Toad fungus traced back to South Africa |

Toad fungus traced back to South Africa

Special to the DailyAdult female boreal toads are typically a third larger than males.

SUMMIT COUNTY – Emergence of a chytrid fungus that infects the skin of boreal toads in Summit County and other amphibians has been traced back to South Africa, says Colorado Division of Wildlife biologist Kevin Rogers.Amphibians rely on their highly porous skin to regulate their environment, and the fungus somehow interferes with that delicate chemical balance.

Rogers says that researchers have tracked the fungus back to South Africa, where it was reported in the 1940s. At the time, he says, aquarium frogs were being shipped from South Africa around the world, possibly spreading the fungus from continent to continent.He described the fungus as sweeping wave-like across different geographical regions, reaching Colorado in the 1970s. In the subsequent decades, amphibian populations in this state and the rest of the Southern Rockies declined at startling rates. Populations at more than 80 percent of previously known boreal toad breeding sites in the region have vanished, according to CDOW research. Locally, the crash was reflected when a boreal toad population near the Henderson Mine (near Ute Pass, in northern Summit County) declined dramatically in the mid-1990s.

The decline has not yet been as dramatic in the Northern Rockies, where boreal toads are still common in Idaho, for example.Based on what is known so far about chytrid fungus, Rogers says the best hope for conserving and recovering the species may be to try and discover whether some of the remnant populations that survived the initial chytrid wave have some genetic resistance to the fungus.

“Some populations have lingered. Maybe there’s some resistance,” he said, explaining that CDOW is experimenting with the progeny of those populations at an aquatic research facility in Alamosa. Other observations from the Henderson site indicate toads in a pond with elevated levels of copper survived the fungal wave. That data has spurred CDOW to experiment with the potential for treating boreal toad habitat with copper sulfate, Rogers said.

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