SYDNEY – A team of scientists in Australia is investigating the causes of the unexpected recovery of frog populations in the north of the country after a devastating fungus hit them more than three decades ago, an academic said on Thursday.
An outbreak of the chytridiomycosis fungus in the 1980s and 1990s caused the decline or disappearance of various frog species in the area known as the Wet Tropics, in the northeast state of Queensland.
Researcher Donald McKnight said that the pathogen proliferates in cold and high places, and that the main area affected was on the plateaus where the populations of these amphibians are now recovering, despite the disease’s persistence.
As an example, McKnight said that the Australian waterfall frogs, which disappeared from every survey conducted in the 1990s in Girramay National Park, were detected again from 2001 onwards.
The researcher from James Cook University said in a press release that this species and others, such as the green-eyed tree frog, are now proliferating in many high places.
He added that the populations of green-eyed tree frog found in the plateau recover rapidly, and had even at one point returned to the numbers before their decline.
Changes in the frogs’ behavior, in their immune system and in the bacterial community that inhabits it are the hypothesis that the research posits to explain this recovery.
Among other theories are the possibilities that the disease has become less virulent, that there have been changes in the environment which becomes less favorable for the fungus or that the pathogenic outbreak was caused by environmental factors that have not been repeated.
Another study published earlier this year by James Cook University noted that the fungus reproduces better in temperatures between 17-25 degrees Celsius, and found that frogs of dry forest with more exposure to the sun survived better than those of tropical forests.