Persistent organochlorines, cytochrome P450 enzyme activities and highly carboxylated porphyrins in glaucous gulls (Larus hyperboreus)

We collected 40 adult and 21 juvenile glaucous gulls (Larus hyperboreus), from colonies on Bear Island in the Barents Sea. Organochlorines (4 pesticides and 9 polychlorinated biphenyls (PCBs)), microsomal 7-ethoxyresorufin-O-deethylase (EROD) activity, microsomal testosterone hydroxylation and highly carboxylated porphyrins (HCPs) were quantified in liver samples. The hepatic EROD activity was low compared to other studies on fish-eating birds and only marginally associated with PCB-levels. Microsomal testosterone hydroxylase activity was only observed at the 6 beta -position and could not be related to organochlorine levels. The low P450 associated enzyme activities in the glaucous gull may indicate limitations in metabolic capability which could contribute to the high accumulation of organochlorines in this species. Levels of HCPs were generally not elevated (