Bioaccumulation factor for 32P measured in @entity2084 , XXXX , and catfish, Ictalurus punctatus.

@entity3151 @entity2084
The ratio of the bioaccumulation factors for 32P and @entity3151 was determined for edible tissue in two species of freshwater fish by measuring the specific activity (32P activity per milligram @entity3151 ) in muscle relative to feed. The 32P tracer was added to the feed at a uniform level throughout the study. Feeding was at two levels: ad libitum and at a lower but constant intake per body weight. In the main experiment, @entity2084 were maintained in a large flow-through tank and sacrificed at approximately weekly intervals for 51 d of 32P accumulation and 28 d of depuration to compare the specific activity with values predicted with a calculational model. In experiments performed in smaller aquaria, the specific activity in @entity2084 and catfish muscle was compared at two feeding levels and two temperatures. In addition, unfed fish were exposed to 32P in water at a known specific activity to determine the extent of @entity3151 uptake directly from water. The pattern of specific activity increase and decrease in fish muscle during the accumulation/depuration experiment was consistent with a one-compartment model, so that specific activity ratios at steady state could be predicted from measurements during relatively brief exposures. On this basis, the ratio of the bioaccumulation factors of 32P and @entity3151 in fish feeding ad libitum was 0.081 for @entity2084 and 0.17 for catfish. Hence, at a mean @entity3151 bioaccumulation factor of 70,000, the factors for 32P are 6,000 and 12,000, respectively. The ratios were less at lower @entity3151 intakes associated with lower feeding rates; moreover, the lesser value for @entity2084 occurred at a much lower @entity3151 intake than by catfish. The bioaccumulation factor ratio was lower by an order of magnitude at a water temperature of 11 degrees C than at 16-27 degrees C, and was lower by two orders of magnitude when @entity3151 uptake was from water by unfed fish.
