MEPS 135:69-75 (1996)  -  doi:10.3354/meps135069

To determine if the onset of intertidal life is a critical time for survival, we examined the fate of newly settled Balanusglandula, an intertidal barnacle, on natural rocky substrata in Barkley Sound, British Columbia, Canada. In total, 552 individual settlers were mapped and followed daily during their first 3 to 5 d after settlement in May 1992 and were then periodically re-examined over a 45 d period. A sharp decline in survivorship occurred during the first day after settlement. For settlers arriving on 16 and 17 May, mortality during the first day after settlement (38.0%) was almost as high as all mortality during the following 44 d (40.1%). Mortality during the first day after settlement was 1.5 to 6.0 times higher than during the second day for settlers arriving on 16, 17 and 18 May. There was no relationship, however, between percent first day mortality and densities of recruits or of grazers (limpets, littorines). The elevated levels of first day mortality were also not consistent with desiccation stress, wave exposure, or size-specific changes in vulnerability. The first moments after settlement may constitute a bottleneck for the survival of barnacles settling in the intertidal zone. For organisms such as B.glandula, selective pressures for traits such as time of settlement relative to the tidal cycle, selection of settlement micro-site, and energy reserves at settlement could be most intense during the first day in the benthic habitat.

Bottleneck . Bulldozing . Early juvenile . Density-dependent mortality . Recruitment . Sessile invertebrates . Settlement . Survivorship