TEMPORAL AND SPATIAL SCALES OF INFLUENCE ON NEARSHORE FISH SETTLEMENT IN THE SOUTHERN CALIFORNIA BIGHT

Recruitment variation in marine populations is clearly affected by physical processes in the ocean. We therefore examined correlations between long-term, high-frequency data on fish settlement on artificial substrates and oceanographic processes operating at different spatial and temporal scales. We sought, for example, associations with processes occurring close in time and space to settlement events (suggesting processes affecting local delivery) or with those at particular spatial and temporal lags (suggesting influences on larval transport and survival or, at even greater time lags, on larval production). We used as response variables an 8-yr, biweekly record of settlement of three groups of fishes to sites in the Santa Barbara Channel, California, USA. Predictor variables were day-specific physical processes resolved to "local" scales and then binned and lagged to represent "regional" and "basin" spatial scales and more distant time horizons. We used linear models to assess the amount of variability in settlement associated with variation in processes at different spatial and temporal scales, representing different processes such as food availability or physical transport. We found that settlement is linearly associated with a combination of large-scale factors at long time lags, consistent with variation in production at sources and early larval survivorship, and with small-scale factors at short time lags, consistent with processes aiding delivery of competent individuals to suitable nearshore habitat. Species groups differ in the relative strength of these factors, potentially because of different biological attributes.