Interannual variation and spatial distribution of decapod larvae in a region of persistent coastal upwelling

The California Current System is characterized by strong coastal upwelling that drives high primary production with implications for life in the plankton. We investigated the role of environmental variability at local, regional, and basin-wide scales in determining decapod larval distributions across space and time over 8 yr (2004 to 2011). We focused on an area of the California Current off the coast of central California, USA, characterized by a strong upwelling jet, a retentive zone with high primary production, a buoyant bay outflow plume, and proximity to both open coast and bay habitats. While multiyear studies of holoplankton distributions have revealed strong effects of basin-scale environmental variability, we did not find that basin-scale environmental changes resulted in major shifts in meroplankton distributions. Instead, meroplankton distributions in the California Current remained consistent across years-the oceanographic environment affected meroplankton distributions along complex shoreline topography but not across the shelf. Chlorophyll fluorescence and variables associated with regional upwelling were most correlated with larval distributions, indicating an association between larval distributions and primary production. We also found that environmental variability did not explain much of the variability in the larval distributions (only 5 to 20%), indicating that larval behaviors and demographic variables mediated the role of physical forcing in determining larval distributions. Larval distributions provide us with clues to determine larval transport and survival, adding to our understanding of how marine populations are connected, identifying threats to their persistence, and informing effective marine conservation and resource management planning.