MEPS 543:201-208 (2016)  -  DOI: https://doi.org/10.3354/meps11589

ABSTRACT: In spite of growing evidence for potential larval retention close to parental populations, it is still commonly assumed that large-scale transport mechanisms overwhelm local reproductive patterns and control larval settlement. Here, we evaluated the likelihood of settlement rate regulation by local biological factors and remote physical transport in a population of the intertidal tropical barnacle Chthamalus bisinuatus. Results indicated that juvenile recruitment and larval settlement may be substantially regulated by local reproductive output and pelagic food supply. Seasonal reproduction, with peak activity during summer, is followed by juvenile recruitment with no apparent lag over successive (ca. 15 d) sampling dates. Likewise, high-frequency (1 d) time-series analyses connected the main steps of the process: naupliar release correlates to cyprid supply in nearshore waters 7 d ahead, and cyprid supply is followed by larval settlement after an additional 4 to 5 d. Positive correlations between residuals of release vs. settlement relationships and chl a concentration (a proxy of phytoplankton biomass) also suggest food limitation for late naupliar stages. Tidal and wind transport did not explain the temporal variation in larval supply, and larval settlement responded only weakly to the wind of the day, suggesting a modest and very local effect. Addressing transport hypotheses alone is likely an inadequate approach to understand the supply-side ecology of marine invertebrates living in meso-oligotrophic systems such as the one examined in this study. A better understanding of processes affecting reproductive output and pelagic larval survival in addition to transport mechanisms, is likely required.

KEY WORDS: Rocky shores · Self-recruitment · Larval behavior · Larval competency · Metamorphosis · Food limitation