Monitoring of the species composition and abundance of the phytoplankton biomass, this monitoring is made up of 18 units, which are carried out on 18 different points in time. Each monitoring unit consists of: - The sampling of phytoplankton (chlorophyll a and phytoplankton taxa) - Determining the abundance of Indicator Taxa: Phaeocystis cell counts - The relevant environment variables needed for the characterization of phytoplankton - Completion of data in data sheets and in the format required for input into the database BMDC