BODY-SIZE VARIATION EXHIBITED BY AN INTERTIDAL LIMPET - INFLUENCE OF WAVE EXPOSURE, TIDAL HEIGHT AND MIGRATORY BEHAVIOR

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. Limpe t body size increased with increasing tidal height. This increase in s ize with tidal height was correlated with exposure to wave splash and migratory behavior. In areas of high and intermediate wave splash, the re was a significant positive correlation between increased limpet siz e and tidal height, while in sheltered conditions there was no signifi cant gradient in body size. Transplant experiments suggested that the size gradient could be maintained by the upward migration of large lim pets and downward migration of small limpets. In the area with little size gradient, there was no significant directional migration of trans planted limpets. Limpets initially exhibited a fixed migratory respons e when displaced both within an area and between areas differing in ex posure. However, after an acclimation period of 5 days in a new exposu re condition, the response of transplanted L. digitalis was indistingu ishable from that of limpets native to that condition, The findings su ggest that both fixed short-term and flexible long-term migratory beha vior are in part responsible for the maintenance of body size gradient s.