Selective bioaccumulation of chlorinated pesticides and metabolites in Arctic seabirds K. Borga˚ a, * , H. Hop b , J.U. Skaare c,d , H. Wolkers b , G.W. Gabrielsen b a Norwegian Institute for Water Research, P.O. Box 173, Kjelsa˚ s, N-0411 Oslo, Norway b Norwegian Polar Institute, N-9296 Tromsø, Norway c National Veterinary Institute, P.O. Box 8156 Dep., N-0033 Oslo, Norway d Norwegian School of Veterinary Science, P.O. Box 8146, N-0033 Oslo, Norway Received 19 January 2006; received in revised form 12 April 2006; accepted 13 April 2006 Avian chlorinated pesticide accumulation is highly species-specific. Abstract Chlorinated pesticides and metabolites (CPs) were quantified in the seabird species: little auk (Alle alle), Bru¨nnich’s guillemot (Uria lomvia), black guillemot (Cepphus grylle) and black-legged kittiwake (Rissa tridactyla). The purpose was to evaluate avian accumulation of selected CPs based on their concentrations and relative patterns, their relation to dietary descriptors (stable isotopes of carbon and nitrogen), to enzymes in- volved in biotransformation, as well as CPs’ accumulation potential relative to the recalcitrant polychlorinated biphenyl PCB-153. In all species, the CP pattern was dominated by p,p 0 -dichlorodiphenyltrichloroethane (DDE) and hexachlorbenzene (HCB). Except for HCB, concentrations were not related to trophic position. Most CPs were quantified in black guillemot, indicating a slower elimination compared to other seabird species. Bru¨nnich’s guillemot showed efficient elimination of chlordanes, whereas the opposite was found for little auk. Kittiwake showed higher accumulation of persistent CP and metabolites than auks, whereas accumulation of less recalcitrant CPs was low. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Auks; Gulls; Organochlorines; Stable isotopes; Cytochrome P450 1. Introduction Arctic seabirds tend to accumulate high concentrations of organochlorine contaminants (OCs) (Bourne and Bogan, 1972; Gabrielsen et al., 1995; Fisk et al., 2001a). OC concen- trations in birds occupying high trophic positions, such as glaucous gulls (Larus hyperboreus), are high enough to cause concern about effects (Gabrielsen et al., 1995; Bustnes et al., 2005). In Arctic seabirds occupying lower trophic positions, the OC concentrations are lower than threshold levels for pos- sible effects found in other seabird species (Braune et al., 2001; Borga˚ et al., 2005; Fisk et al., 2005). Seabirds, as other vertebrates, accumulate OCs mainly from the diet, usually leading to biomagnification; increasing OC concentrations with increasing trophic position in the food web (e.g. Fisk et al., 2001b). Several marine food web studies, spanning over a broad range of trophic positions, have demonstrated relationships between OC concentrations and dietary descriptors such as stable carbon and nitrogen iso- tope ratios (d 13 C and d 15 N, respectively) (Broman et al., 1992; Ruus et al., 1999; Fisk et al., 2001b; Hop et al., 2002; Hoekstra et al., 2003). Due to elimination of the lighter isotopes 12 C and 14 N, the heavier isotopes 13 C and 15 N are enriched and may be used to distinguish animals based on their carbon source (d 13 C) and trophic position (d 15 N) (Hobson and Welch, 1992; Hobson et al., 1995). However, within a species, or when comparing species covering a narrow trophic range, d 13 C and d 15 N may not help explaining the variation in OC * Corresponding author. Tel.: þ47 22 18 51 00; fax: þ47 22 18 52 00. E-mail address: katrine.borga@niva.no (K. Borga˚). 0269-7491/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2006.04.021 Environmental Pollution 145 (2007) 545e553 www.elsevier.com/locate/envpol