Science News - May 5, 2012

disinfectant, and their clothes are vacuumed. But scientists and the staff manning tourist expeditions are laxer, as revealed in the new seed counts.

“Everyone has a favorite jacket, and there’s a tendency for staff to wear the same gear a lot and not clean it as much,” Crosbie says.

Some areas flagged in the new study have already been infiltrated. An upcoming paper in Conservation Biology reports that an aggressive species of alien grass has appeared outside three scientific research stations on the Antarctic Peninsula.

Poa annua made its Antarctic debut in the 1980s, after having been brought — unintentionally — to a Polish outpost on King George Island. The weedy plant escaped and grew in patches on the island, which is close enough to the mainland to be considered part of Antarctica. Wind then carried seeds 1. 5 kilometers away from the station, where the grass sprouted on debris left behind by a retreating glacier.

“It’s starting to get to the point where this grass is beyond control in Antarctica,” says Kevin Hughes, an environmental scientist with the British Antarctic Survey.

International law forbids the introduction of new species to Antarctica. But the rules are fuzzier about what steps should be taken to deal with species that have become established in the wild. Nothing has been done to get rid of the grass intruder, Hughes says.

What impact the plant will have on

Tens of thousands of foreign seeds may make their way to Antarctica each summer,
a recent analysis finds. Most of the potentially troublesome seeds collected as
part of the analysis (some shown) were carried by scientists and expedition staff.

native life isn’t yet known. But the same species has already overrun islands near — but not part of — Antarctica. On the island of South Georgia, the grass has replaced indigenous vegetation in some spots and stunts the growth of beetles that have trouble digesting the grass.

This fly, Trichocera maculipennis, has
been seen in a new home—on King
George Island, off Antarctica’s coast.

What’s bugging Antarctica

Plants aren’t the only potential invaders. Research stations have become beachheads for microbes, fungi, insects and worms. In 2005, construction vehicles brought by ship to a British outpost came with attached soil teeming with life. Produce imported to feed visitors can also carry infested dirt.

“About 12 percent of all fresh food items traveling to Antarctica are contaminated,” says Dana Bergstrom, a polar ecologist with the Australian Antarctic Division in Kingston. Bergstrom and colleagues reported that statistic last year in Biological Conservation after examining more than 11,250 fruits and vegetables shipped to nine research stations.

Contaminated soil is supposed to be destroyed when discovered, but a few foreign agents have slipped through the defenses.

Flies made themselves at home in the
sewage system of an Australian research
station and in a British station’s liquor
store. Initial efforts to eradicate the
insects failed at the Australian base.
Their eggs endured, allowing the pests
to spawn year after year. When reporting
on the insects in 2005 in Polar Biology,
Hughes and colleagues suggested that
the bugs couldn’t survive the bitter
cold outside, meaning they probably
wouldn’t spread into the wild.