Darters are small species of colorful fish that live mainly in riffles (rapids) of rivers and streams. There are currently about 150 darter species, and most are astoundingly colorful, especially during the breeding season.
Water quality in our rivers and streams has an effect on indicator species like the darters. The same can be said for North American frogs and amphibians. Something has been happening that could doom many of these highly diverse and interesting organisms to extinction.
In the Blue River of Southern Indiana, at least three species of native darters are endangered or threatened. These three species are the variegate darter (Etheostoma variatum), the bluebreast darter (E. camurum) and the spotted darter (E. maculatum). This is probably the only stream in Indiana where these three species occur in abundance. They have become extinct or nearly so in all other rivers and streams of Indiana.
The findings of this study provide significant information on the status of the darter community in the Blue River. Compared with the results of a previous more general study of darter communities conducted on the Blue River in 1986, this study reveals whether the populations of the three darter species being studied are stable, increasing or declining and in danger of disappearing from the river altogether.
The Blue River has been described as the best remaining example of a natural and scenic river in Indiana. In 1975, it was designated a State Scenic River for the over 45 miles of the river that courses through Washington, Harrison and Crawford Counties. This designation helps government regulators to terminate or modify any projects, public or private, that would harm the river's natural features. The Nature Conservancy has also designated the Blue River one of Indiana's Last Great Places. Based in part on research done at Indiana University Southeast, the Nature Conservancy of Indiana has established a Field Office in Corydon. This office is attempting to purchase ecologically sensitive property along the river and is conducting research in the area. I.U.S. has provided student interns for three of their projects.
The population estimates of darters found in the Blue River also indicates if these designations are working to maintain the quality of the river. As noted above, darters are an indicator species. With large populations of darters found, it may be concluded that the water quality and habitat quality of the Blue River remain at an acceptable level. Conversely, with low numbers of darters found, the river may be in ecological decline.
This project provides two important findings. First and most importantly, it gives information on the status of three endangered or threatened species. Secondly, it reveals information about the current ecological quality of the Blue River.