Short- and long-term movements of the patellid limpet Patella flexuosa within gaps in intertidal mussel beds

Abstract

Short-term and long-term movements of the patellid limpet Patella flexuosa Quoy and Gaimard were studied on an intertidal rocky shore where a mytilid, Hormomya mutabilis (Gould), formed an extensive mussel zone. At low tide, all the limpets were found resting within gaps in the mussel zone, which were formed after mass dislodgement of the mussels by waves. The foraging areas of all the marked limpets were restricted to within the gaps during four 24h diving observations. All of these limpets displayed homing behaviour after short excursions with a maximum average distance of 6.7 cm from their homes. During short-term observation periods of about 4-5 days, no marked limpets moved from one gap to another gap across the mussel bed of H. mutabilis. During long-term observation periods of one month, however, 10-30% of marked limpets shifted their homes to different gaps that had a lower limpet density. The shell length of these emigrants was, in general, significantly smaller than that of nonemigrants. The percentage of emigrants tended to be higher in summer and autumn than in winter and spring. The movement of P. flexuosa within patchy habitats is discussed with a focus on the difference in site fidelity between small and large limpets.