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Stream dwellers gather in different combinations depending on location.
Water doesn鈥檛 reach all streambeds evenly. And, as it travels, it picks up different chemicals and lifeforms depending on which soil it contacts. In a short stream that flows every summer, organisms form mutually supporting groups that need all that water but few nutrients. At the end of a long stream, you might find communities that thrive together on more and in less water.
Researchers are now testing what rising temperatures will do to streams. Will these diverse communities disappear when more water consistently fills the streambeds?
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You need water to survive, so how do you live in a place that鈥檚 totally dry for 10 months? Water flows into Antarctica鈥檚 streams only during the short summer, and, in some streams, not even then. Streambed residents in Antarctica can simply pause their lives for a year, for decades鈥�even for centuries. Without water, they stop growing, repairing, and reproducing. If and when meltwater reaches their rocky habitats, their metabolisms restart.
If there was life in the channels we鈥檝e seen on Mars, billions of years ago, it might have resembled the living things in Antarctica鈥檚 streams.
Left: The Onyx River in Antarctica (Melissa Li / NSF), right: Mars landscape (NASA)