Foraging ecology drives mercury contamination in chick gulls from the English Channel

Abstract

Highlights• Wide variations in Hg concentrations were found between the different species of gull • Hg concentrations were the highest in Great black-backed gulls • Hg exposure was different among the colonies of Great black-backed gull • Regardless of the breeding site, δ 15 N explained Hg concentrations • Feeding habitat (proxied by δ 34 S) has a major influence on Hg concentrations

Development of an integrated indicator to assess chemical contamination in different marine species: The case of mercury on the French Atlantic continental shelf

“…𝐶 𝑐𝑜𝑙𝑜𝑛𝑦 * 𝑠𝑝 ) varied from 0.06 to 0.69 mg kg -1 w.w. (Supplementary Material, Table S3) and the differences observed in Hg contamination among species can be explained by trophic position and foraging ecology (terrestrial versus marine resources) of the species. The most contaminated bird was the great black-backed gull, which has the highest trophic level among the monitored species, and feeds mostly on marine resources (Binkowski et al, 2021). On the other hand, the herring gull showed the lowest Hg concentrations, which is consistent with the terrestrial and low trophic level diet of this species.…”

“…Mercury concentrations were measured in the flesh (the whole soft tissues) for bivalves, the muscle for fish, the blood for birds and the liver for mammals. Methodologies for Hg analysis are detailed in Lebigre et al (2022) for bivalves, Mauffret et al (2023) for fish, Binkowski et al (2021) for birds and Méndez-Fernandez et al (2022) for mammals. A conversion of Hg concentrations to wet weight (w.w.) was achieved with an individual conversion factor obtained by weighing the mass difference before and after freeze-drying for fish samples.…”