Population characteristics of the gastropod Cantharidus pulcherrimus on intertidal platforms in the Perth area of Western Australia

Abstract

The trochid gastropod Cantharidus pulcherrimus is shown to be abundant on intertidal rock platforms in the Perth metropolitan area of Western Australia, where it is concentrated in the Sargassum algal zone. In this zone C. pulcherrimus is found living on macroalgae rather than the underlying rock. Density of snails varies seasonally, with maximum density occurring in summer and minimum density in autumn. Recruitment of juveniles into the population occurs during the winter (June-August). The young snails grow rapidly and spawn at one year of age in March or April. A small proportion of the adults survives for a second year. Loss of snails as macroalgae are washed from the platform by winter storms is the largest known source of mortality. The life history strategy of C. pulcherrimus is discussed in relation to that of other trochids.