A model investigation of the influence of submesoscale frontal dynamics on dispersal trajectories of near-surface, passive larvae around the Monterey Peninsula

Frontal regions concentrate plankton, which attracts larger marine species, and thereby accumulates biomass. Using a case study of kelp rockfish (Sebastes atrovirens) populations in central California, we demonstrate how submesoscale fronts modulate connectivity between populations in Carmel and Monterey Bays. We apply an offline nesting configuration (down to 120 m resolution) of the Regional Modeling System (ROMS) with realistic atmospheric and tidal forcing, from which Lagrangian trajectories are calculated by OpenDrift. Particles were released daily during the 2014 and 2015 spring upwelling seasons from coastal marine protected areas (MPAs) and maintained a depth of 2 m throughout their trajectory. The predominant direction of near-surface transport is offshore and to the south/southwest, preventing the majority of particles released from successfully recruiting near their release locations. Submesoscale SST fronts are frequently present in this area and act as transient barriers to exchange between populations. We focus on a recurrent submesoscale front near the entrance to Carmel Bay that is typically attached to the coastline with large positive relative vorticity and negative divergence. There are two main flavors of this front with differing impacts on particle transport. We present statistical analysis of the front and its impact on passive particle trajectories.