Magazine article Science News

Beat Goes On: Carp Heart Keeps Pace When Fish Lacks Oxygen

Magazine article Science News

Beat Goes On: Carp Heart Keeps Pace When Fish Lacks Oxygen

Article excerpt

Without oxygen, a mere human dies in minutes, but a Scandinavian fish not only can survive but also maintains a normal heart-heat for days, say researchers.

The crucian carp (Carassius carassius) has long been recognized as a champion survivor, thriving even in shallow ponds that freeze over during long Northern winters. These waters can turn into dead zones as creatures exhaust the oxygen in the water.

What researchers haven't known, though, is what strategy the carp follows for such a feat, says Jonathan A. W. Stecyk of Simon Fraser University in Burnaby, British Columbia. Turtles, the other vertebrates famed for roughing out times with no oxygen, reduce their heart functions to only about 10 percent of normal.

The new study of the crucian carp, however, shows that its heart rate dips when oxygen drops but rises again to essentially normal rates, Stecyk and his colleagues report in the Oct. 1 Science. "This is the first time we've seen in vertebrates that the heart will perform like this," he says. "I hope it will spur medical research" into protecting human hearts during transplant or malfunction.

Lakes that freeze over in the winter and pile up with snow pose dangers beyond the chill, according to physiological ecologist Gordon Ultsch of the University of Alabama in Tuscaloosa. The snow keeps light from reaching photosynthetic inhabitants, so even they can't provide any oxygen.

Without oxygen, animals' metabolic pathways elm up with excessive lactic acid. "Turtles can accumulate huge amounts of lactic acid that would stone kill you or me," says Ultsch. …

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