09/16/11

Chytrid Fungus: Hope for Fighting Deadly Amphibian Disease

Researchers at Oregon State University have discovered a freshwater organism that might help in fighting the chytrid fungus, which is a principal cause for the worldwide amphibian decline. A freshwater species of zooplankton, called Daphnia magna, could provide a tool for biological control of the deadly fungus whose impact, one researcher has called “the most spectacular loss of vertebrate biodiversity due to disease in recorded history.”

Daphnia magna is a variety of water fleas of the genus Daphnia, some species of which are commonly used as food for aquarium fish. It was known that the zooplankton could devour some types of fungi. Oregon researchers wanted to find out whether Daphnia magna could also consume the chytrid fungus that has been devastating amphibian populations worldwide, including Colorado’s endangered boreal toad.

Through extensive research, scientists confirmed that Daphnia magna could consume the free swimming spores of the fungal pathogen. According to lead researcher Julia Buck, an OSU doctoral student in zoology, in an Oregon State University press release:

We feel that biological control offers the best chance to control this fungal disease, and now we have a good candidate for that. Efforts to eradicate this disease have been unsuccessful, but so far no one has attempted biocontrol of the chytrid fungus. That may be the way to go.

Now scientists need to conduct field studies to confirm the zooplankton’s effectiveness in a natural setting. The OSU scientists have found that Daphnia inhabits amphibian breeding sites where chytrid transmission occurs and may be able to stem the unprecedented population declines and extinctions.

For background on the chytrid fungus, please see the video below that we found on the Save the Frogs site, produced by the National Science Foundation:

The Oregon State University research was reported in the journal Biodiversity and Conservation, and was  supported by the National Science Foundation. Click here for the full report.

09/27/10

U.S. Agency Proposes Legislation to Help Stem Spread of Chytrid Fungus

In an effort to stem the spread of the deadly chytrid fungus that is wiping out amphibian populations, the U.S. Fish and Wildlife Service (FWS) is considering banning the importation of amphibians and their eggs without a permit certifying the animals are disease-free. The chytrid fungus has caused the extinction of at least 200 amphibian species and continues to be one of the greatest threats to amphibians.

Northern Leopard Frog, a North American native species

In a statement, Rowan Gould, Acting Director of the U.S. Fish and Wildlife Service, said,

The worldwide decline of amphibians is of great concern to us. Chytrid is attributed as a major cause of this amphibian mortality. We understand that halting the spread of the fungus or eradicating it will take more than just regulating importation and transportation of infected amphibians, but it is a major step in the right direction.

According the the FWS website, under the Lacey Act, the Department of the Interior is authorized to regulate the importation and interstate transport of wildlife species determined to be injurious to the welfare and survival of native wildlife. Current regulations prohibit the release into the wild of all species of live amphibians or their eggs, except as authorized. But, of course, this law isn’t easily enforced. Many pet frogs are let “free” in local ponds, potentially infecting native species.

A listing under the Lacey Act would not affect a person or institution that currently owns an amphibian and does not transport it to another state or U.S. territory.

At FROGS ARE GREEN, we applaud this proposed legislation and feel it would be a huge step toward controlling the spread of the chytrid fungus that threatens the survival of so many amphibian species, including native species listed under the Endangered Species Act.

The FWS is seeking input from the public. You can leave a comment until December 16, 2010. Please take a few minutes to comment and to show your support for a measure that will genuinely help amphibians.

More information: Statement from the U.S. Fish and Wildlife Service

Information from Save the Frogs about the frog legs trade and the spread of infectious diseases.

07/15/10

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