Variation Among Species and Populations, and Carry-Over Effects of Winter Exposure on Mercury Accumulation in Small Petrels

21 pages, 11 figures, 6 tables, supplementary material https://www.frontiersin.org/articles/10.3389/fevo.2022.915199/full#supplementary-material.-- Data Availability Statement: The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

Even in areas as remote as the Southern Ocean, marine organisms are exposed to contaminants that arrive through long-range atmospheric transport, such as mercury (Hg), a highly toxic metal. In previous studies in the Southern Ocean, inter-specific differences in Hg contamination in seabirds was generally related to their distribution and trophic position. However, the Blue Petrel (Halobaena caerulea) was a notable exception among small seabirds, with higher Hg levels than expected. In this study, we compared the Hg contamination of Blue Petrels and Thin-billed Prions (Pachyptila belcheri), which both spend the non-breeding season in polar waters, with that of Antarctic Prions (Pachyptila desolata), which spend the winter in subtropical waters. We collected body feathers and blood samples, representing exposure during different time-frames. Hg concentrations in feathers, which reflect contamination throughout the annual cycle, were related to δ13C values, and varied with ocean basin and species. Blue Petrels from breeding colonies in the southeast Pacific Ocean had much higher feather Hg concentrations than expected after accounting for latitude and their low trophic positions. Both Hg concentrations and δ15N in blood samples of Blue Petrels were much lower at the end than at the start of the breeding period, indicating a marked decline in Hg contamination and trophic positions, and the carry-over of Hg burdens between the wintering and breeding periods. Elevated Hg levels may reflect greater reliance on myctophids or foraging in sea-ice environments. Our study underlines that carry-over of Hg concentrations in prey consumed in winter may determine body Hg burdens well into the breeding season

This study was funded by the Deutsche Forschungsgemeinschaft (DFG) in the framework of the priority programme SPP1154 “Antarctic Research with comparative investigations in Arctic ice areas” (Grant No. Qu148/18). The fieldwork at Kerguelen was supported financially and logistically by the Institut Polaire Français Paul Emile Victor (IPEV, Programme N°109, C. Barbraud) and the Terres Australes et Antarctiques Françaises. We are grateful to the Contrat de Projet Etat-Région (CPER) and the Fonds Européen de Développement Régional (FEDER) for funding the Advanced Mercury Analyzer and the isotope-ratio mass spectrometers of LIENSs laboratory. The Institut Universitaire de France (IUF) is acknowledged for its support to PB as a Senior Member. This study represents a contribution to the Ecosystems component of the British Antarctic Survey Polar Science for Planet Earth Programme, funded by NERC. Logistical support in Bird Island was provided by the Collaborative Gearing Scheme of the Natural Environment Research Council Antarctic Funding Initiative (AFI-NERC)

With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

Peer reviewed