My research focuses on the understanding of the functioning of microbial communities. I address this question by organizing my work around the following two themes: 1/ Diversity and functioning of biofilms and microbial mats: mainly in aquatic ecosystems (freshwater and marine). I am mainly interested in coastal ecosystems with a clear preference for the tidal zone. I study the diversity of microorganisms in these biofilms and their role in the functioning of ecosystems. 2/ Interactions in microbial ecosystems: between microorganisms (communication, ...) or between a host and a microorganism (symbiosis, ...)