http://www.time.com/time/magazine/article/0,9171,1149382,00.html
Hardy and plentiful as they seem, frogs are actually very frail
things, with a semipermeable skin that leaves them vulnerable to
even the slightest hiccup in their environment. So when entire
species of brightly colored harlequin frogs started dying off in
the cloud forests of Central and South America about 25 years ago,
scientists suspected that something in the amphibians'
ecosystems--they weren't sure what--had gone awry.
.........
The critters in question are favorites of scientists studying
climate change. Quick and polychromatic, the frogs spend their days
near stream banks, where their constant motion and vibrant hues
make it easy for researchers to count them. Previous studies have
shown that it's not heat alone that kills harlequins but also a
pathogen--the chytrid fungus--that attacks their skin. The chytrid
is actually a cool-weather organism, doing best at temperatures
from 63°F to 77°F. Paradoxically, an effect of global warming is to
increase cloud cover in the tropical forests, lowering daytime
temperatures and making the frogs more vulnerable to fungal
assault.
...........
Frogs are what scientists call an indicator species: particularly
sensitive animals that are the first to go when the climate starts
to change. Their extinction may increase pressure on government and
industry to dial back greenhouse gases. The harlequins, after all,
are only the beginning.
