Seabirds as bioindicators of past and current mercury contamination : a global approach

• Main Author: Cusset, Fanny
• Other Authors: LIttoral ENvironnement et Sociétés (LIENSs), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS), Centre d'Études Biologiques de Chizé - UMR 7372 (CEBC), La Rochelle Université (ULR)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Université de La Rochelle, Paco Bustamante, Yves Cherel
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: HAL CCSD 2023
• Subjects: Hg; Seabirds; Bioindicators; Remote oceans; Spatial monitoring; Temporal monitoring; Oiseaux marins; Bioindicateurs; Océans éloignés; Spatial; Temporel; [SDV.BA]Life Sciences [q-bio]/Animal biology; [SDV.SA]Life Sciences [q-bio]/Agricultural sciences; Arctic Ocean; Southern Ocean
• Online Access: https://theses.hal.science/tel-04516268; https://theses.hal.science/tel-04516268/document; https://theses.hal.science/tel-04516268/file/2023Cusset212660.pdf

Mercury (Hg) is a toxic metal, and its impacts on human and environmental health are a major concern. Globally, the amount of Hg released into the environment, through anthropogenic activities, has steadily increased since the Industrial Revolution. Both natural and anthropogenic Hg disperse globally and deposits in all ecosystems, including in remote oceans. Oceans, which cover 70% of the Earth’s surface, are poorly documented in international monitoring programs of Hg, particularly in intertropical and polar regions. In the current context of global climate, determining spatial and temporal trends in Hg contamination in these undocumented regions is crucial. Seabirds are excellent bioindicators of Hg contamination in the oceans, both across space and time, as they integrate and reflect Hg contamination of marine food webs on which they feed. After dietary assimilation, Hg is mainly excreted during moult and stored permanently in feathers. Therefore, seabird feathers represent valuable archives and act as a time-machine thanks to museum specimens. In this context, the present PhD thesis uses seabirds as bioindicators of Hg contamination in marine ecosystems, mainly from three remote oceanic regions ‒ the Arctic Ocean, the intertropical region (Pacific, Atlantic and Indian Oceans) and the Southern Ocean ‒ with two main objectives: (1) map contemporary Hg contamination at large spatial scale, and (2) document its temporal trends since the 19th century retrospectively, by using both museum-held and free-living seabirds. Thanks to unique spatial and temporal coverage, this work represents a valuable contribution to international monitoring programs that are fully involved in the implementation and effectiveness evaluation of the Minamata Convention, which aims to control and reduce anthropogenic Hg emissions at the global scale. Le mercure (Hg) est un métal toxique, qui constitue une menace majeure pour l’Homme et la biodiversité. Naturellement présent dans l’environnement, le Hg est aussi rejeté en quantité ...