Issue 5

Don't Forget the Fish and Other Aquatic Organisms

by Kim MacQueen

We’re only human. When we think of water quality, we think first of drinking water—our drinking water. But the same principals for providing clean, clear water for human use also hold true for freshwater fish and other aquatic wildlife. For the fish, crayfish, mussels, and other animals making their home in the Southeastern United States, the difference between healthy and unhealthy water is the difference between life and death.

And there are a lot of them to consider. More than half the Nation’s freshwater fish live here. At nearly 600 species, they represent one of the world’s most diverse faunas. The South contains 165 fishes of concern in 14 different families, as well as rare darters, minnows, topminnows, dace, catfishes, and sculpins. Nearly 270, or 90 percent, of freshwater mussel species occur in the Southeast, the majority in the Tennessee River basin that curves through the middle of the region. Land use changes, channelization, sedimentation, and dam construction have severely affected the viability of this group of animals, which depend on freeflowing water to survive.

The crustacean fauna—mostly crayfish—is also broad and diverse, including 159 species of concern, 60 critically imperiled. Years of agricultural, industrial, and recreational use of forestlands challenges the fish, mussels, and crustaceans. Nearly all are threatened in some way by pollution, damming, sedimentation, and habitat loss.

As one might expect, practices that preserve intact forests produce the highest quality drinking water. They also provide the best habitat for aquatic species, regulating temperature and cleaning water as it percolates through the soil.

In recent years, Best Management Practices and improved road and stream crossing designs have helped keep sediment out of forest streams, but sediment is still a major problem for many aquatic species. Suspended sediment decreases water clarity and makes things difficult for animals trying to see to catch food. As sediment loads increase, fish gills can become clogged, growth rates reduced, and egg and larval development impeded. As sediment settles to the bottom of a stream or river, it can smother eggs and newly hatched larvae or fill in spaces that have provided habitat. (...continued...)