Coastal and marine ecosystems are under pressure from various human activities, which exert direct and indirect impacts on underwater biota. Relevant management policies urgently need detailed information on ecological impacts of the activities. The COMA project analyzed the impacts of human activities and pressures on marine ecosystem were from three different viewpoints: (1) What evidence there is of ecosystem responses to single and multiple pressures?, (2) How different human activities impact the marine ecosystem?, and (3) What evidence there is of the sustainable levels of human activities? By applying a review, a meta analysis and three case studies, COMA addressed the questions, provided advice and suggested an approach for management.