Abstract:
Gooseneck barnacles, Pollicipes polymerus, form clusters in the mid-upper rocky intertidal on exposed coasts of the northeast Pacific. Clusters compete for space, losing only to mussels, Mytilus californianus, and larvae settle gregariously on adults. By tagging juveniles with calcein, I studied recruitment and growth of juveniles in large and small clusters and on solitary adults. Recruitment was patchy; many adults contained no recruits, and three adults in each cluster contained 47 % of recruits. More juveniles per adult were found on edges than centers of clusters, and juveniles on edges grew faster than those on the inside of clusters. There was no effect of cluster size on recruitment or growth. Solitary adults had more recruits than clusters, and juveniles on solitaries grew faster than those from clusters. These results imply solitaries should quickly grow into clusters, and clusters accrete from their edges. These patterns may help Pollicipes compete with mussels.