DIFFERENTIAL INVESTMENT IN EGGS BY ARCTIC-BREEDING GLAUCOUS GULLS (LARUS HYPERBOREUS) EXPOSED TO PERSISTENT ORGANIC POLLUTANTS

Although egg size is a widely studied life-history trait in evolutionary ecology, it is largely unknown whether exposure to persistent organic pollutants (POPs) can influence the allocation of resources to avian eggs and, if so, how. It is well established that female birds exposed to POPs transfer these compounds to their eggs. However, little is documented with regard to contaminant-related changes in egg quality, such as egg mass, albumen mass, yolk mass, lipid, and water content. We report positive correlations between the concentrations of several major classes of POPs (organochlorines, brominated flame-retardants, and metabolically derived products) in plasma of Arctic-breeding Glaucous Gulls (Larus hyperboreus) and in the yolk of the last-laid egg of their clutches. The contributions of the different POP classes to the summed POP concentration were also positively correlated between female plasma and egg yolk. In addition, Glaucous Gulls with a relatively high concentration of sum (Sigma) chlordanes and total-(alpha)-hexabromocyclododecane in their plasma laid smaller eggs. Eggs into which females had deposited a relatively low concentration of Sigma PCB and a relatively high concentration of Sigma DDT were also smaller. The POP patterns of yolk and maternal plasma were associated with changes in water and lipid content of the yolk. These results suggest that egg quality-and, thus, offspring performance-may be affected not only by the direct transfer of contaminants from the female to the egg, but also through associated changes in egg size and composition. Received 3 March 2008, accepted 23 August 2008.