Aliens in Antarctica! It sounds like a science fiction thriller. But in fact, Aliens in Antarctica was the first major investigation into the effect of human activities in Antarctica on the invasion potential of alien (non-native) species. And the results may surprise.
Australian Antarctic Division terrestrial ecologist, Dr Dana Bergstrom, led the Australian component of the project during the International Polar Year (2007–09). Dr Bergstrom’s team examined fresh fruit and vegetables destined for Australian Antarctic and subantarctic stations, for seeds, spores and eggs that could pose a threat to Antarctic ecosystems if they became established. Together with teams associated with the British, South African, French and Japanese Antarctic research programs, they examined more than 11 250 items of fresh fruit and vegetables sourced from six continents and destined for nine Antarctic stations.
The teams’ report, published in the journal Biological Conservation in March, showed that fresh food was a significant pathway for the transport of soil, microorganisms and invertebrates (such as insects, spiders and slugs) into Antarctica. Soil was found on 12% of imported fresh food, 28% of food items showed microbial infection (rot caused by bacteria and fungi), and more than 56 invertebrates were collected.
As one gram of soil can contain over a billion bacteria, and some 90 different soils are estimated to be introduced into Antarctica each year, the potential exists for alien microbes to become established in Antarctica.
‘The consequences of such introductions are, as yet, unknown, but are likely to impact upon existing microbial community structure, with implications for biogeochemistry and ecosystem functioning, and may cause disease in native plants and invertebrates,’ the report authors say.
Similarly, many of the fungi identified during the project were known to be ‘generalists’, occurring in many environments outside Antarctica and therefore more likely to be able to adapt to Antarctic conditions than ‘specialist’ fungi.
The project teams also found a strong link between the numbers of alien insects on stations and the level of logistic activity involving food transport to the station. For example, the number of insects caught at the UK’s Rothera station was highest following the major ship resupply of the station in December, when the station population and fresh food consumption was high.
The report provides a list of measures to reduce the risk of alien introductions from fresh food to the Antarctic and subantarctic. These include:
- Transporting food when transit times between the departure point and Antarctica is shortest, to reduce the likelihood of spoilage;
- Ensuring root vegetables and leafy vegetables have been cleaned to remove soil and invertebrates;
- Avoiding sourcing out-of-season foods, which may have already been cold-stored for many months, as they may be more susceptible to spoilage and risk carrying cold-selected microorganisms;
- Storing produce in refrigerators or cool rooms during transit by ship;
- Destroying any insects discovered on ships or aircraft;
- Inspecting food for spoilage or invertebrates before offloading in Antarctica;
- Disposing of food waste and packaging in appropriate ways, such as incineration, or sterilisation by autoclaving.
Dr Bergstrom says around 90% of the 2000 pieces of fresh fruit and vegetables inspected prior to export to Australian Antarctic and subantarctic stations were deemed clean.
‘Australia already has many of the suggested measures in place and the Australian Antarctic Division works closely with its providores to reduce the risk of introductions to Antarctica,’ she says.
‘When these measures are adopted by organisations operating across the whole region, Antarctica’s biosecurity will be enhanced and the current risk to the native biota be effectively reduced.’