An international team of amphibian experts including Museum Curator Christopher Raxworthy has discovered that a fungus responsible for the precipitous decline of frog populations worldwide has now been detected in Madagascar.
In a paper published today in the journal Scientific Reports, the researchers document the detection of Batrachochytrium dendrobatidis (Bd) in the island’s wild amphibians. The discovery is already spurring conservationists to action in Madagascar, which is home to about 7 percent of the world’s amphibian species.
“For many years, it appeared that Malagasy frogs had been living in a Bd fungus-free zone of the world, protected by the natural island isolation of Madagascar. However, our results now clearly show that this is not the case,” said Raxworthy, a co-author on the paper who helped collect the first frog specimens that tested positive for Bd, which causes the infectious amphibian disease chytridiomycosis.
The fungus was first discovered in 2010-11 in Madagascar’s remote Makay Massif, in the south-central region of the island. Surprisingly, this area is far from seaports, airports, and major towns and roads, and so does not fit a typical pattern of human introduction.
For their study, the researchers screened more than 4,100 amphibians across Madagascar and confirmed the presence of Bd in five locations on the island. It appears to follow a seasonal pattern, with greater detectability during the dry season.
Now the paper’s authors are working on determining whether the fungus they have detected belongs to the same deadly strain that is threatening more than one third of the planet’s amphibians. Bd has been detected in more than 500 species worldwide, and at least 200 species have declined as a result of chytrid infection.
So far, there have been no frog deaths reported in Madagascar that are associated with Bd, but the researchers say that shouldn’t prevent the development of an aggressive strategy for monitoring, preventing, and mitigating the infection.
“The hope now is that the Bd fungus strain in Madagascar will be non-threatening to the native frogs,” said Raxworthy. “But we need to very carefully monitor the situation in the wild, as experimental trials have already shown that Malagasy frogs are vulnerable to the deadly strains of this fungus.”
Madagascar harbors an extraordinary array of amphibian diversity, with more than 290 described species and over 200 undescribed candidate species.
“Ninety-nine percent of the frogs in Madagascar are only found in Madagascar,” said Falitiana Rabemananjara, coordinator of the Chytrid Emergency Cell in Madagascar and co-author on the paper. “That means that if the Bd presence in Madagascar is lethal or becomes lethal to frogs, we could lose a significant portion of the world’s amphibian diversity. With an integrative, proactive approach, we are going to do everything we can to prevent that from happening.”
“We know how bad this could be, but this time we can still make a difference by preventing the kinds of mass die-offs we’ve seen in other countries,” said Reid Harris, co-author on the paper and director of international disease mitigation for the Amphibian Survival Alliance (ASA). “Together, the global conservation community is addressing the emergency at its inception, putting into practice what we’ve learned in the midst of—or even after—extinctions in places like Central America.”