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Country-wide surveillance efforts help prevent salamander fungus
For more than a decade, Evan Grant has traveled to vernal pools, streams and forests in different national parks and wildlife refuges in the northeastern United States to sample amphibians. Grant — a researcher with the U.S. Geological Survey’s Amphibian Research and Monitoring Initiative (ARMI) and a member of The Wildlife Society — is currently looking at occupancy trends of wood frogs (Lithobates sylvaticus) and spotted salamanders (Ambystoma maculatum) across the region. He is also examining population dynamics of the federally endangered Shenandoah salamander (Plethodon Shenandoah) in the Blue Ridge Mountains, and in Maryland, he’s tracking amphibian diseases.
But recently, the possibility of a disease that attacks salamanders, which may enter the U.S., has taken Grant’s research in a new direction. While chytridiomycosis, a deadly disease caused by a chytrid fungus pathogen Batrachochytrium dendrobatidis, is devastating frog populations across the world, its counterpart Batrachochytrium salamndrivorans — or Bsal — that causes the disease in salamanders hasn’t yet crossed into the country.
As a result, Grant, who serves as ARMI’s northeast region coordinator, has been surveying amphibians as part of a coordinated national effort led by ARMI colleague Hardin Waddle to detect whether Bsal has been introduced into wild populations. Other research is focused on developing measures to address the disease if it does make its way into the country.
Bsal is currently causing severe population declines of salamanders in the Netherlands, Belgium and recently Germany, but wildlife biologists worry the fungus is on its way to the U.S. through pet trade. In response, earlier this year, the U.S. Fish and Wildlife Service published an interim rule under the Lacey Act to ban 201 salamander species from being brought into the U.S.
“The U.S. is the worldwide center of diversity for salamanders,” said Grant, noting that past research has shown newts are very susceptible to the disease. As a result, he helped create a county-level risk model for the U.S., an effort led by the USGS National Wildlife Health Center. “In particular, in the mid-Atlantic region of the U.S., in southern California and in the Pacific northwest, there’s elevated risk for the introduction of the fungus and serious potential consequences if the pathogen escapes into the wild,” Grant said. One species that could be affected is the red-spotted newt (Notophthalmus viridescens), that’s found in the eastern and central parts of the U.S., he says.
As part of a paper published last year, before the Lacey Act revision proposal, Grant and his team looked at counties with high densities of pet shops in the U.S. to determine which areas would be more susceptible to the disease. They also looked at environmental suitability for growth of the pathogen. The researchers plan to sample up to 30 individuals from populations of newts, particularly from those counties with elevated risk from the fungus.
In addition, biologists across the country are developing rapid response plans if the fungus is, in fact, detected. “We also have a chain of communication to know as soon as possible if it is found,” Grant said.
“It’s a unique situation that the fungus is not detected in the U.S. yet,” Grant said. “It’s also a unique opportunity to think about proactive management and things we can do right now to prepare populations if the disease should be introduced, or to be ready to respond once the salamander fungus is detected.”
Grant and others continue to collect samples of salamanders, track populations of amphibians, and conduct research on the local threats to populations in different regions of the U.S. In a recent study, Grant and his colleagues looked at data that showed the decline of U.S. amphibian between 1993 and 2013. He found each individual region in the U.S. may have different factors contributing to amphibian decline. “The analysis shows no global smoking gun of amphibian decline, but more of a smoking arsenal,” he said. “This research changes the way we need to think about amphibian conservation by showing that local action needs to be part of the global response to amphibian declines, despite remaining questions in what is causing local extinctions,” Grant said in a press release.