Multivariate data analyses of chlorinated and brominated contaminants and biological characteristics in adult guillemot (Uria aalge) from the Baltic Sea

Adult guillemot (Uria aalge) birds, 10 females and 10 males, drowned in trawl nets near Stora Karlso in the Baltic Sea, were collected in 2000. Several of the animals' biological characteristics were recorded. The birds' pectoral muscles were individually analyzed for their concentrations of organochlorines (M) and brominated flame retardants (BFRs), dichlorodiphenyltrichloroethanes (DDTs), polychlorinated biphenyls (PCBs), hexachlorocyclohexanes, trans-nonachlor, hexachlorobenzene, hexabromocyclododecane (HBCD), and polybrominated diphenyl ethers (PBDEs). The dominating contaminant was p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) with a geometric mean concentration of 12 900 ng/g lipid weight (Iw). The concentration of Sigma PBDE (80 ng/g Iw) was similar to that of HBCD (65 ng/g Iw). The total concentration of all OCs was approximately 150 times higher than that of all BFRs. For the statistical evaluation of the data, we used multivariate analysis techniques such as principal components analysis, partial least-squares (PLS) regression, and PLS discriminant analyses. No differences between the two sexes were found, either in contaminant concentrations or in biological characteristics. We found that some biological characteristics covaried with the concentrations of several Us and BFRs, e.g., a negative correlation between liver weight and concentration of contaminants. The concentrations of most Us but not of BFRs showed a decrease with increasing lipid content. Further, a PLS model with M as X and BFRs as Y showed that the contaminants formed two groups, each with distinctive correlation patterns. The PLS model could be used to predict with varying accuracy the concentration of BFRs in the individual muscles from their concentration of OCs.