On 5 January 2016, two helicopters landed a team of researchers in a place that, at least geographically, is at the frontier of ecological science: the McMurdo Dry Valleys, Antarctica, the most remote of the Long-Term Ecological Research sites funded by the US National Science Foundation. The team, led by Dr. Diana Wall, Colorado State University (third from the left in the picture below), Dr. Byron Adams, Brigham Young University (fourth from the left), Dr. Ross Virginia, Dartmouth College and Dr. John Barrett, Virginia Tech, is studying the soil biological communities of a place unlike any other in the world.

 

C-507 team group picture at MGPPart of the 2015-2016 Soils Team near Many Glaciers Pond in Taylor Valley. (Top row (Left to right): Jess Trout-Haney, Ruth Heindel, Diana Wall, Byron Adams, Tandra Fraser, Dan Bransford; Front row (left to right): Xia Xue, Walter Andriuzzi).

Imagine you are in a huge valley surrounded by glaciers and ice-capped mountains. The silence is surreal, and the cold fierce. You are more than 10° further South than the Antarctic polar circle, a distance similar to that between England and Iceland. Summer time here means that the daylight is almost permanent – and so is the cold, relentless wind. Ahead of you there is a small lake that stubbornly refuses to freeze. Turn around, and you will see the mouth of a huge glacier, a wall of ice that puts any human fortress to shame. At first the glacier looks small and just a short walk away, but don’t be fooled, you may not reach it and come back in time for the helicopter to pick you up if the weather turns bad. Distances are deceiving in such an empty space.

There is no green for the eyes to rest upon, not even a patch of mosses or lichens. No bird songs, no buzz of insects. And yet – or perhaps because of it – everywhere the elements conjure up the illusion of noisy, visible life. A sudden ripple in the pond makes you think of a surfacing fish, but it was just the wind. Long lines of compacted terrain help you walk across the sandy surface, but they are the results of cracks made by the freezing and thawing of the permafrost, neither human nor animal feet had a role in making them. The wind carved some rocks in shapes of horns and turtles, but nothing moves except sand and dust.

The place seems utterly lifeless. But it’s not.

Minuscule animals live in the dry, saline soil spared from the grip of the ice that covers most of this strange continent. The nematode Scottnema lindsayae, a worm usually less than 1 millimeter long, is in many places the largest organism to be found. It can be surprisingly abundant, feeding on the even sturdier microbes and of whatever organic matter it can find (some of the latter perhaps thousands of years old). Invisible cyanobacteria on the surface manage to get enough energy from the UV-packed light of the ephemeral Antarctic summer to set a miniature food web in motion. Deep in the ice-covered lakes, communities of phytoplankton and bacteria thrive undisturbed.

 

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The team at work in Many Glaciers Pond in Taylor Valley. Photo by Walter Andriuzzi

All these organisms are tough, superbly adapted to these hostile conditions. They can inactivate when it gets too cold, tolerate high salinity, cycle carbon and nutrients in a soil that has less organic matter than most deserts. But even these survivors are facing hard times. Human-induced climate change is making environmental conditions increasingly unpredictable. More freeze-thaw cycles impose physiological stress, and may lead to mismatches in the organisms’ responses to seasonal temperature fluctuations. Increasing ice-melting events and lake level rise across the valleys could be spreading some species at the expense of the dominant, dry-specialist ones. Lessons learnt from the McMurdo Dry Valleys may give hints on the fate of other, more complex ecosystems that are also shaped by an unforgiving environment and a changing climate.

The ongoing long-term ecological studies in this ecosystem have therefore two aims: to understand and protect one of the few truly pristine ecosystems left on Earth, and to generate ecological knowledge that will feed into broader research issues.

by Walter Andriuzzi

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