12 



96-hr bioassay and aeration was then continued for four additional 

 days, making a total treatment of five days for the remaining waste. 

 Sludge was settled and supernatant decanted for acute toxicity 

 bioassay after five days of treatment. 



RESULTS 



Acute Toxicity of Chlorinated Catechols 



Ninety-six Hour Exposure 



Tetrachlorocatechol was found toxic to sockeye alevins, fry and 

 smolts at low concentrations. The 96-hr TL of newly hatched natural 

 and hatchery-incubated sockeye alevins (body weights approximately 

 10 mg) to tetrachlorocatechol was 0.7 ppm (TABLE 2). In contrast to 

 the freshly hatched alevins, the 96-hr TL 's of advanced hatchery 

 alevins (body weights 15 and 18 mg) were 1.1 and 1.3 ppm. The 96-hr 

 TLjj^'s of sockeye fry from Cultus hatchery and Pitt Lake incubation 

 channel were 0.8 and 0.9 ppm, respectively. Natural sockeye smolts 

 had a 96-hr TL^ of 0.8 ppm. The foregoing data indicate that natural 

 smolts, freshly hatched natural and hatchery alevins, hatchery fry 

 and incubation channel fry were about equally susceptible to 

 tetrachlorocatechol while advanced sockeye alevins appeared somewhat 

 more resistant. 



Pink saljnon alevins and fry had 96-hr TL 's of 0.29 and 0.26 ppm, 

 respectively (TABLtj 2). These results showed that in the early life 

 stages pink salmon were more susceptible to tetrachlorocatechol than 

 were sockeye. 



Dichlorocatechol was less toxic to sockeye and pink salmon than 

 was tetrachlorocatechol. The 96-hr TL ranged from 2.4 to 2.7 ppm 

 for sockeya advanced alevins and fry, respectively (TABLE 3). In 

 contrast to results obtained with tetrachlorocatechol, advanced pink 

 salmon alevins (96-hr TL of 2.0 ppm) were almost as tolerant of 

 dichlorocatechol as were sockeye. 



