Open Eye: It's time to worry about the frogs

What does the declining population of amphibians mean? Yvonne Cook reports

Where are the frogs going? The fate of amphibians has been worrying experts worldwide over the last nine years. And evidence is emerging that more of us should be worried too.

It first became apparent in 1989, that species of frogs and toads had started to vanish, quite suddenly, in locations as far apart as South America, Australia and the Pacific northwest of the USA.

More worryingly, they were disappearing not only from areas where their habitats were under threat, but from nature reserves, national parks and other areas set up to protect wildlife.

Out of the experts' concern was born the Declining Amphibian Populations Task Force, a global organisation of scientists and volunteers, which since 1991 has been based at the Open University in Milton Keynes. Tim Halliday, Open University Professor in Biology, is its international director.

"The declining amphibian phenomenon seemed to be telling us two things. First, it cast serious doubt on the assumption that animals can be protected by setting up reserves. Second, it suggested that amphibians were subject to some adverse environmental process that affects them on a global scale," said Tim.

The second conclusion was highly disputed, with some experts claiming the declines were due simply to natural population fluctuations.

As the Task Force put together data collected from its 3000-plus members and 100 regional groups across the world, certain things became clear: the declines were occurring globally, but not in all regions of the world; and while many declines could be explained by human activities such as deforestation, draining of wetlands and changes in farming practices, some could not.

Attention began to focus on environmental factors, and disease. Amphibians - frogs, toads, newts and salamanders - are found on every continent except Antarctica. The American continent is particularly rich in species. In one reserve in Costa Rica alone, 20 out of 50 frog species have apparently become extinct within the last 20 years.

Tim Halliday calls amphibians an 'environmental barometer'. "Amphibians are particularly dependent on clean water. They have very thin skins, through which water passes easily, so they are extremely susceptible to pollutants such as herbicides and pesticides."

But the evidence from Task Force data was pointing to another factor. This came into the limelight in June this year with the publication of a paper which pinned responsibility for recent dramatic declines on a fungal infection, chytridiomycosis, which appears to be a new disease.

What surprised scientists, said Tim, was that dead and dying frogs found as far apart as Australia and Central America, were suffering from this same disease.

"One possibility is that this disease has been carried from one place to another by some agent - people, or fish, for example. The other is that it's one of those diseases that exist in the amphibian population worldwide, but amphibians have only just become susceptible to it. This would point to something in the environment which is reducing their resistance to the disease."

Parallels for this exist in patterns of human disease - some have suggested the rising incidence of asthma could be due to a reduction in people's level of resistance. On a more mundane level, we all carry the virus that causes cold sores around with us, but it is only when we're tired and "run down" that it strikes.

So why should amphibians be becoming more susceptible? More evidence is needed before this question can be answered, but the suspicion that environmental stress may play a part is strong.

Possibilities include chemical pollution but also global warming or the reduction of the earth's ozone layer. It is known from other work that some amphibian species are vulnerable to increased levels of ultraviolet radiation caused ozone reduction.

"People in different parts of the world are trying to raise money for a rapid reaction force, so that if there are reports of dead or dying frogs anywhere we can get someone there quickly to investigate," said Tim.

"At the moment we don't know how widespread it is, or what percentage of frogs are affected." Whether it could affect newts or salamanders is not known either, nor exactly how it is spread, although the Task Force has recently produced guidelines for anyone involved in amphibian research to try and prevent their inadvertently spreading the disease from one site to another.

The good news is that no cases of the disease have yet been found in Britain. As well as collecting data, the Task Force is concentrating on raising awareness - and money, to fund research into potential causes of decline. But its time is running out - collecting evidence must ultimately be translated into action, says Tim.

"We will probably produce a final report for the year 2001, which is going to be a big year for biodiversity, and then we are going to stop what we're doing. We'll hand over to other people what we have found, and let them do what they want to do with it.

"The hope is the Task Force will be followed by a global conservation organisation. In the meantime, perhaps we should all be grateful to the frogs."

Tim says: "Because of their great sensitivity to changes in habitats they may be giving us early warning of major and widespread environmental change. And the factors that have been shown to affect amphibians, like solar radiation and chemical contamination, affect all forms of life, including humans."

More information about the Declining Amphibian Populations Taskforce is available on: www.open.ac.uk/OU/Academic/Biology/J_Baker/JBtxt.htm.

The taskforce's quarterly newsletter FROGLOG is also available on the Web; or write to:

Professor Tim Halliday

Department of Biology, Open University, Walton Hall, Milton Keynes MK7 6AA, UK

Start your day with The Independent, sign up for daily news emails
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs Education

Guru Careers: Graduate Software Developer / Junior Developer

£20 - 28k + Benefits: Guru Careers: We are seeking a Graduate Software Develop...

Recruitment Genius: Graduate Trainee Teacher - Maths

£18000 - £21000 per annum: Recruitment Genius: This organization is the larges...

Guru Careers: Graduate Software Developer / Junior Developer

£20 - 28k + Benefits: Guru Careers: We are seeking a Graduate Software Develop...

Reach Volunteering: Would you like to volunteer your expertise as Chair of Governors for Livability?

Voluntary and unpaid, reasonable expenses are reimbursable: Reach Volunteering...

Day In a Page

Fifa corruption: The 161-page dossier that exposes the organisation's dark heart

The 161-page dossier that exposes Fifa's dark heart

How did a group of corrupt officials turn football’s governing body into what was, in essence, a criminal enterprise? Chris Green and David Connett reveal all
Mediterranean migrant crisis: 'If Europe thinks bombing boats will stop smuggling, it will not. We will defend ourselves,' says Tripoli PM

Exclusive interview with Tripoli PM Khalifa al-Ghweil

'If Europe thinks bombing boats will stop smuggling, it will not. We will defend ourselves'
Raymond Chandler's Los Angeles: How the author foretold the Californian water crisis

Raymond Chandler's Los Angeles

How the author foretold the Californian water crisis
Chinese artist who posted funny image of President Xi Jinping facing five years in prison as authorities crackdown on dissent in the arts

Art attack

Chinese artist who posted funny image of President Xi Jinping facing five years in prison
Marc Jacobs is putting Cher in the limelight as the face of his latest campaign

Cher is the new face of Marc Jacobs

Alexander Fury explains why designers are turning to august stars to front their lines
Parents of six-year-old who beat leukaemia plan to climb Ben Nevis for cancer charity

'I'm climbing Ben Nevis for my daughter'

Karen Attwood's young daughter Yasmin beat cancer. Now her family is about to take on a new challenge - scaling Ben Nevis to help other children
10 best wedding gift ideas

It's that time of year again... 10 best wedding gift ideas

Forget that fancy toaster, we've gone off-list to find memorable gifts that will last a lifetime
Paul Scholes column: With the Premier League over for another year, here are my end of season awards

Paul Scholes column

With the Premier League over for another year, here are my end of season awards
Heysel disaster 30th anniversary: Liverpool have seen too much tragedy to forget fateful day in Belgium

Liverpool have seen too much tragedy to forget Heysel

Thirty years ago, 39 fans waiting to watch a European Cup final died as a result of a fatal cocktail of circumstances. Ian Herbert looks at how a club dealt with this tragedy
Amir Khan vs Chris Algieri: Khan’s audition for Floyd Mayweather may turn into a no-win situation, says Frank Warren

Khan’s audition for Mayweather may turn into a no-win situation

The Bolton fighter could be damned if he dazzles and damned if he doesn’t against Algieri, the man last seen being decked six times by Pacquiao, says Frank Warren
Blundering Tony Blair quits as Middle East peace envoy – only Israel will miss him

Blundering Blair quits as Middle East peace envoy – only Israel will miss him

For Arabs – and for Britons who lost their loved ones in his shambolic war in Iraq – his appointment was an insult, says Robert Fisk
Fifa corruption arrests: All hail the Feds for riding to football's rescue

Fifa corruption arrests

All hail the Feds for riding to football's rescue, says Ian Herbert
Isis in Syria: The Kurdish enclave still resisting the tyranny of President Assad and militant fighters

The Kurdish enclave still resisting the tyranny of Assad and Isis

In Syrian Kurdish cantons along the Turkish border, the progressive aims of the 2011 uprising are being enacted despite the war. Patrick Cockburn returns to Amuda
How I survived Cambodia's Killing Fields: Acclaimed surgeon SreyRam Kuy celebrates her mother's determination to escape the US

How I survived Cambodia's Killing Fields

Acclaimed surgeon SreyRam Kuy celebrates her mother's determination to escape to the US
Stephen Mangan interview: From posh buffoon to pregnant dad, the actor has quite a range

How Stephen Mangan got his range

Posh buffoon, hapless writer, pregnant dad - Mangan is certainly a versatile actor