Ground temperatures in the top few centimetres of the soil profile are key in many biological processes yet remain very poorly documented, especially in the polar regions or over longer timescales. ...They can vary greatly seasonally and at various spatial scales across the often highly complex and heterogeneous polar landscapes. It is challenging and often impossible to extrapolate soil profile temperatures from meteorological air temperature records. Furthermore, despite the justifiably considerable profile given to contemporary large-scale climate change trends, with the exception of some sites on Greenland, few biological microclimate datasets exist that are of sufficient duration to allow robust linkage and comparison with these large-scale trends. However, it is also clear that the responses of the soil-associated biota of the polar regions to projected climate change cannot be adequately understood without improved knowledge of how landscape heterogeneity affects ground and sub-surface biological microclimates, and of descriptions of these microclimates and their patterns and trends at biologically relevant physical and temporal scales. To stimulate research and discussion in this field, we provide an overview of multi-annual temperature records from 20 High Arctic (Svalbard) and maritime Antarctic (Antarctic Peninsula and Scotia Arc) sites. We highlight important features in the datasets that are likely to have influence on biology in polar terrestrial ecosystems, including (a) summer ground and sub-surface temperatures vary much more than air temperatures; (b) winter ground temperatures are generally uncoupled from air temperatures; (c) the ground thawing period may be considerably shorter than that of positive air temperatures; (d) ground and air freeze–thaw patterns differ seasonally between Arctic and Antarctic; (e) rates of ground temperature change are generally low; (f) accumulated thermal sum in the ground usually greatly exceeds air cumulative degree days. The primary purpose of this article is to highlight the utility and biological relevance of such data, and to this end the full datasets are provided here to enable further analyses by the research community, and incorporation in future wider comparative studies.
The Antarctic Treaty System, acknowledged as a successful model of cooperative regulation of one of the globe's largest commons (1), is under substantial pressure. Concerns have been raised about ...increased stress on Antarctic systems from global environmental change and growing interest in the region's resources (2, 3). Although policy-makers may recognize these challenges, failure to respond in a timely way can have substantial negative consequences. We provide a horizon scan, a systematic means for identifying emerging trends and assisting decision-makers in identifying policies that address future challenges (2, 3). Previous analyses of conservation threats in the Antarctic have been restricted to matters for which available evidence is compelling (4). We reconsider these concerns because they might escalate quickly, judging from recent rapid environmental change in parts of Antarctica and increasing human interest in the region (see the map). We then focus on a more distant time horizon.
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•Antarctic species of Mesobiotus are strongly divergent from other Mesobiotus species.•Widely used taxonomic species groups “Furciger” and “Harmsworthi” have no systematic ...support.•Mesobiotus has radiated in Antarctica since it was isolated from other continents.•First pan-Antarctic study of a specific tardigrade group.
Antarctica has been isolated and progressively glaciated for over 30 million years, with only approximately 0.3 % of its area currently ice-free and capable of supporting terrestrial ecosystems. As a result, invertebrate populations have become isolated and fragmented, in some cases leading to speciation. Terrestrial invertebrate species currently found in Antarctica often show multi-million year, and even Gondwanan, heritage, with little evidence of recent colonisation. Mesobiotus is a globally distributed tardigrade genus. It has commonly been divided into two “groups”, referred to as harmsworthi and furciger, with both groups currently considered cosmopolitan, with global reports including from both the Arctic and the Antarctic. However, some authors considered that Meb. furciger, as originally described, may represent an Antarctic-specific lineage. Using collections of tardigrades from across the Antarctic continent and publicly available sequences obtained from online databases, we use mitochondrial and nuclear ribosomal sequence data to clarify the relationships of Antarctic Mesobiotus species. Our analyses show that all Antarctic members belong to a single lineage, evolving separately from non-Antarctic representatives. Within this Antarctic lineage there are further deep divisions among geographic regions of the continent, consistent with the presence of a species complex. Based on our data confirming the deep divisions between this Antarctic lineage, which includes representatives of both groups, we recommend that the use of furciger and harmsworthi group terminology is now abandoned, as it leads to systematic and biogeographical confusion.
The Antarctic Peninsula is one of three regions of the planet that have experienced the highest rates of climate warming over recent decades. Based on a comprehensive large-scale resurvey, allowing ...comparison of new (2009) and historical data (1960s), we show that the two native Antarctic vascular plant species have exhibited significant increases in number of occupied sites and percent cover since the 1960s: Deschampsia antarctica increasing in coverage by 191 % and in number of sites by 104 %. Colobanthus quitensis increasing in coverage by 208 % and number of sites by 35 %. These changes likely occurred in response to increases of 1.2 °C in summer air temperature over the same time period. Both species exhibited changes with elevation due to the interaction of multiple drivers (climatic factors and animal disturbance), producing heterogeneity of responses across an elevation gradient. Below an elevation of 20 m fur seal activity exerted negative impacts. Between 20 and 60 m, both plant species underwent considerable increases in the number of sites and percent cover, likely influenced by both climate warming and nutrient input from seals. Above an elevation threshold of 60 m the maximum elevation of the sites occupied decreased for both species, perhaps as a consequence of physical disturbance at higher elevations due to the permafrost conditions and/or the snow cover thickness and persistence. Understanding the role of disturbance drivers for vegetation change in cold regions may become a research priority to enable improved forecasting of biological responses and feedbacks of climate warming on ecosystems in these globally influential regions.
Climatic changes can induce geographic expansion and altitudinal shifts in the distribution of invasive species by offering more thermally suitable habitats. At the remote sub-Antarctic Kerguelen ...Islands, the predatory insect Merizodus soledadinus (Coleoptera: Carabidae), introduced in 1913, rapidly invaded coastal habitats. More recent colonisation of higher elevation habitats by this species could be underlain by their increased thermal suitability as the area has warmed. This study compared the effect of elevational range shift on the morphology and physiology of adult M. soledadinus sampled along two altitudinal transects (from the foreshore to 250 m a.s.l.) and a horizontal lowland transect orthogonal to the seashore (400 m length). Although high inter-individual and inter-transect variations in the traits examined were present, we observed that body mass of males and females tended to decrease with elevation, and that triglyceride contents decreased with distance from the shore. Moreover, protein contents of females as well as those of 26 metabolites were influenced significantly by distance to the foreshore. These results suggest that future climate change at the Kerguelen Islands will further assist the colonisation of lowland inland and higher altitude habitats by this aggressively invasive predator, by making previously sub-optimal habitats progressively more suitable.
Antarctica is an isolated continent whose conditions challenge the survival of living organisms. High levels of endemism are now known in many Antarctic organisms, including algae, tardigrades, ...nematodes and microarthropods. Bdelloid rotifers are a key, widespread and abundant group of Antarctic microscopic invertebrates. However, their diversity, regional distribution and endemism have received little attention until recently. We provide the first authoritative review on Antarctic Bdelloidea, based on published data and new collections. Our analysis reveals the extreme levels of bdelloid endemism in Antarctica. Sixty-six bdelloid morphospecies are now confirmed from the continent, and 83–91 putative species are identified using molecular approaches (depending on the delimitation method used). Twelve previously unknown species are described based on both morphology and molecular analyses. Molecular analyses indicate that only two putative species found in Antarctica proved to be truly cosmopolitan. The level of endemism based on the available data set (95%) is higher than that in any other continent, with many bdelloid species occurring only in maritime or continental Antarctica. These findings are consistent with the long-term presence of Bdelloidea in Antarctica, with their considerable isolation facilitating intraregional radiation, providing further evidence that does not support the microbial global ubiquity hypothesis that “everything is everywhere.”
We review the scientific literature, especially from the past decade, on the impacts of human activities on the Antarctic environment. A range of impacts has been identified at a variety of spatial ...and temporal scales. Chemical contamination and sewage disposal on the continent have been found to be long-lived. Contemporary sewage management practices at many coastal stations are insufficient to prevent local contamination but no introduction of non-indigenous organisms through this route has yet been demonstrated. Human activities, particularly construction and transport, have led to disturbances of flora and fauna. A small number of non-indigenous plant and animal species has become established, mostly on the northern Antarctic Peninsula and southern archipelagos of the Scotia Arc. There is little indication of recovery of overexploited fish stocks, and ramifications of fishing activity on bycatch species and the ecosystem could also be far-reaching. The Antarctic Treaty System and its instruments, in particular the Convention for the Conservation of Antarctic Marine Living Resources and the Environmental Protocol, provide a framework within which management of human activities take place. In the face of the continuing expansion of human activities in Antarctica, a more effective implementation of a wide range of measures is essential, in order to ensure comprehensive protection of the Antarctic environment, including its intrinsic, wilderness and scientific values which remains a fundamental principle of the Antarctic Treaty System. These measures include effective environmental impact assessments, long-term monitoring, mitigation measures for non-indigenous species, ecosystem-based management of living resources, and increased regulation of National Antarctic Programmes and tourism activities.
Cryptobiosis is a reversible ametabolic state of life characterized by the ceasing of all metabolic processes, allowing survival of periods of intense adverse conditions. Here we show that 1) entire ...moss individuals, dated by
C, survived through cryptobiosis during six centuries of cold-based glacier burial in Antarctica, 2) after re-exposure due to glacier retreat, instead of dying (due to high rates of respiration supporting repair processes), at least some of these mosses were able to return to a metabolically active state and remain alive. Moss survival was assessed through growth experiments and, for the first time, through vitality measurements. Future investigations on the genetic pathways involved in cryptobiosis and the subsequent recovery mechanisms will provide key information on their applicability to other systematic groups, with implications for fields as divergent as medicine, biodiversity conservation, agriculture and space exploration.
Antarctica is considered among the world’s last great wildernesses, but its current network of Antarctic Specially Protected Areas (ASPAs) is inadequate, unrepresentative and at risk, needing urgent ...expansion due to the vulnerability of Antarctica to increasing threats from climate change and human activities. Among the existing ASPAs, no. 129 Rothera Point is unique because its designation related specifically to the monitoring of the impacts associated with the neighbouring Rothera Research Station, operated by the United Kingdom. The station is located on Adelaide Island (Antarctic Peninsula) in Antarctic Conservation Biogeographic Region 3 (ACBR3). We aim here to: (1) provide an improved description of the botanical values of the ASPA, and detailed vegetation mapping as for the establishment of future monitoring, (2) assess the representativeness of the ASPA vegetation within a wider geographical context encompassing Marguerite Bay and Adelaide Island and, (3) use this case study as a contribution to the ongoing discussion within the Antarctic Treaty System on the future development of the continent-wide ASPA network. Even though this specific ASPA was not initially designated for its biodiversity value, a higher species richness was recorded within the ASPA than outside the protected area on Rothera Point. Within the local geographic context, based on the available data, Rothera Point is characterized by high biodiversity and, above all, Léonie Island exhibits the greatest floristic richness within Marguerite Bay and Adelaide Island, being a biodiversity hot-spot of exceptional value. This case study emphasizes the continued existence of significant knowledge gaps relating to Antarctic terrestrial biodiversity, and the urgent need for large-scale assessment of the biological values of Antarctica, as one of the main challenges for the implementation of a robust and representative system of protected areas in terrestrial Antarctica, to protect this global natural heritage in the face of current and predicted future environmental change.
Abstract
Bryum is a moss genus that is widely distributed across the planet. Many of its species are characterized by large phenotypic and morphological plasticity, generating uncertainty in species ...identification exclusively based on morphological characteristics. In Antarctica, the extreme and harsh environmental conditions are further likely to promote intra-specific morphological variation, leading to complexity in the taxonomic attribution of Bryum species. In this study, we apply molecular phylogenetic analyses to assist in developing accurate species identification of B. pseudotriquetrum and two other relatively abundant Bryum species (B. archangelicum and B. pallescens) currently reported as Antarctic species.
A total of 51 Bryum samples collected in Antarctica (22) and from all other continents (29) were sequenced for ITS nrDNA and rps4 cpDNA regions, using markers widely used in moss phylogenetic studies. Phylogenetic trees were constructed including ITS (23) and rps4 (34) sequences representing the three more frequent of the seven Bryum species currently reported from Antarctica as well as several other Bryum species and related genera, incorporating all sequence data available in the literature and accessible databases. The molecular analyses provide strong support for a match between morphological and molecular attribution of specimens identified as B. pseudotriquetrum. The data also provide evidence of currently unrecognized Bryum diversity in Antarctica, with the identification of one individual of B. uliginosum. However, the analyses suggest that all Antarctic specimens currently assigned to other Bryum species are morphological variants of B. pseudotriquetrum. The integration of molecular and morphological analyses supports the presence of B. pseudotriquetrum as the most widely distributed species of the genus in Antarctica and of B. uliginosum with a much more restricted distribution (South Sandwich Islands). Our data suggest that further investigation is required of B. archangelicum and B. pallescens in other continents globally, as the identity of none of the herbarium specimens examined in this study could be confirmed with molecular data.
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