Response to Copper 



Having characterized linear swimming velocities for B. amphitrite nauplii 

 under defined conditions, the effects of sublethal levels of copper on svk'imming 

 speeds were investigated. A primary stock solution of 10,000 ppm Cu in 

 dilute nitric acid was adjusted to 1-4 ppm secondary stock solutions using 

 deionized water. Final test solutions were obtained by serial dilutions with 1 ju 

 filtered natural seawater at 32-34°/oo. Total copper was determined by heated 

 graphite absorption on a HGA-2100 coupled to a Per kin-Elmer 360 atomic 

 absorption spectrophotometer. 



Newly hatched B. amphitrite nauplii were exposed to various copper levels 

 for 24 hours at 20°C. Replicate samples of nauplii for each exposure level were 

 then video taped in a darkened room using the described darkfield 

 illumination. Total mortality at 24 hours post-exposure was determined. 

 Larvae were not fed during the experiment. Analyses indicated a 3-15 percent 

 decrease in total copper occurred during a 24-hour static exposure. In the first 

 test, nauplii were exposed to levels ranging from control (3 ppb) to 

 approximately 50 ppb Cu (Table 18-3). No increased mortality was observed; 

 however, MLV of nauplii exposed to 10 through 47 ppb Cu nearly doubled 

 relative to control values. Close agreement was observed in replicate samples. 



In a second test, three higher copper levels were added: 120, 185, 350 ppb. 

 After the 24 hour Cu exposure period, nauplii were transferred to clean filtered 

 seawater with the mixed algal diet. Significant mortality at 24 hour 

 post-expossure occurred only at 350 ppb Cu. However, a delay in molting was 



Table 18-3. Mean Linear Velocities (MLV) of 



Balanus Amphitrite Stage II Nauplii Exposed to Sublethal 



Copper Levels for 24 Hours at 20°C 



280 



