Recently, a Russian research team reached the waters of Lake Vostok. Vostok is one of the largest lakes on Earth, but the body of water escaped attention for many years because it's buried under 3,700m of ice in Antarctica. There is no word yet on what has been found in the lake itself, but researchers now had a glimpse at the life present within it. That's because some of the lake's waters freeze onto the underside of a glacier that transits across the surface of the lake, trapping any organisms within it.

By sequencing the DNA and RNA trapped in the ice, the authors found what appears to be a diverse community of bacterial species, including some that suggest that Vostok has the equivalent of deep-sea hydrothermal vents. And, perhaps more intriguingly, it appears to have animals living under the ice.

The challenge with any of these studies is avoiding contamination (see, for example, the bigfoot genome). So, the authors of this paper took a rather extreme measure to eliminate it: they chilled some bleach and dipped the ice cores in that to wipe out anything that might have accumulated on the surface. They also froze some sterile water and treated it identically to the their ice core samples. These controls did produce some DNA sequences, but the vast majority of it was human, human acne bacteria, the E. coli bacteria used in labs, or, oddly, cow (maybe someone was eating lunch in lab that day?).

The DNA from the Vostok samples was much richer and more diverse than that. A huge range of bacterial species was present, including many groups that live in fresh and saltwater environments, in soil, and in sediments. There were even some unexpected finds. Cyanobacteria normally make a living by doing photosynthesis, but their DNA was found in the lake, which is buried under enough ice that light never reaches it. Archaea have picked up a reputation as extremophiles, but there were only two sets of sequence from them in the ice. The vast majority of the sequences were bacterial.

Some of the sequences come from bacterial groups that were first identified at deep-sea hydrothermal vents. Those are powered by volcanic activity, and the authors note that Vostok fills a rift valley, which might allow similar structures to form in the lake itself. Alternately, the bacteria could be living in water that seeps into hot areas under the lake bottom and sporadically get ejected into the lake.

But perhaps the biggest surprise is the presence of sequences that indicate multicellular life. Many of those are from fungi, but a number of them appear to be from animals, including arthropods, a mollusk, cnidarians, and crustaceans. A couple of factors support the idea that animals may be present. One is that members of these groups have been found at deep-sea hydrothermal vents. The second is that a number of bacterial species are either animal pathogens or part of the gut community.

All in all, the DNA pictures suggest there may be a large community of creatures living deep under the ice. What it doesn't make clear is if it's a thriving community (like that which we've seen at deep-sea vents) or a sparse one that's barely scraping by. DNA sequences can be suggestive, but there's always the chance that two closely related species have adapted to very different environments. So it's a bit dangerous to infer too much from the presence of some of the groups here. To really get a clear picture of life in the lake, we'll probably have to figure out a way to send something down to look.

PLoS one, 2013. DOI: 10.1371/journal.pone.0067221 (About DOIs).