Scientists find tiny life forms and ancient animal remains in a cold desert
The largest ice-free region in Antarctica is a barren but beautiful area known as the McMurdo Dry Valleys. When the British explorer Robert Falcon Scott first came across the valleys more than 100 years ago, he described them as lifeless: "... we have seen no living thing, not even a moss or a lichen; all that we did find... was the skeleton of a Weddell seal, and how that came there is beyond guessing. It is certainly a valley of the dead..."
Scientists have since found that Scott was wrong. The Dry Valleys are one of the driest deserts in the world—they average less than half an inch of precipitation a year. But they are not lifeless. In that dry habitat of sand and rocks, there are entire ecosystems of microscopic organisms that spring to life when water is added. For a few weeks each summer, the temperatures are warm enough—and the sun strong enough—to melt glacial ice, which can create streams. Colorful mats of bacteria grow along the streambeds and tiny organisms live in the damp soils surrounding the streams. But the streams dry out completely, so the organisms must be able to withstand freeze-drying, often for many years.
Survival of the Fittest
The organisms that survive—and thrive—in such harsh conditions can withstand freeze-drying. Most are microscopic, but a few are visible (barely) to the naked eye. The largest organisms in the Dry Valleys are the collembola, commonly known as springtails. (In the northern part of the Antarctic Peninsula, there is an insect called a midge that is larger.) But what about penguins? Like sea birds and seals, penguins aren't considered truly terrestrial, even though they spend time on the ice and land. Researchers joke that springtails are the "elephants" of the continent (30 springtails lined up would be about an inch long). Other common, but uncommonly tough, organisms include tiny worms called nematodes. There are also rotifers, mites, and tardigrades (also called water bears, which look like potatoes with eight bear-like claws).
Byron Adams of Brigham Young University and Eric Sokol of Virginia Tech are two researchers in the group of scientists who call themselves "The Wormherders." They study the relationships between the organisms and the soils they live in. Many teams of scientists study the Dry Valleys as part of a worldwide project called LTER, for Long Term Ecological Research. As Sokol explains it, "a common thread among all of us is our effort to understand how the biota [living organisms] and the environment are connected, and how they will change as the climate changes. Some scientists focus on nutrients in the soil or water, others study glaciers. Many study the biota that live in the soils, streams, and lakes, others study geology."
Preserved Pieces of the Past
But what about that mummified seal that Scott and his team of explorers found so many miles from the sea? Good question! It turns out that a lot of seals end up in the Dry Valleys, but not on purpose. It's clear the seals got lost, but not clear why. Once a seal ends up there, its body can be preserved by the dry cold for a thousand years, which is why there are so many seal mummies scattered around the valleys. Paul Koch of the University of California, Santa Cruz, and Brenda Hall of the University of Maine, are two researchers who have been studying the seal mummies to find clues about the conditions in which the seals once lived hundreds, or even thousands, of years ago. Their findings help scientists know what questions to ask about how animals lived, their diets, and how they responded to changing climate. According to John Nye, a researcher on the team, more than 300 seal mummies were found this season.
Koch and Hall have also found mummified elephant seals in areas where the animals are very rare today. They believe that a warmer climate thousands of years ago enabled animals such as the elephant seals to live along the Ross Sea coast. By studying the mummified remains of seals, researchers might be able to anticipate the effects of climate change on wildlife.