MICHIGAN STATE (US)—Researchers are developing conservation techniques to save the hellbender salamander, a species that for unknown reasons has had little interest in reproducing on its own for several decades.
Veterinarians from Michigan State University, in collaboration with researchers from the Nashville Zoo and Antwerp Zoo in Belgium, are helping develop ways to sample and freeze sperm for future re-stocking of genetically viable hellbenders back to streams and rivers.
The hellbender—also known as the snot otter or devil dog—is the largest salamander found in North America, and can grow to up to 30 inches long and live 30 years or more. They live in a geographic range from Arkansas northeast to New York and have remained relatively unchanged since the time of the dinosaurs.
“The hellbender in the United States is becoming endangered, and to make things more difficult, they are very secretive,” says Dalen Agnew, a member of MSU’s department of pathobiology and diagnostic investigation.
Agnew and Carla Carleton are focusing specifically on evaluating the freezing techniques, known as cryopreservation, developed to keep the hellbender sperm viable.
“The best we can tell, in most hellbender populations there has been no breeding in the wild for several decades.”
While other researchers figure out why—environmental degradation, habitat loss, and biological changes are all possibilities—the team led by Robert Browne of the Antwerp Zoo is making sure the species does not go extinct, preserving its genetic diversity.
“The work between the Nashville Zoo and Michigan State University for the cryopreservation of hellbender sperm is a global model for the genetic management of threatened amphibians,” Browne says.
Dale McGinnity, the Nashville Zoo’s curator of ectotherms, initiated the project so the frozen salamander sperm can produce hellbenders genetically adapted to their local environments and fit for restocking.
“This process of cryopreservation is very species specific,” Agnew says. “It’s a lot like cooking; each species needs its own ingredients and formula. We’re basically applying modified fish technologies to amphibians.”
So far, the team has seen some promising results: Early tests show researchers have been successful in keeping frozen sperm alive for six months, which indicates the sperm could survive for hundreds of years in cold storage, allowing the team to establish a collaborative gene banking program.
“Dr. Agnew and Dr. Carleton’s expertise and equipment were invaluable in helping us validate and document the results of our initial cryopreservation trials with the hellbender semen,” Sally Nofs of the Nashville Zoo says
The researchers are also studying the comparative structure of hellbender sperm using electron photomicrographs, in collaboration with the MSU Center for Advanced Microscopy. This will allow scientists to learn more about the characteristics of the unique amphibian and to ensure its survival.
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