Drilling into subglacial Lake Whillans. Photo: NASA/JPL-Caltech.
Antarctica is not an easy place to live under the best of conditions. But scientists with the British Antarctic Survey have discovered evidence that life can thrive even in the most harsh environments of this already unforgiving continent. The BAS recently published a study in the journal Diversity announcing their discovery of multiple extremophiles in Lake Hodgson, a subglacial lake on the Antarctic Peninsula.
“It's the first time any subglacial lake has been studied,” the study's author, David Pearce, said. Though a Russian team is currently studying water samples from Lake Vostok and a micro-submersible has explored the waters of Lake Whillans, the BAS team's report is indeed the groundbreaker when it comes to life in the sediments of Antarctica's 380 subglacial lakes.
A map of Antarctica's subglacial lakes. Photo: NASA Earth Observatory.
100,000 years ago, Lake Hodgson was buried by advancing glaciers, and has remained covered in ice ever since. During the Last Glacial Maximum, some 20,000 years ago, over 1,500 feet of ice separated the lake from the surface. It's now categorized as an emerging subglacial lake thanks to global warming, which has caused glacial recession around the poles.
Panning a subglacial lakebed for life has been a longtime goal for biologists, but direct sampling has always presented technological challenges. However, now that warmer climates have melted the ice cover over Lake Hodgson to around 12-15 feet, the BAS team could finally access the mud.
In the case of the seminal Hodgson study, researchers drilled through the ice cover and into the sediment, which is about 305-feet deep. The sample they obtained contained 20 cultures of extant extremophile microbes in the top inch, which immediately settled the matter of whether or not life could survive such difficult conditions. Perhaps even more interesting was the discovery of fossilized DNA fragments embedded deeper in the sample–proof that microbes eked out a living back when the ice cover was several hundred feet deep.
The results of the study are of obvious interest to astrobiologists. “We can start to built a picture of what limits life in extreme conditions and then start thinking about what might limit life on other planets,” Pearce said.
Or, as the case may be, moons. If microbes can survive the conditions of subglacial Antarctic lakes, maybe they are hanging out in Europa's vast underground ocean. Of course, we can't know for sure until we drill into the Jovian moon's thick ice crust. But finding creatures that can survive freakishly barren environments on Earth will give us valuable insights into finding them elsewhere too.