Hope for Frogs in Fight Against Chytrid Fungus

This week  Scientific American reported that researchers in California and Virginia have identified a symbiotic bacteria living on frogs’ skin that protects them from chytrid, a fungal disease contributing to the extinction of one-third of the world’s amphibians.  They discovered this naturally occurring bacteria, toxic to the chytrid fungus, in the skin of mountain yellow-legged frogs and redback salmanders.

The chytrid fungus most likely began in African Clawed frogs, which carry the fungus that causes chytrid, but don’t die from it. In the 1940s these frogs were raised in captivity for pregnancy tests.  Most of the frogs were released once this method was no longer used for the tests. They infected amphibians in the United States and around the world.

So far scientists have not found a way to combat this deadly disease that spreads quickly in amphibian populations. Individual animals can be treated, but not large populations of amphibians.

But in this recent study, frogs inoculated with a solution containing the symbiotic skin bacteria survived. The scientists plan to introduce the bacteria to the wild with with a method called bioaugmentation. They hope to increase naturally occurring bacteria so that it can spread to even more frogs and other amphibians.

This summer the scientists will be conducting tests in isolated areas to ensure that  bioaugmentation will be safe and environmentally friendly. If successful, this might offer the first real hope for warding off the mass exinction of the earth’s amphibians. Good news indeed for our froggy friends!

Mountain Yellow-legged frog


Good news for The Mountain Yellow-legged Frog

I’ve been reading some pretty gloomy stories lately about the worldwide amphibian decline, but I’ve also read a surprising number of hopeful stories as well.  Here’s one Susan passed along to me:

A population of a rare, almost extinct western frog, the Mountain Yellow-legged Frog (Rana mucosa) has been found in the San Jacinto Wildnerness in Southern California. Until last month researchers had estimated only 122 adult Mountain Yellow-legged Frogs remained in the wild. This species was once widespread, but declined over the years when non-native trout were added to recreational fishing waters, disturbing local ecosystems. Tadpoles often become prey to non-native fish such as trout. 

Biologists from the U.S. Geological Survey and the San Diego Natural History Museum made the discovery. Reading this article from the Environmental News Service, I realize how many zoos, state, local, and federal government agencies need to be involved and motivated to save an endangered species.  The San Diego Zoo, for example, has a program is to breed mountain yellow-legged frogs in captivity and return them to their native habitat. 

Kudos to all biologists, museums and zoos, and government agencies involved in this effort!

Courtesy of U.S. Geological Servey
Courtesy of U.S. Geological Survey
To learn more about this, I recommend watching the PBS Nature special The Thin Green Line. (You can watch it online.)  This absorbing documentary is about all aspects of the amphibian decline, but includes a segment on the Mountain Yellow-legged Frog in Yosemite.  Check out The Mountain Yellow-Legged Frog site as well.