- Growing more than two feet in length, the hellbender (Cryptobranchus alleganiensis) is the largest salamander species in North America.
- Hellbenders have been on the decline for at least 30 years, and in some parts of their range have disappeared completely. Researchers think this may be because they require cool, clean water, and much of their habitat has been degraded by human activity.
- There’s another cause of alarm for hellbender researchers: a pathogenic fungus that stands to devastate salamander populations if it gets to North America.
- So far, research indicates hellbenders can survive this fungus. But they are less able to if they’re already stressed by environmental degradation.
Growing more than two feet in length, the hellbender (Cryptobranchus alleganiensis) is the largest salamander species in North America.
Hellbenders have been on the decline for at least 30 years, and in some parts of their range have disappeared completely. Researchers think this may be because they require cool, clean water, and much of their habitat has been degraded by human activity.
There’s another cause of alarm for hellbender researchers: a pathogenic fungus that stands to devastate salamander populations if it gets to North America.
So far, research indicates hellbenders can survive this fungus. But they are less able to if they’re already stressed by environmental degradation.
Mucus secretions ooze from the skin of a massive two-foot (61cm) salamander as it waits in a bucket to be measured, swabbed, and installed with a tracker.
“It will snot up a whole bucket,” Doctor of Veterinary Medicine Becky Hardman told Mongabay.
Hellbenders— likely named for their bizarre, tortured appearance — are the largest salamanders in North America, live over 30 years, and, at this very moment, have the attention and focus of dozens of dedicated minds, like Hardman’s, across the United States.
“Each salamander is like gold,” Hardman says. “Every catch is so much work and they are nearly impossible to recapture.”
Hardman catches hellbenders (Cryptobranchus alleganiensis) from Arkansas to Tennessee, and often, this work this requires a whole team.
“We dive with respirator hoses and 50lb (23kg) weights to bring us to the bottom,” Hardman says. Once on the bottom, researchers crawl across the current. Some team members use a lever system to lift heavy rocks while others cautiously swim underneath the rock where a bizarre, solitary salamander might, by some slim chance, be hiding in its nest. “Four people working for an hour might find one,” she says, “and it is dangerous. You don’t want to lose your oxygen line with weights attached to your body.”
The coming plague
So why are folks risking life and limb to wrangle these elusive “snot otters”? To understand that, we’ll begin with the frog apocalypse. Over the past few decades, a disturbing amphibian plague has driven nearly 200 species of amphibians, mostly frogs, to or closer to extinction. In areas such as the French Pyrenees, it has not been uncommon to see carpets of dead frogs littering the landscape. The culprit: the dreaded chytrid fungus (Batrachochytrium dendrobatidis) aka Bd.
Death by Bd is a gruesome business. Fungal spores infect the skin, and the growing fungi unravels proteins to eat the amino acids building blocks inside. Frogs become sleepy, shed their skin, stop eating, and their hearts stop beating in just a few weeks.
Many healthy adult salamander species, including hellbenders, seem to be resistant to Bd. However, when in 2013, a sister species to Bd, Bsal (Batrachochytrium salamandrivorans) was detected in Northern European salamanders, researchers went on high alert. Large-scale die-offs of fire salamanders (Salamandra salamandra) were observed in a natural preserve in the Netherlands and similar outbreaks have been reported in Germany and Belgium in both wild and captive populations.
Researchers believe that Bsal is actually native to Asia, and that its spread into non-native areas where salamanders may not have evolved natural resistance to the disease could prove catastrophic for salamander populations, much in the same way that Bd was massively lethal for frogs.
Fortunately, Bsal has not been detected in North America —yet. But researchers worry the global, largely unregulated amphibian pet trade presents a real risk for the spread of Bsal.
In response to this looming threat, a coalition of people from government, academia, and private industry gathered at an international workshop in 2015 to form the Bsal Task Force. The task force’s task: to focus on the management, policy and research of Bsal and to devise a plan of rapid response should it breach the North American continent. The task force will be releasing a comprehensive strategic plan in 2019 that will serve as a roadmap for an organized response.
The team is drawing upon the hard-learned lessons from past invasions: Bd, which has wreaked havoc on frogs around the world; white nose syndrome, a fungus that devastated bat populations; the chestnut blight, which wiped out millions of American chestnut trees in the early 1900s. The take home from disasters such as these: prevention is the best cure, but if action is required, make it swift, coordinated, and comprehensive.
Creatures with a purpose
So, why all this dramatic concern about these seemingly insignificant and slimy creatures? Beyond their innate value as vital members of an ecosystem, salamanders are surprisingly vital to the health of forests.
In some North American forests, such as in the Hubbard Brook Forest in New Hampshire, the biomass (dry weight) of salamanders can be as great as the biomass of all small mammals combined. So, while each salamander may play a relatively minor role, as a whole, their contributions to the food web and ecosystem functioning are significant.
Salamanders also provide a variety of ecosystem services—or direct benefits to humans. Their impressive ability to regenerate limbs is of interest to the biomedical community, as are their fascinating skin secretions, which can have antibiotic, anesthetic, and analgesic properties.
Salamanders also eat many of the insects and worms that break down and release carbon from leaf litter. Thus, by some estimates, salamanders are responsible for keeping 179 pounds of carbon per acre locked up, mitigating the effects of climate change.
So, what about hellbenders specifically? Not only are they large, charismatic curiosities, their health can tell us much about the health of the water they live in. Hellbenders breathe through their skin. The rippling, “lasagna-like” folds along their bodies give them extra surface area through which they can pull oxygen directly from the water (and may also be the origin of the nickname “lasagna lizard”).
Thus, hellbenders require clean, fresh, swift-flowing water to survive. Because of this unique feature, their presence, health, and survival in a stream can be an indicator of the water quality and health of the stream itself – a sort of “canary in the coal mine” effect. If hellbenders are faring poorly, so, likely, is the stream.
A species on the decline
The historic range of the eastern hellbender includes most of eastern U.S. streams within the Ohio and Mississippi drainages. This was essentially northern Alabama, northeastern Mississippi, and northern Georgia all the way north through Pennsylvania and up through southern New York. Hellbender declines were reported as early as the 1980s in the eastern U.S and though the range has retracted some, mostly, researchers are seeing decreasing numbers throughout their range with sporadic local extinctions, especially around areas with reduced forest buffers. The situation appears to be worse in Mississippi and Alabama, where hellbenders have not been seen alive for four years.
The Ozark hellbender (Cryptobranchus alleganiensis bishopi) is native to the Ozark Mountains of Missouri and Arkansas. This subspecies is listed as federally endangered and has disappeared from most of its native streams.
More recently, Ozark hellbenders in Arkansas began appearing with strange skin lesions and deformities (or disappearing altogether), and scientists like Deb Miller at the Center for Wildlife Health at the University of Tennessee began to take notice. She asked Becky Hardman, to come on board to investigate the causes of these declines and monitor populations of both the Ozark hellbender in Arkansas and the Eastern hellbender in Tennessee. This work quickly became Hardman’s doctoral research at the University of Tennessee Knoxville. For her study, Hardman asks: what is happening with the environment, the hellbenders, and the pathogens? And can you evaluate the health of hellbenders in the wild without harming them?
For the latter, it appears so. Hardman and her team take weight and length measurements, make notes about lesions and deformities, take a small skin sample and a skin swab to look at pathogens and skin microbes. In some individuals, she surgically implants radio-transmitters in several individuals for research teams who want to more accurately assess hellbender habitat use and movements.
Though her research is ongoing, one thing she can say for sure is that habitat quality matters. Overall, sickness and disease increase in more degraded habitats. So, while a healthy hellbender in a healthy stream can resist Bd, a critter stressed from dirty water is much more likely to suffer.
Back in the lab at the Center for Wildlife Health at the University of Tennessee Knoxville, scientists Matt Gray and Deb Miller are studying the effects of Bd, Bsal, and ranavirus (another noxious amphibian killer) on juvenile hellbenders.
So far, young hellbenders can be infected but are not dying when exposed to Bsal. This is promising news for the hellbender, but effects of the disease could differ in the wild, especially in a situation where poor habitats and dirty water are stressing hellbenders and weakening their defenses.
In collaboration with the Tennessee Hellbender Recovery Project, Michael Freake of Lee University monitors eastern hellbenders and studies their genetics and conservation. Recently, Hardman and Freake teamed up with Bill Sutton, a researcher and assistant professor at Tennessee State University, to increase healthy hellbender numbers by moving them around. The team plans to physically relocate healthy adults from streams with thriving hellbender populations to streams with absent or dwindling populations where they should, theoretically, be able to thrive.
“Essentially, we are trying to get more eggs in the basket,” Freake said.
This approach differs from other researchers who have raised hellbenders in captivity and re-introduced them into the wild. Lab-reared salamanders behave differently, Freake says, and may have less chance of surviving than a hellbender with experience in the wild.
Help needed
Besides their obvious fascination with lasagna lizards, all of these researchers have one thing in common: they are terrified of what Bsal could mean for North American salamanders.
“What we really need is government supported programs to ensure pathogen-free trade of amphibians,” Matt Gray said. “Pathogen-free trade is required for domestic animals but not wildlife. At a minimum, the government needs to support efforts to monitor amphibian pathogens in trade and captive populations, as well as in the wild.”
And, what can the average person do to protect North American salamanders from Bsal? Researchers have some recommendations. First off, if you have a pet frog or salamander, do not release it into the wild, as it may carry disease. Also, it is important to decontaminate any tank contents before dumping them outside. Simply pour the tank water or contents into a bucket with bleach and let it sit for a few hours to kill pathogens. Diluted bleach is non-toxic in the environment – but Bsal, not so much.
Or better yet, scientists say, just don’t buy frogs and salamanders.
Another important piece of the puzzle is protecting habitat and water quality. Because, for many organisms, it is disease combined with environmental stress that results in death.
And our effects on hellbenders can manifest in surprising ways. On the bank of a river frequented by human visitors, the strangest thing happened to Hardman. An adult hellbender emerged from the stream and crawled straight towards her! Not one to miss a golden opportunity, she and the TSU team decided to prep for surgery and quickly felt an unusually large lump inside the body. Thinking it may be a tumor, Hardman took extra care with the little beast. But when they finally released it, they watched in horrific amusement as it vomited up nonother than an entire hotdog.
The relationship between humans and animals can be complex. And, so it seems, the fate of salamanders is linked to the wellbeing of the web of life— humans, snot otters, and all.
Banner image: A sensitive hellbender cruises around its aquatic world. Image courtesy of Todd W. Pierson.
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