Amphibians in decline

The amphibian decline crisis first became apparent in the late 1980s, when biologists began to realise that many amphibians that had previously been abundant simply weren't there any more. Of particular concern were 'enigmatic' declines, meaning the disappearance of amphibians from national parks, nature reserves and other localities where there was no habitat destruction going on and where biodiversity is, supposedly, protected. 

Over the last 20 years, a great deal of research has been carried out into the causes of amphibian declines. As well as habitat loss and disease, these include: climate change that has altered rainfall patterns; increased ultra-violet radiation resulting from reduced ozone in the Earth's atmosphere; pollution of amphibian habitats, particularly by agrichemicals such as pesticides, herbicides and fertilizers; and over-exploitation of amphibians for food and the pet trade. 

Amphibian declines are most dramatic in tropical regions of the world, where amphibian diversity is higher and human economic development is occurring fastest. Britain is, however, experiencing amphibian declines that mirror what is going on in the rest of the world. Britain's frogs, toads and newts used to thrive in a landscape largely devoted to agriculture which contained numerous small ponds where they could breed and abundant hedgerows, woodland in which they could live on land. Since the Second World War, however, the modernisation of agriculture has meant that hedgerows have been destroyed and ponds filled in; in some rural parts of Britain, over 90% of ponds have been destroyed over the last 50 years. Creative Commons Image summerrunner2009 under CC-BY-NC-SA licence Pesticide use: one of the threats to amphibians

Amphibians lead mostly secretive lives, living under ground or hidden in vegetation and coming out only at night. Only for a brief period in spring are people aware of their presence. This may account for the fact that, until recently, people have not been aware of their rapid decline. On a global scale, this decline not only raises the alarm about the deterioration of natural habitats, but also signals a growing problem for human health. Amphibians are dependent for their survival on a plentiful supply of fresh water that is free of chemical contaminants and harmful microbes; so are people. Human population growth and climate change are combining to create a situation in which a large and increasing proportion of the human population is denied access to sufficient, clean water. The rapid decline of the world's amphibians is a warning that this most precious of natural resources is under serious threat.