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Canopy‐forming macroalgae are key species on temperate rocky shores. However, there is a lack of understanding of how the relative balance of physical and biological factors controls the establishment and persistence of intertidal macroalgae. Here we present an integrated study of the relative importance of wave‐induced forces and grazing for the recruitment and survival of the canopy‐forming intertidal macroalgae Fucus vesiculosus and F. spiralis. A set of overtopped breakwaters provided a nearly unconfounded gradient in wave exposure between seaward and landward sides. A biomechanical analysis was performed based on empirical measurements of maximum drag forces in breaking waves, a model of long‐term maximum wave height, and the breaking stress of Fucus spp. The estimated maximum flow speed (7–8 m/s) on the seaward side of the breakwaters was predicted to completely dislodge or …