Monitoring of sediment quality in the backshore marshes of the Ile de Ré

As part of the Ile de Ré Wetlands Territorial Agreement (Accord de Territoire, formerly called CTMA) between the Ile de Ré Community of Municipalities and the Loire-Bretagne Water Agency, a bacteriological and physicochemical monitoring network for the quality of water and sediments in the channels was established in 2024. It consists of annual monitoring at 16 sampling stations (at each channel entrance). These priority areas, the nature of the elements analyzed, and the monitoring frequency were defined collaboratively. The elements analyzed include: bacteriological parameters (E. coli, enterococci), major heavy metals, 18 PAHs, 7 PCBs, organotin cations, as well as data relating to particle size, organic carbon, total nitrogen and phosphorus, and pH. The aim of this monitoring is to identify localized or recurring pollution, whether from the sea, stormwater runoff, or the marshes themselves, and to take appropriate action. The economic stakes related to the uses of the marshes and the ecological stakes are significant. It is crucial to protect them from pollution.