BIOACCUMULATION AND BIOMAGNIFICATION OF POLYCYCLIC AROMATIC-HYDROCARBONS IN AQUATIC ORGANISMS

Uptake and degradation of polycyclic aromatic hydrocarbons were studie d in a laboratory scale food chain consisting of Dunaliella tertiolect a (microalga), Mytilus galloprouincialis (mussel) and Dicentrarchus la brax (fish), in tanks supplied with open water flow. The toxicants, be nzo(a)pyrene and 7,12-dimethyl benz(a)anthracene, were added and sampl es were taken every ten days. Bioaccumulation of toxicants in the food chain steps and the physiological response of organisms' xenobiotic-m etabolizing enzyme systems were tested. Mixed-function oxygenase enzym es were evaluated through quantitation of benzo(a)pyrene-monooxygenase in the mussels and ethoxyresorufin-O-diethylase in the fish. In the m ussels benzo(a)pyrene and 7,12-dimethyl benz(a)anthracene are bioaccum ulated in contrast with the seabasses in which only negligible quantit ies were found. These different responses among mussels and fish are p robably caused by the very efficient detoxification enzymatic system l ocated in the liver of the fish. The mussel is confirmed as a biomonit or of hydrocarbons in the environment because of its ability to bioacc umulate, whereas seabass shows a strategy of survival in contaminated environments based on an active oxidative enzymatic system.