Feather mercury content of grey-faced petrels (Pterodroma gouldi): Relationships with age, breeding success, and foraging behaviour, in known age individuals

• Published in: The Science of the total environment 2024-11, Vol.951, p.175778, Article 175778
• Main Authors: Rewi, S.T., Fessardi, M., Landers, T.J., Lyver, P.O’B., Taylor, G.A., Bury, S.J., Dunphy, B.J.
• Format: Article
• Language: English
• Subjects: Breeding outcome; Demography; Marine pollution; Mesopelagic; Senescence; Stable isotopes
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.175778

Seabirds have been touted as excellent bioindicators of mercury pollution. We utilised grey-faced petrel (Pterodroma gouldi) feathers to assess interannual differences in total mercury (THg) concentrations in adults (2020−2021) and chicks (2019–2021) breeding in the Auckland region of New Zealand. For adults, we also correlated feather THg with bird age (3–37+ years) and breeding outcome (i.e., Non breeder, Egg failed, Chick reared) recorded for that season i.e., 2020 and 2021. Interannual differences in chick feather THg were matched with bulk stable isotopes (δ13C, δ15N) to map the influence of adult foraging behaviour on chick feather THg values. Adult feather THg levels were similar across the years investigated i.e., mean ± S.D. 38.2 ± 12.8 (2020), and 39.5 ± 14.7 (2021) ug g−1 (some of the highest THg values recorded for seabirds). A slight, but significant decrease in THg accumulation was evident as age increased but feather THg had no significant influence on breeding outcome. Interannual differences in chick feather THg concentrations were 7.78 ± 1.6 (2019), 4.23 ± 1.45 (2020) and 6.97 ± 4.41 (2021) μg g−1, (p