Studies of Patella vulgata L. I. Growth, reproduction and zonal distribution

Abstract

A population of Patella vulgata L. from a sheltered coast at Robin Hood's Bay, North Yorkshire, has been studied. On alternate spring-tides (from September 1964 to December 1966) the population was sampled at seven stations along a transect line which extended from between M.H.W.S. and M.H.W.N. to between M.L.W.N. and M.L.W.S. The population was found to have a polymodal frequency distribution, the components of which were dynamically maintained. Each component represented a separate year group, the growth of which was maximal during the summer and was depressed over the winter. This pattern persisted from year to year but varied in degree, some years supporting higher growth rates than others. Animals five years old and over were few in number and had no measurable growth rate. The limpets matured for the first time in their second year as males. Females first appeared in the third year and thereafter were present in increasing numbers. Gonad maturation coincided with the period of maximum increase in body size. The settlement of the young limpets was usually first detected in January. The pattern of their settlement and subsequent survival was responsible for the zonal pattern of the total population.