seen at 48 hours post-exposure; only 35 percent of nauplii exposed to 185 ppb 

 Cu had molted to Stage III, as opposed to nearly 70 percent at lower copper 

 levels. (Figure 18-5.) Analysis of variance for naupliar MLV indicated a 

 significant (p=0.01) difference between control (2 ppb), intermediate (18-186 

 ppb), and highest (350 ppb) copper levels. Swimming speeds significantly 

 increased at sublethal copper levels but rapidly declined at or near the lethal 

 level (Figure 18-6.) The shift in distribution of linear velocities for test groups 

 at these three exposure levels is clearly illustrated by frequency histograms 

 (Figure 18-4). 



In the third experiment, B. improvisus nauplii (from South Carolina) were 

 exposed to Cu levels ranging from control (3 ppb) to 190 ppb for 24 hours at 

 25°C. Following video taping at 24 hours, nauplii were transferred to filtered 

 seawater with algal diet and reared at 25°C. At 24 hours, post-exposure 

 mortality at 190 ppb was 100 percent; at 150 ppb, 20 percent. Rearing to 

 cyprid stage indicated no significant mortality differences between controls 

 and nauplii exposed up to 98 ppb Cu. However, development time appeared 

 delayed by Cu exposure as low as 50 ppb (Table 18-4). 



100 



molt 



2 3 00 



Figure 18-5. Mortality 24 Hours Post Exposure and Percent 

 Larvae Molting to Stage III, 48 Hours Post Exposure, for 

 Balanus amphitrite Stage II Nauplii Exposed to Various Copper 

 Concentrations for 24 Hours at 20OC. 



281 



