The large-scale proliferation of pelagic Sargassum in the Tropical Atlantic from 2011 has been the subject of increasing attention because of its negative consequences on the environment, fishing, and socioeconomic activities when stranding on coastal areas. This recurrent phenomenon presents strong seasonal and year to year variations. Anticipating the abundances and stranding on seasonal scale poses important challenges in terms of observations and modeling. We show that skillful seasonal forecast of Sargassum distribution can be achieved with up to 7 months in advance over the Tropical Atlantic, by integrating both transport and current knowledge on physiology of Sargassum. This forecast is designed to help marine stakeholders to develop mitigation and resilience strategies through anticipatory decision-making.
