Intertidal Zonation of Barnacles: The Influence of Planktonic Zonation of Larvae on Vertical Distribution of Adults

Abstract

The nonoverlapping vertical distributions of sessile species in the marine intertidal are usually considered to result from two interacting factors: (1) broadly restricted settlement of juveniles in the vertical horizon, and (2) postsettlement mortality which affects species differently. Investigated here is the role of larval behavior in molding the zonation of the acorn barnacles Balanus glandula and Balanus crenatus. I document the vertical distributions of: (a) adults, (b) newly settled spat, and (c) planktonic cyprid larvae. The data show that the vertical distribution of adults is a reflection of the vertical zonation of cyprids in the plankton and settlement patterns of spat. Although postsettlement mortality and substratum selection occur, presettlement behavior can strongly influence vertical zonation of sessile organisms.