Aliens are landing in Antarctica. Seeds, spores, mites, lichens and mosses alien to the continent have been brought unwittingly by scientists and tourists, and could disrupt life in the icy wilderness.
Antarctica is best known for penguins as well as seals and whales, but scientists are finding a host of other tiny organisms from springtails -- closely related to insects -- to mosses. And they fear global warming may create conditions suitable for outside marauders such as rats or mice in Antarctica, where the biggest land creature is now a tiny flightless midge.
Among plants a type of European grass -- agrostis stolonifera -- may be among threats if the icy climate thaws. "It's a species that gets everywhere, it's already on most of the Antarctic islands," said Dana Bergstrom of the Australian Antarctic Division, who leads an international research project entitled "Aliens in Antarctica".
"It would just create lawns," she said. Invasive species have long disrupted life on earth, from rabbits brought to Australia by European settlers to zebra mussels from Russia clogging pipes and piers in North America's Great Lakes, and now Antarctica is a target.
"Antarctica is the last bastion of a pristine environment compared to the rest of the world," Bergstom said in a telephone interview. "It has been isolated by the southern ocean -- people are starting to break that barrier," she said. New species are getting in partly because visitors' clothes often contain seeds, spores or insect eggs.
So far, invaders have bridgeheads on Antarctic islands ringing the continent, which have been getting warmer in recent decades. Among the most damaging were reindeer on South Georgia and rats and cats on Macquarie Island, Bergstrom said.
Elsewhere in Antarctica, grass was found growing under a Japanese research hut. Invasive plants were found near a Russian station and a wide variety of fungi near an Australian station.
People are acting to try to stem the invasion, even as visitor numbers rise. "Our flowers are all plastic. We are not allowed to bring in any living thing," said Atle Markussen, head of the Troll scientific research station in a sector claimed by Norway, pointing to a vase of fake red roses on the canteen table.
"The restrictions about alien species are very strict," he said in the base, set amid jagged mountains that look like the homes of fabled Troll giants. Temperatures during a recent summertime visit were about minus 10 Celsius (14 Fahrenheit) -- far too cold for roses. Even around Troll, on the edge of mountains 250 km (155 miles from the sea, tens of thousands of Antarctic and snow petrels thrive. Four species of mite, for instance, have been found in recent years and lichen clings to some rocks.
About 40,000 people visit Antarctica every year, mostly tourists on the coast, and the continent has a summer population of about 4,000 researchers. A big threat is that climate change, blamed by the UN Climate Panel on greenhouse gases from burning fossil fuels, may make Antarctica more habitable for damaging outsiders.
Rats or mice aboard ships might jump off on the Antarctic peninsula, the least chilly region snaking northwards towards the southern tip of South America.