Bioaccumulation of Kepone by spot (Leiostomus xanthurus): Importance of dietary accumulation and ingestion rate

Abstract

The relative extent of dietary accumulation and bioconcentration of Kepone by spot (Leiostomus xanthurus) was quantitatively evaluated at food rations of 4, 8 or 20% of the average wet weight of fish. [ 14C]Kepone was utilized to determine bioconcentration and dietary accumulation separately, while [ 14C]Kepone-contaminated food (grass shrimp, Palaemonetes pugio) and unlabeled Kepone in water were used to determine simultaneously accumulation from both sources. Grass shrimp and spot were exposed to the same aqueous Kepone concentration (0.04 μg/l). A first-order pharmacokinetic equation was used to model Kepone accumulation kinetics during the 19-day uptake and 28-day clearance phases. A doubling of contaminated food ration caused a doubling of the whole-body Kepone concentration in spot. Spot fed an 8% ration of uncontaminated food and exposed to aqueous Kepone did not bioconcentrate significantly greater amounts of the pesticide than fish fed a 4% ration and exposed to the same aqueous concentration. When spot were exposed to contaminated water and food, Kepone contributions from each source were additive. Feeding rate, however, was very important in determining final Kepone body burdens in spot. The dietary source of Kepone represented approximately 9, 18 and 37% of the total body burden bioaccumulated by fish fed 4, 8 and 20% food rations, respectively, but assimilation efficiencies of Kepone from the food source were low. The laboratory results further suggest that dietary accumulation of Kepone by spot may play an important role in determining final Kepone concentrations in spot in the James River, Virginia.