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The two non-native grasses that have established long-term populations in Antarctica (Poa pratensis and Poa annua) were studied from a global multidimensional thermal niche perspective to address the biological invasion risk to Antarctica. These two species exhibit contrasting introduction histories and reproductive strategies and represent two referential case studies of biological invasion processes. We used a multistep process with a range of species distribution modelling techniques (ecological niche factor analysis, multidimensional envelopes, distance/entropy algorithms) together with a suite of thermoclimatic variables, to characterize the potential ranges of these species. Their native bioclimatic thermal envelopes in Eurasia, together with the different naturalized populations across continents, were compared next. The potential niche of P. pratensis was wider at the cold extremes; however, P. annua life history attributes enable it to be a more successful colonizer. We observe that particularly cold summers are a key aspect of the unique Antarctic environment. In consequence, ruderals such as P. annua can quickly expand under such harsh conditions, whereas the more stress-tolerant P. pratensis endures and persist through steady growth. Compiled data on human pressure at the Antarctic Peninsula allowed us to provide site-specific biosecurity risk indicators. We conclude that several areas across the region are vulnerable to invasions from these and other similar species. This can only be visualized in species distribution models (SDMs) when accounting for founder populations that reveal nonanalogous conditions. Results reinforce the need for strict management practices to minimize introductions. Furthermore, our novel set of temperature-based bioclimatic GIS layers for ice-free terrestrial Antarctica provide a mechanism for regional and global species distribution models to be built for other potentially invasive species., (© 2017 John Wiley & Sons Ltd.)

Climate change leads to species range shifts and consequently to changes in diversity. For many systems, increases in diversity capacity have been forecast, with spare capacity to be taken up by a pool of weedy species moved around by humans. Few tests of this hypothesis have been undertaken, and in many temperate systems, climate change impacts may be confounded by simultaneous increases in human-related disturbance, which also promote weedy species. Areas to which weedy species are being introduced, but with little human disturbance, are therefore ideal for testing the idea. We make predictions about how such diversity capacity increases play out across elevational gradients in non-water-limited systems. Then, using modern and historical data on the elevational range of indigenous and naturalized alien vascular plant species from the relatively undisturbed sub-Antarctic Marion Island, we show that alien species have contributed significantly to filling available diversity capacity and that increases in energy availability rather than disturbance are the probable underlying cause.

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The continent of Antarctica has remained relatively free of the impacts of invasive species to date. However, Antarctica is under increasing anthropogenic pressure from human activity and climate change, elevating the risk of alien species introductions. Scientific research and the maintenance of research stations by Antarctic Treaty Parties requires the transfer of large amounts of equipment and cargo, which can harbour biosecurity risk material. Here, we assess two decades of data collected by the Australian Antarctic Division on the detection of biosecurity risk material in its facilities and vessels, both during transport and in Antarctica. We use these data to identify emerging risk species or pathways, to compare the variability in detections over time and to construct a consequence table to facilitate effective responses and resource allocation to future detections, translating our research findings into guidance for decision-makers. We find that, despite the development of policy instruments, monitoring and management for the prevention of alien species introductions to Antarctica, the risk of introductions is ongoing. We highlight areas of concern, including the transport of live spiders and the continuing potential for cargo to harbour biosecurity risk material and the benefit of ongoing training and investment and support for staff and expeditioners in the reporting of non-native species detections. Finally, we provide tools and recommendations for decision-makers and on-ground managers in the Antarctic biosecurity space, based on our research. Future studies on the establishment risk of commonly transported species would assist in improving these tools. [ABSTRACT FROM AUTHOR]

Aims: To identify potential hull fouling marine invasive species that could survive in East Antarctica presently and in the future. Location: Australia's Antarctic continental stations: Davis, Mawson and Casey, East Antarctica; and subantarctic islands: Macquarie Island and Heard and McDonald Islands. Methods: Our study uses a novel machine‐learning algorithm to predict which currently known hull fouling MIS could survive in shallow benthic ecosystems adjacent to Australian Antarctic research stations and subantarctic islands, where ship traffic is present. We used gradient boosted machine learning (XGBoost) with four important environmental variables (sea surface temperature, salinity, nitrate and pH) to develop models of suitable environments for each potentially invasive species. We then used these models to determine if any of Australia's three Antarctic research stations and two subantarctic islands could be environmentally suitable for MIS now and under two future climate scenarios. Results: Most of the species were predicted to be unable to survive at any location between now and the end of this century; however, four species were identified as potential current threats and five as threats under future climate change. Asterias amurensis was identified as a potential threat to all locations. Main conclusions: This study suggests that the risks are very low, but plausible, that known hull fouling species could survive in the shallow benthic habitats near Australia's East Antarctica locations and suggest a precautionary approach is needed by way of surveillance and monitoring in this region, particularly if propagule pressure increases. While some species could survive as adults in the region, their ability to reach these locations and undergo successful reproduction is considered unlikely based on current knowledge. [ABSTRACT FROM AUTHOR]

The eradication of invasive species from islands yields significant conservation returns. However, novel challenges continue to arise as projects expand in their scope, complexity and scale. Prey‐loss and secondary poisoning were historically considered to have limited impact on native top‐order predators when planning eradications, but this has rarely been tested quantitatively.We used a 10‐year timeseries of Brown Skua Stercorarius antarcticus lonnbergi breeding surveys and isotopic dietary analysis on Macquarie Island to investigate how prey‐loss and secondary poisoning deaths resulting from the eradication of an abundant invasive prey species, European rabbits Oryctolagus cuniculus, affected a top‐order predator.Skua nest density declined from 7.14 nests/km2 (95% CI: 6.01–8.27) in the presence of rabbits (pre‐eradication) to 3.73 nests/km2 (95% CI: 2.96–4.51) in the first 3 years after the eradication of rabbits, before showing signs of recovery in the 4 years thereafter. However, breeding success dropped from 1.01 chicks/nest (95% CI: 0.76–1.26) to as low as 0.38 chicks/nest (95% CI: 0.23–0.53) with little evidence of recovery.Secondary poisoning affected a greater number of skuas than anticipated prior to the eradication, including skuas nesting in areas where rabbits were not typically hunted as prey. We highlight that invasive prey often replace native prey in the diet of native predators rather than provide an additional source of food, and rapid eradication of non‐native prey can have long‐term impacts for predators, particularly when recovery of native prey is slow.Synthesis and applications. Monitoring programmes that complement large‐scale eradication projects and address (a) trophic‐driven declines in predator populations and (b) population‐level impacts of secondary poisoning are integral to ensuring bottom‐up effects of eradications are anticipated and adequately quantified. If prey deficits caused by eradication of invasive prey are expected to be severe but short‐lived, supplementary feeding programmes may buffer against increased predation pressure on native prey and reduced breeding success of native predators. Alternatively, if the rapid recovery of native prey is not expected to occur naturally, breeding programmes and translocation of native prey prior to assist recovery of native predators should be considered to support ecosystem restoration. [ABSTRACT FROM AUTHOR]

Isolation and climate have protected Southern Ocean Islands from non-native species. Relatively recent introductions have had wide-ranging, sometimes devastating, impacts across a range of species and ecosystems, including invertebrates, which are the main terrestrial fauna. In our comprehensive review, we found that despite the high abundance of non-native plants across the region, their impacts on native invertebrates are not well-studied and remain largely unknown. We highlight that non-native invertebrates are numerous and continue to arrive. Their impacts are multi-directional, including changing nutrient cycling regimes, establishing new functional guilds, out-competing native species, and mutually assisting spread of other non-native species. Non-native herbivorous and omnivorous vertebrates have caused declines in invertebrate habitat, but data that quantifies implications for invertebrates are rare. Predatory mammals not only indirectly effect invertebrates through predation of ecosystem engineers such as seabirds, but also directly shape community assemblages through invertebrate diet preferences and size-selective feeding. We found that research bias is not only skewed towards investigating impacts of mice, but is also focused more intensely on some islands, such as Marion Island, and towards some taxa, such as beetles and moths. The results of our review support and build on previous assessments of non-native species in the Antarctic region—that the responses of invertebrate fauna on these islands are under-reported and often poorly understood. Given the importance of invertebrates as indicators of environmental change, and their potential utility in quantifying change associated with island restoration projects (such as eradications), these knowledge gaps need to be urgently addressed. [ABSTRACT FROM AUTHOR]

Alien species pose an increasing threat to the biodiversity of the Antarctic region. Several alien species have established in Antarctic terrestrial communities, some representing novel functional groups such as pollinators and predators, with unknown impacts on ecosystem processes. We quantified the unintentional introduction of alien invertebrates to the Antarctic region over a 14-year period (2000-2013). To do this, probable pathways (Australian Antarctic cargo operations) and endpoints (research stations) for invertebrate introductions were searched. In addition, we undertook a stratified trapping programme targeting invertebrates on supply vessels in transit to the Antarctic region and also at cargo facilities in Australia during the 2012-2013 austral summer field season. Our results show that a diverse suite of invertebrate taxa were being introduced to the Antarctic region, with 1,376 individuals from at least 98 families observed or trapped during the sampling period. Many individuals were found alive. Diptera, Coleoptera and Lepidoptera were the most common taxa, comprising 74 % of the collection. At the family level, Phoridae (small flies) and Noctuidae (moths) were most commonly observed. Individuals from 38 different families were repeatedly introduced over the study period, sometimes in high numbers. Food and large cargo containers harboured the most individuals. These findings can assist in improving biosecurity protocols for logistic activities to Antarctica, thereby reducing the risk of invasions to the Antarctic region. [ABSTRACT FROM AUTHOR]

The Arctic and Antarctic polar regions are subject to multiple environmental threats, arising from both local and ex-situ human activities. We review the major threats to polar ecosystems including the principal stressor, climate change, which interacts with and exacerbates other threats such as pollution, fisheries overexploitation, and the establishment and spread of invasive species. Given the lack of progress in reducing global atmospheric greenhouse- gas emissions, we suggest that managing the threats that interact synergistically with climate change, and that are potentially more tractable, is all the more important in the short to medium term for polar conservation. We show how evidence-based lessons learned from scientific research can be shared between the poles on topics such as contaminant mitigation, biosecurity protocols to reduce species invasions, and the regulation of fisheries and marine environments. Applying these trans-polar lessons in tandem with expansion of international cooperation could substantially improve environmental management in both the Arctic and Antarctic. [ABSTRACT FROM AUTHOR]

Biological invasion is one of the key threats to the conservation of the broader Antarctic region. We provide an evidence-based assessment of the status of biological invasion in the region as a basis for future monitoring and management. We adapted the indicator framework for global biological invasion monitoring by collating information on (i) numbers of alien species and those invasive species impacting biodiversity (ii) trends in the extinction risks of native species impacted by invasive species and (iii) trends in relevant agreements, management intention and species eradications. Drivers of invasion including risk-associated human activities and trends were also evaluated. The number and trends in activities associated with invasion risk are broadly distributed across the region and increasing. Over 560 alien species from a wide range of taxa occupy the region, concentrated largely on the Southern Ocean Islands, with a high proportion of these considered to be invasive and to have negative biodiversity impacts. There has been a decline in the conservation status of species in the region that are impacted by invasives. Although policy responses to deal with the problem have increased since the 1970s, as have the number of successful eradications, management implementation statistics are patchy and progress in this area less apparent. The Antarctic Biological Invasions Indicator (ABII) provides a system for information exchange across the region and a vehicle for targeted monitoring and surveillance. It also enables inclusion of the region in global efforts to track both IAS and interventions for managing the threat. In a region that appears particularly prone to impacts from alien species, substantial further effort is needed to implement and monitor the effectiveness of management responses. [ABSTRACT FROM AUTHOR]

Aim To investigate taxonomic homogenization and/or differentiation of insect and vascular plant assemblages across the Southern Ocean Islands (SOI), and how they differ with changing spatial extent and taxonomic resolution. Location Twenty-two islands located across the Southern Ocean, further subdivided into five island biogeographical provinces. These islands are used because comprehensive data on both indigenous and non-indigenous insect and plant species are available. Methods An existing database was updated, using newly published species records, identifying the indigenous and non-indigenous insect and vascular plant species recorded for each island. Homogenization and differentiation were measured using Jaccard’s index (JI) of similarity for assemblages across all islands on a pairwise basis, and for island pairs within each of the biogeographical provinces. The effects of taxonomic resolution (species, genus, family) and distance on levels of homogenization or differentiation were examined. To explore further the patterns of similarity among islands for each of the taxa and groupings (indigenous and non-indigenous), islands were clustered based on JI similarity matrices and using group averaging. Results Across the SOI, insect assemblages have become homogenized (0.7% increase in similarity at species level) while plant assemblages have become differentiated at genus and species levels. Homogenization was recorded only when pairwise distances among islands exceeded 3000 km for insect assemblages, but distances had to exceed 10,000 km for plant assemblages. Widely distributed non-indigenous plant species tend to have wider distributions across the SOI than do their insect counterparts, and this is also true of the indigenous species. Main conclusions Insect assemblages across the SOI have become homogenized as a consequence of the establishment of non-indigenous species, while plant assemblages have become more differentiated. The likely reason is that indigenous plant assemblages are more similar across the SOI than are insect assemblages, which show greater regionalization. Thus, although a suite of widespread, typically European, weedy, non-indigenous plant species has established on many islands, the outcome has largely been differentiation. Because further introductions of insects and vascular plants are probable as climates warm across the region, the patterns documented here are likely to change through time. [ABSTRACT FROM AUTHOR]

The impact of introduced ship rats (Rattus rattus) on recruitment of the megaherbPleurophyllum hookeriBuchan. (Asteraceae) was examined on subantarctic Macquarie Island, an island with no extant native terrestrial vertebrates.Pleurophyllum hookeri(Asteraceae) forms a dominant component of the Macquarie Island vegetation and is restricted to the subantarctic. The Macquarie Island population ofP. hookeriis the most extensive and intact. Introduced ship rats (Rattus rattus) are well established in tall tussock grassland of Macquarie Island. We detected rat activity for the first time withinP. hookeriherbfields, in autumn 2000. We found rats were destroying up to 90% of racemes. By excluding rats from caches of inflorescences that they had formed, we found they were having a significant negative effect on initial recruitment and seedling survival within the caches. However, because of high seedling mortality after 1 year, there was no sustained impact of the exclosures onP. hookeriseedling density. [ABSTRACT FROM AUTHOR]