Coastal ecosystems provide a wide range of ecosystem services (ES) subject to strong human pressure and are included in conservation policies that aim to increase their resilience. Implementing resilience measures requires knowledge of the public perceptions of social-ecological systems so that commitment to environmental protection may be enhanced. Few studies address public percepion of the evolution of social-ecological systems and integrate the diversity of ES (regulating, provisioning and cultural). This article is based on a survey of 476 inhabitants and deals with their perceptions of past (50 years) and future (+15 years) ES. It focuses on the Thau lagoon (French Mediterranean) that offers many ES and where managers prioritize traditional uses such as shellfish farming and fishing. Respondents’ answers were compared with the results of scientists’ and experts’ evaluations to assess the level of public knowledge. The results indicate consistency in the qualitative and quantitative responses of local residents concerning the long-term evolution of ES and show them to have a fairly sound knowledge. However, there are some differences in trends with substantial variation for several ES probably related to judgement or anchoring biases. Furthermore, a majority of local residents had a mixed perception of local structuring ES. This innovative approach to the perceptions of ES momentum suggests that improved conservation policies must: (i) take into account the different communication and awareness requirements of people and (ii) integrate local knowledge through dialogue.