How could such a lively ecosystem hang on while the rest of the world was dead or dying? Beatty thinks wave action and storms near the shore aerated the waters, mixing life-giving oxygen into the first 50 meters (160 feet) of ocean. "There's a pretty sharp break between where life is and isn't," Beatty said. Just a few meters deeper in the ancient ocean, and the number of genera (a category of life one level broader than species) plummets from 23 to one -- lethal conditions are back in full effect. "This is a healthy community living right next door to a very unhealthy one." Beatty calls this narrow band between the pounding surf of the shoreline and the noxious deep ocean the "habitable zone." He thinks he's seen evidence of it in several places outside the rocks of the Canadian Arctic, and believes life may have fled to the zone repeatedly in Earth's past to weather mass extinctions. "People have certainly had the thought that there would be refuges during mass extinctions," David Bottjer of University of Southern California said. "This is really the first time someone has made a good piece of science out of it." Related Links: Treehugger.com: Sea Level Fluctuations Played a Crucial Role in Planets Mass Extinctions |
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