This dataset contains seasonal physiological measurements from controlled laboratory experiments on two dominant suspension-feeding species expected to colonise floating offshore structures: the blue mussel (Mytilus edulis; AphiaID 140480) and the wrinkled barnacle (Balanus crenatus; AphiaID

106215). The measured parameters include clearance rates, respiration rates, faecal pellet production rates, and faecal pellet sinking velocities. Mussels were collected from an aquaculture longline at the Westdiep SeaFarm, while barnacles were manually retrieved from the intertidal beachhead at Raversijde (Oostende, Belgium). All experiments were conducted using natural seawater collected from offshore sites in the Belgian part of the North Sea. Measurements were repeated across multiple seasons to capture temporal variability in physiological performance. The dataset was produced within the SWiM and EcoMPV projects and is suitable for reuse in ecosystem and biogeochemical modelling, including simulations of phytoplankton dynamics associated with large-scale offshore marine photovoltaic (MPV) developments.