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Deadly Frog Fungus Invades Madagascar

Mar 02, 2015 05:20 PM EST
Heterixalus luteostriatus, Ankarafantsika, Madagascar
(Photo : Flickr: Frank Vassen) Heterixalus luteostriatus in Ankarafantsika, Madagascar

A deadly fungus that has been ravaging amphibian populations across the world has somehow found its way to the isolated island of Madagascar, according to new surveys. And that's the stuff of nightmares for conservationists, as the island happens to boast countless frog species, 99 percent of which can be found nowhere else in the world.

A study recently published in the journal Nature details how the fatal fungus Batrachochytrium dendrobatidis (Bd) seems to have first appeared in the Madagascar wild nearly five years ago. The researchers are quick to add that they are unsure how it got there, or even if it wasn't already there and simply not at endemic levels, but now it can be found in up to 100 percent prevalence in five different major amphibian habitats on the island.

"Representatives of all native anuran (frogs, toads, and other non-tailed amphibians) families have tested Bd-positive, and exposure trials confirm infection by Bd is possible. Bd's presence could pose significant threats to Madagascar's unique "megadiverse" amphibians," the study authors wrote in their report.

This was determined after an international team of researchers examined skin swabs and tissue samples from 4,155 amphibians tested for Bd between 2005 and 2014.

A stunning number of these samples, representing all 500+ species of frogs in Madagascar - which in turn represent about seven percent of the world's total number of amphibian species - tested positive for the fungus.

What subsequent field studies didn't find, however, was sick frogs. That's despite Bd epidemics in the rest of the world causing mass-deaths and even extinctions of entire species. A PNAS study published back in 2010 revealed that one forest in Panama even lost 30 species to the fungus over the course of a single year. (Scroll to read on...)

An Bd infected frog goes rigid as the fungus causes its skin to overproduce keratin and harden.
(Photo : Wiki CC0 - Forrest Brem) An Bd infected frog goes rigid as the fungus causes its skin to overproduce keratin and harden.

"If we are talking about impacts in terms of biodiversity, the loss in Madagascar would be much higher [than previous loses]," researcher Gonçalo Rosa, from the Durrell Institute of Conservation and Ecology, recently told The Guardian.

Still, Madagascar's unique amphibian megaverse may be a blessing in disguise. There is a small chance that the Bd variant found there is not particularly deadly, or the unique genetics of the region include a resistance to the fungus - which normally hardens amphibian skin and even dehydrates them.

Or, as Rosa's colleagues fear, the disease simply is being seen in its earliest stages, with the worst yet to come.

Still, there's certainly no time for panic. Researchers are even now working to better understand how Bd works and why it is so wildly killing off nature's amphibians. They hope to be able to identify what species are most likely to survive a pandemic, helping conservationists prepare even if humanity does not intervene.

For more great nature science stories and general news, please visit our sister site, Headlines and Global News (HNGN).


- follow Brian on Twitter @BS_ButNoBS


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