ABSTRACT
Human disturbance alters key attributes of aquatic ecosystems such as water quality, habitat structure, hydrological regime, energy flow, and biological interactions (Karr and Dudley, 1981; Ward and Stanford, 1989; Sparks, 1995). In great rivers, this is particularly evident because they are disproportionately degraded (Karr et al., 1985a; Simon and Sanders, 1999; Gammon and Simon, 2000) by habitat alteration (Ward and Stanford, 1995; Poff et al., 1997) and industrial and municipal discharges (Pearson and Krumholz, 1984; Simon and Stahl, 1998). Water quality degradation as a result of point and nonpoint source pollution further impacts the ecological integrity of large rivers such as the Ohio River (Sparks et al., 1990; Bayley, 1995). By examining patterns in the responses of fish assemblages to potential stressors associated with point source discharges, it may be possible
to assess the extent to which pollution alters water quality and affects biotic integrity (Karr and Dudley, 1981; Bayley, 1995; Yoder and Rankin, 1995a).
