Reconstructing spatiotemporal trends of major contaminants in northern white-tailed eagle (Haliaeetus albicilla) populations using long-term feather collections

Datum: 25 oktober 2019

Locatie: Campus Drie Eiken, S1 - Universiteitsplein 1 - 2610 Antwerpen-Wilrijk (route: UAntwerpen, Campus Drie Eiken)

Tijdstip: 17 uur

Organisatie / co-organisatie: Departement Biologie

Promovendus: Jiachen Sun

Promotor: Marcel Eens en Igor Eulaers

Korte beschrijving: Doctoraatsverdediging Jiachen Sun - Faculteit Wetenschappen, Departement Biologie


The release of a large number of persistent contaminants by human activities remains of paramount environmental concern. Long-term and large-scale spatiotemporal trend monitoring is crucial for the adequate assessment of the effectiveness of legal regulations, as well as for identifying hotspots of continued or emerging contamination. The present thesis aimed to reconstruct spatiotemporal trends of three major groups of persistent contaminants: mercury (Hg), legacy organochlorines (OCs), and perfluoroalkyl substances (PFAS).

We sampled archived body feathers of an established sentinel species – the white-tailed eagle (Haliaeetus albicilla) from the West Greenland coast (n = 124; 1884 - 2013), the Norwegian coast (n = 102; 1866 - 2015), and the central Swedish Baltic coast (n = 152; 1967-2011). We observed generally highest concentrations of Hg, OCs, and PFASs in Swedish feathers, except for chlordanes, hexachlorobenzene and perfluorooctanesulfonamide (FOSA), which were elevated in Greenland feathers. These results likely indicate the relative difference between local contaminant influx in Sweden versus the long-range transport to Greenland. Overall decreasing temporal trends of Hg and OCs were observed across all three studied subpopulations, except for Hg and PCBs in Greenland. Such declining trends suggest that the measures taken to reduce Hg and OC emissions have been generally effective. Comparably, decreasing trends of perfluorooctane sulfonate (PFOS) and FOSA in both Greenland and Norwegian feathers aligned well with the phase-out of their precursor compound. However, PFOS levels in the Swedish feathers remained elevated and are not decreasing, suggesting prolonged contamination in the Baltic Sea region. Perfluoroalkyl carboxylates (PFCAs) by contrast are still being used, and were consequently observed to continuously increase in all three subpopulations. In addition, feather corticosterone remained constant over time in the Swedish feathers and therefore, may not be a suitable physiological proxy for temporal changes in contaminant exposure.

The present PhD work underscores the suitability of archived museum feathers in reconstructing long-term spatiotemporal trends of contaminants. Since temporal trends have not been decreasing consistently across the studied subpopulations, we encourage continued monitoring. There is also a need for further regulatory efforts on reducing the emission of contaminants of legacy concern such as Hg, PCBs and PFOS, as well as legislations on the use of contaminants, such as PFCAs, which mostly are currently not restricted in production.