Hyloscirtus colymba tree frog being fed after being treated for Chytridiomycosis. Photo taken by Rhett A. Butler at Summit Park.
Frog populations worldwide are facing two apocalypses: habitat destruction and a lethal plague, known as chytridiomycosis. Over 30 percent of the world’s amphibians are currently threatened with extinction and it is thought at least 120 species have gone extinct in just the last 30 years. Unfortunately, a new study in Proceedings of the National Academy of Sciences (PNAS) finds that the two threats—habitat loss and chytridiomycosis—are likely to leave no frog population undisturbed. According to the study, frogs that live in still-pristine habitats are more susceptible to chytridiomycosis than those that are already suffering from habitat loss.
Examining tropical frog populations in Costa Rica, Australia, and Brazil’s Atlantic Forest, the researchers found “that paradoxically, habitat loss is negatively associated with occurrence, prevalence, and infection intensity of [chytridiomycosis] in amphibian populations in the tropics.” The finding goes against research of other animal diseases, which usually find that risk of disease increases in disturbed habitats.
In this case the researchers suspect that either the lethal disease depends on the ecosystem having an undisturbed microclimate, or that a decline in amphibian diversity and abundance—due to habitat loss—slows the spread of the disease.
The finding also explains why the presence of chytridiomycosis is often seen in higher altitudes where forest is less disturbed.
The researchers conclude that “disturbed habitats may act as shelters from disease, but only for the very few species that can tolerate deforestation” and recommend that in order to save the world’s remaining frogs, conservationists must “look to interactions between habitat loss and disease”.
CITATION: C. Guilherme Becker and Kelly Zamudio. Tropical amphibian populations experience higher disease risk in natural habitats. Proceedings of the National Academy of Sciences. 2011. www.pnas.org/cgi/doi/10.1073/pnas.1014497108.
(04/28/2011) In forests, ponds, swamps, and other ecosystems around the world, amphibians are dying at rates never before observed. The reasons are many: habitat destruction, pollution from pesticides, climate change, invasive species, and the emergence of a deadly and infectious fungal disease. More than 200 species have gone silent, while scientists estimate one third of the more than 6,500 known species are at risk of extinction. Conservationists have set up an an emergency conservation measure to capture wild frogs from infected areas and safeguard them in captivity until the disease is controlled or at least better understood. The frogs will be bred in captivity as an insurance policy against extinction.
(02/16/2011) Last August, a group of conservation agencies launched the Search for Lost Frogs, which employed 126 researchers to scour 21 countries for 100 amphibian species, some of which have not been seen for decades. After five months, expeditions found 4 amphibians out of the 100 targets, highlighting the likelihood that most of the remaining species are in fact extinct; however the global expedition also uncovered some happy surprises. Amphibians have been devastated over the last few decades; highly sensitive to environmental impacts, species have been hard hit by deforestation, habitat loss, pollution, agricultural chemicals, overexploitation for food, climate change, and a devastating fungal disease, chytridiomycosis. Researchers say that in the past 30 years, its likely 120 amphibians have been lost forever.
(09/08/2010) Alejandra Goyenechea, International Counsel at Defenders of Wildlife and Chair of the Species Survival Network’s (SSN) Amphibian Working Group, spoke with Laurel Neme on her ‘The WildLife’ radio show and podcast about the global amphibian trade. In her interview, Alejandra Goyenechea discusses the benefits of frogs and the many threats – such as habitat loss, climate change, pollution, invasive species, disease, and overexploitation – to their survival. Did you know frogs indicate environmental quality, like canaries in a coal mine? Or that many have medicinal properties, like the phantasmal poison dart frog which produces a painkiller 200 times the potency of morphine?