The Black-headed Gull's Adaptation to Polluted Environments: The Role of the Mixed-function Oxidase Detoxication System

This study was conducted to explore the role of the mixed-function oxidase (MFO) detoxication system in the ‘adaptation’ process of gulls to polluted environments. In two different populations of Black-headed Gull (Larus ridibundus), feeding in one case in a lagoon and in the other on an inland rubbish-dump, MFO hepatic activities (aldrin epoxidase, 7-ethoxyresorufin o-deethylase, NADPH-cytochrome c reductase, NADH-cytochrome c reductase, and NADH-ferrycianide reductase) and chlorinated hydrocarbon residues were determined. All the enzymatic activities detected, and the PCB residues, were higher in the Gulls feeding on the inland dump than in the gulls feeding in the lagoon. The results obtained suggest that the development of a strong detoxication system constitutes an important ‘survival mechanism’ for these birds when feeding customarily in polluted environments.