Avoidance responses of estuarine fish exposed to heated-dechlorinated power plant effluents

Factorial experiments were conducted on the avoidance responses of striped bass (Morone saxatilis) and Atlantic menhaden (Brevoortia tyrannus) exposed to heated dechlorinated waters such as might be discharged from power plants. Neither species avoided fully dechlorinated water at any acclimation temperature. Acclimation temperature had an important effect on avoidance of partially dechlorinated water by the fish. Greatest avoidance occurred at an acclimation temperature of 30C; both species avoided 34C when acclimated to 30C regardless of chlorine concentrations. Up to a 0.15 mg residual chlorine per litre did not induce avoidance responses in either species . It was concluded that intermittent chlorination in power plants would have minimal adverse effects on these species if dechlorination was practised.