Deadly amphibian fungus reaches last Central American holdout region

Amphibian populations have declined worldwide, partly because of a deadly fungus – that has now emerged in what was the last geographical holdout.

Amphibian populations have been declining worldwide, and one factor in the losses is a fungus that causes a deadly disease called chytridiomycosis. Until recently, researchers had hopes that one area of Central American amphibian habitat might have remained fungus-free. But the disease has now turned up in the last geographical holdout, a site in Panama, according to biologists at the Smithsonian Conservation Biology Institute, the Smithsonian Tropical Research Institute, and the Panama Amphibian Rescue and Conservation Project.

Updated map of how the fungus is moving through the neotropics. Map from the Panamanian Amphibian Rescue and Conservation Project.

This fungal disease has wiped out huge numbers of amphibians globally, and biologists blame it for killing about 50% of frog species and 80% of individual amphibians in one area of Panama alone. The fungus, a chytrid called Batrachochytrium dendrobatidis, achieved those infamous numbers within five months of its arrival. That’s why finding chytridiomycosis in the last disease-free area is such a terrible discovery.

The area of Panama where chytridiomycosis just turned up is called Darien. With the presence of the fungus there, biologists have had to revamp their amphibian rescue plans as time runs shorter and shorter. In many cases, captive breeding is the last hope. In quotes from a news release, Brian Gratwicke, biologist at the Smithsonian Conservation Biology Institute and international coordinator for the Panama Amphibian Rescue and Conservation Project, said, “We would like to save all of the species in the Darien, but there isn’t time to do that now. We have already succeeded in breeding three species in captivity. Time may be running out, but we are looking for more resources to take advantage of the time that remains.”

The Panama Amphibian Rescue and Conservation Project has established an assurance colony for two species endemic to the Darien, including the Toad Mountain harlequin frog (Atelopus certus), shown here. Image Credit: Brian Gratwicke, Smithsonian Conservation Biology Institute

In addition to being disease-free until recently, Darien also has the reputation of being one of Central America’s largest wild areas. Only four years ago, tests showed amphibians along the Darien border to be free of the fungus. But by January 2010, two percent of tested frogs turned up with infections. According to Doug Woodhams, a researcher at the Smithsonian Tropical Research Institute, the disease emerged a lot faster than anyone had predicted. “The unrelenting and extremely fast-paced spread of this fungus is alarming,” he said in a news release.

Researchers have already established captive colonies of two frog species that don’t exist anywhere else in the world but the Darien. These endemic frog species are the Pirre harlequin frog (Atelopus glyphus) and the Toad Mountain harlequin frog (Atelopus certus). But according to Gatwicke, researchers are rushing to raise funds for housing for additional species and to breed additional species, especially at the National Zoo, which already has a breeding program for the critically endangered Panamanian golden frog.

Why do these people even care about a bunch of frogs (and other amphibians like toads, newts, salamanders, and caecilians)? A third of this group of animals is at risk of extinction, in part because of this rapidly spreading fungal disease and also because of climate change, loss of habitat, and pollution. If the Earth were a coal mine, these animals, with their delicate, moisture-requiring skin, amphibious lifestyle, and lungs, are our canaries. The fungus isn’t marching across the planet because it took a mind to. It’s able to do so because of many factors, some related to human activity. Add to that the untapped and unknown potential of this vanishing biodiversity for people – yes, amphibians are important to people for their pest control and the medical possibilities of their antimicrobial skin secretions – and we’re facing a real alarm about a substantial loss.

Can anything be done besides trapping animals and breeding them in captivity in the hope of rescuing at least a few species? Of course, biologists like Woodhams and others are working on it. There may be bacteria already existing on the skin of some frogs that could take on the fungus – bacteria and fungi are notorious adversaries – or other disease-fighting skin chemicals that researchers could harness to combat the fungus. Yet, even in spite of the anti-fungus and breeding efforts of researchers like Doug Woodhams of the Smithsonian Tropical Research Institute and Brian Gratwicke of the Smithsonian Conservation Biology Institute and the Panama Amphibian Rescue and Conservation Project, that still leaves us with human factors to address, including climate change and habitat destruction.

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Emily Willingham