( An experiment in a dry Antarctic stream...)Freeze-dried mats of microbes awaken in Antarctic streambed

The results showed the resilience of life in the harsh polar environment, where temperatures are below freezing for most of the year and glacial melt water flows for only five to 12 weeks annually, said Professor Diane McKnight of CU-Boulder's Institute of Arctic and Alpine Research. Such research on life in extreme environments is of high interest to astrobiologists, who consider Antarctica's McMurdo Dry Valleys an analogue for Mars because of its inhospitable climate and intermittent water flow.

"This was something we did not anticipate," said McKnight, whose research group is working at Antarctica's McMurdo Dry Valleys Long Term Ecological Research, or LTER, site funded by the National Science Foundation. "These mats not only persisted for years when there was no water in the streambed, but blossomed into an entire ecosystem in about a week. All we did was add water."

McKnight gave a presentation on the experiment at the Ecological Society of America's 90th Annual Meeting held Aug. 7 to Aug. 12 in Montreal.

The river channels under study feature intermittent streams that link glaciers to frozen lakes on the valley floor, she said. The streambeds contain photosynthetic microbes known as cyanobacteria, which collectively occur as thin, rubbery mat-like structures that can spread several meters across the streambed surface.

The experiment began in the 1994 research season, when the team used sandbags to divert water from an active streambed in the McMurdo Dry Valleys into the dry streambed, she said. A time series of aerial photographs, coupled with carbon isotope analyses of the cyanobacteria that measured variation in atmospheric carbon over decades, indicated the streambed had been
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Source:University of Colorado at Boulder