A Giant Among Salamanders
Eric Teitsworth waded through tall grasses and shrubs along a river bank while on the lookout for a giant salamander found only in North Carolina. Every few feet, he pulled on the string of traps he’d placed in the water to look inside.
He pulled up a few tiny fish, and a couple crayfish. But more often, he pulled up nothing.
Teitsworth, an NC State graduate student, wasn’t particularly surprised. This salamander, called the Neuse River waterdog, is rare – it’s only found in rivers, streams and creeks in central and eastern North Carolina, and nowhere else in the world.
It’s also in decline. Teitsworth and Krishna Pacifici, associate professor in the NC State Fisheries, Wildlife and Conservation Biology program, confirmed the waterdog has declined dramatically since the 1980s, echoing conclusions that North Carolina Wildlife Resources Commission biologists made several years ago. In July, the waterdog was listed as threatened by the U.S. Fish and Wildlife Service.
“We think this species is declining, we’re not entirely sure why, so we want to look at it before it blinks out entirely,” Teitsworth said.
A giant among salamanders
Eventually, Teitsworth, Pacifici and Jeff Humphries, a wildlife diversity biologist from the Wildlife Resources Commission, got to the 24th trap. A cry of delight and surprise rang out.
Inside the trap was a light brown, spotted salamander with red-colored gills near its throat. It was a Neuse River waterdog, at last.
This was only the second waterdog Teitsworth has caught in a trap since March, although he’s been looking for it in rivers, streams and creeks from the Triangle all the way to New Bern. He’d been able to see a few others by snorkeling in the water, but he said it shows just how difficult it can be to find them. They are typically more active in cooler temperatures, he explained.
Teitsworth filled a tray of water, and put the waterdog inside. He photographed it, measured it, weighed it, tagged it and took a small tissue sample. It was likely a female, between 5 and 10 years of age, he said, pointing out the telltale anatomy on its underbelly.
While this salamander only measuring about six inches long, the species can be considered somewhat of a giant among salamanders. On average, the adults Teitsworth catches are closer to 7 to 7.5 inches, but the largest one he’s caught was a touch over 10 inches. They can live up to 20 years, and have unique spotting patterns on their back.
The gills around their necks get their red color from their transparent skin exposing oxygen-carrying blood underneath. They also can “breathe” through their skin, and through their lungs if there isn’t a lot of oxygen in the water.
They’re important in water ecosystems – not only as a predator, but also as food for other animals.
Their long lifespan is one of the challenges for researchers in fully understanding population changes, Pacifici said.
“They’re so long-lived,” Pacifici said. “It’s fascinating, but it makes it difficult to understand, with certainty, how their population is changing.”
In the 1980s, researchers from the North Carolina Museum of Natural Sciences in Raleigh, led by Alvin Braswell, started doing surveys to estimate the waterdog population frequency. North Carolina Wildlife Resources Commission biologists did a follow-up survey 2011-2015, finding they had disappeared from 35% of their historic range.
Teitsworth and Pacifici have built on the commission’s work to confirm the species has declined since the 1980s. They did not find the waterdog in about 60% of the 131 locations they looked for it.
Now, they are trying to delve into the deeper questions – not just how many waterdogs are still out there, and where, but also what’s causing them to disappear.
Funded by the U.S. Fish and Wildlife Service, Teitsworth and Pacifici are trying to characterize the habitat where the salamanders are found, and where they’re not, to understand the factors that contribute to their decline. They want to fully understand how different land-use characteristics around waterways can impact those waterways.
“I’m trying to understand the current distribution, and from that, what are some of the habitat characteristics that influence where it’s found, as well as some of the landscape characteristics,” Teitsworth said.
Already, they have some ideas about what’s going on.
“We’re starting to learn some of what we think is threatening them,” Teitsworth said. “It’s a cumulative effect of everything we’re doing on the landscape – landscape change is pervasive.”
In particular, they think land-use changes that affect water flow in streams, rivers and creeks could play a role.
“It seems as though watershed stability, particularly around erosion and sedimentation, seems to be a large stressor,” Teitsworth said. “We can probably also lump in things like water quality, potentially even an invasive species being a problem.”
They explained that development can alter the waterdog habitat by increasing the amount of impervious surface, which can increase the force and amount of water running into a river or a creek. That can disrupt places the waterdog looks or food, or in how and where waterdogs lay their eggs.
“Typically in a healthy stream, you would have patches of rocky cobblestone, and faster and slower moving water,” Teitsworth said. “Increasing water flow into the river can change the natural habitat and homogenize it.”
They’re hoping to catch waterdogs in different life stages so they can understand whether, and where, they’re successfully reproducing. Their work could inform regulators’ efforts to develop a recovery plan for the species.
Holding on in tributaries
In total, Teitsworth found two waterdogs in the 40 traps he checked that day at that site, before continuing on to the next one.
The Little River in Johnston County, where Teitsworth was surveying for waterdogs that day, is one location he returns to periodically.
He thinks upstream pollution impacts likely play a role in whether he’ll find them, and the area upstream of the site where he goes on the Little River is more rural. In some locations he said he’s only captured a few adults. The Eno River is one of those.
“I have no idea if they are reproducing there,” he said.
Teitsworth added that he’s unlikely to find them in the main stem of the Neuse River for example, but they’re still sometimes in the tributaries.
“Like this one,” he said.