A message from Professor Tim Halliday, |
| Why you should care about the global decline of amphibians In the last 20 years, several species of amphibians (frogs, toads, newts and salamanders) have gone extinct. The World Conservation Union (IUCN) recently published its Global Amphibian Assessment, concluding that 32% of the world’s 5743 known amphibian species are threatened by extinction. Data gathered by the IUCN/SSC Declining Amphibian Populations Task Force (DAPTF) reveals that, of 3020 amphibian populations that have been monitored in recent years, 21.5% have declined and 10% have become extinct. These figures are clear evidence that the natural systems that support all forms of life are collapsing. While many amphibian declines have occurred in parts of the world where expansion of human populations and activity has destroyed natural habitat, many have occurred in protected areas, such as national parks, that were specifically created to protect biodiversity. In the words of David Wake, co-founder of the DAPTF, ‘putting a fence around biodiversity isn’t working’. Amphibian populations are being adversely affected by a number of factors, notably climate change, chemical contamination and increased ultraviolet radiation, against which protected area designation is ineffective. This raises serious questions about a fundamental assumption of national and international policy on the protection of biodiversity, that we can set up areas around the world where plants and animals are ‘safe’. Amphibian populations are dependent, to varying degrees, on access to clean freshwater habitats, for their survival. The recent dramatic declines among amphibian populations and species suggest that all is not well in the freshwater biome. The World Wildlife Fund for Nature maintains a Living Planet Index, based on continuous monitoring of 323 plant and animal species around the world. In 2004, it was reported that, between 1970 and 2000, biodiversity in the world’s freshwater habitats fell by 50%. This makes fresh water the most threatened of the world’s biomes, more threatened even than tropical forest. Amphibian declines are but one symptom of a profound malaise affecting global supplies of fresh water, on which all terrestrial biodiversity, and human life, depends. A feature of many amphibian declines, including some that have occurred in protected areas, is that they have been very rapid; populations, and whole species, have gone from abundance to extinction in two or three years. A major factor in this process has been infectious disease, particularly a fungal infection called chytridiomycosis. The fact that chytridiomycosis only affects amphibians should not make us complacent, and we should not regard it as an anomalous event. All forms of life are susceptible to infectious disease, and a remarkable feature of chytridiomycosis is that it appears to have become globally distributed in a very short space of time; how this has happened is not clear. We need urgently to find out, because what chytridiomycosis can do, other diseases, of wild plants and animals, of crops, of domestic animals, of human beings, may also be able to do. Chytridiomycosis may be but one disease that humans have helped to spread around the world. In describing what is going on in the world at present, biologists and politicians tend to use vague euphemisms such as ‘biodiversity crisis’. The reality is that we are witnessing a major, global extinction event, the extent of which we can only guess. Amphibian Declines are part of a major, and presently unpredictable change in life on Earth. As long ago as 1952, Rachel Carson predicted a ‘Silent Spring’ if humans did not change their relationship with the natural environment. For many amphibians, the silent spring has become a reality, and in many parts of the world the call of frogs has been silenced. Tim Halliday DAPTF website • What you can do about Declining Amphibian Populations • Midwest Frogs Home Page |