EARLY-LIFE HISTORY TRAITS AND RECRUITMENT PATTERNS OF CARIBBEAN WRASSES (LABRIDAE)

Despite the fact that recruitment can significantly influence the popu lation dynamics of benthic marine populations, relatively Little is kn own about the biological and physical processes controlling recruitmen t. We selected eight closely related coral reef fishes (wrasses in the family Labridae) to examine the temporal and spatial patterns of juve nile recruitment to the Caribbean island of Barbados. We used a compar ative approach to study the relationships among patterns of recruitmen t, early Life history traits, and aspects of the physical environment. For 10 wk during each of three peak recruitment (spring) seasons (199 0-1992), we used a biweekly census of recently settled juveniles (8-25 mm standard length, SL) to measure the abundance of six congeners, Ha lichoeres bivittatus, H. radiatus, H. poeyi, H. garnoti, H. pictus, an d 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-calcula tion of settlement day for all collected juveniles. We compared tempor al patterns of recruitment among species, and spatial patterns of recr uitment for the most common species. Temporal patterns of recruitment were consistent among seasons for most of the labrids examined, althou gh the magnitude of recruitment was less predictable (particularly for H. poeyi, H. maculipinna, and B. rufus). The eight labrids could be d ivided into two groups based on their early Life history traits and wi thin-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 s ettled at fairly large sizes (9-12 mm SL) during the new moon and firs t 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 se ttled at relatively smaller sizes (8-10 mm SL) during the third-quarte r moon and second minimum amplitude tide. We compared temporal pattern s of T. bifasciatum recruitment between Barbados and Caribbean Panama in an attempt to identify further the proximate environmental cues ope rating during settlement. Contrasting patterns of T. bifasciatum recru itment between the two geographical locations probably result from dif ferences in the relative timing of the lunar and tidal amplitude cycle s. Recruitment of labrids to Barbados occurred along the entire west c oast 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 ubiqui tous along the west coast. Species-specific juvenile densities did not often vary significantly among sites following major recruitment even ts, although overall densities were generally lower at a central site. Lower recruitment to that site likely results from reduced rates of l arval supply due to prevailing offshore tidal flows. Thus, temporal an d spatial patterns of labrid recruitment to Barbados appear to be more predictable than previously thought for reef fishes. In particular, v ariation in the tidal amplitude cycle may influence both the timing of settlement and, to a lesser degree, the spatial scale of larval suppl y. Finally, the interaction of larval biology with such physical proce sses is evident in the correlation between temporal patterns of recrui tment and early life history traits. The functional nature of this rel ationship clearly warrants further study.