COPPER SENSITIVITY OF ADULT PACIFIC OYSTERS 313 



many oysters held in water containing high concentrations of copper 

 were observed beating when they were removed from the shell; no 

 significant difference in copper content was found in animals with 

 and without a firm heartbeat. Permeability changes may occur 

 before the heart is affected, however. Consequently, the results of 

 the copper analysis do not demonstrate conclusively that morteility 

 was caused by an excessive amount of copper in the tissues. 



Results of the ^ "^ Cu experiment indicate that the flux of copper 

 is much greater in oysters maintained at 800 and 2400 /ig Cu/liter 

 than in the controls in seawater. If the concentration of copper in 

 oyster tissues were regulated, the flux should remain constant with 

 changes in copper concentration in seawater. Since this did not 

 occur, strict homeostatic control probably does not take place. The 

 decreased rate of ^"^Cu accumulation with increased copper concen- 

 tration does suggest a small amount of regulation of copper intake, 

 however. Whether this is the result of changes in transport across 

 membranes or changes in the circulation of seawater by the oyster is 

 not known. 



Coombs (1974) reported that copper in oyster tissues occurs in 

 at least two different forms, one a readily solubilized component and 

 the second firmly bound to tissues. No information is available on 

 which fraction is related to mortality. 



ACKNOWLEDGMENTS 



The research reported here was performed under the auspices of 

 the U.S. Nuclear Regulatory Commission, research order 

 No. 60-76-144, and the U. S. Department of Energy, contract 

 No. W-7405-ENG-48. 



We thank Jack Dawson, Rose Carrillo, and James Alexander for 

 their assistance in this investigation and the Coast Oyster Company, 

 Eureka, Calif., for supplying the oysters. 



Reference to a company or product name does not imply 

 approval or recommendation of the product to the exclusion of 

 others that may be suitable. 



REFERENCES 



American Public Health Association, 1975, Standard Methods for the Examina- 

 tion of Water and Wastewater, 14th ed., Washington, D. C. 



Ayling, G. M., 1974, Uptake of Cadmium, Zinc, Copper, Lead, and Chromium in 

 the Pacific Oyster, Crassostrea gigas. Grown in the Tamar River, Tasmania, 

 Water Res., 8: 729-738. 



