Résumé
Posidonia oceanica is a marine angiosperm endemic from the Mediterranean. Despite their protection, its meadows are regressing. The economic valuation of ecosystem services (ES) assesses the contribution of ecosystems to human well-being and may provide local policy makers help in territorial development. To estimate the economic value of P. oceanica seagrass and the meadows that it forms to better account its presence in coastal development, identification and assessment of ES provided are first performed. Then goods and benefits (GB) and their economical values are estimated. In total, 25ES are identified and 7 GB are economically evaluated. The economic value of GB provided by P. oceanica ranges between 25.3 mil- lion and 45.9 million €/year which means 283–513 €/ha/year. Because of the lack of existing available data, only 7 GB linked to 11/25ES have been estimated. Despite this overall undervaluation, this study offers a value for coastal development policies to take into account.