New fungus threatens North American salamanders

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The Ensatina salamander, a lungless salamander common along the west coast of the US, is one of hundreds of species of salamanders endemic to North America threatened by a new fungal pathogen from Asia. Photo via Tiffany Yap.

Scientists call for ban on imports

Staff Report

FRISCO — Federal wildlife officials are dragging their feet by failing to implement a ban on salamander imports from Asia, scientists said this week, explaining that a devastating fungus is likely to spread into the U.S. via the pet trade.

The new malady is closely related to chytrid fungus, which has been implicated in the massive die-off of frogs and toads around the world. The salamander fungus has already spread across parts of Europe, where it has resulted in a 96 percent fatality rate among the European salamander species that it infected.

Salamanders are an important part of forest ecosystems but also a popular pet worldwide. Nearly three quarters of a million salamanders were imported into the U.S. between 2010 and 2014, 99 percent of them from Asia, where the fungus likely originated. Recent studies have shows that at least two U.S. salamander species are very susceptible to the new pathogen.

“This fungus is much worse than the chytrid fungus, which is more like a lingering disease that affects the skin and puts stress on the salamander until it dies,” said David Wake, a professor in the graduate school at UC Berkeley and the director and founder of AmphibiaWeb, an online database of information on amphibian biology. “Bsal is an acute infection that just turns them into little masses of slime in three to four days.”

The Center for Biological Diversity initiated an online petition in May to institute a ban, which is supported by key scientists, but the federal government has been slow to act.

“There is a lot at stake here if the U.S. Fish and Wildlife Service doesn’t stop imports now to prevent the introduction of this devastating pathogen to North America,” said co-author Michelle Koo, a UC Berkeley researcher in the Museum of Vertebrate Zoology and associate director of AmphibiaWeb, an online database of information on amphibian biology.

A paper describing the potential effects of the fungus on U.S. and Mexican salamanders will appear in the July 31 issue of the journal Science.

Scientists say they know that some North American salamander populations are vulnerable to the new pathogen and they created a map showing which populations are at the highest risk of declines and extinctions from the fungus. Pinpointed hotspots are in the southeastern United States, particularly the southern extent of the Appalachian Mountain range and its southern neighboring region; the Pacific Northwest and the Sierra Nevada; and the central highlands of Mexico.

Through AmphibiaWeb, Koo is working with the U.S. Forest Service to create an online portal where biologists can record occurrences of Bsal infection, in order to track the spread of the fungus.

Co-author Vance Vredenburg, who has studied the chytrid or Bd fungus for more than a decade, noted that more than 200 species of amphibians have gone extinct or are near to extinction as a result of infection, making it the most devastating infectious wildlife disease ever recorded.

“I have seen the effects of Bd on frogs, to the point where I’ve seen tens of thousands of animals die in the wild in pristine areas, here in California, right in front of my eyes,” said Vredenburg, an associate professor of biology at San Francisco State University.

The new fungus, he said, “is an imminent threat, and a place where policy could have a very positive effect. We actually have a decent chance of preventing a major catastrophe.”

Salamanders are one of the most abundant vertebrate animals in many North American ecosystems and play a number of key ecological roles, Koo said.

“Because salamanders are small, often nocturnal and live underground, they are an often overlooked but integral part of the ecosystem,” she said. “They’re frequently the top predator and can make up the majority of the animal biomass of a forest. This fungus puts at risk an important part of a healthy forest.”

One of the European salamanders shown to be highly susceptible to the fungus is a member of the plethodontid family, which has its greatest biodiversity in the U.S. Nearly two-thirds of the 675 salamander species are plethodontids, including the familiar California slender salamander, and they make up the majority of salamanders in the U.S.

“California salamander populations are already way down because of the drought,” Wake said. “We need a ban now to head off this new fungus; otherwise, we will have to spend a lot of money to eradicate it.”

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