Frogs are evocative of the fragility of nature. Their slight, but flexible forms are suited to only the most specific freshwater environments. Despite their seeming fragility, frog species have survived for 250 million years, outliving dinosaurs on earth. While they have been remarkably effective in their environmental niches, they are also very susceptible to change and thus we can consider the demise of frogs as an important environmental indicator.
Frogs have very permeable skins: they can breathe through their skins, which makes them very well suited to cope with an aquatic life. Unfortunately this increases their risk of absorbing undesirable elements like chemicals, fertilizers and pesticides that contaminate the water they live in. The American Glass Frog for instance, has skin so thin that it’s organs are visible. The bad news is, frog numbers are in serious decline worldwide. Conservation International (CI) estimated that about 170 species of frogs and toads have become extinct worldwide. The Global Amphibian Assessment carried out between 2004-2008 found that 43% of existent species are at risk of disappearing. At least nine species have gone extinct since 1980. Another 113 species have not been found in recent years and are considered to be possibly extinct.
The decline in frog populations is indicative of a global biodiversity crisis, “Amphibians are telling us that there is something wrong with our ecosystems”, says CI spokesperson Robin Moore. Amphibian expert at the University of California, David Wake says the disappearance of such evolutionary successes, “seems to point to the extreme deterioration of our environment.” Climate change, acid rain, parasites, alien species predation, herbicides, pesticides and other pollutants in our waterways including sewerage may be to blame. In 2008, a serious decline in the Brazilian and Australian frogs was found to have been caused by a suffocating fungus, made more common by the decline in environmental health. In 2010, a common herbicide, atrazine, was found to cause gender change in frogs in the U.S. Thinning of the ozone layer has also been implicated in some frog decline cases, the excess of UV said to disrupt the development of frog embryos. Indeed, frogs are disappearing from seemingly untouched, pristine natural environments in isolated places deep in South American forests, making a case for climate change and ozone depletion.
The survival of frogs is important to humans and planetary ecosystems alike. Frogs perform important ecosystem services by controlling insects that transmit diseases and many hold medical potential for humans. For instance, the venom of poison frogs, used by indigenous hunters in Central and South America, are being used to create new painkillers.
Protection and rehabilitation efforts are underway. The US Environmental Protection Agency has established plans to protect frogs from environmental contaminants, but has also faced numerous lawsuits on it’s failure to do so. In 2010, 1.6 million acres of land in California was designated as a protection zone for the Californian red-legged frog after public distress about it’s decline.
You can help slow the decline of frogs. Volunteer with a local watershed or conservation group, plant native species in your garden, or (if you have the space) start a frog pond. Frog ponds are easy to establish and many local city councils and local ecology groups exist that can help you identify the species in your area, and find the species necessary to your pond to attract them.
Lastly, we all need to do whatever we can to minimize the impact of climate change that is contributing to the loss of frog populations. As Alan Pounds, the resident ecologist at the Tropical Science Center, located in the Monteverde Cloud Forest Preserve in Costa Rica pointed out, “We should be listening to the message from the frogs. They are warning use about environmental deterioration that threatens all species and our own well being”