Amphibians Under Threat

The April 2009 issue of National Geographic Magazine has an article about the dramatic, worldwide decline of amphibians (frogs and salamanders) due to a fungus that has been spreading rapidly over the last couple of decades.

The fungus, chytridiomycosis, targets the protein keratin which increases in frogs as they mature. So, a pond with the fungus may be teeming with tadpoles, but have no adult frogs. (And once those frogs mature, they will die too, and then the source of future tadpoles is gone...)

Even areas that are remote from civilization, like lakes high up in the Sierra mountains, have seen devastating die offs of frogs as the fungus has reached those seemingly isolated spots. The following quote seems to sum up the problem:

" 'Today's amphibians have taken not just a one-two punch, but a one-two-three-four punch. It's death by a thousand cuts,' says University of California, Berkeley, biol­ogist David Wake. Habitat destruc­tion, the introduction of exotic species, commercial exploitation, and water pollution are working in concert to decimate the world's amphibians."

Add to these other items the spread of the chytrid fungus, and the population of frogs and salamanders across the planet are in trouble. Hundreds of species have already gone extinct. Many other species are now found only in captivity, where scientists hope they can keep them around through breeding programs, and then reintroduce them to the wild once (if?) the situation with the fungus is resolved.

"Why care about frogs? 'I could give you a thousand reasons,' says herpetologist Luis Coloma. Because their skin acts not only as a protective barrier but also as a lung and a kidney, they can provide an early warning of pollutants. Their insect prey carries human pathogens, so frogs are an ally against disease. They serve as food for snakes, birds, even humans, playing a key role in both freshwater and terrestrial ecosystems. 'There are places where the biomass of amphibians was once higher than all other vertebrates combined,' says David Wake. 'How can you take that out of the ecosystem without changing it in a major way? There will be ecological consequences that we haven't yet grasped.' "

It all goes back to Aldo Leopold's rule about intelligent tinkering: be sure you keep all the parts.

For a quick slide show of frogs from around the world, click here!