Human footprint models allow visualization of human spatial pressure across the globe. Up until now, Antarctica has been omitted from global footprint models, due possibly to the lack of a permanent ...human population and poor accessibility to necessary datasets. Yet Antarctic ecosystems face increasing cumulative impacts from the expanding tourism industry and national Antarctic operator activities, the management of which could be improved with footprint assessment tools. Moreover, Antarctic ecosystem dynamics could be modelled to incorporate human drivers. Here we present the first model of estimated human footprint across predominantly ice-free areas of Antarctica. To facilitate integration into global models, the Antarctic model was created using methodologies applied elsewhere with land use, density and accessibility features incorporated. Results showed that human pressure is clustered predominantly in the Antarctic Peninsula, southern Victoria Land and several areas of East Antarctica. To demonstrate the practical application of the footprint model, it was used to investigate the potential threat to Antarctica's avifauna by local human activities. Relative footprint values were recorded for all 204 of Antarctica's Important Bird Areas (IBAs) identified by BirdLife International and the Scientific Committee on Antarctic Research (SCAR). Results indicated that formal protection of avifauna under the Antarctic Treaty System has been unsystematic and is lacking for penguin and flying bird species in some of the IBAs most vulnerable to human activity and impact. More generally, it is hoped that use of this human footprint model may help Antarctic Treaty Consultative Meeting policy makers in their decision making concerning avifauna protection and other issues including cumulative impacts, environmental monitoring, non-native species and terrestrial area protection.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Species Distribution Models (SDMs) combine information on the geographic occurrence of species with environmental layers to estimate distributional ranges and have been extensively implemented to ...answer a wide array of applied ecological questions. Unfortunately, most global datasets available to parameterize SDMs consist of spatially interpolated climate surfaces obtained from ground weather station data and have omitted the Antarctic continent, a landmass covering c. 20% of the Southern Hemisphere and increasingly showing biological effects of global change. Here we introduce MERRAclim, a global set of satellite-based bioclimatic variables including Antarctica for the first time. MERRAclim consists of three datasets of 19 bioclimatic variables that have been built for each of the last three decades (1980s, 1990s and 2000s) using hourly data of 2 m temperature and specific humidity. We provide MERRAclim at three spatial resolutions (10 arc-minutes, 5 arc-minutes and 2.5 arc-minutes). These reanalysed data are comparable to widely used datasets based on ground station interpolations, but allow extending their geographical reach and SDM building in previously uncovered regions of the globe.
The distribution of terrestrial biodiversity within Antarctica is complex, with 16 distinct biogeographic regions (Antarctic Conservation Biogeographic Regions) currently recognised within the ...Antarctic continent, Peninsula and Scotia Arc archipelagos of the Antarctic Treaty area. Much of this diversity is endemic not only to Antarctica as a whole, but to specific regions within it. Further complexity is added by inclusion of the biodiversity found on the islands located in the Southern Ocean north of the Treaty area. Within Antarctica, scientific, logistic and tourism activities may inadvertently move organisms over potentially long distances, far beyond natural dispersal ranges. Such translocation can disrupt natural species distribution patterns and biogeography through: (1) movement of spatially restricted indigenous species to other areas of Antarctica; (2) movement of distinct populations of more generally distributed species from one area of Antarctica to another, leading to genetic homogenisation and loss of assumed local patterns of adaptation; and (3) further dispersal of introduced non-native species from one area of Antarctica to another. Species can be moved between regions in association with people and cargo, by ship, aircraft and overland travel. Movement of cargo and personnel by ship between stations located in different biogeographic regions is likely to present one of the greatest risks, particularly as coastal stations may experience similar climatic conditions, making establishment more likely. Recognising that reducing the risk of inter-regional transfer of species is a priority issue for the Antarctic Treaty Consultative Meeting, we make practical recommendations aimed at reducing this risk, including the implementation of appropriate biosecurity procedures.
•Distinct biogeographic regions have been identified across ice-free Antarctica.•Anthropogenic mixing of species may alter existing community structure and function.•Ships operating between stations in different regions present the greatest risk.•Similar climatic conditions at coastal stations may increase establishment risk.•Risks can be reduced by implementing biosecurity measures when moving between regions.
Aim
Correlative species distribution models (SDMs) are subject to substantial spatio‐temporal limitations when historical occurrence records of data‐poor species provide incomplete and outdated ...information for niche modelling. Complementary mechanistic modelling techniques can, therefore, offer a valuable contribution to underpin more physiologically informed predictions of biological invasions, the risk of which is often exacerbated by climate change. In this study we integrate physiological and human pressure data to address the uncertainties and limitations of correlative SDMs and to better understand, predict and manage biological invasions.
Location
Western archipelagos of the Southern Ocean and martime Antarctica.
Taxon
Eretmoptera murphyi (Chironomidae), invertebrates.
Methods
Mahalanobis Distances were used for correlative SDM construction for a species with few records. A mechanistic SDM was built around different fitness components (larval survival and life stage progression) as a function of temperature. SDM predictions were combined with human activity levels in Antarctica to generate a site vulnerability index to the assess colonization risk of E. murphyi. Future scenarios of ecophysiological suitability were built around the warming trends in the region.
Results
Both SDMs converge to predict high environmental suitability in the species' native and introduced ranges. However, the mechanistic model indicates a slightly larger invasive potential based on larval performance at different temperatures. Human activity levels across the Antarctic Peninsula play a key role in discerning site vulnerabilities. Niche suitability in Antarctica grows considerably under long‐term climate scenarios, leading to a substantially higher invasive threat to the Antarctic ecosystems. In turn changing conditions result in growing physiological mismatches with the environment in the native range in South Georgia.
Main conclusions
Long‐term studies of invasion potential under climate benefit from integrating correlative predictions with physiological experiments, as the invasion potential varies depending on the area and the timescale examined. This study also highlights a conservation paradox whereby the accidental introduction of an insect represents a threat to the Antarctic ecoystems that contrasts with its endangered status at the native range.
Biological invasions are one of the most important threats to Antarctic biodiversity. Springtails (Collembola) make up most of the diversity in soil arthropod communities in Antarctic terrestrial ...ecosystems. However, the potential range expansion of already established alien springtails and their consequent impacts on Antarctic ecosystems remains largely unknown. Species Distribution Models (SDMs) are a useful tool to identify areas potentially suitable for the geographical spread of alien species that are as yet unoccupied. In Antarctica, however, the application of SDMs is relatively less developed and initially received greater attention in marine rather than terrestrial environments. Here, we implement an ensemble forecasting approach and compute eight modelling algorithms to better understand the geographic distributions and potential range dynamics of four reportedly established alien springtail species (
Hypogastrura viatica
,
Folsomia candida
,
Mesaphorura macrochaeta
and
Proisotoma minuta
) on the Antarctic Peninsula. Our models identify several ice-free areas across the South Shetland Islands which offer highly suitable environmental conditions for establishment. Thus, biosecurity provisions ought to be reinforced in those sites more vulnerable to invasions. Model predictions of our ensemble SDM approach would benefit from additional field sampling effort across the introduced range and could be complemented with mechanistic models that critically need experimental physiological data to define the fundamental climatic niche of each species.
Two small swards of two grass species (
Agrostis stolonifera
and
Agrostis capillaris
) previously unrecorded on Macquarie Island (54°30′S, 158°56′E) were found during the 2013–2014 austral summer. ...Their discovery leads to an assessment of their introduction status and invasive risk. Several evaluations were conducted on the plants regarding their extent, taxonomy, reproductive status and invasive potential. It is possible that the two species were accidentally introduced by human activities due to their proximity to human-frequented sites. No further occurrences were found, indicating that although the species were established, they were, respectively, restricted to two small swards of less than 1 m
2
each. Observations of floral development in the field at the end of summer suggested that no sexually reproductive material was produced. Indoor cultivation of sampled specimens at the island station showed a faster development with mature flowers at the end of the summer but still no seeds. The bioclimatic niches of the two species were modeled with MaxEnt software. Biomodeling results indicate that reasonably favorable habitat is available on Macquarie Island for the successful colonization of both species.
Agrostis stolonifera
showed a higher invasion risk than
A. capillaris
. Our observations indicate that the two species are strong candidates for invading the island despite having phenological constraints. As a result, the two swards were removed by the island’s management authority. Further introductions and establishment of non-native plant species are expected to occur on sub-Antarctic islands under current global change scenarios.
Biodiversity loss has increased globally in recent years. The major threat to Antarctica's unique terrestrial biodiversity is the establishment of non‐native species. Nonetheless, while preventing ...the introduction of non‐native species from outside, Antarctica has received increasing research attention, the movement of species within and between Antarctic biogeographic regions remains largely unexplored.
Within a biogeographical framework, we attempt to disentangle the role of abiotic and movement factors leading to potential range expansion in the Antarctic Peninsula of two native Collembola: Cryptopygus antarcticus and Folsomotoma octooculata.
We found that, although locations exist with similar abiotic conditions to those already occupied by both species in non‐colonised areas of the Antarctic Peninsula, connectivity via wind to these currently unoccupied areas is smaller than that between present occurrences. Thus, wind transport might result in range expansion very sporadically. Meanwhile, we found that human‐influenced sites at the north‐eastern tip of the Antarctic Peninsula had similar climates to locations where both species are currently found. Thus, range expansion could occur to these areas if these invertebrates are inadvertently transported through human activities.
This article provides a proof of principle for combining Antarctic biogeographical and meteorological data to deliver practical recommendations to environmental managers.
Within a biogeographical framework, we attempt to disentangle the role of abiotic and movement factors leading to potential range expansion in the Antarctic Peninsula of two native Collembola.
We found that connectivity via wind to these currently unoccupied areas is smaller than that between present occurrences. Thus, wind transport might result in range expansion very sporadically.
Thus, range expansion could occur at human‐influenced sites at the north‐eastern tip of the Antarctic Peninsula if these invertebrates are inadvertently transported through human activities.
Understanding how temperature determines the distribution of life is necessary to assess species' sensitivities to contemporary climate change. Here, we test the importance of temperature in limiting ...the geographic ranges of ectotherms by comparing the temperatures and areas that species occupy to the temperatures and areas species could potentially occupy on the basis of their physiological thermal tolerances. We find that marine species across all latitudes and terrestrial species from the tropics occupy temperatures that closely match their thermal tolerances. However, terrestrial species from temperate and polar latitudes are absent from warm, thermally tolerable areas that they could potentially occupy beyond their equatorward range limits, indicating that extreme temperature is often not the factor limiting their distributions at lower latitudes. This matches predictions from the hypothesis that adaptation to cold environments that facilitates survival in temperate and polar regions is associated with a performance trade-off that reduces species' abilities to contend in the tropics, possibly due to biotic exclusion. Our findings predict more direct responses to climate warming of marine ranges and cool range edges of terrestrial species.
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