Current macrophyte distribution (light green areas) and lower macrophyte limit (dark green areas). The potential macrophyte distribution (turquoise area) corresponds to the theoretical lower macrophyte limit under good ecological conditions (Trophic Reference State) as defined by the European Water Framework Directive. Mussel filtration by colonies attached to the 58 % FPV system—covering the macrophyte-free zone as simulated by GLM-AED2—resulted in an expanded macrophyte distribution (brown area). The legal 40 m shoreline distance is marked with a red dashed line.