The project aims to contribute to a better understanding of the trofic interactions between diatoms and harpacticoid copepods and more specific to the functional role of these interactions on the biodiversity of both primary producers and consumers. The objective will be realised in three part: I. Methodological aspects of ex situ experiments based on stable isotope analysis; II. Diversity of copepods and the effect of diatoms and the effect of copepods on diatoms.