Antarctica shelters abundant microbial life in water miles below the icy surface
Tuesday, March 23, 2010
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 underway 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."