AVOIDANCE RESPONSE OF THE COMMON SHINER TO CHLORINE 829 



TABLE 1 



CHLORINE AVOIDANCE TRIALS AT VARIOUS 

 ACCLIMATION TEMPERATURES 



Type of Acclimation 



avoidance trial Major components temperature, C 



TRC 30-70% CRC-FRC, 12, 18, 24, 30 



depending on river 



vi^ater quality 

 CRC 97% chloramine, 12,24 



mainly monochloramine 

 TRC in preferred 30-70% CRC-FRC, 12,24 



temperature depending on river 



water quality 

 CRC in preferred 97% chloramine, 12, 24 



temperature mainly monochloramine 



NH3 Ammonium ion 12, 24 



various proportions depending on the New River water quality each 

 day (Table 1). 



The second type of chlorine avoidance trial, chloramine avoid- 

 ance, consisted of total residual treatments comprised mainly of 

 CRC. These trials were carried out at 12 and 24°C in the same 

 manner as the TRC trials, except that the original stock solution of 

 calcium hypochlorite used to chlorinate one water bath was also 

 dosed with ammonium chloride. Dissociation of the ammonium 

 chloride resulted in the ammonia ions' combining with FRC to form 

 a solution comprised primarily of CRC. More than 90% of the 

 solution was monochloramine (determined amperometrically), and 

 pH levels ranged from 7.5 to 8.4. Ammonia levels were measured at 

 the beginning and the end of each 10-min time interval. To ascertain 

 the possible interference of excess ammonia with fish responses, we 

 carried out a series of trials using an ammonium chloride solution 

 separately from the chloramine tests. Ammonia solutions from 0.015 

 to 0.275 mg/liter were established in one-half of each trough, and 

 fish responses at 12 and 24° C were evaluated as in chlorinated 

 trials. 



To evaluate fish responses relative to power-plant thermal 

 discharges, we carried out additional trials in which the chlorinated 

 water was heated. After the con.rol period was completed, the 

 temperature in one water bath ^vas raised above the acclimation 

 temperature of 12 or 24°C to the preference temperature. This 

 created two distinct temperature regions in the avoidance trough. A 



