Karen R. Lips

What's killing the frogs?

For reasons that are difficult to fathom, people have a special place in their hearts for frogs. Frogs are odd-looking creatures with Karen Lips, in her Carbondale office. (Powledge.)

Karen Lips, in her Carbondale office. (Powledge.)

qualities that both mystify and entrance humans. They can breathe through their skins, live both in and out of the water, hop amazingly well, have an intriguing life cycle, snare insects with their outrageously long tongues, and have great big eyes that keep tabs on everything around them. Some are camouflaged to near-invisibility, while others display bright colors seldom seen elsewhere in nature. Some frogs can be turned into poison strong enough to kill mammals.

And now something is killing the frogs themselves. Perhaps because of the mystery surrounding their deaths, perhaps because of humans’ special fondness for frogs, science has plunged headlong into studying what it calls a global decline in amphibians.

Many theories. Many theories have been advanced to explain what seems to be a sudden and unprecedented surge in the death of frogs, toads, and salamanders in many of the places where they once thrived. Frogs have received most of the attention.

Habitat destruction by humans, often cited as the leading enemy of global biodiversity in general, is a frequently mentioned candidate; the draining of wetlands is particularly devastating to amphibians.

Among the other possibilities are climate change (including drought); acid precipitation; pesticides and fertilizers; excessive ultraviolet radiation (UV-B) caused by thinning of Earth’s ozone layer; normal fluctuations that take place in any population; a yet-to-be-identified substance in the water where amphibians live; predation by exotic species, such as fish introduced to streams for sport or food, that consume the frogs’ eggs and larvae. Some scientists seek diseases caused by microscopic agents, such as fungi or viruses.

Deformities, too. To complicate the mystery, it’s not just that the frogs are dying off. In many areas, researchers are finding amphibians that lack eyes or legs and demonstrate other deformities. And to compound matters even further, science is hindered in its work by a lack of useful baseline data. Frogs have always been around, and it was easy to assume they would continue to be around.

There were few surveys of amphibians in remote places, such as the higher elevations in Central America, where human disturbance has been minimal and where exposure to synthetic chemicals and introduced predators were not a problem. And yet it is in these near-pristine places where many recent die-offs have been recorded. These are the places where Karen Lips does her work.

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