Avoidance behavior of juvenile striped bass,Morone saxatilis,subjected to simultaneous chlorine and elevated temperature conditions

The avoidance responses of juvenile striped bass (Morone saxatilis) were evaluated by exposing test organisms to simultaneous elevated temperature (0, 2, 4, and 6?C) and total residual chlorine (TRC) (0.00, 0.05, 0.10 and 0.15 mg/L) conditions at four acclimation temperatures ranging from 15–30?C. An unbalanced 3-factor factorial design was used to develop response surface avoidance models at all acclimation temperatures. The percent avoidance models at 15?C showed that the interaction term (TRC×δT) was the most important term influencing avoidance; TRC was the most important factor at 20?C; the models at 25 and 30?C showed that δT was the most important factor. The results of tests conducted at 15?C suggest that preference for a higher temperature overrides a chlorine avoidance response to 0.15 mg/L TRC. Avoidance responses of striped bass tested at acclimation temperatures of 20, 25, and 30?C showed that preference for a higher temperature (6?C δT) did not override a chlorine avoidance response. A significant difference (p<0.01) existed between avoidance models at all acclimation temperatures; greatest avoidance generally occurred for all combinations of test conditions at 30?C.