Amphibians just can't seem to catch a break. As if habitat destruction, pollution, pesticides and introduced predators weren't enough to usher them into a modern-day mass extinction, this diverse class of semi-aquatic creatures now has another deadly invasive disease to contend with: Batrachochytrium salamandrivorans, or "Bsal" for short.
First described in 2013, Bsal is an invasive fungus that deals exclusively in the mycological destruction of salamanders and newts. The fungus came to the attention of scientists in 2008 after fire salamanders in the Netherlands began turning up dead with clusters of lethal fungal lesions covering their skin:
Scientists hypothesize that the disease was likely passed to European salamanders by the commercial trade of Asian salamanders, which are immune carriers of the Bsal fungus. Between 2008 and 2011, the number of salamanders in the Netherlands dropped by a staggering 96 percent, and today, Bsal continues to spread across northern Europe without mercy. A new study published in the journal Nature says the fungus has the power to completely destroy the "highly susceptible salamander population" across the content.
In 2014, researchers began studying fire salamanders in Belgium. Within six months, the population was just a tenth of its original size. And by 2016, later less than one percent survived, according to the study.
Sexually mature salamanders are especially likely to be infected thanks to their interaction with others. Researchers also found the fungus "was able to form spores with thick walls that allowed it to survive for longer and spread further, including on the feet of water birds," the Associated Press reports.
Scientists speculate that it's only a matter of time before the epidemic jumps across the ocean to North America.
How a prior deadly fungus may help
It's a bleak situation, but scientists on the front lines in the fight against this pathogen do have one thing in their corner — decades-worth of combined knowledge on Bsal's close cousin, Batrachochytrium dendrobatidis (“Bd” for short).
For the past 25 years, scientists have watched as millions of amphibians have succumbed to Bd. This virtually unstoppable fungus causes chytridiomycosis, a lethal amphibious skin disease that has no viable cure in the wild and boasts a 100 percent mortality rate in numerous species. Coupled with the larger issue of global amphibious decline, Bd was something of a death knell for already struggling species.
One of the first researchers to observe the devastation wrought by Bd was Karen Lips, an amphibian ecologist and professor of biology at the University of Maryland. In the winter of 1993, Lips was a PhD student working on her dissertation in Costa Rica when she first observed the then-unknown disease wreak havoc on local frog populations.
“[I] was watching the frogs die before my very eyes,” Lips writes in an op-ed for Scientific American. “It was stunningly fast. Entire valleys would be wiped out in a few months. We worked furiously to document and understand what was happening, driven to tell the world about what we were seeing.”
So where did this devastating force originate? Like Bsal, the catalyst for the Bd epidemic is generally agreed to be the result of the global pet trade. By the time scientists first began noticing these mass die-offs, it was already too late. Once the fungus is released into an aquatic ecosystem, it moves swiftly and takes no prisoners.
And now history is poised to repeat itself with Bsal.
While scientists were too late to stop the global spread of Bd, the discovery of this new and equally lethal disease that exclusively targets salamanders and newts represents a rare second chance to get things right.
Protecting North America from Bsal
This opportunity for scientists to hit the ground running in North America — where Bsal has yet to land — is especially pressing given that the continent is home to the most robust diversity of native salamanders in the world. There are more than 150 different species within the the U.S. alone and dozens more when you factor in Mexico and Canada. And while you might not see them often, these stealthy amphibians do important work for our ecosystems, including sequestering CO2 that would otherwise waft into our atmosphere and become trapped. So yeah, saving salamanders isn't just important for their sake, but for the sake of humans, too.
With decades of Bd research already on the docket, scientists are in a better position to respond proactively to a future Bsal epidemic. And thanks to the close evolutionary relationship between the two fungi, scientists can make recommendations for preventative trade policy measures to government entities. This means there may be a chance to halt, or at least stave off, the arrival of the fungus in North America.
"Researchers are using the skills, knowledge and tools we developed studying Bd for 20-plus years to study Bsal," Lips tells MNN. "It has helped a lot with the policy angles because we could never say anything definitive regarding Bd in the early days."
After a 2014 study concluded that Bsal presented a 100 percent mortality rate in 11 out of 17 species of European and North American salamanders, the U.S. Fish and Wildlife Service responded by banning the import of 201 salamander and newt species that are known to carry the Bsal infection.
The move is filed under the Lacey Act of 1900, which is a conservation law that allows the U.S. government to prohibit the trade of wildlife, fish and plants that are deemed "injurious to the health and welfare of humans; the interests of forestry, agriculture, or horticulture; or the welfare and survival of wildlife or the resources that wildlife depend upon."
The USFWS ban is an encouraging step, but there’s still much left to do to ensure the continued safety of not only our amphibious friends but many other forms of native wildlife. After all, salamanders aren't the only critters at risk.
Take a moment to consider the staggering decline of North American bat populations at the hands of white nose syndrome — yet another mycological disease originating from another continent (Europe) that has no known cure, treatment or method of preventing transmission.
"If we want to reduce the numbers of invasive pathogens and parasites imported into the U.S.," Lips explains, "then we should implement some sort of system that requires testing of all live animal imports for dangerous pathogens, and [create] a plan for how to address those pathogens that have already been imported and are causing damage. These types of solutions depend on various other parts of the U.S. government to get involved, as USFWS has limited authority."
Of course, the power to save salamanders and newts doesn't only lie with scientists and policymakers. Whether you're a geeky amphibian enthusiast or you simply appreciate all the hard work these diverse creatures do to make our planet healthy and rich, there are plenty of ways you can lend salamanders and newts a hand.
In the infographic below, comic artist and science communicator Rosemary Mosco answers the question, "What can I do to help salamanders?"
Editor's note: This story has been updated with new information since it was originally published in June 2016.