SPONAUGLE, S.*; GRORUD-COLVERT, K.; RSMAS, Univ. of Miami; RSMAS, Univ. of Miami: Influence of early life history traits on recruitment success and early survival in a coral reef fish
For organisms with complex life histories, life history traits of early stages may influence the survival of subsequent stages. We surveyed and collected 13 monthly cohorts of the reef fish, the bluehead wrasse, Thalassoma bifasciatum, from the Florida Keys to examine how variation in water temperature influences early life history (ELH) traits and juvenile recruitment. We also repeatedly sampled nine of the cohorts over sequential 3 d periods during the first 2 wks of juvenile life to determine whether early survival is related to particular ELH traits. Otoliths of new settlers were analyzed to obtain individual and cohort-specific data on ELH traits. Larval growth was directly related to water temperature, and fast-growing larvae in warm waters had shorter pelagic larval durations. Water temperature explained 61% of the variation in size of recruitment events, but only if four cohorts settling during the nearshore passage of mesoscale eddies were removed from the analysis. Eddy passage may disrupt the larval food supply or advect larvae out of the system. For successful recruits, cohort-specific survival on the reef was selective with respect to at least one ELH trait, but the traits and strength of selection varied among cohorts. Most frequently, survivors had wider otolith metamorphic band widths (thought to be a proxy for condition) and faster juvenile growth rates. These traits were also the most variable among new settlers, with variability decreasing with recruit age. Higher condition settlers were frequently, but not always, smaller at settlement. The variable pelagic life of T. bifasciatum may provide multiple ways to achieve a minimum settlement condition, thereby complicating selective mortality.