In the context of current global warming, future trend of Arctic Ocean primary production, the substance of marine food-webs, is poorly understood, making it essential to understand the ecophysiological light/temperature-response of diatoms (growth, productivity, acclimation, Si uptake). Indeed, Arctic Ocean primary production is closely related to the seasonal diatom photosynthetic productivity and species succession. It integrates the functional and ecological diversity of growth and life forms, cell size, depth-adaptation. Therefore, there is a need to comprehend how the functional and ecological diversity of Arctic diatoms’ light/temperature-response explains the present and future trends of Arctic marine primary production. This is the objective of ArtDÉco project.