Shore level differences in barnacle (Chthamalus dalli) recruitment relative to rock surface topography

Local recruitment of marine invertebrates is often variable and can be an important determinant of population structure and dynamics. Here, we examined recruitment of barnacles relative to rock surface topography (cracks) over 4 years at 5 sites in Hokkaido, Japan. We used recruitment over multiple years to test for differences in barnacle response to rock surface topography among shore levels under natural conditions and varying recruit densities. Our results showed that barnacles exhibit different recruitment patterns in relation to surface topography over small spatial scales (50 cm) with barnacles in upper intertidal associating more with cracks (p < 0.0001). In general, we found that barnacles tend to recruit more frequently within cracks in the upper shore and this result was not a function of barnacle density or available crack sites.