Effects of limpets on competition and diversity in a community of marine sessile invertebrates

The effect of disturbance on species diversity was explored in a benthic marine fouling community of sessile macroinvertebrates. Mediterranean intertidal limpets Patella coerulea L. (Gastropoda, Prosobranchia) served as an experimental disturbance agent, when transplanted to subtidally immersed panels on which a fouling community developed for seven months. The panels were then removed and the invertebrate populations censused and compared with those on panels with no limpets. The movement of the limpets on the experimental panels constituted the disturbance: while foraging for algae the limpets bulldozed and removed young animal recruits. It was found that the limpets (a) allowed individuals of different species to persist in relative proximity to each other; and (b) promoted species diversity by increasing evenness through reduction of dominance.