Why Study Frogs?

We interviewed Bill Karasov, a UW-Madison Professor and Wisconsin Sea Grant researcher interested in wildlife toxicology (the study of how toxins in the environment affect wildlife).

Q: What is an example of the kind of research studies your students work on?

A: As shown in this picture, graduate student Robin Jung is checking tadpoles inside an enclosure that she placed in a wetland along Green Bay, Wisconsin.

As an experiment, Robin collected eggs of frogs and put them in enclosures placed in wetlands that are either relatively clean or relatively contaminated. Do you think that eggs and tadpoles do better in less contaminated environments?

Q: Why study frogs?

A: The eggs, larvae and adults are food for many fish, birds and mammals. When amphibians are contaminated, they pass toxins along to their predators.

When amphibians disappear, this can affect those other animals. And, like the miners' canaries, a decline in amphibians is like a red flag, warning us that something is wrong with the environment that we all share. Finally, many of us have an ethical sense that we should protect life on earth as best we can.

Q: What research projects are you working on now?

A: I am interested in wildlife toxicology, the study of how toxins in the environment affect wildlife. We are studying whether frogs living in a contaminated ecosystem lay eggs that will hatch normally into tadpoles that grow and mature normally.

We are especially interested in whether the sex organs (gonads) of frogs that metamorphose from tadpoles growing in the contaminated ecosystem are normal. This is because some contaminants in the environment are thought to disrupt sexual development. In the laboratory we are testing some of these chemicals for their effects on frogs.

Q: How do you conduct your research?

A: We study leopard frogs (Rana pipiens), green frogs (Rana clamitans), and American toads (Bufo americanus). We picked them because they are common enough in the ecosystem that we can reliably find them to study, and we know that if we collect some we are not harming their populations.

We collect eggs of these frogs and put them in enclosures placed in wetlands that are either relatively clean or relatively contaminated. This way we can study what happens right in the natural environment. We also collect eggs and adults and bring them to the laboratory where we expose them to known amounts of certain chemicals. We make many measurements on them, such as how many hatch, how fast they grow, how long it takes them to metamorphose (turn from tadpoles to frogs), how much chemical ends up in their bodies, whether their organs are normal, and how some enzymes in their bodies react to the chemicals.

Q: What tools and technology do you use?

A: We use microscopes to look closely at tissues, centrifuges to separate and isolate specific parts of cells of tissues, spectrophotometers to measure amounts of contaminants or levels of enzymes in tissues, chromatography to measure amounts of certain chemicals or proteins, and computers to analyze all the data.

Q: What advice would you give a student interested in your field?

A: This is a really interesting and exciting field for those who love biology and are concerned about protecting wildlife and the environment.

If you want to help advance knowledge about wildlife toxicology it is best if you study both natural history and fundamentals of modern biology and its techniques. You should like studying new things, because we are always learning more and more through science, and even professional scientists have to keep learning to keep up!