A lethal fungal pathogen that has already devastated European salamander populations now looms over North America—home to the world's greatest salamander diversity and an ecological catastrophe scientists know is coming but may struggle to prevent.
Batrachochytrium salamandrivorans, known as Bsal, has driven fire salamander populations in Europe to decline by more than 90 percent since its discovery in the Netherlands in 2013. An otherwise healthy salamander can succumb to infection in under two weeks. Now, with the eastern United States hosting over 100 salamander species—many found nowhere else on Earth—the fungus represents an extinction-level threat.
"Unlike Bd, this time we know it's coming," explained researcher Evan Grant, referencing Batrachochytrium dendrobatidis, the chytrid fungus that has already driven hundreds of amphibian species toward extinction worldwide. That catastrophe unfolded before scientists fully understood the threat. With Bsal, researchers have the advantage of foreknowledge—and the burden of acting before disaster strikes.
The stakes extend far beyond salamanders themselves. These unassuming amphibians play outsized ecological roles in forest ecosystems, functioning as both predators and prey while transferring energy through food webs. By consuming invertebrates that break down leaf litter, salamanders facilitate carbon sequestration—one California species alone prevents an estimated 72 metric tons of carbon from entering the atmosphere annually.
In Virginia forests, red-backed salamanders reach densities of four individuals per square meter—biomass rivaling that of birds or small mammals. Their disappearance would trigger ecosystem cascades: insect population explosions, altered decomposition rates, disrupted nutrient cycling, and prey shortages for predators from snakes to woodland birds.
Laboratory studies reveal many native North American salamanders show high vulnerability to Bsal infection, yet the fungus has not been detected on the continent—making this a rare case where . Federal authorities implemented import bans on 365+ susceptible salamander species in 2016 and 2025, blocking the most obvious pathway for pathogen arrival.
