Frogs and salamanders, those amphibious bellwethers of environmental danger, are being killed in Yellowstone National Park. The predator, Stanford researchers say, is global warming.
Biology graduate student Sarah McMenamin spent three summers in a remote area of the park searching for frogs and salamanders in ponds that had been surveyed 15 years ago. Almost everywhere she looked, she found a catastrophic decrease in the population.
The amphibians need the ponds for their young to hatch, but high temperatures and drought are drying up the water. The frogs and salamanders lay eggs that have a gelatinous outer layerbasically "jelly eggs," McMenamin saysthat leaves them completely unsuitable for gestation on land. If the ponds dry up, so do the eggs. "If there isn't any water, then the animals simply don't breed," she said.
Biology Associate Professor Elizabeth Hadly, McMenamin's graduate adviser and co-author of a research paper published this week on the website of the Proceedings of the National Academy of Sciences, has worked in Yellowstone since 1981 and has witnessed the ponds going dry. "They're just blinking off," she said. "It's depressing."
"Precipitous declines of purportedly unthreatened amphibians in the world's oldest nature reserve indicate that the ecological effects of global warming are even more profound and are happening more rapidly than previously anticipated," the researchers wrote.
The disappearing ponds lie in picturesque northern Yellowstone, specifically the lower Lamar Valley, which holds dozens of small fishless ponds where the habitat has been ideal for the breeding and larval development of blotched tiger salamanders, boreal chorus frogs and Colombia spotted frogs. As the world's first national park, it is one of the most environmentally protected areas in the world.
The researchers studied climate and water records going back a century, ranging from handwritten log
|Contact: Dan Stober|