Frogs in Blue Ridge area dying; surprising pathogen identified

Project looks at environmental crisis: what's killing off frogs and salamanders in the Southeastern Blue Ridge Mountains? Researchers discover a surprising culprit.

For years now the global die-off of amphibians (frogs, toads, salamanders, etc.) has raised increasing alarm bells around the world.

Here in the Southeastern United States, scientists from various research centers and zoos have been studying declining populations of amphibians native to the chain of magnificent, old green mountain known as the Blue Ridge Mountains.

According to a recent news release, two years of sampling frogs and salamanders deep in the Blue Ridge Mountains has raised concerns about an infectious disease. Yet, surprisingly, the disease is not the one caused by chytrid, the fungus devastating amphibians around the globe.

Instead, the monitoring program led by researcher Betsie Rothermel has documented a local die-off of wood frogs blamed on Ranavirus, a group of viruses that can infect amphibians, reptiles and fish.

“Although some lab results are still pending, it looks like Ranavirus is the emerging disease of greatest concern at our study site,” said Rothermel, who works with Archbold Biological Station, an independent research facility in Florida.

The find has added to an already wide-ranging project that is assessing disease impacts on aquatic-breeding amphibians in the Blue Ridge, while also developing methods and collecting data for tracking the region’s lungless salamander populations. Lungless, or plethodontid, salamanders breathe through their skin and comprise two-thirds of the world’s salamander species. The work is based at the Georgia Wildlife Federation’s Wharton Conservation Center, 130 wooded acres on the Tallulah River headwaters in Towns County.

Chytrid remains a focus. But sampling of a small pond on the property, former home of the late conservationist Charles Wharton, revealed nearly 100 percent mortality of wood frog tadpoles from Ranavirus in 2008 and again this spring, according to John Jensen, a senior wildlife biologist with the Georgia Wildlife Resources Division’s Nongame Conservation Section.

“We’re finding animals infected with both chytrid and Ranavirus but it seems … that Ranavirus is responsible for most of the mortality we have observed,” Jensen said.

More study is needed to see if other area ponds are also experiencing die-offs. Wood frogs are a secretive but likely abundant frog in the mountains and parts of the Piedmont Region.

Rothermel said there also have been Ranavirus outbreaks in the Great Smoky Mountains National Park. Species such as newts and green frogs appear less susceptible. That could be a double-edged sword, however, if they carry the virus and pass it on to more susceptible species like wood frogs.

This points to another rarely-considered threat, innocently posed by animals lovers themselves. Often children or enthusiastic adults may capture tadpoles, frogs, salamanders or small fish to bring home as pets, then, in an act of kindness release them into the yard , a local park, vacant lot or waterway.

Unfortunately, despite the best of intentions by such animal lovers to encourage and support local wildlife, this translocation can introduce the disease into resident populations.

Please resist the temptation to bring pets or specimens home from your Mountain Vacation . . . even if it's an endemic species to be released into your backyard habitat. With this virulent contagious disease, it's just too risky.

The report goes on to say that under the direction of research assistant Emilie Travis, the amphibian crew began sampling and marking terrestrial salamanders at night this summer. Daytime surveys of stream salamanders will ramp up next year, along with a program to involve citizen scientists in the sampling.

“It’s possible some plethodontid salamanders are infected, too,” Rothermel said.

If so, she said the question is the same: What does that mean?

The project could lay the foundation for what Rothermel considers a need in the Southern Appalachians: a network of long-term amphibian monitoring sites. Amphibians are widespread and sensitive to environmental change. One study estimated the density of black-bellied salamanders in 2.5 acres along a Southern Appalachian headwater stream at 11,294 salamanders, or more than 218 pounds.

“Significant changes in abundance or distribution of these species would indicate widespread problems … in our forested ecosystems,” Rothermel said.

Atlanta Botanical Garden, Zoo Atlanta, the University of Georgia, the Georgia Wildlife Federation and the Wildlife Resources Division have provided support, including volunteers, for the State Wildlife Action Plan project. The action plan is a comprehensive strategy that guides Wildlife Resources Division and Georgia Department of Natural Resources efforts to conserve biological diversity.

Jerry McCollum, Wildlife Federation president and chief executive officer, hopes that documenting the Wharton Center’s natural diversity will in the long-term establish that property as a helpful index to
research other sites.

Georgians can help conserve amphibians and other animals not legally hunted, fished for or trapped, as well as native plants and habitats, through buying wildlife license plates featuring a bald eagle or a
ruby-throated hummingbird. They can also donate to the Give Wildlife a Chance state income tax checkoff. Both programs are vital to the Nongame Conservation Section, which receives no state funds.

Visit www.georgiawildlife.com for more information.

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