Factors of importance for bioaccumulation and effects of new and old POPs in a seabird top predator, the great skua

Despite declining levels of many persistent organic pollutants (POPs) such as PCB and DDT, new emerging pollutants, notably brominated flame retardants (BFRs) and perfluorinated compounds (PFCs) have increased in northern ecosystems, including the Arctic, in the last two decades. The knowledge about the transport and effects of OCs is considerable, but such information is very scarce for the new contaminants. In this study we aim at elucidating the origin of- and factors affecting the distribution and lev els of these POPs, in addition to their potential ecological effects at different latitudes, following two gradients to the high Arctic. We will study a high trophic level seabird which is distributed from temperate regions to the high Arctic; the great s kua Catharacta skua. The study will be undertaken at three main (Shetland, Iceland and Bear Island) and four auxiliary locations. All pollutants will be measured in blood samples, both from adults and young. This will provide information about pollutants that are acquired in the breeding area and also some information about contaminants that originate from the winter locations. We will test the hypothesis (by observational and experimental approaches) that birds in extreme environments (with shorter seaso ns and more unpredictable climate) are more vulnerable to the adverse effects of pollutants, than birds in more predictable climate with longer breeding season. The observational approach will be by relating various life history traits (reproductive perfo rmance and survival) and other sensitive traits (immune system, stress hormones, blood parameters) to blood concentrations of various POPs while the experimental approach will be by adding eggs to incubating birds and by relieving birds from their parasit e burden; this in relation to contaminant concentrations in the blood.