Seafloor massive sulphides at deep-sea hydrothermal vents and natural gas hydrates in some methane seeps are of interest for resource extraction. However, the cost-benefit of deep-sea mining (DSM) need to accurately account for the scale of environmental impact, the ecosystem services that might be compromised and the potential mitigation measures that can be implemented. DSM may remove the habitat locally where the mining operations will take place and create localized sediment plumes caused by mining collectors at the seafloor, potentially introducing complex mixtures of potentially toxic elements in the water column. The climate change impact is the major concern related to the exploitation of deep-sea methane hydrates while the potential effects of sediment removal and resuspension have been much neglected so far. In situ experiments with local fauna are scarce but considered essential to better assess the potential impact of DSM . During this project, experiments will be performed at vents of the Mid-Atlantic Ridge (MAR) and at seeps in the northwest Pacific. This project aims to develop sound methodologies and discover new biomarkers from deep-sea species that can be used to assess and monitor environmental risk in deep-sea chemosynthetic ecosystems. It will contribute to answer the question: What are the potential environmental impacts of deep-sea resource exploitation of vents and seeps? The innovative aspects of this project are: 1) first in situ experiments at methane seeps addressing the potential ecotoxicological effects of sediments resuspension; 2) first study dedicated to the identification of specific biomarkers responding to sediments/sulphides and Cu exposure in deep-sea chemosynthetic species; 3) provide new insights into the evolution and adaptation to environmental change of congeneric species from different chemosynthetic environments.