Early life history traits and recruitment patterns of Caribbean wrasses (Labridae)

Despite the fact that recruitment can significantly influence the population dynamics of benthic marine populations, relatively Little is known about the biological and physical processes controlling recruitment. We selected eight closely related coral reef fishes (wrasses in the family Labridae) to examine the temporal and spatial patterns of juvenile recruitment to the Caribbean island of Barbados. We used a comparative approach to study the relationships among patterns of recruitment, early Life history traits, and aspects of the physical environment. For 10 wk during each of three peak recruitment (spring) seasons (1990-1992), we used a biweekly census of recently settled juveniles (8-25 mm standard length, SL) to measure the abundance of six congeners, Halichoeres bivittatus, H. radiatus, H. poeyi, H. garnoti, H. pictus, and H. maculipinna, and two confamilial labrids, Thalassoma bifasciatum and Bodianus rufus. Analysis of the otoliths of a sample of collected specimens provided estimates of larval durations, postsettlement ages, sizes at settlement, and juvenile growth rates, enabling back-calculation of settlement day for all collected juveniles. We compared temporal patterns of recruitment among species, and spatial patterns of recruitment for the most common species. Temporal patterns of recruitment were consistent among seasons for most of the labrids examined, although the magnitude of recruitment was less predictable (particularly for H. poeyi, H. maculipinna, and B. rufus). The eight labrids could be divided into two groups based on their early Life history traits and within-season temporal patterns of recruitment. Halichoeres bivittatus, H. radiatus, H. poeyi, H. garnoti, and H. pictus had larval durations that were relatively short and invariant (means of 23-27 d), and all settled at fairly large sizes (9-12 mm SL) during the new moon and first maximum amplitude tide. In contrast, T. bifasciatum, B. rufus, and H. maculipinna had larval durations that were longer or more variable, and all three were able to delay metamorphosis. These three species settled at relatively smaller sizes (8-10 mm SL) during the third-quarter moon and second minimum amplitude tide. We compared temporal patterns of T. bifasciatum recruitment between Barbados and Caribbean Panama in an attempt to identify further the proximate environmental cues operating during settlement. Contrasting patterns of T. bifasciatum recruitment between the two geographical locations probably result from differences in the relative timing of the lunar and tidal amplitude cycles. Recruitment of labrids to Barbados occurred along the entire west coast of the island. Although some labrids had rather specific habitat requirements (e.g., B. rufus associated exclusively with large seaward-facing coral heads such as Montastrea spp.), most species were ubiquitous along the west coast. Species-specific juvenile densities did not often vary significantly among sites following major recruitment events, although overall densities were generally lower at a central site. Lower recruitment to that site likely results from reduced rates of larval supply due to prevailing offshore tidal flows. Thus, temporal and spatial patterns of labrid recruitment to Barbados appear to be more predictable than previously thought for reef fishes. In particular, variation in the tidal amplitude cycle may influence both the timing of settlement and, to a lesser degree, the spatial scale of larval supply. Finally, the interaction of larval biology with such physical processes is evident in the correlation between temporal patterns of recruitment and early life history traits. The functional nature of this relationship clearly warrants further study.