RIP biplots of the native mussel, Mytilus edulis (blue), and coexisting ‘oyssel’ reefs (orange) using biomass data from the Wadden Sea (mean ± S.E.). Squares indicate clearance rate (CR; L h-1 g-1) at minimum food level, circles indicate average CR over all food levels, triangles indicate CR at maximum food level (mean ± S.E.). Impact increases from bottom left to top right.