COPPER SENSITIVITY OF ADULT 

 PACIFIC OYSTERS 



F. L. HARRISON and D. W. RICE, JR. 



Environmental Sciences Division, Lawrence Livermore Laboratory, 



University of California, Livermore, California 



ABSTRACT 



Sensitivity of the Pacific oyster, Crassostrea gigas, to copper w^as evaluated in 

 experiments of about 2-w^eeks duration. Groups of 8 to 10 animals were exposed 

 to copper concentrations ranging from 100 to 1300 /ig/liter in a high-volume 

 flow-through bioassay system. Copper concentrations in the oysters and the 

 major chemical form of copper in the water were determined. In addition, 

 experiments were performed with Cu to determine accumulation rates and 

 distribution. The family of mortality curves of time vs. concentration for oysters 

 was unlike that for other organisms in that the greatest mortality at 96 hr 

 occurred in animals at intermediate rather than high copper concentrations. 

 However, typical mortality curves were obtained by correcting the duration of 

 copper exposure of each oyster by a factor related to the amount of time the 

 shells were open. Significant mortalities occurred at copper concentrations of 

 200 /ig/liter and higher. Analysis of the data yields an LC50 at 48 hr of 

 650 /ig/liter, an LC50 at 96 hr of 430 jug/liter, and an incipient LC50 of 

 230 /ig/liter. Distributions of ^"^Cu in oysters after a 24-hr exposure differed in 

 animals maintained in water containing high and low concentrations of copper. 

 The flux of copper into tissues was related to copper concentrations in the 

 water; this indicated that there was little metabolic regulation. 



Shellfish resources of estuarine and marine ecosystems can be 

 harmed by increased levels of heavy metals in water. Of the heavy 

 metals commonly released as a result of man's activities, copper is of 

 special interest because of the known sensitivity of aquatic organisms 

 to it (Becker and Thatcher, 1973). Oysters accumulate copper 

 (Galtsoff, 1964; Pringle et al., 1968; Shuster and Pringle, 1969; 



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