September 1, 2008

Researchers Set Out To Rediscover Rare Amphibians

Scientists from Manchester University and Chester Zoo have ventured into Costa Rica with hopes of finding some of the world's most endangered frogs.

Their journey will take them deep into the forests of Monteverde where they will be on the lookout for the rare amphibians, including the golden toad, last seen about 20 years ago.

"Costa Rica's highlands used to be major biodiversity hotspots - but in many areas, amphibian populations have been completely decimated," said team leader Andrew Gray, from the University of Manchester's Manchester Museum.

In the 1980s, herpetologists noted that amphibian populations were declining, but were unable to pinpoint the reasons why.

A decade later, researchers isolated a previously unknown fungus, Batrachochytrium dendrobatidis, which was infecting amphibians, effectively suffocating them by making it impossible for them to breathe across their skin.

Nearly one-third of all amphibians are threatened with extinction and about 120 species are already extinct, according to the Global Amphibian Assessment.

Many experts blame the disease caused by the chytrid fungus, which is widespread among regions in Central America. Other causes are thought to include habitat destruction and changes in climate.

"For the last 10 years, I've been working with others to ensure the future for frogs that have so far escaped extinction," Gray said.

"One of the main things I have been doing is establishing breeding populations in Manchester Museum for a number of very, very rare species - including the splendid leaf frog (Cruziohyla calcarifer), the yellow-eyed leaf frog (Agalychnas annae) and the lemur leaf frog (Hylomantis lemur).

"I've also been working with the Costa Rican authorities and scientists to put conservation measures into place at the sites where any rare frogs are found."

Last year, Gray caught a glimpse of the Ithsmohyla rivularis in the cloud forests of Monteverde - a frog that was thought to have gone extinct about 20 years ago.

"To find this species last year that was thought to have become extinct at the same time as the golden toad was incredible - it is the rarest tree frog in the world," he said.

Now, having been given the OK by Costa Rican officials, Gray has set out to collect certain species and bring them back to Manchester.

"We are returning to thoroughly search the site in the hope of finding more specimens," Gray said.

"It's not going to be easy - they live deep in the Monteverde rainforest, they are only a couple of centimeters in size and they only come out in the dead of night - and while the males do call, the females don't make a sound."

Having been given hope from the recent find of Ithsmohyla rivularis, the team intends to spot the iconic golden toad.

Scientists only discovered the colorful toad in 1966, and by 1987 there were approximately 1,500 of them left. Two years later, the amphibian had virtually vanished from the rainforest.

"We are going to be trekking through an area where the golden toad used to thrive. It is very unlikely we will find one - but as last year's discovery showed us, never say never."

Image Courtesy U.S. Fish and Wildlife Service


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