March 18, 2009

‘Chicken Frog’ Latest Victim Of Deadly Fungal Disease

The "mountain chicken frog" of the tiny Caribbean island of Montserrat is the latest victim of a lethal fungal disease that is devastating amphibian populations throughout the world.

British researchers say that just two small pockets of mountain chicken frogs (Leptodactylus fallax) are all that remain disease-free on the entire island.  Conservationists are working to take the surviving frogs, some of the world's largest, into captive breeding programs.

Experts believe the chytrid fungus entered Montserrat on small frogs stowing away in consignments of produce from Dominica.

"We've always been afraid that frogs coming in banana consignments from Dominica would bring chytrid and that it would then spread into the center of the island," John Fa, director of conservation science at Durrell Wildlife Conservation Trust, told BBC News.

"The northern populations are closer to the port, and the disease appears to have spread southward along the river systems."

"Essentially, all populations to the north and north-west of the center hills have been decimated, and there are just two remaining populations of seemingly healthy animals in the south-eastern corner."

A 2005 expedition found no sign of fungal infection.

Hunting was already beginning to impact populations of the frogs in both Caribbean islands prior to the arrival of the chytrid.  The islands are the only places on Earth where the frogs occur naturally.

A significant percentage of Monserrat's chicken frog populations were also affected by the volcanic eruptions that started in 1995.  However, the creation of an "exclusion zone" around the volcano's slopes has provided some relief to wildlife by shielding it from human forces.

Events on Montserrat now appear to be repeating what occurred on Dominica in 2002, when 80 percent of the island's mountain chicken frogs were devastated within 15 months of the fungus arriving.

The fungus (Batrachochytrium dendrobatidis), first identified over ten years ago, has spread through hundreds of amphibian species throughout the world.  It some species, extinction results in a matter of months, while others are seemingly immune.

"We still don't know how chytrid kills frogs, and there's some very basic stuff about the biology of the fungus that we need to understand," said Andrew Cunningham from the Zoological Society of London, in an interview with BBC News.

"We've known about it for 10 years, but so little money has been spent on it.

"If this was killing mammals or birds in the same way it's killing amphibians, millions and millions would have been spent on it."

Chemicals can be used to rid amphibians of the fungus in captivity, but there is currently no way to cure them in the wild, or to eradicate infected water bodies.  Because of this, conservation groups are working towards establishing captive populations.

Durrell and other conservation organizations already have mountain chicken in captivity, and will be gathering more from the healthy Montserrat populations in the weeks ahead.

Unlike some other initiatives, however, the organization plans to treat and return some frogs to the wild within a few years, placing them in areas that are chytrid-free.


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