Miles below the ice, scientists find abundant life
Antarctica makes up more than 10 percent of the world's land mass, but it was long assumed that - except for some hardy penguins - it had virtually no life. With ice and snow blanketing virtually the entire continent, the environment was believed to be just too harsh and barren to support anything beyond occasional human visitors.
Antarctica remains as foreboding as ever, but scientists have in recent years learned they were spectacularly wrong about its inhabitants. While the life might not be visible, it is most definitely there: in the snow, in the ice, in the lakes and streams under the ice, and in the waters under the ice sheet.
It is the kingdom of microbes, of tiny bacteria and other microscopic organisms that in some Antarctic regions eke out a bare existence, and in others are almost flourishing. They are extremely small, but one Antarctic researcher has calculated that the mass of living cells in Antarctica equals or exceeds all the living creatures in the freshwater lakes, rivers and streams elsewhere on Earth.
"There was this idea until not very long ago that Antarctica was a place frozen in time, without life," said Chuck Kennicutt, an oceanographer and co-chair of a conference held last week in Baltimore on subglacial Antarctic research.
"Every field season we learn how dynamic and alive it actually is," he said, referring to period between October and February, when the continent is its warmest and research activity is greatest. "When it comes to understanding our planet, Antarctica is about the last frontier."
The conference, which drew 100 scientists from around the world, was called at an especially auspicious time for those interested in life and subglacial systems on "The Ice," as the continent is often called.
That's because three major projects are under way that, over the next five years, will greatly expand and refine our knowledge about hidden worlds that only recently were discovered.
An American team, a Russian team and a British team is each preparing to do something never undertaken before: to drill through the sometimes miles-deep snow and ice to enter and study one of the hundreds of remarkable Antarctic liquid lakes that, like the microbes, were unknown until very recently. Scientists say these lakes - mostly freshwater, some containing salts - remain permanently and surprisingly wet because of the enormous, heat-producing weight of the ice, because of the relative warmth of the bedrock and because of the vast system of streams and rivers that also flow unseen beneath the glaciers.
The efforts are part pure science and part an attempt to learn, during a time of climate change, about the workings of the continent that contains some 70 percent of the planet's fresh water. In addition, Antarctica and its subglacial lakes are of great interest to NASA and astrobiologists worldwide searching for life beyond Earth. The discovery of life in the Antarctic ice and the prospect of similar finds in the lakes have greatly increased their hopes that parallel kinds of life may be found on Mars and Jupiter's moon Europa, which is covered in ice but has vast oceans underneath.
"Ten years ago, you could put the community of scientists involved in this work around one table, and now we have a big room that's filled," said John Priscu, a professor at Montana State University and pioneer in the field of Antarctic microbes, having spent more than 25 seasons on The Ice. "We've learned a lot since then, but the next five years will produce so much more," he said. "This is no longer a curiosity but is important science."
Consider the discoveries already made at Blood Falls in East Antarctica, where water periodically gushes up from a briny pool 1,300 feet below the surface and turns deep red as it cascades down a glacier face.
The falls were first explored by Robert Falcon Scott's expedition in 1903, but they were extensively studied only recently by Dartmouth College teacher and researcher Jill Mikucki and Priscu, her former doctoral adviser. They found that the source of the falls - a sunless, 23-degree pool three times saltier than the ocean, trapped under the ice for at least 2 million years - was home to at least 17 types of microbes. Similar to how other organisms use oxygen, the microbes use iron in their environment to "breathe," and an oxidized (or rusted) version of the iron then spews out with the brine. As Priscu describes it, the microbes, in effect, "eat rocks."
They also function at a surprising level of sophistication. "The microbes clearly live together as a community: They need each other to survive," said Mikucki, whose work was supported by the National Science Foundation. "Waste produced by one will be food for another. Really, there's no reason to think that isn't common around Antarctica."
The Blood Falls research involves water coming up from beneath the ice. But the newer projects require drilling down deep to where sometimes vast lakes lie enclosed in miles of ice and snow.
The first group scheduled to break through is the Russian team at Lake Vostok, the largest body of freshwater on the continent and the fourth largest lake, in terms of volume, on the planet. The Russians began drilling their Vostok ice core in 1957 but didn't know there was a massive lake below until 1995. They have drilled down almost three miles and are now within 300 feet of the water, and they hope to break through early next year.
Because of its enormous size and its location at the center of the continent, Vostok is generally considered the jewel in the crown for Antarctic study. Scientists have found microbes living (or, some say, just present) in most sections of the ice core pulled up so far, and they expect more are living in the darkness of the lake water and, most important, in the sediment below the mile-deep lake.
One tantalizing theory says that microbes at the bottom of the lake may be descendants of organisms that lived there 25 million to 30 million years ago, before Antarctica broke off entirely from the other continents and its forested environment turned into an icy one. If true, scientists will have found extreme forms of life cut off from the sun and the planet's surface for eons, which is precisely what they're looking for on frigid planets and moons. "We are expecting surprises," said Valery Lukin of the Russian Arctic and Antarctic Research Institute.
The British program focuses on Lake Ellsworth, situated near the wide start of the Antarctic Peninsula. That team will also be drilling through several miles of ice in search of microbial and other life forms in water that hasn't seen light for millions of years.
The U.S. effort, located in West Antarctica, will study a subglacial ecosystem that includes rivers, lakes and the area where the land ends and the ocean beneath the Ross Ice Shelf begins.
Called the Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project, it will continue for six years and will study life under the glaciers as well how the glaciers and ice sheet move, how the subglacial water flows, and any implications for climate change. The WISSARD project is funded by the NSF with $13 million in economic stimulus funds, plus additional logistics support.
"We believe this will be transformative science," said Lisa Clough, NSF project manager. She said it will be looking at the differences in microbes that live in subglacial rivers, subglacial lakes and then under the Ross Ice Shelf. Microbes play a central role in "cycling," or transforming, such elements as carbon, nitrogen and sulfur through the environment, and how and where they do it have major implications for more complex forms of life, for dynamics within the glaciers, and potentially for climate change.
Scientists have known for some time about fish, seals, crustaceans and other marine life that lives in or passes through the dark waters under the ice sheets of the Southern Ocean. But referring to the Antarctic life on land below the ice, Clough said: "This is a new and unexplored world, and we want to know who's home."
The program will begin in earnest this coming field season and will ultimately include the drilling of at least 15 boreholes. The team will use hot water drill technology, which is considered to be most environmentally friendly because it doesn't require chemical lubricants and melters. Clough said that learning how to enter the pristine Antarctic lakes without contaminating them is among the toughest challenges the teams will face and will be one of the highest priorities.
Mary Voytek, head of the NASA astrobiology program, said that the space agency is similarly interested in methods for exploring extreme microbial environments without contaminating them, both for reasons of what's called "planetary protection" and to maintain the integrity of the science. "The last thing we want to do is go to another planet and find something we brought with us," Voytek said at the Baltimore conference.
The issue of contamination is already a heated one. The Lake Vostok drilling initially used kerosene and Freon, and scientists from around the world voiced concern that these chemicals would contaminate the untouched subglacial lake at contact. The Russians said they have since devised techniques to protect against polluting the lake, and they have submitted them to an international body that sets guidelines for Antarctic and glacial drilling. Those new plans will limit what the Russians initially collect from Vostok and will keep them from going deeper into the lake for some years, but their representatives said they embraced them anyway.
Brent Christner of Louisiana State University and Montana State's Priscu have published studies of Lake Vostok ice core samples in which they report microbial life on the order of 100 to 1,000 cells per milligram of water. (Christner is the one who estimated that living cells in Antarctica could outnumber those in all the world's other lakes and rivers.) Russian microbiologist Sergei Bulat argues that the number is much lower - around 10 cells per milligram - and that the Americans are counting microbes that arrived with the drilling or while the ice cores were being shipped and studied.
The difference in cell counts has led to different conclusions about the nature of the life in the Vostok ice. Bulat said in Baltimore that he finds so few cells that there cannot be a microbial "community" and that they are likely finding remains of bacteria blown in on the wind. The Americans speak instead of an ecosystem in the ice with microbes that work together in terms of the chemicals they use and expel.
"Given what we know about the persistence and adaptability of life," Priscu said, "I can't see why microbes wouldn't be living across Antarctica, just like they live everywhere else."
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