Organohalogenated contaminants in eggs of rockhopper penguins (Eudyptes chrysocome) and imperial shags (Phalacrocorax atriceps) from the Falkland Islands

In this study, we evaluated the use of seabird eggs of two common bird species from the Falkland Islands as bioindicators of contamination with organohalogenated contaminants (OHCs). We compared contamination levels and profiles of different OHCs between eggs of the rockhopper penguin (Eudyptes chrysocome) and the imperial shag (Phalacrocorax atriceps). In addition, laying order effects on OHC concentrations and profiles were also investigated in both species. For polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) as well as polybrominated diphenyl ethers (PBDEs), concentrations were significantly lower in eggs of rockhopper penguins (27.6 ± 0.70 ng/g lw, 56.5 ± 1.33 ng/g lw and 0.98 ± 0.04 ng/g lw, respectively) compared to the imperial shags (140 ± 5.54 ng/g lw, 316 ± 11.53 ng/g lw, 1.92 ± 0.15 ng/g lw, respectively). On the other hand, 2′MeO-BDE 68 and 6MeO-BDE 47, two brominated compounds of reported natural origin, were significantly higher in the penguin eggs (0.55 ± 0.05 ng/g lw and 7.01 ± 0.64 ng/g lw, respectively) compared to the shag eggs (0.17 ± 0.03 ng/g lw and 0.50 ± 0.06 ng/g lw, respectively). In addition, PCB, OCP and PBDE contamination profiles differed markedly between the two species. Various factors, such as diet, feeding behaviour, migratory behaviour and species-specific metabolism, may be responsible for the observed results. For both rockhopper penguins and imperial shags, PCB, OCP and PBDE concentrations and profiles did not significantly change in relation to the laying order. This suggests that, for both species, any egg of a clutch is useful as a biomonitoring tool for OHCs. Although our results showed that OHCs have also reached the Falkland Islands, concentrations were relatively low compared to other studies. However, future monitoring may be warranted to assess temporal trends of different OHCs.

Research highlights
► Organohalogenated pollutants in eggs of two bird species from the Falklands
► Statistically higher concentrations of PCBs, OCPs and PBDEs in imperial shags
► Statistically higher concentrations of methoxylated PBDEs in rockhopper penguins
► In general, concentrations were relatively low compared to other studies.
► Concentrations and profiles did not change in relation to the laying order.