http://www.msnbc.msn.com/id/15176444/site/newsweek/displaymode/1098Frogs: Global Warming's First Victims
Climate change is no longer merely a matter of numbers from a computer model. With startling swiftness, it is reordering the natural world.
Oct. 16, 2006 issue - Draped like a verdant shawl over Costa Rica's Tilarán Mountains, the Monteverde cloud forest has long been a nature lover's idyll. Hidden birds flirt to the whisper of rushing streams and epiphytes tumble from the mist, while delicate flowers bloom impossibly from the jungle's maw. With luck you might even catch the iridescent flash of the resplendent quetzal, the elegant symbol of the Central American rain forest.
There's one member of this pageant that won't be turning up, however: the Monteverde harlequin frog. Named after its palette of yellow, red and black, this miniature amphibian—a member of the genus Atelopus—had thrived in these Costa Rican mountains for perhaps a million years. Yet the last time
J. Alan Pounds, an ecologist who has studied the cloud forest's wildlife for 25 years, spotted one in Monteverde was in 1988. Its cousin, the golden toad, went missing about the same time. Indeed, the more scientists search, the grimmer the situation looks. A study by 75 scientists published earlier this year in the journal Nature estimated that two thirds of the 110 known species of harlequins throughout Central and South America have vanished. And that may be just the beginning.
The loss of a species is sad enough, not least a jewel like the harlequin, which one researcher described as a tropical Easter egg. What has puzzled scientists is why. For millennia, this denizen of tropical America survived by adapting to whatever changes nature threw its way. Suckers lining the underbelly of tadpoles allow them to cling to rocks without being flushed downstream. The adult's carnival-like costume warns potential predators to stand clear or risk a deadly dose of tetrodotoxin. But apparently there's one peril the harlequin couldn't trump: climate change.
Monteverde gets its lifeblood from the trade winds, which blow moisture uphill where the air cools and condenses into clouds. An ark of plants, insects and animals flourishes in the cool misty mountains. Gradually, though, a warming trend has raised nighttime temperatures and increased cloud cover, which makes for cooler days by blocking solar radiation. The subtle change, which might go unnoticed by us bipeds, is thought to have been ideal for chytridomycosis, a disease caused by a waterborne fungus that has flared up throughout tropical Central and South America. Scientists believe the chytrid disease kills the frogs by blocking their natural ability to absorb water through their porous skin (and perhaps also by releasing a toxin), essentially causing them to die of dehydration.