MEPS 169:289-293 (1998)  -  doi:10.3354/meps169289

ABSTRACT: Settlement abundances of barnacles are determined by larval supply and the ratio of settlement to larval supply (K). This ratio can be divided into 2 functions: the ratio of settlement on bare space to larval supply (k₁), and the loss of cyprids due to the preempting of rock space by sessile organisms (k₂). To examine the 3 functions of settlement (i.e. larval supply, k₁ and k₂ ) of the barnacle Semibalanus cariosus, we monitored the daily water column larval supply and the daily settlement density in plots where all benthos were removed and in natural-community plots, which were left undisturbed, during one settling season. In both low- and mid-tidal sites, k₁ explained >75% of day-to-day variability in K. k₁ and k₂ were density dependent, while daily settlement densities were linearly related to larval supply. k₁ varied with tidal height and daily larval supply, but not with other physical variables. k₂ varied with daily settlement densities in community-removal plots and was not related to any physical or biological variable. Such density dependence in k₁ and k₂ may have been caused by 3 processes: (1) inhibition of larval settlement by planktonic larvae, (2) enhancement of settlement by conspecifics (and their chemical attractants) on days with relatively low larval density, and/or (3) preemption of suitable settlement substrata by settlers that attached on days with relatively high larval density.

KEY WORDS: Barnacle · Density dependence · Key factor analysis · Settlement