RESPONSES OF ICHTHYOPLANKTON 



805 



Chlorine Experiments 



Striped bass larvae exposed to different chlorine concentrations 

 with and without simultaneous temperature elevations of 8.3° C AT 

 (29.4°C) displayed a complex pattern of mortality at 24 hr (Fig. 5). 

 There were no differences in mortality among barrel controls 

 exposed at ambient temperature at all chlorine doses. Barrel controls 

 exposed to elevated temperatures had significantly higher mortalities 

 (P < 0.05) at free chlorine concentrations of 1.09 and 2.47 ppm. At 

 free chlorine concentrations of 0.31, 0.59, 1.09, and 2.47 ppm, all 

 simulator-run groups had higher mortalities than barrel controls at 

 ambient temperature. 



Carp exposed to chlorine doses at ambient temperature displayed 

 increased mortality (>10%) at 24 hr and at doses above 1.90 ppm. 

 Simultaneous exposure to 11.1°C AT (30.4°C) and 1.90 ppm 

 chlorine produced 90.2% mortalities in simulator-exposed organisms 

 and 52.0% mortalities in barrel controls. Variable response among 

 replicates prevented statistical comparisons among groups. 



100 



0.1 



0.2 0.5 1.0 2.0 



FREE CHLORINE CONCENTRATION, mg/liter 



Fig. 5 Percent mortality of striped bass larvae at 24 hr after a 5-min 

 exposure to several doses of free chlorine. •, simulator exposed. A, 



barrel control. , exposure at 8.3°C AT (29.4°C actual 



temperature). , exposure at ambient temperature (21.1 C). 



