Filamentation and eddy−eddy interactions in marine larval accumulation and transport

A coupled particle-tracking/ocean circulation model of an idealized eastern boundary upwelling current is used to explore the mesoscale pathways of larval transport. We find that simulated larvae are often organized into filaments found between mesoscale eddies that correspond to attracting Lagrangian coherent structures (LCS). Such structures are material curves that map filamentation and transport boundaries, often corresponding to the locations of sea-surface temperature fronts. Filamentation and eddy-eddy interactions aggregate larvae from many source regions and release times into small, highly dense packets that can be transported back to the shelf. Larval densities in these packets can be up to 2 orders of magnitude greater than initial release densities near the coast and are robust to strong levels of random 'swimming' perturbations. This study suggests that coherent flow structures play an important role in pelagic transport of marine larvae.