Deadly Amphibian Fungus Abroad Threatens Certain U.S. Regions

The areas of the United States that are most at risk of a potentially invasive salamander fungus are the Pacific coast, the southern Appalachian Mountains and the mid-Atlantic regions, according to a recently published U.S. Geological Survey report.

These findings can help managers protect already declining amphibians in the U.S. from the Batrachochytrium salamandrivorans, or Bsal, fungus. Bsal is decimating wild salamander populations in Europe and could emerge in the U.S. through the captive amphibian trade. The new USGS study identifies areas of the U.S. with high likelihoods of two risks: Bsal introduction and severe consequences for local salamanders.

“The eastern U.S. has the highest diversity of salamanders in the world, and the introduction of this new pathogen is likely to be devastating,” said Katherine Richgels, a USGS researcher and the lead author of the study. “Our findings can help with early Bsal detections by highlighting high-risk areas.”

Scientists developed a county-specific Bsal risk assessment for the U.S. by analyzing characteristics of Bsalecology, such as optimal temperatures for fungal growth, and data on amphibian imports, pet trade establishments and the regional diversity of salamander species. They found that if Bsal enters the country:

• The total risk of Bsal to salamanders is highest throughout the eastern U.S., particularly the mid-Atlantic states of New York, Massachusetts, Rhode Island, Connecticut, New Jersey, Pennsylvania, Delaware and Maryland.
• The Pacific coast and Appalachian Mountains are likely to have significant population declines due to high concentrations of diverse salamander species and mild climates that are well suited to Bsal growth.

“Amphibians are the most endangered vertebrates in the world,” Richgels said. “Disease risk assessments like ours can help managers prevent and mitigate losses of vulnerable U.S. salamanders.”  

Bsal was first identified in 2013 as the cause of mass wild salamander die-offs in the Netherlands and Belgium. Captive salamander die-offs due to Bsal have occurred in the United Kingdom and Germany. Scientists believe Bsal originated in Asia and spread to wild European populations through the import and export of salamanders.

“Bsal represents one of the most significant disease threats to U.S. wildlife since the emergence of white-nose syndrome, which has devastated hibernating bat populations in the eastern U.S.,” said Anne Kinsinger, Associate Director of Ecosystems for the USGS.

The USGS risk assessment informed a U.S. Fish and Wildlife Service interim rule prohibiting the importation and interstate transport of certain salamander species. The USGS National Wildlife Health Center is leading early detection surveillance for the potential introduction of Bsal in the U.S. Early detection would allow for rapid management actions to prevent and control the spread of the fungus should it be found.

Among the hundreds of invasive species already established in the U.S. is the microscopic chytrid fungus that has devastated amphibian populations. On February 18, the Department of the Interior released an interdepartmental report. The report proposes to stop the introduction and spread of invasive species through a coordinated set of actions to find and eradicate potential invasive species before they spread and cause harm.

For more information on emerging wildlife diseases, please visit the USGS National Wildlife Health Center website.