(CN) – Of all the non-native insect species found in Antarctica, scientists said Wednesday a nonbiting species of midge presents the biggest risk to the continent’s terrestrial ecosystems.
The research team from the University of Birmingham and the British Antarctic Survey shared their preliminary finding Wednesday at the British Ecological Society's annual meeting in Birmingham, England. The team is studying how the Eretmoptera murphyi, a flightless midge, is able to survive in extreme polar conditions and what impact it has on the region.
The midge is thought to have been inadvertently transferred from South Georgia, an island in the Atlantic north of Antarctica where it is endemic, to Signy Island in the Antarctic during a plant transplant experiment in the 1960s. It has since successfully established itself on the island – thrived, actually – and now has an estimated biomass 2-5 times greater than all native arthropods combined in the area where it resides.
According to the researchers, this single 'decomposer' species can lead to the release of as much nitrogen as is introduced in areas frequented by seals. On Signy Island, this equates to a three- to four-fold increase relative to areas where the midge is not found.
As an animal that feeds on dead organic matter with no competitors or predators on the island, E. murphyi is able to release large volumes of nutrients into the soil. This in turn affects peat decomposition and soil structure, thereby having wider impacts on all levels of biodiversity.
"It is basically doing the job of an earthworm, but in an ecosystem that has never had earthworms", said Jesamine Bartlett, a doctoral candidate at the University of Birmingham who presented the findings at the conference.
To assess the ecological impacts of E. murphyi, the team collected information on its abundance and that of other invertebrates and microbes as well as environmental variables such as water content, organic carbon, soil nitrogen content and substrate composition. These were then compared to locations on the island where the midge did not occur.
More soil and shallower moss banks were present at sites where the midge was most abundant, suggesting that the midge is eating its way through the peat in the moss banks and turning it into soil.
"This is concerning as Signy Island hosts some of the best examples of moss banks in the Antarctic region. It is also home to Antarctica's only two flowering plant species, the hair grass and pearlwort," Bartlett said.
The threat of introducing invasive species into the Antarctic's long-isolated ecosystems is growing, not least due to rapid regional warming and increased levels of human activity.
Around 3,000 scientists and 42,000 tourists visit Antarctica each year, according to the Council of Managers of National Antarctic Programs and the International Association of Antarctic Tour Operators.
"Visitors to Antarctica are subject to increasingly strict biosecurity measures, but accidental introductions continue to occur", said Peter Convey of the British Antarctic Survey. "Midge larvae, for instance, are tiny and cannot be seen easily with the naked eye. Tourists and researchers may be bringing them in from their stopovers in the sub-Antarctic and moving them around the continent in the mud on their boots."
As part of this study, the ecologists highlight the risk of transferring soil and invertebrates throughout the Antarctic Treaty area and are looking at existing biosecurity protocols to minimize the spread of invasive species.
"We already know that E. murphyi is physiologically capable of surviving conditions much further south, for example on the Antarctic Peninsula, so controlling the risk of spread is critically important." Dr. Scott Hayward, also from the University of Birmingham, concluded.
The British Ecological Society annual meeting brings together 1,200 ecologists from more than 40 countries to discuss the latest research.
Founded in 1913, the British Ecological Society is the oldest ecological society in the world and boasts 6,000 members from more than 120 countries. The group promotes the study of ecology through its six academic journals, conferences, grants, education initiatives and policy work.
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