It starts with a cluster of milky white eggs, the fragile orbs wrapped in a cloud of slime.
Inside each grape-sized egg, an embryo will develop, its unblinking eye staring into the water. When it hatches about two months later, the larva will be small enough to perch on a quarter. Eventually, it will develop into one of the largest amphibians in North America: the hellbender salamander.
Nicknamed “snot otters,” hellbenders once thrived in cold, fast-moving Missouri streams — but in recent decades, their populations have plummeted. To help prevent this endangered species from disappearing altogether, researchers at the St. Louis Zoo and Missouri Department of Conservation have spent the past decade breeding and releasing thousands of individuals back into the wild.
By some estimates, hellbender populations in Missouri have declined by more than 75% since the 1980s.
Like other salamanders, hellbenders are very sensitive to environmental changes, said Lauren Augustine, St. Louis Zoo's curator of herpetology, and when it comes to their rapid decline, there isn’t a “smoking gun.”
“In addition to climate change affecting the temperature of the ecosystems, they’re also susceptible to pollution, disease and habitat modification, like runoff,” Augustine said. “It’s likely a combination of these stressors that are impacting wild populations.”
Scientists also detected the deadly amphibian disease known as Chytridiomycosis in Missouri hellbenders in 2006. The Chytrid fungus has been linked to massive amphibian die-offs worldwide, though it’s unclear how much it’s driving hellbender declines.
There are two subspecies in Missouri — the Ozark and eastern hellbenders — and both are included on the state’s endangered species list. The Ozark hellbender was listed as federally endangered in 2011.
For the past decade, conservation researchers from the St. Louis Zoo and MDC have been breeding hellbenders in captivity — a scientific Hail Mary to haul the amphibians back from the edge of statewide extinction. Nearly 10,000 zoo-raised hellbenders have been released into rivers in the Ozarks since 2008.
The zoo’s hellbender nursery has been particularly busy this fall, with more than 1,300 hatchlings emerging in about two months.
Unlike some other aquatic species, hellbender eggs require careful monitoring. In the wild, male hellbenders guard the eggs and stir them to be sure each gets enough oxygen. At the zoo, staff reach into the cold water, gently agitating the delicate eggs.
“Hellbenders are a pretty high-maintenance amphibian in terms of conservation breeding and their care at the zoo,” Augustine said. “We have to have cold, highly oxygenated, very clean water.”
The hatchlings will remain at the zoo while they develop into adults, growing their characteristic broad snouts and stubby legs. Hellbenders can take up to eight years to reach full maturity, but young individuals born in captivity can be released into the wild by the time they’re 2 years old.
It’s a slow process, but bit by bit, the team hopes to restore hellbenders to Missouri rivers.
Follow Shahla on Twitter: @shahlafarzan
