WASHINGTON — North America, a Garden of Eden for salamanders, faces a dire threat from a recently discovered fungal disease. But biologists say that lessons learned from the last worldwide wave of amphibian die-offs are helping to rush a new animal import ban and other measures into effect that could prevent the introduction and spread of the deadly disease here.
Fears of widespread die-offs come from the 2013 discovery in northern Europe of a previously unrecognized Batrachochytrium fungus nicknamed Bsal (SN: 10/5/13, p. 18). This fungus has already ravaged populations of rare salamanders in the Netherlands by eating away their skin. There’s no known way to rid most wild populations of the disease. But the good news is that there’s no sign — yet — that Bsal has reached North America, Karen Lips of the University of Maryland in College Park reported February 12 at the annual meeting of the American Association for the Advancement of Science.
Lips was one of several biologists at the meeting who has had the rare horror of witnessing a previous wave of lethal fungus, called Bd, sweep through new territory and kill amphibians by the thousands. She and colleagues pleaded for a faster, more informed attempt at defense this time.
What she and fellow speakers called the most important defense has just been put in place: an interim measure from the U.S. Fish and Wildlife Service that, as of January 28, bans imports of 201 species of salamander to the United States. Even moving those species across state lines is no longer permitted. This pet-trade measure matters, the speakers explained, because international shipping of animals infected with Bsal apparently carried the fungus from its longtime home in Asia to Europe, where such species as fire salamanders had no resistance to it (SN: 11/29/14, p. 6).
With a Bsal threat looming in the United States, herpetologist Joe Mendelson of Zoo Atlanta urged anyone who notices a dead salamander to report it via the new Amphibian Disease Portal. One of the lessons of the last die-offs was how difficult it was for scientists to observe catastrophes as they happened. Infections burned through remote sites in months, with scavengers quickly cleaning up carcasses. To catch the earliest signs of any Bsal outbreaks, “we want to see dead salamanders,” Mendelson said. “Well, we don’t want to…”
If the Bsal pathogen slips in to North America, such widespread species as the Eastern newt could prove disastrously susceptible, said Ana Longo of the University of Maryland and the Smithsonian Conservation Biology Institute. North America has the greatest diversity of salamander species in the world, with close to 200 of the known 700 or so species. The Appalachians and the West Coast are especially rich in species, and the threat of disease savaging them has amphibian researchers “all very worried,” said Patricia Burrowes of University of Puerto Rico in San Juan.
Burrowes’ research on the disease ecology of Bd, the first amphibian-killing fungus to be discovered, has helped demonstrate just how difficult managing, or even predicting, outcomes of disease invasion can be. The other animals sharing the habitat, the microbes that teem on their skin and the details of local climate all make a difference. Burrowes’ current project shows that even small patches of sunlight beaming through gaps in the canopy of a tropical forest could, in theory, create refuges where the Bd fungus might not grow well on a basking animal.
The biggest lesson that scientists learned from the previous invasion is that one fungus disease can quickly crash local populations of a lot of species, says Vance Vredenburg of San Francisco State University. He was working at a remote lake in California over a decade ago when mountain yellow-legged frogs that had looked fine the day before were floating belly up by the hundreds the next day. “We just couldn’t believe what was happening.”