It wasasummerdayin January when Peter Convey pulled up a weed in Antarctica for the first time. The alien plant stuck out among the
native species eking out an existence on
the rocky debris beneath his feet.
Convey doesn’t know for sure how the
intruder, a rugged relative of the ornamental plant gerbera, traveled from its
usual home 1,000 kilometers away in
Tierra del Fuego. A seed may have drifted
in on the wind or hitched a ride on the
feather of a bird crossing the Southern
Ocean. But Convey suspects that some
human unwittingly delivered the species during fieldwork or while touring
the remains of a whaling station nearby.
With Antarctica more trafficked by
human feet than ever, scientists fear that
Convey’s pulled plant and others like it
herald a coming invasion. In the same
way stink bugs, Asian carp and kudzu
have become abundant enough to alter
ecosystems across North America, earning the name “invasives,” species entering the Antarctic could multiply and
spread. If so, nonnative plants— and
even insects— may disrupt the most
pristine landscape on Earth.
A handful of foreign creatures, including a particularly hardy kind of grass,
have already shown that they’re tough
enough to put down roots at the end of
the Earth.
“Several nonindigenous species have
now gotten a toehold on the Antarctic
continent,” says Convey, a polar ecologist with the British Antarctic Survey
Researcher Peter Convey pulled up
this plant, a relative of an ornamental,
in Antarctica. The species normally
resides 1,000 kilometers away.
Antarctic
Peninsula
King
George
Island
Deception
Island
Invasion risk
after collecting and counting seeds carried into antarctica,
researchers identified places around the continent at risk
of being colonized by a nonnative plant species (darker
red indicates higher risk). oft-visited areas that also have
relatively mild climates may be ideal spots for an outside
invader to take hold and flourish.
in Cambridge, England. “Some of these
species have already proven to be inva-
sive in other places.”
When the 50 countries signed on to
the Antarctic Treaty meet in June, the
issue of nonnative species will be on the
agenda. Researchers will present find-
ings on potential plant invaders from
the first study that counts how many
seeds enter Antarctica and identifies
hot spots where the seeds could sprout.
Planting red flags
Worrying about immigration in a land
mostly covered by ice may seem like
a waste of time. But about a third of a
percent of the continent is ice-free during the summer, an area almost the size
of the Dominican Republic. Microbes,
mosses, invertebrates and two species
of flowering plant that can tolerate the
inhospitable conditions call these bare
patches of ground home. Having long
lived in isolation, the creatures aren’t
used to competing with outsiders.
But isolation, at least from people,
is no longer an option. Tourism brings
about 33,000 people to the continent
each year. Scientists and their sup-
port staff add another 7,000. More than
70,000 seeds cling to the shoes, cloth-
ing and bags of a single summer’s worth
of visitors, say researchers from eight
countries who have collected, counted
and identified thousands of stowaway
seeds. The scientists, who reported the
results in March in the Proceedings of
the National Academy of Sciences, also
checked the places where humans hang
out for spots warm enough to nurture
these unwelcome seeds.
