The general goals of this research were to study aspects of community stability of a sea urchin-dominated barren state and the transition of the system towards a kelp-forest-dominated state. Specifically, it aimed to elucidate: (1) primary responses of algae to reduced grazing pressure, and successional processes involved in the development towards a L. hyperborea kelp forest, and (2) the organism and population responses of sea urchins to improved availability of macroalgal food-plants. In addition, variability in the mass mortality gave valuable information about the reduction in sea urchin density needed to initiate kelp recovery.