HABs occur naturally, but human activities that disturb ecosystems seem to play a role in their more frequent occurrence, intensity and spatial extent (Hallegraeff et al., 2004). Increased nutrient loadings and pollution, food web alterations, non-native species, current modifications and climate change all play a role (NOAA, 2018). Regarding impacted economic activities, HAB events are managed on a crisis basis, leading to closures of contaminated areas and/or ban commercial products based on in situ monitoring and alert systems. Developments in remote sensing science can bring a significant added value to existing monitoring systems. For instance, remote sensing can support the development of an alert system that could result in much faster response times. To assess to which extent it can mitigate the socioeconomic impacts of HABs (monitoring and management costs, avoided economic losses, risk management by stakeholders), but also to understand the adaptation dynamics of economic activities to HAB events and the way they are managed, a system approach has been implemented to describe the HAB socio-ecosystem of the French-administrated part of the English Channel. It will help to address the intrinsic complexity of HABs and their impacts.