In an Antarctic Desert, Signs of Life
By CORNELIA DEAN
Published: February 3, 1998
LAKE HOARE CAMP, Antarctica— WHEN the explorer Robert Falcon Scott discovered the Taylor Valley in 1903, he called it ''a valley of the dead.'' As he wrote later in ''The Voyage of the Discovery,'' the valley's brown hills are covered with coarse sand strewn with numerous boulders. There are no plants on its hillsides and no fish in its lakes.
''We have seen no sign of life,'' Scott reported, ''not even a moss or lichen.''
But while Taylor Valley hardly teems with life, Scott was wrong to call it dead. Millions of microscopic plants and animals live here, hidden in the soil, under the perennially frozen surfaces of the lakes and even inside rocks. Researchers who have traveled to this wilderness think they offer important clues to life in more conventional earthly ecosystems, and even to how life might be lived elsewhere in the solar system.
Taylor Valley is one of the ''dry valleys'' across McMurdo Sound from the big American base at McMurdo, the hub of Antarctic exploration. It does not rain here and hardly ever snows. This time of year, the austral summer, the sun neither rises nor sets; it simply moves around the horizon in a circle, bathing the valley in 24-hour light. The rest of the year, except for a few weeks in spring and fall, the sun never rises at all and the valley is plunged in perpetual darkness.
The ecosystem in this harsh environment is rudimentary -- so rudimentary that researchers believe they will be able to model it completely. If they succeed, other scientists will be able to use their model as a starting point for understanding how the web of life is woven in lusher, more complex realms.
The top spot on the food chain here is occupied by microscopic nematode worms, ''the largest land-dwelling creatures in the Dry Valleys,'' as Andrew Parsons put it. Mr. Parsons is a research associate with Dr. Diana H. Wall, director of the Natural Resource Ecology Laboratory at Colorado State University and one of the chief researchers working here. Mr. Parsons calls Taylor Valley ''the simplest ecosystem on the planet.''
Dr. Wall, along with other scientists and more than a dozen graduate students, assistants and volunteers, has spent all or part of the current summer in the Taylor Valley. They study the algae and microbes living in its soil and lakes, how much sunlight it receives and how much water runs off its glaciers. Most important, they are tracing how the creatures that live in this environment adapt to each other and to the Antarctic's extreme conditions.
''We're using the Dry Valley soils as a model for the more complex soils that exist in the rest of the world,'' said Dr. Wall, who spent a few weeks here this season, her eighth since 1989. The dearth of species here makes relationships between organisms and their environment easier to discern, she said.
''In normal soils, the soil organisms are extremely complex,'' she said. ''You've got almost as many species in the soil as you have above ground.'' For example, she said, soil scientists have found as many as 110 different nematode species living in the grassland soil of Colorado, ''and then you've got earthworms and ants and so on.'' In Taylor Valley, the soil is home to only bacteria and three species of nematode.
Perhaps more important, ''this is one of the few places on earth where you can pick up a handful of soil and not find a nematode at all,'' said Dr. Ross Virginia, a professor of environmental studies at Dartmouth College and another principal researcher in the Taylor Valley project. As a result, Taylor Valley offers researchers ready-made control sites for comparing factors that influence survival and abundance of the tiny, unsegmented worms.
''We're right on the edge of life here,'' he said.
Dr. Wall said there was little information about how the nematodes got to Taylor Valley in the first place, but much study of how they prosper. ''One of the things we are looking at is how do you get a soil community?'' she said. ''How does one become established?'' Here, she said, the researchers can scatter nematodes in areas where none now exist and track where they grow and where they do not. ''We can look at the soil chemistry and physics and say how is that soil different from anywhere else.''
The researchers work at a Long Term Ecological Research site established by the National Science Foundation at Lake Hoare, which is about two miles long and lies at the edge of the Canada Glacier. The glacier ends in a sharply scarped lobe about half-way up the 18-mile valley.
The scientists camp here for days or weeks at a time, collecting samples in the field, doing preliminary analysis in small prefabricated laboratory buildings here, and then returning by helicopter to McMurdo Station, about 50 miles away. There, in the Crary Laboratory of the National Science Foundation, they examine and analyze their samples and prepare them for shipment to the United States or Britain for further study.
The nematode researchers, dubbed ''worm herders'' by the helicopter pilots who ferry them and their samples, are measuring what factors affect the abundance and variety of nematodes. Among other things, they have discovered that when it is too cold and dry, nematodes enter a state of suspended animation, called anhydrobiosis, in which they lose up to 99 percent of the water in their bodies.