Satellite view of Antarctica
A satellite view of Antarctica. Plants and animals hitching on the clothes of tourists and scientists are invading Antarctica, according to a new study. REUTERS/NASA NASA

Antarctica is being invaded by non-native plants and animals hitchhiking on the clothes of tourists and scientists visiting the continent, according to a new study.

Researchers found the average tourist brings 9.5 foreign seeds along when visiting Antarctica. Scientists brought far more - up to 25 seeds each. These seeds can upset the ecological balance of the polar continent, according to the study.

Researchers estimate that 70,000 seeds are brought to Antarctica each year.

What we found was that people's boots and bags were the things that had most material attached, Kevin Hughes, co-author of the study and an environmental researcher from the British Antarctic Survey, told the BBC.

I guess the tongue of the boot is an ideal place for seeds to be caught when you're tying up your laces.

Two non-native species of grass and two species of springtail, tiny insect-like animals, have established themselves in the north-west area of Antarctica called Deception Island. Other grass species have sprung up near research stations.

Many people have thought Antarctica is just an ice-covered place, there's no chance that things are going to establish there, but of course that's not true, Steven L. Chown, co-author of the study and director of the Center for Invasion Biology, told The Boston Herald. One of the things that surprised us all was simply the scope of the numbers of seeds coming into the continent.

Tourists tend to visit the places in Antarctica that are relatively warm, which is where the invasive species thrive.

Antarctica has warmed faster than any other part of the globe, approximately 5.5 degrees Fahrenheit (3 degrees Celsius) over the last 50 years. As the trend continues and more ice melts, the invasive species will continue to grow and spread, according to the study.

In the future, other ice-free areas will also be at risk as global climate change continues to impact the Antarctic, Chown told OurAmazingPlanet.

Hughes said even if guidelines are instituted to check vehicles, clothes and boots for seeds and organisms before stepping foot onto Antarctica, it's likely that the spread will be impossible to contain.

I think it's safe to say that wherever people go, it's inevitable that they bring other species with them; and no matter what we do, our best efforts will only reduce the rate at which species are introduced, we'll never prevent it altogether, he told the BBC.

Previous papers estimated the number of seeds coming in based on the number of visitors or cargo arriving on the continent, according to Wired. This study was the first to use hard evidence.

This is an extremely important paper, Peter Convey, an ecologist with the British Antarctic Survey who was not involved in the study, told Wired. This research was an obvious next step, but a big one. Their risk estimates are based on objective data rather than hand waving.

Proceedings of the National Academy of Sciences published the study on Monday.