast-paced global change, it has become urgent to understand the biogeochemical response of the Arctic environment to external forcing. The Canadian Arctic Shelf Exchange Study (CASES) is an interdisciplinary project put together by scientists from across Canada whose primary goal is to gain a better understanding of the Canadian Arctic environment. Objectives include evaluating issues such as the impact of climate change – extent of sea ice cover - on biological productivity and the carbon cycle. In order to predict the potential evolution of the complex Canadian Arctic system, the intricacies of its current dynamics must first be understood.

Tidal wetlands, such as tidal marshes and mangroves, are hotspots for carbon sequestration. The preservation of organic matter (OM) is a critical process by which tidal wetlands exert influence over the global carbon cycle and at the same time gain elevation to keep pace with sealevel rise (SLR). The present study assessed the effects of temperature and relative sea level on the decomposition rate and stabilization of OM in tidal wetlands worldwide, utilizing commercially available standardized litter. While effects on decomposition rate per se were minor, we show strong negative effects of temperature and relative sea level on stabilization, as based on the fraction of labile, rapidly hydrolyzable OM that becomes stabilized during deployment. Across study sites, OM stabilization was 29 % lower in low, more frequently flooded vs. high, less frequently flooded zones. Stabilization declined by ∼ 75 % over the studied temperature gradient from 10.9 to 28.5 • C. Additionally, data from the Plum Island long-term ecological research site in Mas-Published by Copernicus Publications on behalf of the European Geosciences Union. 3190 P. Mueller et al.: Global-change effects on early-stage decomposition processes sachusetts, USA, show a pronounced reduction in OM stabilization by > 70 % in response to simulated coastal eutrophication, confirming the potentially high sensitivity of OM stabilization to global change. We therefore provide evidence that rising temperature, accelerated SLR, and coastal eutrophication may decrease the future capacity of tidal wetlands to sequester carbon by affecting the initial transformations of recent OM inputs to soil OM.

The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition explored the coupled central arctic climate system from late September 2019 to late September 2020. The project was based on and around the icebreaker Polarstern, as it was frozen into, and drifted with, the arctic sea ice from the Siberian sector of the Arctic, past the North Pole, and on towards the Fram Strait. The expedition was designed as a "sea ice Lagrangian" experiment, wherein a specific region of sea ice was passively followed over the course of a year, serving as an integrator of thermodynamic, dynamic, chemical, and biological interactions with the atmosphere and ocean. The overall scientific goal for the mission was to understand the processes driving the ongoing rapid decline of sea ice as well as the implications of those changes on the regional and global climate systems. In particular, the expedition was constructed in a way to observe and understand the physical, chemical, and biological processes that serve to couple and link the arctic atmosphere, sea ice, ocean, and ecosystem. Guiding science questions for the mission include: 1. What are the seasonally varying energy sources, mixing processes, and interfacial fluxes that affect the heat and momentum budgets of the arctic atmosphere, ocean, and sea ice?