Larval quality is shaped by matrix effects: Implications for connectivity in a marine metapopulation

Abstract

Variation in the phenotype or "quality" of dispersing individuals can shape colonization success and thus local dynamics and patterns of connectivity in a metapopulation. In marine reef systems, larval dispersal typically connects fragmented populations, and larval quality may be shaped by developmental history at the natal reef (e.g., parental effects) and/or by conditions in the pelagic environment (e.g., food, temperature, hydrodynamics, predator regime). We extract information recorded within the incremental bands of fish "ear stones" (otoliths) to reconstruct the early life histories of reef fish, to evaluate whether larval quality is a function of natal populations, dispersal histories, or both. We sampled sagittal otoliths from 282 common triplefins (Forsterygion lapillum) collected at approximately weekly, intervals between December 2003 and March 2004, from three sites within Wellington Harbor (New Zealand) and three sites along the adjacent Wellington South Coast. We used image analysis to quantify otolith traits and to reconstruct five larval phenotypes (pelagic larval duration, size-at-hatch, early larval growth, late larval growth, and an instantaneous larval growth rate), followed by a principal components analysis to derive a composite measure of larval quality. We used laser ablation-inductively coupled plasma-mass spectrometry to quantify otolith microchemistry, followed by a set of cluster analyses (based upon 13 statistical descriptors of time series for ea…