Magazine article Americas (English Edition)

The Frogs and the Fungus: Thanks to Dedicated Teams of International Scientists, Endangered Amphibians in the Central, Mountain Region of Panama Are Getting Help in Their Struggle against a Deadly Disease That Threatens Their Survival

Magazine article Americas (English Edition)

The Frogs and the Fungus: Thanks to Dedicated Teams of International Scientists, Endangered Amphibians in the Central, Mountain Region of Panama Are Getting Help in Their Struggle against a Deadly Disease That Threatens Their Survival

Article excerpt

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Death lurks silently in the jungles of Panama. It can come in an instant, in a viper's strike or the jaguar's neck-breaking bite. But for other creatures, death may arrive slowly and mysteriously, brought on by undetectable assailants--plagues of microscopic organisms that threaten not just individual animals but entire populations. Such epidemics can drive already fragile species to the brink of extinction.

Consider the case of Panama's critically endangered golden frog. By any standard, the golden frog is a jewel--small and delicate, sometimes a pure carroty-orange in color but often patterned with jet-black spots, blotches, or stripes on a striking banana-yellow body. It is also a cultural icon in the mountains of central Panama.

Nestled in the crater of an extinct volcano is the rural resort of El Valle de Anton. The crater's valley is a farmer's paradise, filled with deep fertile soils and shielded by walls of lush montane cloud forests. At the Sunday market, Panamanian weekenders and foreign tourists browse through an impressive variety of fruits, vegetables, flowers, and local handicrafts, including many that depict the golden frog. It is perhaps the most recognizable symbol of the region-rightly so, since the forests of El Valle are where it was discovered.

Pre-Columbian peoples were well acquainted with the creature they knew as rana dorada; in fact, they venerated it by crafting clay and gold talismans in its image. These artifacts, known as huacas, were said to represent fertility and are prized by collectors of ancient art. Legend has it that living golden frogs are ultimately transformed into huacas upon their death, so anyone seeing or possessing this species will be rewarded with good fortune. Despite this promise, few Panamanians today can claim to have laid eyes upon the living talisman. The golden frog is restricted to only two Panamanian provinces where a variety of factors threaten its survival. Vital habitat is lost each year to small farms, commercialized agriculture, woodlot operations, livestock range, industrial expansion, and real estate development. Where suitable habitat remains, environmental integrity is increasingly threatened by water and air pollution, and the frogs themselves continue to be snatched up by private collectors. And then there is the more recent assault brought on by the plague known as chytrid.

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Chytrid is short for chytridiomycosis, a disease caused by a fungus with the nearly unpronounceable Latin name of Batrachochytrium dendrobatidis. The fungus was discovered in 1997 when a colony of blue poison dart frogs at the Smithsonian Institution's National Zoo in Washington, DC, experienced a mysterious die-off. Once scientists knew what they were looking at, or for, subsequent examinations of museum specimens indicated that chytrid was present in the skins of African clawed frogs collected as far back as the 1930s. Presumably, when thousands of these frogs were shipped worldwide--they were not only sold for the pet trade but also used as subjects in diagnostic human-pregnancy tests--chytrid went along for the ride and spread to wild populations on several continents. Said San Diego Zoo veterinarian Allan Pessier, an expert regarding chytrid: "The Out of Africa hypothesis may require more validation, but it's a good place to start."

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A number of fungi make up the chytrid family, but this is the only one known to infect vertebrates. It happens, as well, to be exceptionally lethal to amphibians. Waterborne spores invade their highly permeable skin, through which precious oxygen is received from the atmosphere. Once imbedded, the fungus causes the outermost skin layer to thicken, dramatically reducing the absorption of water and oxygen, ultimately dehydrating and possibly asphyxiating its host. While this may be an overly simplified explanation of chytrid's effect, the reality remains that there may be no safe quarter for amphibians living in tropical freshwater environments. …

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