Interaction between seston quantity and quality and benthic suspension feeders in the Oosterschelde (The Netherlands)

The benthic suspension feeders Cerastoderma edule and Mytilus edulis form the major part of the biomass of all ecogroups in the Oosterschelde.#Mean biomass on mussel cultureplots in the western part is 340 g ADW/m2 and on cockle banks 63 g ADW/m2. Because of filtration a seston flux towards the bottom exists of 170 to 600 g suspended particulate matter/m2/day on a year average basis. Of this biodeposited material the greater part is resuspended immediately. Because 20 to 25% of the total volume is filtered per day, limitation of algal biomass is expected. Density and growth show a decrease from west to east, not fully corresponding with food quantity and quality. Some model calculations of seston depletion in relation to current speed, water depth and length of mussel and cockle banks are presented, with reference to future reduction of current velocities because of the construction of a storm surge barrier.