MEPS 552:195-210 (2016)  -  DOI: https://doi.org/10.3354/meps11746

ABSTRACT: Larval settlement of Chthamalus spp. barnacles was measured daily at small spatial scales (~1 km) at 3 sites in Baja California, Mexico, along with water-column temperature, currents, and coastal winds. Synchronous settlement occurred at all sites throughout the 2 mo study. In general, no significant spatial pattern in settlement rate was detected, but on occasions when spatial differences occurred, the exposed and bay sites showed significantly greater settlement than the reef site. Autocorrelation artifacts in the environmental and settlement time series were removed with autoregressive integrated moving average analyses and their residuals were used in a principal component analysis to determine the independent modes of variability in environmental factors that explained the settlement patterns at each site. We found that settlement at the exposed site was only associated with the wind, which had not been detected previously. Settlement at the 2 other sites was associated with vertical isotherm displacements, suggesting the importance of internal waves at these more southern sites. Our results suggest that (1) the offshore larval pool does not vary greatly at the small spatial scales (~1 km) of this study, resulting in generally homogeneous, synchronous settlement, (2) a complex suite of factors may interact to result in settlement at the same site, and (3) settlement may be forced by different factors at sites in very close proximity due to differences in geomorphology and/or bathymetry, resulting in alongshore variability in transport mechanisms, which may explain the occasional spatial heterogeneity in settlement detected in this study.

KEY WORDS: Chthamalus spp. · Larval settlement · Internal waves · Onshore winds · Spatial-temporal variability