Where have all the frogs gone? Frogs and other amphibians are dying off worldwide at an alarming rate. Many species have gone extinct already. But why?
Amphibians as a class include frogs, salamanders, and toads. They have been around for 350 million years, and inhabit a wide variety of habitats around the world. The young are born from eggs, usually within an aquatic environment. They enter a larval stage with gills that are similar to those of fish. For frogs, we call this stage a tadpole. During their metamorphic stage, they grow lungs and legs so that they can live on land. However, frogs have a second way to transport oxygen into the body. They breathe through their skin. This is called cutaneous respiration. This is an important difference that exists between amphibians and reptiles. Amphibians are much more vulnerable to being poisoned by toxins in their environment.
Several theories have been offered by scientists to account for the dwindling populations of frogs. These include:
1. Habitat destruction or modification
4. Introduction of foreign species.
5. Climate change
6. Endocrine-disrupting pollutants
7. Destruction of the ozone layer. Ultraviolet radiation is not filtered properly without ozone, and has been shown to be especially damaging to the skin, eyes, and eggs of amphibians.
8. Fungal and other diseases.
Because of their sensitivities to changes in their environment, the death of frogs and other amphibians acts as a warning that these changes, in large part produced by man, are unhealthy to the biosphere. Frogs are the canary in the coal mine. Their disappearance is an alarm that indicates that something is going terribly wrong. The reduction in the numbers of frogs can also have a deleterious effect on the environment. For instance, with fewer tadpoles to consume algae, ponds can become deficient in oxygen for the aquatic species that depend on it. The loss of frogs also places pressure on the predators that depend on them for food. This significantly disrupts the food web.
Conversation projects are underway to help mitigate the declines in amphibian populations. Several organizations now exist to help manage environments and develop a greater understanding for how amphibian extinction works, and the how we can prevent it. Who knows? We may end up preventing our own extinction at the same time.
Blog posts are written by Shore House members and staff.