Antarctic tourists and scientists may be inadvertently seeding the icy continent with invasive species, a new study says.
Foreign plants such as annual bluegrass are establishing themselves on Antarctica, whose status as the coldest and driest continent had long made it one of the most pristine environments on Earth.
But a boom in tourism and research activities to the Antarctic Peninsula may be threatening the continent's unique ecosystems, scientists say. (See a high-res Antarctica map.)
For the study, ecologist Steven Chown at the University of Stellenbosch in South Africa and colleagues vacuumed the clothes, footwear, bags, and gear of approximately 2 percent of people who visited during the Antarctic summer from late 2007 to early 2008. That amounted to 853 scientists, tourists, and accompanying support workers and ships' crew members. (Read more about the gear required for Antarctic travel.)
"Endless hours were spent vacuum-cleaning clothes and gear. ... If one is doing so on a ship underway on a rough ocean, it can take a strong stomach," Chown recalled.
The results revealed more than 2,600 seeds and other detachable plant structures, or propagules, had hitched a ride to Antarctica on these visitors.
On average, tourists each carried two to three seeds, while scientists each carried six. However, the annual number of tourists now far outnumbers that of scientists—about 33,000 tourists to about 7,000 scientists in the 2007-2008 Antarctic summer. As a result, tourists and scientists likely pose similar risks overall to Antarctica, Chown said.
Antarctic Invaders Used to the Cold
Disturbingly, the scientists said, 49 to 61 percent of the foreign plant material that reaches Antarctica are cold-adapted species that can withstand and colonize in extreme conditions.
The plants likely get stuck to cold-weather gear that travelers had used in other frigid climes prior to arriving to Antarctica.
For instance, Arctic species such as chickweed and yellow bog sedge have been found in Antarctica, according to the study, published March 5 in the journal Proceedings of the National Academy of Sciences.
Based on the nature of these foreign species and the present climate of Antarctica, the areas at highest risk are the Antarctic Peninsula coast and surrounding islands, the study said.
According to climate projections for 2100 from the UN's Intergovernmental Panel on Climate Change (IPCC), invaders may also take root in the coastal, ice-free areas to the west of the Amery Ice Shelf and, to a lesser extent, in the Ross Sea region.
What's more, rising temperatures along the Antarctic coast will likely aid these intruders' survival. (See an interactive map of global warming's effects.)
Even so, "it should not be imagined that Antarctica will suddenly be covered in flowering plants and weeds," Chown said.
"Much of it is still a very harsh place, and plants do not grow on ice, which still dominates the continent."
Cleaning Gear May Reduce Risks
Polar ecologist Peter Convey said the study "provided objective assessment that both governmental and tourism operations in the region pose significant risks."
But knowing the risks also means knowing how to manage them, said Convey, of the British Antarctic Survey, who was not part of the study.
For instance, cleaning outer gear and bags is very effective at reducing the number of seeds that can reach Antarctica. "In essence, take it new or take it clean," study leader Chown said.
Chown and team also plan to present their work to the Committee for Environmental Protection of the Antarctic Treaty.
"We hope they will use the information further" to develop ways to lessen the impact, Chown said.