Experimental manipulations of the density of Cymbula granatina on rocky shore community

Densities of a commonly-harvested intertidal limpet Cymbula granatina were manipulated at two sites within a no-take marine protected area on the west coast of the Cape Peninsula in South Africa, using four treatment levels ranging from zero to maximum natural densities, together with control plots, to evaluate the effects of different harvesting intensities on rocky shore community composition. Following removal or thinning of C. granatina, community composition changed: cover of corticated and ephemeral algae increased and recruitment of C. granatina decreased. These outcomes were, however, dependent on the time frame considered, as algae underwent an annual cycle, and the effects of limpet removal were evident predominantly during the summer upwelling season when the algae proliferated. The management implications of the results of this experiment are discussed.