Dietary uptake of HCBP in channel catfish : The effect of fish contaminant body burden

Groups of juvenile channel catfish (Ictalurus punctatus) were exposed for 10 days to control or contaminated sediment, spiked with 14 C-hexachlorobiphenyl (HCBP, 130 μg.kg -1 dry weight), in order to establish a known body burden. At the completion of that exposure, subsamples of fish were taken for HCBP analysis and the remaining fish were transferred to clean media. Each group transferred to clean media was then divided into two subgroups and offered either control or contaminated diet for 4 weeks. The contaminated diet (Tubifex worms) was spiked with 14 C-HCBP (16.6 μg.kg -1 wet weight). Feeding rates of Tubifex were quantified as were fish growth rates and lipid levels. Fish (five specimens) were collected at the beginning of the dietary exposure and after 10, 20, and 30 days of exposure. Average individual growth rate constants were similar in all fish groups and ranged from 0.005 d -1 to 0.007 d -1 . Both fish groups fed contaminated Tubifex accumulated HCBP in an apparent linear fashion over the study period. The bioaccumulation factors (BAFs) were 1.38 and 1.66 for accumulation from sediment and uptake from food, respectively. The dietary uptake efficiency for HCBP was found not to be affected by contaminant present in the fish body.