Antarctic seabirds, including Adélie penguins (Pygoscelis adeliae), south polar skuas (Catharacta maccormicki) and southern giant petrels (Macronectes gigantus), are high trophic level predators that accumulate persistent organic pollutants (POPs) present in the marine food webs in which they forage. Diet and migration patterns influence the level of POP residues per species. Here we examine POP levels within the three bird species based on migratory patterns and trophic level using stable isotope analysis of δ15N and δ13C. Southern giant petrel and south polar skua tissues are expected to contain POP concentrations several orders of magnitude higher than Adélie penguins due to higher trophic level foraging in the petrels and skuas and winter migratory patterns that include industrialized areas. Further, we investigate the use of nonmetabolizable POPs as tracers for the transfer of lipid stores from mother to egg in Antarctic seabirds.
While results indicate both δ15N and δ13C increase with the trophic level of Antarctic seabirds, δ13C increases more than the predicted 1-2‰ with trophic level in migratory seabirds, possibly due to latitudinal fractionation of δ13C in the southern hemisphere. Multiple regression analysis of POP concentrations with δ15N and δ13C indicate that both diet and migration influence POP concentrations in Antarctic seabirds. Highly volatile compounds such as hexachlorobenezene (HCB), demonstrate significantly higher concentrations in bird tissues with an increase in δ15N, but show no relationship with δ13C. Conversely, alpha-chlordane shows no relationship with nitrogen stable isotopes, but demonstrates significantly higher concentrations with enrichment in δ13C. Differences in the relative abundance of POPs may provide a new venue for insight into migratory Antarctic seabird ecology. For example, significantly higher p,p’-DDE/HCB ratios found in petrel eggs relative to Antarctic organisms, such as Adélie penguins and Antarctic krill, may indicate that female giant petrels transfer a large fraction of lipid reserves and lipophilic POPs acquired outside of Antarctica to their eggs. Subsequently, these birds appear to rebuild lipid stores while in Antarctica with the lower p,p’-DDE/HCB indicative of the Antarctic marine food web.