The Pandemic Ahead for North America’s Salamanders and Forests
Posted by Richard Conniff on July 30, 2015
Let’s say it’s 1880 and you discover irrefutable evidence that misguided human behavior is about to cause extinction of passenger pigeons—and you have this evidence in time to prevent the disaster from occurring. Or, to bring it closer to home, let’s say it’s 1990 and you have the power to stop the chytrid fungus pandemic that was unknown then, but about to send frogs worldwide twitching and suffocating to their miserable deaths. You’d do something, right?
That’s the situation the United States is in right now, with another unbelievably numerous and ecologically important animal group. The likely victims this time are salamanders and—hang on–before you say “I’m not going to waste time worrying about slimy little animals that live under rocks,” consider first that salamanders are adorable (check out the photo above), second, that they are characteristically North American, and third, that they are vital to the health of our forests.
For salamanders, North America is the Garden of Eden, and they are our true biodiversity: Of the 676 known salamander species in the world, almost half live on this continent, with hotspots of salamander abundance in the southern Appalachians, the Sierra Nevadas, and the highlands of Central Mexico.
The problem this time is that a new variety of chytrid fungus, called Bsal (short for Batrachochytrium salamandrivorans) has recently turned up in Asia, and it is already starting to do to salamanders what its notorious cousin Bd (short for Batrachochytrium dendrobatidis) has done to frogs. On introduction to the Netherlands in 2013, Bsal caused a mass die-off of European fire salamanders. Then it jumped to Belgium. In the laboratory, it killed off almost all of the European and North American salamander species tested.
The good news is that Bsal doesn’t appear to have reached North America. But so far the U.S. government has not taken any public action to keep it from getting here, though an article just out in Science warns that the arrival of Bsal could cause rapid “declines and extinctions in the world’s richest and most diverse salamander fauna,” with the likelihood of “severe” impacts on the health of North American forests.
The threat to salamanders comes from people who ostensibly love salamanders. They want them for pets. So the pet trade has imported almost 800,000 salamanders over the past five years. According to the paper in Science, 99 percent of these imports come from Asia (mostly Hong Kong, mainland China, Singapore, and Japan)—and they include the salamander genera that are reservoirs of Bsal.
This pathogen doesn’t bother the imported pets; they’ve always lived with Bsal and appear to be immune. But the zoopores these imported pets carry are highly transmissible in water, by direct contact, or otherwise, to North American species that have never encountered Bsal before. And the habitat suitable to Bsal coincides with all three North American salamander hotspots.
Vance Vredenburg, a herpetologist at San Francisco State University and co-author of the Science study, has spent much of his career studying the Bd fungus, as it has driven roughly 200 frog species to the brink of extinction, or beyond. “I’ve seen tens of thousands of animals die in the wild in pristine areas, here in California, right in front of my eyes,” Vredenburg said. “It is just an unbelievable sight to see all these dead animals.”
But the devastating spectacle of frog die offs from Bd might just be the key to stopping Bsal. At the beginning of the Bd pandemic, said Vredenburg, “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.” Bd turned out to be the most destructive infectious wildlife disease ever recorded, and that painful lesson is still fresh enough, Vredenburg thinks, to persuade the U.S. Fish and Wildlife Service (FWS) to ban live salamander imports, until there is a plan in place to detect and prevent the spread of Bsal.
The standard argument against such a ban is that it would represent government interference in international trade, with the potential for a charge of unfair trade practice, or that it would cause major economic hardship. But Karen R. Lips, a salamander specialist at the University of Maryland, has worked with FWS analyzing both the biological risk and the economic effects. “Based on what little information you can get from the pet trade,” she said, “we think it’s a luxury trade, and relatively small, so the actual financial impact is relatively small.” On the other hand, the impact of Bsal on North American forests could be enormous, because salamanders are a major factor in the transport of energy and carbon from the leaf litter back into the ground and into tree roots.
The Center for Biological Diversity and the group Save the Frogs filed a petition in May seeking an emergency moratorium on the trade. FWS is currently working on a response, likely to be issued sometime in the next six months. But that will be almost two years after the discovery of Bsal in the Netherlands.
That delay is symptomatic of a major impediment to protecting the United States in an era of emerging diseases, according to William Karesh, a veterinarian and wildlife disease specialist with Ecohealth Alliance. It’s a problem of fragmentation: FWS has responsibility for regulating wildlife trade, but concerns itself mainly with trade in endangered species. The U.S. Geological Survey meanwhile diagnoses and studies wildlife diseases and the USDA does the same thing for domestic animals (and some wildlife). But as the Government Accounting Office has complained, they do not collaborate adequately and no single agency looks at all animal diseases. Finally, the Centers for Disease Control become involved when those diseases leap to humans. The result is that the United States imports about 250 million exotic animals a year with almost no oversight—until a disease breaks out and it is too late to act. And this is in an era of Ebola, SARS, and innumerable other diseases.
The FWS responses may still come soon enough to stop Bsal. But write your representatives in Congress now to make sure that happens. And remind them of the urgent need to streamline our response to the threat of emerging disease. It’s also worth stopping in at your local pet shop. The people there may not even realize that participating in this trade could make them the agents of the next great deadly pandemic.