The limpet Patella vulgata L. at night in air: effective feeding on Ascophyllum nodosum monocultures and stranded seaweeds

Abstract

Opportunistically, the limpet Patella vulgata will switch from microphagous grazing to feeding on attached macroalgae or, a novel finding, on accumulations of stranded seaweeds. Macroalgal food is ingested primarily at night during emersion, when the thalli come to lie on the rock surface and are sufficiently damp. Monocultures of Ascophyllum nodosum are not immune to the destructive effects of limpets as previously thought. Patella vulgata can graze them down to complete disappearance, thus pushing Ascophyllum back to refuges where P. vulgata is absent or rare. Such refuges were found along a wide range from very sheltered to strongly wave-exposed rocky shores in Brittany, France. By a combination of its macrophagous and microphagous feeding habits, P. vulgata can control mid-tidal macroalgal assemblages in a similar fashion to the action of sea urchins upon kelp communities inhabiting the lower intertidal and shallow sublittoral zones of rocky shores.