Hidden under Antarctic ice that's sometimes miles thick and millions of years old are vast lakes teeming with creatures that scientists have yet to identify.
Now the discovery of a new so-called "sub-glacial" lake in what could be the planet's biggest canyon is fueling speculation that the dark, frigid waters of the South Pole might hold clues to figuring out whether life exists under potentially similar conditions beyond Earth. Scientists believe that oceans that could support life are churning under the icy shell of Jupiter's moon Europa, for example.
"Even 10 or 20 years ago, no one thought you would find organisms on a frozen planet," said Bowling Green State University biologist Scott Rogers, who has discovered new bacteria and other microbes in Antarctic lake ice samples.
"You just thought there was no way these organisms could survive those conditions," said Rogers. "Now we know that's not true. Organisms can survive not only in cold water but some live in the ice."
Using satellite date and aerial radar observations, a team of British scientists recently unveiled a canyon that they estimate is 621 miles long and more than half a mile deep, a geologic formation comparable to the Grand Canyon. The team first announced the discovery earlier this year, but at a recent meeting of the European Geosciences Union in Vienna they provided more details about how they believe the canyon contains a massive lake.
If correct, the new lake could become a treasure trove of insights into life that not only survives, but thrives, under harsh conditions.
'We still don't know what it is.'
Rogers discovered around 3,400 forms of life from ice samples extracted from the bottom of more than two miles of ice covering Lake Vostok, the largest sub-glacial lake at 150 miles long and 37 miles wide.
"We can't identify about half of them," said Rogers. "We suspect a good proportion are viruses. The other half we have identified. We've found thousands of unknown organisms."
The critters in the lake live without sunlight, so Rogers believed heat and chemicals from thermal vents on the lake floor could be sustaining them.
Since more than two miles of ice has covered Lake Vostok for 15 million years, the organisms Rogers discovered might have evolved with little or no interaction with the world, though he suspects they have mixed with water flowing in and out of the sub-glacial lake over the eons.
Of three samples of genetic material he discovered in some two-million-year-old ice cores from the bottom of the Lake Vostok ice shelf, for example, he still hasn't figured out if one has been discovered before. He grew cultures out of all three, nothing that while he took precautions he didn't think the microbes were dangerous.
"We still don't know what it is," said Rogers. "We just know we grew it in the lab. It was a bacterium. But it didn't make anyone sick here so I don't think it was a pathogen. But we are careful with that."
Included among the bacteria he found were some that live only in the guts of fish as well as on bivalves, like clams and mussels. "We made the inference there might be fish down there," he said.
Doubts have been cast on Rogers' work, however, because he obtained his ice cores from Russian scientists who might have contaminated their samples as they drilled. He claims that he was able to take samples from ice that was not contaminated.
"There are some strange stories out there," Mahlon Kennicutt, a professor emeritus of oceanography at Texas A&M University, said. "Most people don't don't believe there is anything more than microbes" in Antarctica's approximately 400 sub-glacial lakes.
But there's no question the lakes are teeming with life. Scientists who sampled water from Lake Whillans in Antarctica found 130,000 cells in each milliliter of lake water, a concentration that resembled deep ocean water, according to the journal Nature. The lake contains around 4,000 species of bacteria and other tiny organisms, the researchers found.
Sub-glacial lakes might provide more than a window to potential life on other heavenly bodies. They might also be hiding important traces of how life evolved on prehistoric Earth, said environmental scientist James Haynes of the State University of New York's College at Brockport.
Antarctica was once part of a landmass that included Australia and South America. Marsupials migrated to Australia via Antarctica, then got cut off from the southern continent as they split apart. Today, on the outcroppings of land in Antarctica, scientists have found fossils that suggest Antarctica was once tropical.
Whatever is in those pristine, isolated lakes, including microbes, could provide a glimpse into a past that many believed had been lost forever, he said.
"Life on the entire planet for 2 billion years was just bacteria," Haynes said. "These dudes have been around a long time. They are really tough."
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