Detailed report of a 30-year study of the water quality of the Wabash River.

The fish community of the middle Wabash River has been studied since 1973 from the standpoint of its capacity for measuring the biological impact of various kinds of point influences, such as thermal, municipal, and industrial effluents. Of particular interest has been the potential value of various community parameters as indicators of environmental quality, since individual species populations tend to vary markedly from year to year.

"A field investigation concerning the distribution and abundance of fish within a 161 km portion of the Wabash River was undertaken to determine effects of heated effluents and changes in water quality upon the ichthyofaunal communities of the river."--Abstract.

The changes in population trends of fish in the Wabash River resulting from the introduction of thermal effluents were examined for a 14-year period from the standpoint of whether the observed changes could have been predicted from the results of laboratory determinations of thermal tolerance alone. It was concluded that gross changes in community structure could have been predicted but the degree to which most species populations and the community as a whole were influenced would require further detailed information about (1) the chemical and physical characteristics of the environment and (2) the attributes of the resident biota in terms of behavioral responses, physiological capabilities, and life history requirements.

"In 1980 and 1981 the physical habitats and the fish communities of the Wabash River and two of its major tributaries, the Big Vermilion and Sugar Creek, were studies. Physical habitat measurements consisted of depths, velocities, and substrate particle sizes while the fish community was assessed by electrofishing."--Abstract.