Human activity is the latest issue threatening Antarctica; only this time it's the continent's ice-free land that's in trouble.

With visitor numbers surging - Antarctic has over 40,000 a year - and more and more research facilities being built, scientists fret over the well-being of the region's wildlife and plants that live on ice-free land.

"Most of Antarctica is covered in ice, with less than one percent permanently ice-free. Only 1.5 percent of this ice-free area belongs to Antarctic Specially Protected Areas under the Antarctic Treaty System, yet ice free land is where the majority of biodiversity occurs," Dr. Justine Shaw, of the National Environmental Research Program's Environmental Decisions Hub at the University of Queensland, said in a news release.

In short, very little of Antarctica is ice-free, and yet that is where the majority of its biodiversity and where most human activity occurs.

The new study, published in the journal  PLoS Biology, found that all 55 areas designated for protection lie close to sites of human activity. Seven are at high risk for biological invasions, and five of the distinct ice-free eco regions have no protected areas.

What's more, researcher Professor Steven Chown notes that the ice-free area contains very simple ecosystems due to Antarctica's low species diversity - this makes its native wildlife and plants extremely vulnerable to invasion by exotic species as well.

"Antarctica has been invaded by plants and animals, mostly grasses and insects, from other continents. The very real current and future threats from invasions are typically located close to protected areas," Chown said.

"Such threats to protected areas from invasive species have been demonstrated elsewhere in the world, and we find that Antarctica is, unfortunately, no exception."

Interestingly, for a continent that seems to be in the media considerably, mostly because of reports of its melting icebergs as a result of climate change, Antarctica doesn't seem to be well protected.

Antarctica - what researchers refer to as the "last wilderness on Earth" - falls well short of the Aichi Biodiversity Targets, an international biodiversity strategy that aims to reduce threats to biodiversity, and protect ecosystems, species and genetic diversity.

Compared to other protected areas around the world, Antarctica is ranked in the lowest 25 percent.

"If we don't establish adequate and representative protected areas in Antarctica this unique and fragile ecosystem could be lost," fellow researcher Professor Hugh Possingham concluded.