Population regulation in the intertidal limpet Patelloida alticostata (Angas, 1865)

Abstract

Subpopulations of the limpet, Patelloida alticostata, converged slowly toward a density of about 75 per linear meter of vertical rocky shore two years after experimental alteration of densities of adult animals. The changes in number of limpets in subpopulations occurred because large limpets suffered considerable mortality, while recruits experienced almost none. Neither migration, cannibalism, selection of settlement site by the limpets, nor predation by a whelk, acted in a density-dependent manner. Growth rates were density-dependent, and juveniles and recruits reached a much larger size in the absence than in the presence of adult limpets. Increasing the density of adult limpets did not increase the extent of grazing areas and subpopulations of different size compositions utilized similar grazing areas. Food may have been in short supply. These limpets have a great deal of population inertia, accommodating sporadic good recruitment by compensations in growth rates.