Variation in dietary preference related the per- and polyfluoroalkyl substance exposure in two sympatric seabird species from the Yellow Sea, China

Abstract

Top predators such as seabirds may mediate their contaminant exposure through different prey choices. We investigated the diet and per- and polyfluoroalkyl substances (PFAS) exposure in two sympatrically breeding seabirds: streaked shearwaters (Calonectris leucomelas) and black-tailed gulls (Larus crassirostris) from Yellow Sea, China. Stable isotope signatures showed shearwaters had higher δ¹³C and δ¹⁵N, and a broader isotopic niche than gulls. Fecal DNA metabarcoding identified 19 prey taxa in shearwaters, including both demersal and pelagic fish, while gulls primary consumed two pelagic species (Ammodytes personatus and Thryssa kammalensis). Potentially aligned with the different prey items and trophic position, PFAS levels and profiles varied significantly between the two seabirds. Shearwaters showed elevated PFAS levels, with higher ratios of C₄ and C₇ perfluorosulfonic acids, C₇−C₉ and C₁₃ perfluorocarboxylic acids and F-53B, but lower ratios of perfluorooctanesulfonic acid and perfluoroundecanoic acid than gulls. PFAS levels in gulls were positively correlated with the body condition index, rather than δ¹³C or δ¹⁵N, aligning with their age (fledglings) and narrow isotopic niche. In contrast, PFAS in shearwaters showed a positive correlation with δ¹⁵N, highlighting the role of dietary plasticity, e.g. the demersal prey selection associated with fishing activities, in influencing contaminant exposure in seabirds.