828 CHERRY et al. 



range, generally from 0.005 to 0.500 mg/liter CRC (Fava and Tsai, 

 1976; Bogardus, 1977). The objectives of our study were to evaluate 

 the avoidance responses of the common shiner {Notropis cornutus) 

 to separate TRC and chloramine treatments at several acclimation 

 temperatures and to compare these responses with responses to the 

 same chlorinated treatments at the fish's preferred temperature 

 conditions. 



MATERIALS AND METHODS 



Common shiners from the Ohio River drainage were obtained by 

 air freight, in cooperation with the Center for Great Lakes Studies, 

 University of Wisconsin, Milwaukee. Holding facihties, feeding 

 procedures, and temperature acclimation rates were reported earlier 

 (Cherry, Dickson, and Cairns, 1975a). All fish tested were generally 

 less than 2 years old and ranged from 45 to 65 mm fork length. 



Preference temperatures were determined in a horizontal trough 

 heated underneath by a battery of infrared lamps. Two groups of 

 four fish were monitored separately in a 20°C temperature gradient. 

 Fish were allowed 2 to 3 hr to adjust to the environmental 

 conditions, and then temperature selection was determined for fish 

 acclimated to 12 and 24°C. 



Chlorine dosing procedures and equipment used for chlorine 

 avoidance trials were the same as those reported by Cherry et al. 

 (1977). Two water baths fed opposite ends of each avoidance trough. 

 A calcium hypochlorite solution was added to one bath with a 

 peristaltic pump; this created a steep gradient ranging from chlori- 

 nated to untreated water in each trough. After a 60- to 90-min 

 orientation period, and before chlorine was added, fish behavior was 

 continuously monitored for 10 min. The residence time in the 

 prechlorinated side of the trough was the reference for the 

 subsequent chlorine exposures. Target TRC concentrations were 

 established in increments from 0.025 mg/liter in doubling sequence 

 to 0.400 mg/liter. Residual concentrations were measured by 

 amperometric titration (American Public Health Association et al., 

 1976) before and after each dose. Eight replications were obtained, 

 with each fish being timed for 10-min intervals at each target 

 chlorine concentration at acclimation temperatures of 12, 18, 24, 

 and 30° C. The CRC and HOCl concentrations were calculated; the 

 pH was measured with a portable Markson pH meter; and ammonia 

 nitrogen was measured by an Orion specific ion electrode. These 

 treatments, the TRC trials, contained CRC and FRC fractions in 



