Alarm as global study finds one-third of amphibians face extinction

[Guest guest]

http://news.independent.co.uk/world/environment/story.jsp?story=572318

 

Independent

 

 

October 15, 2004

 

Alarm as global study finds one-third of amphibians face extinction

By: Steve Conner

Independent, The

 

They were the first animals with backbones to walk on land. They

witnessed the rise and fall of the dinosaurs and were present at the

birth of a bipedal ape who went on to become the most destructive

species the planet has ever known.

 

Amphibians - frogs, toads, newts and salamanders - are among the

longest surviving animals on earth, yet something dramatic now

threatens that longevity. And mankind is responsible.

 

A global study revealed yesterday that almost a third of amphibians

face extinction - and pollution is cited as the biggest cause. The

three-year survey, involving 500 scientists from more than 60

countries, has found that a third of the 5,743 known species are

threatened with being wiped out and at least 427 are so critically

endangered that they could disappear tomorrow.

 

The animals are so sensitive to the man-made environment that

scientists have likened them to the canary in a coal mine - songbirds

that fell silent, killed in the presence of odourless gas. The latest

and most comprehensive study of amphibians around the world has shown

that for many species of frogs and their nearest relatives the singing

has suddenly and inexplicably stopped - and the same bipedal ape is

almost certainly responsible.

 

" This is a problem way outside what we know, " said Simon Stuart of the

World Conservation Union and leader of the study published in the

online version of the journal Science.

 

Dr Stuart said: " This level of decline is ... extraordinary and

serious because amphibians represent a very important part of the

overall diversity of life. Since most amphibians feel the effects of

pollution before many other forms of life, their rapid decline tells

us that one of earth's most critical life support systems is breaking

down. "

 

The figures in the survey are almost certainly underestimates because

more than 22 per cent of the known amphibian species are too poorly

understood for the researchers to reach a reliable conclusion about

what is happening to them.

 

Populations of almost half of the known amphibian species are in

decline. While 32 per cent of amphibians are threatened with

extinction, only 12 per cent of birds and 23 per cent of mammals are

in the same position. The latest study estimates that up to 122

species have gone extinct since 1980.

 

Dr Stuart said that all animal groups undergo a natural " background "

rate of extinction but, in the case of amphibians, the actual loss of

species is equivalent to the total number of background extinctions

for many tens of thousands of years being squeezed into a single century.

 

" The bottom line is that there's almost no evidence of recovery and no

known techniques for saving mysteriously declining species in the

wild. It leaves conservation biologists in a quandary, " Dr Stuart said.

 

Amphibians are considered uniquely sensitive to man-made changes in

the environment. Their moist, porous skins are vulnerable to

water-borne toxins and infections, and their reliance on two habitats

- freshwater and land - means they cannot survive properly without both.

 

Scientists have suggested many possible reasons for the decline.

Pollution of both water and the atmosphere, human exploitation for

food and medicine and habitat destruction all pose serious threats.

 

But it is clear that amphibians are also disappearing from what appear

to be pristine habitats. At one protected site in Costa Rica, for

instance, some 40 per cent of amphibians disappeared over a short

period in the late 1980s. Other losses occurred almost simultaneously

in Costa Rica, Ecuador and Venezuela.

 

It is this so-called " enigmatic decline " that poses the biggest

problem for conservationists simply because they have little idea

about what needs to be done to address the problem.

 

The authors of the report say: " Enigmatic decline species present the

greatest challenge for conservation because there are no known

techniques for ensuring their survival in the wild. Most enigmatic

declines have been recorded from the Americas south to Ecuador and

Brazil, Australia and New Zealand, but they are spreading, for

instance to Peru, Chile, Dominica, Spain and Tanzania. "

 

Many of these mysterious disappearances seem to take place in tropical

habitats involving amphibians living in mountain streams. Some studies

suggest they may be linked with the global spread of a fungus called

chytridiomycosis, which may be exacerbated by global warming. What is

most worrying is that the decline in amphibians is occurring across

the world.

 

Bruce Young, a zoologist who took part in the global amphibian

assessment, said: " We already knew amphibians were in trouble, but

this assessment removes any doubt about the scale of the problem. " Dr

Achim Steiner, director general of the World Conservation Union, said:

" The fact that one third of amphibians are in a precipitous decline

tells us that we are rapidly moving towards a potentially epidemic

number of extinctions. "

 

Russell Mittermeier, president of Conservation International, said:

" Amphibians are one of nature's best indicators of overall

environmental health. Their catastrophic decline serves as a warning

that we are in a period of significant environmental degradation. "