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Hidden Antarctic lake may contain samples of prehistoric life

Underneath several kilometers of ice, the conditions may be just right to give rise to marine life unlike any the world has ever seen. Lake Vostok, an Antarctic body of water that has spent the last few tens of millions of years underneath a two-miles-thick block of glacial ice, just may be home to a variety of hitherto-undiscovered marine life, possibly including fish, according to a study recently published in the journal PLOS One.

According to the PLOS One study, ice retrieved from Lake Vostok’s surface revealed more than 3,500 genetic traces for certain microbes. About 95% of the gene sequences matched those of certain types of bacteria, with another 5% showing the genetic sequences for multi-celled microbial life—indicating that the chain of evolution had at least progressed beyond single-celled life.

Furthermore, some of those bacteria that the tests identified are ones that we commonly find in the innards of fish. It’s possible, the study authors note, that if these bacteria are living within the lake, fish might be living with them, too.

A few other gene sequences matched bacteria that are commonly found near deep-sea thermal vents. This would suggest that maybe heat sources are present at the bottom of Lake Vostok, as well. If so, then they might have given rise to bacteria in large enough numbers to be food for larger forms of life, which in turn might be nourishment for fish.

None of the findings are definitive proof of any kind of Lake Vostok ecosystem, though. They could merely be remnants of past contamination from the ocean. A complex network of rivers underlie the continent, and incoming ocean water could have simply traveled in along the rivers and washed the bacterial matter upon the ice.

Lake Baikal is a true frontier. A sheet of approximately four kilometers of ice has completely covered it for millions of years, not once letting the atmosphere or the sun’s light reach its surface—unlike some of Antarctica’s glacial ice, Lake Vostok’s ice is permafrost and doesn’t melt during the spring and summer months.

The world did not even know of Lake Vostok’s existence until Russian explorers discovered it in 1956—hence the lake’s name, which is Russian for “East.” Nor did any mapping of the lake take place until British cartographers first took up the challenge in the 1990s.

Researchers say that Lake Vostok’s corner of the Earth, situated some 800 miles from the South Pole, was much warmer 35 million years ago. Temperate forests may have bordered the lake, and its waters may have teemed with diverse networks of life just like any other body of water in the more habitable parts of this planet.

The region cooled gradually into the frozen tundra that it is today, leading to glaciers forming and sealing the lake off from the open air for good around 15 million years ago. Much of the lake’s organisms would have likely died off during the transition.
We won’t know for sure what forms of life the lake holds today—or even if it holds life forms—until we physically dig through the ice and explore the waters directly. An international team has recently started on just that—using a high-powered drill, it is tunneling a hole through the ice sheet in hopes of reaching the water below and extracting some of it for sampling.

There is literally no telling what we might find. The ice sheet has thus been shielding the lake off from the rest of the planetary biosphere. And so any life within the lake has been pursuing an evolutionary course all its own for the past tens of millions of years. An exploration of the lake’s waters could uncover creatures that are fundamentally unlike anything we have ever seen.

It’s not too unusual to find microbes living under deep formations of ice. Antarctica’s glaciers reveal millions of cultures of “extremophile” bacteria and other microscopic organisms that have adapted to survive within zones that are too cold and oxygen-poor for most other life of any size to survive. It’s rare, however, to find larger organisms such as fish living trapped under glaciers.

Then again, fish are known to adapt to extreme environments, too. Deep regions of the outer oceans, for instance, are home to bizaare-looking specimens such as the lanternfish, whose body types have evolved to make the best of extreme water pressures and total darkness. We may yet find that similarly adaptive fish species have found ways to flourish in Lake Vostok’s icy enclosures, as well.

Antarctica, incidentally, could be home to many such isolated ecosystems. Researchers have found more than 400 lakes trapped under thick glaciers. Lake Vostok is the largest, at more than a quarter-mile deep, but it is otherwise not exceptional. Any number of these other lakes might have uniquely evolved systems of life of their own, waiting only for human discovery.