Despite their global distribution and ecological importance, little information about eukaryotic diversity is available from small, shallow and ephemeral freshwater systems. The goal of this project is to monitor monthly and compare protist diversity in one brook and four shallow ponds located in the "Natural Regional Park of the Chevreuse Valley", France during 2 years. The study is based on the identification and comparison and time tracking of operational taxonomic units (OTUs) infered from massive pyrosequencing of amplified 18S rRNA gene fragments of protists in the 0.2-5 µm-size range.