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Striped bass (Morone saxatilis) eggs and prolarvae were exposed to a range of treated bleached kraft mill effluent (BKME) concentrations from 0 to 20 percent effluent by volume (v/v) under continuous flow test conditions. The treated BKME used in the study before dilution had a BOD5 of 18 to 25 mg/l, TSS of 60 to 185 mg/l and true color of 1750 to 1755 mg/l. No mortality attributable to BKME was found in three separate egg studies. No delayed hatching of the eggs occurred in any of the BKME treatments relative to the control treatment. No significant morphological abnormalities (pugheadness, truncation, or scoliosis) were found in prolarvae exposed to BKME from the egg stage through six days post/hatch. Tests with prolarvae revealed that BKME at concentrations from 2 to 20 percent v/v did not cause mortality during exposures up to 60 hours. However, BKME concentrations ranging between 8 to 12 percent up to 20 percent v/v caused increased mortality after 72 hours of exposure.

Effects of total residual chlorine (TRC), change in temperature (ΔT), and exposure time were established for eggs and prolarvae of striped bass, Morone saxatilis, under test conditions designed to simulate entrainment by power plants. Prolarvae were found to be more sensitive than eggs under the same test conditions. In contrast to the predominant effect of TRC and exposure time on eggs, TRC and ΔT and exposure time were all found to be important in causing mortality of prolarvae. The study shows that in an evaluation of the potential effects of chlorinated power plant cooling waters to striped bass ichthyoplankton, a systematic study must be made of the interactions of TRC, ΔT, and exposure time. Key words: chlorine, total residual chlorine, temperature change, ΔT, exposure time, Morone saxatilis, fish eggs, fish larvae, predictive mortality model

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