Fishing for Toxins

Spending a summer on a boat in a Maine river doesn't sound like work.

But for Blake Whitaker, associate professor of natural and applied sciences at Lewiston-Auburn College (LAC), the Androscoggin and Kennebec Rivers are field sites for his study of damage that has been done to the river fish by chemical contamination. To test for toxic chemical mixtures in Maine rivers, Whitaker and his students have been taking samples of small mouth bass from Maine waters, then using genetic analysis to determine the amount of damage in the fish.

The need for Whitaker's research is based on a recent realization that chemicals introduced into the environment mix and continue in combined form. For years the U.S. Environmental Protection Agency set safety standards based on studies of single chemicals under laboratory conditions. By 1998, scientists had become aware that these chemicals exist in the environment as complex mixtures. Certain combinations may have synergistic toxic effects, becoming more dangerous; other combinations cancel one another out, resulting in a less toxic misture.

Whitaker and his students extract a very small amount of blood from an anesthetized fish, store the sample on ice, and release the fish. The blood sample is analyzed for the amount of damage to the DNA of the fish caused by the chemicals. Their results do show damage.

Another genetic analysis is used to determine whether the fish taken in the samples are related to each other. Whitaker's hypothesis is that populations of fish in a highly polluted environment have survived a selection pressure, and thus are genetically distinct, whether in better or worse shape, from other fish in the river. Last year, he examined about 200 fish. This summer he also looked at samples from lakes and loons, heron, and eagles that eat fish.

Whitaker, who holds a Ph.D from Yale University, was the president and scientific founder of ImmuNet, a biotech company, from 1993-1997. He joined LAC in 1997.