Scientists at the British Antarctic Survey say the midge, well-suited to thrive in the extreme conditions, has released large volumes of nutrients into the soil and has altered the manner in which native species had lived and evolved.
The non-biting insect Eretmoptera murphyi has, in effect, removed certain controls on the development of the native community, they said.
"In terms of function, their job is litter turnover -- they help things decay in the soil -- and the population density of this thing in the area where it has been introduced is responsible for more litter turnover than the community that was already there," researcher Peter Convey said.
He was presenting the research at the annual meeting of the British Ecological Society in Birmingham, the BBC reported Tuesday.
"So basically it is bringing a function into an ecosystem that is not very active already," Convey said. "In principle, it can be a fundamental change in the way that ecosystem works."
"If you widen [this issue] beyond this particular species then probably the biggest risk is that we could drive locally or generally extinct some of the unique species that already exist in part of the Antarctic," he told the BBC.