Levels and congener pattern of polychlorinated biphenyls in kittiwakes (Rissa tridactyla), in relation to mobilization of body-lipids associated with reproduction.

Three groups of female kittiwakes (Rissa tridactyla) were collected in a North-Norwegian colony: (i) before breeding; (ii) immediately after egg-laying; and (iii) late in the chick-rearing period. Concentrations of 21 selected individual polychlorinated biphenyls (PCBs) were determined in liver, brain and fat tissues by capillary gaschromatography (GC-ECD). This was done in order to investigate how the mobilization of lipids associated with breeding influences concentrations and compositions of PCBs in these tissues. The results indicate an average decrease in body mass from pre-breeding to late chick-rearing of almost 20%. During this period, the mean concentration of PCBs in brain tissue approximately quadruples. This increase can be attributed to the redistribution of PCBs from utilized depot fat to metabolizing organs. A strong negative correlation was found between body mass and lipid weight PCB-concentrations in all three tissues. The relative amounts of different PCB-congeners were quite similar in different tissues, and showed only minor changes during the breeding period.