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HARRISON AND RICE 



TABLE 1 



CONDITIONS OF TOXICITY TESTS OF COPPER TO ADULT OYSTERS 



*Mean values of six to eight determinations. 



"t"In calculating the 95% confidence intervals, we assumed the error mean square to be 1. 



At each test concentration an LT5 value (time required for 50% 

 mortality of the test population) was determined. The LT5 values 

 ranged from 164 hr at the lowest concentration to 18 hr at the 

 highest concentration (Table 1). 



Concentrations of total and ionic copper in the water were 

 relatively constant during the test period. Deviations from the 

 average concentrations (Table 1) can be attributed to (1) small 

 changes in inflow rates resulting from conformational changes in the 

 tubing of the pumping system, (2) changes in rates of accumulation 

 of copper from the water by the oysters, and (3) analytical errors. 

 The ionic fraction was generally greater than 75% of the total 

 amount of copper present (Table 1). 



Copper Concentrations in Oysters 



Oysters maintained at increased levels of copper in the water 

 contained more copper than those in control groups (Table 2). The 



