Body-size variation exhibited by an intertidal limpet: Influence of wave exposure, tidal height and migratory behavior

Abstract

Body size variation of the intertidal limpet Lottia digitalis (Rathke) and the factors responsible for maintaining it were examined at three central California intertidal sites differing in wave exposure. Limpet body size increased with increasing tidal height. This increase in size with tidal height was correlated with exposure to wave splash and migratory behavior. In areas of high and intermediate wave splash, there was a significant positive correlation between increased limpet size and tidal height, while in sheltered conditions there was no significant gradient in body size. Transplant experiments suggested that the size gradient could be maintained by the upward migration of large limpets and downward migration of small limpets. In the area with little size gradient, there was no significant directional migration of transplanted limpets. Limpets initially exhibited a fixed migratory response when displaced both within an area and between areas differing in exposure. However, after an acclimation period of 5 days in a new exposure condition, the response of transplanted L. digitalis was indistinguishable from that of limpets native to that condition. The findings suggest that both fixed short-term and flexible long-term migratory behavior are in part responsible for the maintenance of body size gradients.