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A simple, elegant precast solution could help bolster an endangered species.
By Robert Whitmore
You may not spend a lot of time thinking about the Eastern Hellbender Salamander, but Greg Lipps sure does. Lipps, an independent consultant to the Ohio Department of Natural Resources, has spent years studying this completely aquatic salamander – an amphibian that has been categorized as an endangered species by the Ohio Division of Wildlife. The Eastern Hellbender is found in swift-flowing rivers and streams in the eastern United States. In Ohio and Missouri, where most of the research has been done, the population has declined 82% since the 1980s, Lipps said.
Lipps is one of a small cadre of biologists who have been working to find ways to rebuild the Eastern Hellbender Salamander population, and he may have found an answer – in a custom-designed, precast concrete habitat that resulted from a collaboration among Lipps, Bluffton Precast Concrete Co. and Norwalk Precast Molds Inc.
The natural habitat for an Eastern Hellbender is a large rock embedded into the substrate of a river that has a small opening where the salamander can weave its way into a cavity and lay eggs. The small opening allows the male salamander to defend its nest from predators such as fish. As development occurs in the water, those large rocks are often silted over, destroying the habitat. Lipps said there is no research to provide a direct link between the availability of the boulders and the decline of the Hellbender, but he would like to find out.
One way to test the theory would be to supplement the habitat, and that’s where the precast concrete solution comes in. A colleague of Lipps’ at the Missouri Department of Conservation, Jeff Briggler, began creating his own artificial Hellbender habitat using chicken wire and concrete. “Jeff built some of them and gave them to the St. Louis Zoo,” Lipps said. Briggler’s artificial habitat soon harbored some happy Hellbenders. “Once you give them the right conditions, they started breeding in captivity, and now they’ve been breeding for two years in a row,” Lipps said. Briggler has also documented their use in the wild.
Lipps wanted to build on Briggler’s work by formalizing the design and creating an artificial habitat that could be placed directly into the river or stream. He searched precast.org for a precast concrete manufacturer located nearby and landed on Bluffton Precast, an NPCA-certified plant in Bluffton, Ohio.
“I called them up and told them I had a rather odd request,” Lipps said. “They said it looked like something they might want to tackle.”
Lipps started working with David Akin, president of Bluffton Precast, showing him pictures of the chicken wire structure and adding his own specifications to the structure. Akin then contacted Eric Hudberg, vice president at Norwalk Precast Molds, to add Norwalk’s expertise to the team.
“We were not sure if they were serious or not,”’said Hudberg. “Dave was asking, ‘Hey, do you think we can build this thing?’ We looked at it and figured, well why not?
“I talked with some of our engineers here,” Hudberg continued. They looked at the photos of Briggler’s homemade hut along with the additional specs that Lipps wanted, like a removable lid, no light leaks, and a knockout in the base where the river bottom would be exposed. An additional modification was a port for the insertion of a water quality monitoring device and a small camera.
“After we got into it, it wasn’t terribly challenging once we broke it down and got into the components,” Hudberg said. “We ended up with a three-piece mold set.”
Lipps worked with his new collaborators at Bluffton and Norwalk and made several modifications to the design. The entry is a tapered tunnel about 20 inches long that leads to a cavity where the eggs can be laid. The hut weighs about 150 pounds and should sit down firmly into the substrate of a river or stream.
“It needs to be big,” Lipps said. “If you think about what a stream potentially goes through every year with ice sheets and floods – it can’t be something that will be pushed around. It needs to be able to stay in place.”
What seems big to a biologist may look tiny to a precaster. Casting of the first salamander hut wasn’t technically difficult, said Akin. One of the challenges was actually its small size. “When you’re used to making things that are up to 20 tons apiece, this is a little different,” he said. “We used our burial vault wire and hand-formed a cage for the top section and another for the base piece. We used our 5,000 PSI burial vault mud with fiber, and then actually poured both pieces on top of a panel form.”
The first finished Hellbender Salamander Habitat Hut rolled out of Bluffton in late January, and Lipps took it to a meeting at the Toledo Zoo the next day. The group made a few modifications that Norwalk and Bluffton will incorporate into the next version of the new product. Word of the precast salamander hut has already circulated in the salamander community, and Lipps is looking forward to taking one of the huts to a conference in Chattanooga, Tenn., later this year. Financial support for the development and production of the Hellbender huts came from the Ohio Division of Wildlife, the Columbus Zoo and the Toledo Zoo.
If the Hellbender hut is successful, it could be used for research, for rebuilding of the population where it has become endangered across the country, and also for mitigation projects. When a stream is disturbed, the developer is often required to mitigate the damage by restoring the stream as closely as possible to its natural state. The hut could prove to be a sensible, less costly way to provide the needed mitigation, Lipps thinks.
Why is important to save a species? The Hellbender salamander grows up to 2 ft long and can weigh in at more than 2.5 lbs. They survive up to 50 years in the wild and are among the most ancient amphibians on earth, according to Lipps. Like the canary in a coalmine, they provide biologists with an indicator of the health of a stream. Where they are present, the stream is likely to be fairly clean and well-oxygenated. And that’s good news for smallmouth bass fishing enthusiasts, for example, because the bass requires a similar habitat.
“If you have healthy streams for Hellbenders, you’ll have good smallmouth bass fishing,” Lipps said. The Hellbender is different from a mayfly, he added. If a stream is degraded, the mayfly population may disappear for awhile, but the mayfly will always come back. “With the Hellbender, once they’re gone … they’re gone.”
In Japan, precast concrete has been used for years to provide habitat for a larger salamander species that is known as a Hanzaki, Lipps said. “They have Hanzaki blocks placed onto retaining walls in Japan to help them bolster their Hanzaki population,” he said. The Hanzaki blocks may have formed the genesis of Lipps’ idea to contact a precaster to provide him with a suitable salamander structure. He wasn’t sure if he would find anybody to take on his unusual customized request. But he didn’t know about the can-do culture of precasters. “I thought I’d be calling precasters for weeks, so I feel pretty lucky that Bluffton was willing to take on the project,” Lipps said.
The Hellbender salamander hut project has provided a little variety for Bluffton’s production team, Akin said. “It’s been a blast. We’ve been back and forth with different drawings. I’ve gone from never having heard of the darn thing to being pretty intimate with it.”
The folks at Norwalk concur. “It’s nice to be involved in something unique that could potentially have some impact,” said Hudberg. “It’s something different from the usual septic tank or burial vault type of project. We did a lot of custom jobs in 2012, so this was a perfect way to end the year.” In the process, the Norwalk team has become fans of the salamander, Hudberg added. “I think we’re going to have to get some Hellbender salamander T-shirts made.”
Robert Whitmore is NPCA’s vice president of Communication.