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. Concentration s of 21 selected individual polychlorinated biphenyls (PCBs) were dete rmined in liver, brain and fat tissues by capillary gas-chromatography (GC-ECD). This was done in order to investigate how the mobilization of lipids associated with breeding influences concentrations and compo sitions of PCBs in these tissues. The results indicate an average decr ease 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 redis tribution of PCBs from utilized depot fat to metabolizing organs. A st rong negative correlation was found between body mass and lipid weight PCB-concentrations in all three tissues. The relative amounts of diff erent PCB-congeners were quite similar in different tissues, and showe d only minor changes during the breeding period.