Competition and intertidal zonation of barnacles at Leigh, New Zealand

Three species of barnacles (Chamaesipho brunnea, C, columna, and Epopella plicata) occupy a large part of the intertidal zone at Goat Island Bay, Leigh. Although settlement and growth patterns vary in the three species, intraspecific competition results mainly in reduced growth rates with increasing density. Smothering of earlier settled specimens occurs occasionally in C. columna. Competition and preferential predation by gastropods restrict C. brunnea to the upper shore. Epopella plicata and C. columna compete for settlement space. At the lower shore levels, competition from oysters, mussels, and algae reduces the rock space available for barnacle settlement.