Leaping to frogs' defence

CRAIG SIMCOX/Dominion Post

HOP TO IT: Frogs are under threat of extinction, but the preservation of some species has been aided with their transfer to Karori Wildlife Sanctuary, says associate professor Ben Bell.

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The threat of extinction frogs are under is the greatest ever faced since the disappearance of dinosaurs.

All Blacks fanatics smarting from the French defeat in the rugby World Cup may not appreciate it just yet but zoologists have declared 2008 International Year of the Frog.

Of course it has nothing to do with the French people, but rather the drastic decline in the number of species of the amphibian.

Phil Bishop of Otago University is leading activities for New Zealand Frog Week, which starts on Sunday.

Faced with a declining population, and in many cases even extinction, Dr Bishop said the consequences for the frog were grim.

Activities next year include an international frog day aptly timed for leap day, February 29, and others to coincide with the green- wearing St Patrick's day.

The forthcoming week was to raise public awareness about the frog but declaring an entire year in the creature's honour also had more serious reasons.

"Extinction is rather serious as there is nothing you can do to reverse it," Dr Bishop said.

In 2005 a global amphibian assessment determined that 2000 frog species were under threat. Dr Bishop called it the greatest possible extinction of species ever faced since the disappearance of dinosaurs.

"If we don't do anything about it in the next five or ten years we could lose 500 species."

Factors including subtle climate changes, the introduction of herbicides to the environment and frogs' increasing proximity to predators were all endangering the species.

The rate of extinction, currently estimated at 33 per cent, far exceeded the 23 per cent for mammals and 12 per cent for birds. In New Zealand scientists' attention was focused on the four species of native frog and three species of introduced frog.

With associate professor Ben Bell of Victoria University's school of biological sciences, Dr Bishop had instigated the Frog Research Group to provide a central focus to ensure the amphibian's protection.

The Archey's frog was already in dramatic decline.

Dr Bishop said research was focusing on chytrid fungus which was prevalent in introduced frogs but it was still to be determined what its role was in the decline of native frogs.

Professor Bell estimated the decline over five years in Archey's frogs as high as 80 per cent. He described other species such as the Cook Strait frog, Maud Island frog and Hamilton's frog as "holding their own". The preservation of some had been secured with their transfer to Wellington's Karori Wildlife Sanctuary.

Otago University had developed a protocol for curing the fungus in the laboratory but wanted to extend those studies to amphibians in the wild.

"We want to exactly work out how the fungus gets transferred from frog to frog," Dr Bishop said.

Unearthing this mystery could go a long way toward preserving a multitude of species of the frogs Dr Bishop described as playing a "critical" part in a healthy natural world.

"They play an important role in the food web of both its predators and prey. A lot of animals depend on amphibians for a food source and areas where frogs have been removed you get a huge increase in insects and insect borne diseases like dengue fever and malaria."

Frogs' sensitivity to contaminants in the air, soil and water meant they acted as environmental "biomonitors" and a warning system to humans if there was anything harmful in the environment.

Amphibians' skin secretions, which were normally resistant to infection by bacterial fungi, contained many chemicals used in human medicine.

Many antibiotics were derived from frog secretions and last year they found a chemical active against the HIV virus – and the potential to maybe find a cure against Aids, Dr Bishop said. "So there's a lot of untapped potential in frog skin that we don't know, and if we don't act soon we'll never know because they'll disappear."

- © Fairfax NZ News