Bioaccumulation of PCBs in Arctic seabirds: influence of dietary exposure and congener biotransformation

• Published in: Environmental pollution (1987) 2005-04, Vol.134 (3), p.397-409
• Main Authors: Borgå, Katrine, Wolkers, Hans, Skaare, Janneche U., Hop, Haakon, Muir, Derek C.G., Gabrielsen, Geir W.
• Format: Article
• Language: English
• Subjects: Aging; Alcids; Alle alle; Animal, plant and microbial ecology; Animals; Applied ecology; Arctic Regions; bioaccumulation; Biological and medical sciences; Biotransformation; Birds - metabolism; Cepphus grylle; cytochrome P-450; Cytochrome P-450 Enzyme System - metabolism; Diet; Ecotoxicology, biological effects of pollution; Environmental Pollutants - pharmacokinetics; enzyme activity; Feeding rate; Female; Fishes; Fundamental and applied biological sciences. Psychology; General aspects; Larids; liver; Male; Marine; Metabolic index; metabolism; Phylogeny; pollutants; polychlorinated biphenyls; Polychlorinated Biphenyls - pharmacokinetics; Rissa tridactyla; seabirds; Seawater; Sex Factors; Stable isotopes; Toxic equivalent concentrations; toxicity; trophic relationships; Uria lomvia; Zooplankton
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2004.09.016

Four seabird species and their prey (zooplankton or fish) were collected in the Barents Sea to determine how dietary exposure, cytochrome P450 (CYP) enzyme activities and sex influenced their hepatic PCB concentrations and accumulation patterns. Five males and five females from each seabird species (little auk ( Alle alle), Brünnich's guillemot ( Uria lomvia), black guillemot ( Cepphus grylle) and black-legged kittiwake ( Rissa tridactyla)) were analysed. PCB concentrations could not be explained directly by carbon source ( δ 13C) or trophic position ( δ 15N), but by a combination of dietary parameters ( δ 13C, δ 15N, migratory pattern, age) and contaminant metabolism. Contrary to previous studies, the PCB pattern differed among seabirds, with a higher proportion of persistent congeners (% of PCB-153, R PCB-153) in black-legged kittiwake than in auks. The PCB pattern also differed among auks, with little auk as the most efficient biotransformer (highest R PCB-153 values of persistent congeners). Based on high R PCB-153 values, Brünnich's guillemot poorly metabolised ortho– meta-unsubstituted congeners, whereas black guillemot poorly metabolised meta– para unsubstituted congeners. Species-specific differences in PCB biotransformation were confirmed by metabolic indices, where PCB patterns in seabirds were adjusted for PCB pattern in prey. The relative contribution of ortho– meta-unsubstituted congeners to ∑PCBsdecreased with increasing EROD activity. There were no differences in PCB concentrations, PCB patterns or cytochrome P450 enzyme activities between males and females. CYP P450 activities (CYP1A- and CYP2B/3A-like: EROD and testosterone 6β-hydroxylation, respectively) were low and did not correlate with concentrations of non- or mono- ortho Cl-substituted PCBs (NO- and MO-PCBs), or with total toxic equivalent concentrations (TEQs) for dioxin-like effects of NO- and MO-PCBs. Contaminant patterns is linked to phylogeny and species-specific differences in enzyme systems and activity.