The overall objective of the proposed project is to evaluate in detail the transfer of the carcinogenic polycyclic aromatic hydrocarbon (PAH) benzo(a)pyrene (BaP) from sediments directly to a facultative detritivorous fish, the gizzard shad (Dorosoma cepedianum). Gizzard shad are an important forage fish in freshwater systems and comprise a significant portion of the diet of the most sought after freshwater sport fish (not including the Great Lakes) in the United States, the largemouth bass. The overall objective will be accomplished by addressing the following three specific objectives: 1) Examine the effects of seasonal parameters (i.e. temperature, body lipids, gonadal development) on the rate and pattern of BaP metabolism in gizzard shad. Fish will be collected at bimonthly intervals for a one year period and will be injected i.p. with radiolabeled BaP under ambient field temperature conditions. Tissues will be analyzed for BaP and Phase I and Phase II metabolites. Body lipids will be measured and gonadal development will be assessed in relation to metabolic parameters. Predictive relationships will be developed among environmental temperature, body lipids, gonadal development, and metabolic parameters. 2) Examine the metabolic rate and pattern of BaP metabolism in gizzard shad of a range of size, age and sexual maturity. Three size-classes of fish will be injected i.p. with radiolabeled BAP and tissues will be analyzed for BaP and Phase I and Phase II metabolites. Rates and patterns of metabolism will be correlated with size/age maturity group, and predictive relationships will be developed. 3) Evaluate the relative importance of food (in this case sediment) versus water as vectors of uptake of BaP by gizzard shad. Experiments will be conducted to determine rates of uptake, metabolism, and elimination of BaP from water alone and from sediment alone. This information will be used in the development of a bioenergetics-based model of the transfer of BaP in the sediment-gizzard trophic system of freshwater lakes and reservoirs.
