• 1 Agglomération et ville de La Rochelle
• 2 LIttoral ENvironnement et Sociétés [LIENSs]

In the context of global climate change, France has committed to achieving carbon neutrality. The territory of La Rochelle, through the La Rochelle Territoire Zéro Carbone project, aims to reach this goal by enhancing its "blue carbon" ecosystems. This study proposes a typology of La Rochelle's blue carbon ecosystems along a land-sea continuum, establishing an unprecedented classification of seven types of environments that could act as carbon sinks : dyked freshwater, brackish, and salt marshes, as well as salt meadows, mudflats, seagrass beds, and the ocean. A second level of classification was introduced for backshore marshes, attributing the concept of blue carbon only to aquatic surfaces. This distinction between water surfaces and emerged surfaces raises questions about the separation between blue carbon and green carbon. Additionally, a geographic database was created, accompanied by maps to locate these environments and assess their surface area, assisting managers and local authorities in their mission to preserve and evaluate the carbon capture and sequestration potential. The study's limitations include the subjectivity of the maritime perimeter assigned to the territory and the categorization of ecosystems between blue carbon and green carbon. This innovative typology, supported by a cartographic framework, provides a better understanding of carbon sinks in the territory and helps to guide public policies toward achieving carbon neutrality.