Abstract
Abstract Rising human activity in Antarctica, combined with continued warming of the polar climate, means the risk of non‐native terrestrial species colonising and establishing in its biodiversity‐ and nutrient‐poor ecosystems is increasing. Of the five non‐native invertebrate species currently in terrestrial Antarctica, the flightless midge Eretmoptera murphyi (Schaeffer, The Museum of the Brooklyn Institute of Arts and Sciences 2:90–94, 1914) is perhaps the most persistent insect invader. Accidentally introduced to Signy Island (60°S) in the 1960s from sub‐Antarctic South Georgia (54°S), E. murphyi has steadily increased its distribution, however, its status has not been reassessed for a decade. Here, we update the distribution of E. murphyi on Signy, specifically assessing whether footpaths to regularly visited research sites represent dispersal corridors. Our findings show that both the abundance and range of E. murphyi have increased significantly since 2009, particularly along paths leading away from the original introduction site, and that the species is now on the cusp of moving into new valley systems. We identify a moderate association with soil/substrate and vegetation types and build Maximum Entropy (MaxEnt) models to predict areas of the island that may be at highest risk of future colonisation. As a detritivore with no competitors or predators, E. murphyi may have a major impact. For example, accelerating nutrient cycling which may have wider impacts on all levels of biodiversity. This study highlights the need for an assessment of current biosecurity protocols applied within the Antarctic Treaty system, as well as the need for systematic regular monitoring of introduced and invasive species in Antarctica.
Highlights
The Antarctic region is the least invaded area in the world, in part thanks to its geographic isolation, harsh climate and limited history of human activity
We identify a moderate association with soil/substrate and vegetation types and build Maximum Entropy (MaxEnt) models to predict areas of the island that may be at highest risk of future colonisation
We recommend that both methods are used in future monitoring of E. murphyi on Signy as a minimum requirement in assessing changes in abundance and distribution over the largest area possible. Such combined approaches to non-indigenous species monitoring are recommended as best practice by Rew et al (2006) in their comprehensive analysis of survey methods used for the monitoring of invasive plant species in the United States. They recommend that all monitoring of species distribution and abundance coincides with the collection of habitat data, such as we have demonstrated here in characterising substrate type and topography, to ‘improve our understanding of factors affecting NIS occurrence, and to produce probability occurrence maps of target species’
Summary
The Antarctic region is the least invaded area in the world, in part thanks to its geographic isolation, harsh climate and limited history of human activity. Few terrestrial species have established naturally in the area south of 60S latitude since the last glacial maximum Further colonisation of non-indigenous species is likely, given the continuing increase in activity around Antarctica as new research stations are established, and land-based exploration as well as tourism expands. With deeper knowledge of species’ physiology, life history, dispersal mechanisms and rate of population expansion, can management and governance processes in the Antarctic be effective in preventing further introductions, as well as minimising the risks of species invasions that have already occurred (Chown et al, 2012; Hughes et al, 2010; Hughes & Pertierra, 2016)
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