Large-scale variability in recruitment of the barnacle Semibalanus cariosus: its cause and effects on the population density and predator

摘要

In marine habitats, regional hydrodynamics often cause large-scale recruitment variability of larvae. However, their resultant effects on the population and associated assemblage are poorly understood. This study was performed to examine recruitment variability of the intertidal barnacle Semibalanus cariosus at 15 sites along 90 km of shoreline on the Kameda Peninsula, Japan, during a 5 yr period. The cause of recruitment variability and its effects on population abundance of S. cariosus and the size and abundance of its predator, the whelk Nucella freycineti, were evaluated. Spatiotemporal variability in recruitment of S. cariosus along the Kameda Peninsula had a large temporal fluctuation with a relatively consistent spatial pattern that was likely to be determined by coastal currents, which are in turn determined by wind patterns. The resultant recruitment variability affected the population and associated assemblage at 2 spatial scales. At the local scale, i.e. within a port, barnacle recruitment variability controlled its population dynamics. At the regional scale, i.e. along tens of kilometers of coastline, the recruitment variability of the barnacle caused geographic variations in its population size and both the body size and the abundance of N. freycineti. These results suggest that regional oceanic current systems strongly affect the benthic assemblage at both local and regional scales by mediation of large-scale spatiotemporal variability in the recruitment of larvae.