Multi-scale effects in early stages of the stenothermal fish, Arctic charr Salvelinus alpinus after combined exposure of temperature and gamma irradiation.

In the context of global change, the aim of this study was to investigate the combined effects of temperature and gamma irradiation (generating oxidative stress) on phenotypic traits (survival, hatching, growth, behaviour) to challenge the ecological risk assessment methodology and on specific biomarker (oxidative stress) to identify toxic mechanisms. Arctic charr S. alpinus embryos were first exposed to combined gamma irradiation and thermal stress until hatching and then to alone thermal stress until juvenile stage. Our study demonstrates that early-life exposure to irradiation (500 µGy h-1) exerts sublethal deleterious effects on Arctic charr larvae, affecting growth, metabolism, behaviour, and stress responses. These results highlight the importance of considering early life stage and realistic environmental conditions particularly the context of multiple pollution, when evaluating the ecotoxicological impacts of ionizing radiation on fish.