IF YOU saw the movie Alien vs. Predator, you鈥檒l know Bouvet Island as the ice-capped island in the Southern Ocean where extraterrestrials battle it out in an epic struggle for supremacy. How ironic, then, that Bouvet is likely to be the last place on Earth invaded by real aliens of a more dangerous kind.
One of the biggest threats to global biodiversity comes from invasive species transported from their natural habitats to places they don鈥檛 belong. The movement began centuries ago, but the scale and speed of modern transport means the problem is no longer restricted to ship-borne rats and cats. Every sort of organism is on the move, hitching rides on ships, aircraft, cars and even people. Nowhere is safe, and while not all alien species run riot at the expense of the locals, their sheer number and variety makes it likely that some will. In the worst instances, alien invaders seriously disrupt local ecosystems and drive native species to extinction.
So where in the world is alien-free? Oceans offer a glimmer of hope: although the deepest trenches are no longer pristine, hydrothermal vents are almost certainly too peculiar to play host to foreigners. The frigid waters of the Southern Ocean have also managed to keep out would-be settlers from warmer waters, although global warming could soon put paid to that.
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Land without aliens is another matter. The remotest parts of the Amazon rainforest and the least accessible regions of deserts might have escaped, but with people moving into ever more isolated parts of every continent it can only be a matter of time. That leaves just a few dots in the Southern Ocean vying for position as the last place on Earth untouched by aliens. Of those, the strongest contender is Bouvet Island. As well as being one of the least hospitable specks of land on the planet, it is the most remote. The nearest land, another uninhabited spot called Gough Island, is 1600 kilometres away.
Since its discovery in 1739, few people have been anywhere near Bouvet and those that ventured close rarely landed. Most of the island is covered in ice, apart from the sheer cliffs rising out of the sea. There is a lava shelf big enough for a few nesting seabirds and a thin strip of beach made of black volcanic sand, but no harbour or landing place. Bouvet became a Norwegian territory in 1927 and was declared a nature reserve in 1971, and apart from an automated weather station installed in 1977, humans have left little trace on it. The only visitors in recent years have been researchers and radio hams (See 鈥淭he last place on earth to make radio contact with the rest of the world鈥�).
For now, Bouvet鈥檚 native species can breathe easy 鈥� not that there are many of them. The island鈥檚 size, isolation and youth 鈥� it鈥檚 less than 1.4 million years old 鈥� means the roll-call is brief: two mosses, three liverworts, 49 lichens, five mites and three springtails. No one has checked the nematodes or tardigrades, but that鈥檚 all to the good. The fewer people who visit, the longer Bouvet will stay alien-free 鈥� assuming of course that there isn鈥檛 an alien colony sleeping under the ice, biding its time until the next attack from outer space鈥�
