Today, April 29th, is Save the Frogs Day, an international day of action designed to draw attention to the plight of some of the world’s most ecologically sensitive and fast-declining species. At around 120 events in twenty countries, environmentalists will call on policymakers and national leaders to protect frogs from threats like habitat destruction and pollution. At a rally today in Washington, DC, frog enthusiasts are urging the US Environmental Protection Agency to ban the herbicide atrazine, which has been linked to the decline of at least some frog species in the United States.
Around the world frogs and toads are disappearing, and scientists estimate about a third of all species are in imminent danger of extinction. Though the exact reason for the decline continues to be a matter of debate, researchers have long speculated that frogs are particularly sensitive to changes in the environment brought on by human activity. This is partly because frogs and other amphibians absorb moisture and oxygen through their skins, and in the process may directly absorb chemical pollutants from the environment.
Frogs are also vulnerable because of their two-part lifecycle: tadpoles and adult frogs rely on different sources of food and shelter, making them twice as sensitive to ecological change. Changes to either the aquatic environment tadpoles depend on or the semi-terrestrial habitat of adult frogs can spell trouble for most frog species. Deforestation, the draining of wetlands, and disruption of natural stream patterns are all types of habitat destruction that can hit frogs hard in one or both parts of their life cycle.
In response to growing concern over the plight of frogs worldwide, frog researchers and conservationists in the scientific community sent a call for the first international Save the Frogs Day, held on April 29th of last year. This year Save the Frogs Day has become an even larger and more coordinated effort, with events planned in countries from the United States to New Zealand and from Uganda to Peru. According to the event web site, this year’s Save the Frogs Day marks “the world’s largest day of amphibian education and conservation action.”
In the United States, groups like the Center for Biological Diversity are asking the Environmental Protection Agency (EPA) to protect frogs by banning or restricting the use of atrazine. The nation’s most commonly used herbicide, atrazine persists for years in the environment after it is used and has been blamed with contributing to amphibian declines. According to at least some studies, atrazine directly affects frogs by inhibiting their ability to reproduce. Perhaps even more importantly, researchers in 2008 discovered the chemical leads to outbreaks of a parasitic worm that infects and kills frogs.
Though intended to kill weeds that compete with corn and other crops, some of the atrazine sprayed on crop fields ends up in local bodies of water where it kills algae near the water’s surface. This allows other types of algae on the bottom of a pond or stream to grow and thrive, in turn leading to a population explosion among snails that feed on this kind of algae. It turns out these snails serve as hosts for parasitic flatworms that also infect frogs. Thus atrazine in the environment sets off a chain reaction that increases frog mortality.
The Center for Biological Diversity is calling on the EPA to ban the use of atrazine, or at least re-evaluate its impacts on frogs and other wildlife. According to the Center, recent studies that show how atrazine harms frogs need to be taken into account as the EPA decides whether to continue allowing the chemical’s use. As frog species around the world continue to decline, this could be a critical step that helps frogs in the United States recover from the brink of extinction.
Photo credit: flickr.com/photos/38635364@N00/23052798/sizes/m/in/photostream/