Endangered species listing for Ozark hellbenders: even tough guys need protection sometimes
But their street-fighter image is no match for the severe stress of habitat alteration that is driving their population dangerously low. The pristine-looking streams they depend on have been dammed, dredged, mined, and polluted to the point that the hellbenders have trouble staying alive and reproducing in them.
The hellbenders like fast-flowing undammed streams, and not just because they look pretty. Hellbenders breathe through their skin, meaning that there has to be a lot of oxygen in the water for them to survive. If you dam a river, it becomes a still lake, and still lakes heat up. And when the water heats up, the oxygen level drops. Not only that, but the dams isolate the hellbender populations into little pockets, which are more susceptible to being wiped out. The Fish and Wildlife Service found that the Beaver, Table Rock, Bull Shoals, and Norfork dams constructed in the 1940s and 50s probably destroyed large numbers of hellbenders.
Gravel mining in the Ozark rivers takes its toll on the hellbenders by mucking up their nesting ground with silt, making it hard for them to reproduce and killing off crayfish, their primary prey species. Contributing to the problem is timber harvest and road building near the streams, which causes bank erosion and sediment buildup – further making it difficult for the hellbenders to eat, breathe, and breed. Farm animals wading in the streams and kicking up sediment doesn’t help that problem, either.
Lead and zinc mining, mostly historic but still going on in places, are doing damage as well. These toxic metals don’t disappear, but accumulate in sediments and the tissue of aquatic creatures – especially those like hellbenders that breathe through their skin, absorbing the pollutants around them. Add to this toxic load mercury, which falls back into rivers and streams after it’s emitted from coal-fired power plants. And don’t forget toxic pesticides and herbicides, used in large quantities in local agriculture, which run off into adjacent streams. While the exact cause is not known, it unfortunately comes at no surprise that substantial numbers of hellbenders living in this toxic environment have been turning up with horrific deformities -- missing limbs or toes, blindness, missing eyes, tumors. In one Missouri waterbody, researchers found that 67 percent of the hellbenders were deformed.
Additionally, there’s the threat from non-native species. Rainbow and brown trout have been introduced to Ozark streams. The problem is, hellbender larvae are hard-wired to recognize and flee from native predators, but they don’t recognize the introduced trout as predators and consequently get gobbled up in great numbers. On top of that, the anglers who are catching the non-native trout sometimes perceive the hellbenders to be a threat to the trout population (even though it’s really the other way around), and will sometimes kill them.
Then there are nutrients. They sound like a good thing, but the problem is that you can have too much of a good thing. Nutrients are chemicals like nitrogen and phosphorus that make things grow, but if nutrient levels are too high you get excessive growth of algae, which chokes out other aquatic life. And that’s what’s happening in the Ozark streams, which are being decimated by nutrient loads from fertilizer, manure runoff from factory farms, and septic systems.
Even climate change plays a role. The pathogen Batrachochytrium dendrobatidis, which causes skin lesions, lethargy, and often death to the hellbenders, has spreading rapidly in hellbender habitat in substantial part due to the warming climate.
The threat of harm from curious collectors and hobbyists is so severe, in fact, that the Fish and Wildlife Service took unusual step of declining to designate protected critical habitat for the hellbender. The Service’s concern was that if they publicly disclose where the hellbenders live, the wrong kind of people will flock there to find them. However, listing the hellbender as endangered would still trigger consultation procedures to ensure that federal projects do not jeopardize the species; and it would become illegal to harm or capture one without a special permit.
It’s not a complete solution, but it’s an essential first step. We hope and trust that the Fish and Wildlife Service will follow through with their proposed listing. It may just give the salamander with the street-fighter name a fighting chance.