Origine et devenir de la matière organique au sein du micro-estuaire temporaire de Fiume Santu (L’Agriate, Haute-Corse)

In relation with meteorological, hydrological and topographic characteristics, Corsica has a very large number of temporarily open/closed micro-estuaries. Agriates contains several of them, including the Fiume Santu’s temporarily micro-estuary. These ecosystems are specific because of their sporadic connection with the sea. The opening and closure depends on both the river flow and the presence of the Posidonia oceanica (L.) Delile “banquettes”. Characterization of the global functioning was based on a multiparameter approach (particulate matter and dissolved inorganic matter descriptors, carbon and nitrogen stable isotope, phytoplankton communities), in order to qualify and quantify the organic matter (OM), along an estuary – coastal zone gradient. The OM sources have been characterized, revealing that the detrital OM is resulting from P. oceanica leaves degradation. This study highlighted four critical periods, with the close link between environmental, physical and biological factors. The matter transfers between different compartments (sediment, detrital, water column) and systems (micro-estuary, ponds, bay, coastal area) by the ecosystem were also demonstrated.