Climate change is leading to a rapid decline of sea-ice extent in the Arctic. This modification is bound to profoundly affect the functioning of Arctic marine ecosystems and understanding its impacts on the marine biodiversity is now a major issue raised by several international organizations. Among other threats, the expansion of ice-free areas is opening new shipping routes and increasing opportunities for extractive industries, thereby contributing to enhanced pollution at sea. With the present research project, I therefore propose to lead a comprehensive study of the indirect impacts of shrinking sea-ice cover on the arctic seabird community through the increase in the environment of two main oil-related pollutants levels (the polycyclic aromatic hydrocarbons and the mercury). Study the seabird community is essential as they represent an essential component of Arctic marine ecosystems but are also extremely sensitive to pollution risks. Moreover, impacts of oil-related pollutants on seabirds have never been investigated at community and pan-Arctic scales. More specifically, I will use new and trans-disciplinary approaches combining pollutant analyses, biotelemetry, bioenergetics modelling and field monitoring to (1) evaluate how levels of oil-associated pollutants changed in the Arctic seabird community over the last three decades. (2) I will use field studies to investigate the impacts of these pollutants on the behaviour, ecophysiology, reproductive success and survival of Arctic seabirds from differently exposed regions. (3) I will model how increasing pollutant levels in the Arctic marine environment are modifying the distribution of the seabird community by affecting their energetic niche. (4) I will finally rely on an international and pan-Arctic sampling network to use the Arctic seabird community as bio-indicators of the state of pollution in the Arctic marine environment and to thereby define sensitive hotpots for Arctic marine organisms.