Hellbender salamanders are huge—and in trouble
The master of the eastern hell (Cryptobranch a. alleganiensis) is not as scary as its name suggests. They’re actually pretty cute, if you can ignore the salamander’s slimy, mucous skin that has earned it nicknames like “snot otter” and “lasagna lizard.”
Although hellbenders can grow up to two feet long, the amphibians are notoriously elusive and prefer to reside under large, flat rocks in well-oxygenated streams that meander through the Appalachian Mountains and the Ohio River Basin. They are also increasingly difficult to spot as their numbers decline due to ecological concerns. Based on a recent environmental study of 90 sites across 73 rivers, researchers at the University of Kentucky now believe they have identified one of the Hellraiser’s main problems. They are losing their habitat to increasingly murky, sediment-filled waters, according to a study published in the journal Freshwater biology.
Study co-author and biologist Steven Price said it’s pretty difficult to catch a hellbender even if you don’t conduct a survey funded by the U.S. Department of Natural Resources.
“They live under large rocks. Raising them safely takes time, people and care,” he said in a university statement. “When you see one in the wild in Kentucky, it’s special.”
Rather than spending countless hours wading through rivers hoping to spot their hellbenders, Tomke, Price and their colleagues instead relied on traces of living organisms known as environmental DNA (eDNA). After collecting and filtering the river water, the team tested the samples for a gene only found in this species. This allowed them to avoid wasting time moving the massive stones or snorkeling for salamanders. Biologists eventually detected Hellbender DNA in 22 locations in Kentucky, 12 of which had historical records linked to the animals. Next, they used a statistical occupancy framework to determine where hellbenders live and when their eDNA is easiest to identify.
“We could clearly link the quality of stream habitat to where hellbender DNA appears,” added study co-author Sarah Tomke. “It brought together the science and showed what managers can do on the ground. »
The team determined that the amphibian’s local habitat was a more important factor in where it lives than overall water chemistry or land cover. Larger streams lined with greater amounts of gravel, cobble, and bedrock were correlated with more hellbenders. However, their numbers declined where grain and silt began to block the crevices beneath the rocks.
“Fine sediment is a big problem,” Tomke said. “It fills potential nesting sites and small spaces that larvae use for shelter. Without this space under the rocks, the animals cannot reproduce or survive for long.”
They also discovered what time of year is best to taste hellbenders. Early autumn, especially during the breeding season in September, seems to be the most judicious time. The creatures lose additional genetic material in early fall, making them easier to detect.
Beyond their uniqueness, the study authors add that hellbenders can be excellent indicators of the health of an ecosystem. When their populations decline, it often harms other species that prey on amphibians.
“Sarah’s project gives us clear habitat goals,” Price said. “First, keep sediment out of waterways. Second, protect and rebuild rock beds and forested banks. That’s how we give this species a chance.”
Fortunately, it appears that the most extensive hellbender mapping effort of its kind was not a complete failure for its participants.
“Seeing a hellbender is incredible, and holding one is next level,” Tomke said.
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