If it makes its way to our shores, a newly discovered fungus from Asia could wipe out large numbers of salamander species and spark a major North American biodiversity crisis, scientists are warning.
Writing Thursday in the journal Science, scientists from San Francisco State University, UC Berkeley and UCLA pinpointed regions of the U.S. where native salamanders, a key part of forest ecosystems, are at particular risk. They asked the U.S. Fish and Wildlife Service to place an immediate ban on live salamander imports until controls are in place to prevent the spread of the deadly fungus.
"This is an imminent threat, and a place where policy could have a very positive effect," Vance Vredenburg, a biologist at San Francisco State University and a coauthor of the piece in Science, said in a statement. "We actually have a decent chance of preventing a major catastrophe."
The new pathogen, Batrachochytrium salamandrivorans (also known as Bsal) is similar to another killer fungus, Batrachochytrium dendrobatitidis (known as Bd), which since 1999 has wiped out more than 200 species of amphibians worldwide. Bd, which in some regions has killed as many as 40% of amphibian species, offs its victims by hardening the animals' skin, interfering with their electrolyte regulation and ultimately causing cardiac arrest.
"This fungus is much worse," UC Berkeley biology professor David Wake, another of the report's coauthors, said in a statement. "Bsal is an acute infection that just turns them into little masses of slime in three to four days."
According to the Science article, researchers first detected Bsal in the Netherlands in 2013, during a mass die-off of European fire salamanders. Scientists determined that the fungus probably arrived there via the pet trade from Asia, where salamanders have resistance to it. And they warned that Bsal probably posed a significant threat to salamanders in other parts of the world, including North America, where the animals were unlikely to have developed resistance. (In lab experiments, American salamanders have proved susceptible to the fungus.)
North America, the team wrote, is "the world's biodiversity hot spot." It is home to 48% of 676 recognized salamander species, which are members of nine of the 10 known families in the order Caudata. Studying habitats on the continent and salamander species richness, the researchers identified three high-risk zones for Bsal infections: the Southeast around the southern end of the Appalachian Mountains, the Pacific Northwest and the Sierra Nevada, and the highlands of Central Mexico.
These areas, they added, are home to many species from the two families most susceptible to the Bsal fungus, Plethodontidae and Salamandridae.
The researchers analyzed salamander imports between 2010 and 2014, determining that the vast majority were Bsal threats. Los Angeles was the largest port of entry for salamander imports, with 419,890 over the five-year period studied. Of those, 418,692 were deemed Bsal threats.
Vredenburg, who has been studying the Bd fungus and its devastating impacts on amphibians for years, saw one ray of hope in the emerging Bsal threat: that people can still do something to prevent it.
"With Bd, no one could even imagine that one pathogen could cause so much damage across all these different species because we had never seen anything like that before. What's encouraging about this time, with Bsal, is that the scientific community figured it out really quickly, and we can learn a lesson from the past," he said.
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