A small, creepy crawly “alien” species is slowly invading the world’s southernmost continent and its presence poses a risk to terrestrial ecosystems in Antarctica.
Eretmoptera murphyi, or a “midge”, is a small, fly-like yet wingless insect native to the nearby sub-Antarctic South Georgia Island. It has since been found on Signy Island, located in the maritime Antarctic, likely by hitching a ride during a plant experiment in the 1960s. Over the last 50 years, the plant has been able to successfully establish a thriving population with two to five times more biomass than all native insects, spiders, and crustaceans combined.
To find out how the midge is able to survive in such extreme polar conditions, as well as quantify what sort of impact it might be having on the region, researchers collected information on it and other invertebrates, microbes, and environmental variables like water content, organic carbon, soil nitrogen content, and substrate composition and then compared those against other places where the midge wasn’t found. In places where the midge was most abundant, there was more soil and shallower moss banks – an indication 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,” said researcher Jesamine Bartlett, from the University of Birmingham, in a statement.
Results suggest the “decomposer” species (one that feeds on organic matter and doesn’t compete with any predators on the island) may release as much nitrogen as is introduced in places that are frequently visited by seals. On Signy Island, this could equate to an increase of three to four times as much when compared to places the midge hasn’t been introduced.
"It is basically doing the job of an earthworm, but in an ecosystem that has never had earthworms," said Barlett.
E. murphyi is capable of surviving in conditions even further south, so controlling its spread is “critically important”. Its presence furthermore indicates how invasive species could impact Antarctica’s long-isolated ecosystem – a growing threat that is only magnified due to rapid warming and increased human activity. Earlier this year, for example, researchers found invasive kelp in Antarctica for the first time.
"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."
- The preliminary results were presented today at the British Ecological Society's annual meeting. The researchers say they hope their work highlights the risk of transferring soil and invertebrates in isolated regions. They are also continuing to investigate existing biosecurity protocols in order to minimize the spread of future invasive species.