Distribution of crab larvae in relation to tidal fronts in Delaware Bay, USA

Replicate observations of hydrographic structure and crab larval distributions were conducted at ebb-tide, flood-tide and non-frontal sites In lower Delaware Bay.Results show that frontal structure is restricted to the upper 2 m of the water column and that convergent velocities associated with the fronts are sufficient to collect buoyant and upward-swimming plankton at the surface.Despite this, maximum concentrations of larvae at fronts were found at depths greater than the frontal pycnocline, while larvae at the non-frontal site showed no significant difference in their abundance with depth.While the observed frontal distributions may be due to a balance between upward swimming by the larvae and downward movement of water at the frontline, ecological effects are mltlgated by the ephemeral nature of the fronts O Inter-Research/Printed in F. R. Germany