Slope-Dependent Biophysical Modeling of Surf Zone Larval Transport

Abstract

Onshore transport of intertidal invertebrate larvae at a reflective (steep beach slope) and an intermediate (relatively gradual beach slope) beach is modeled. Physical model calculations are conducted with the measured bathymetry data and averaged wave data obtained during the summer of 2010 at Sand City beach, CA (intermediate beach) and the summer of 2011 at Carmel River State Beach, CA (reflective beach). The physical model output is then used in a Lagrangian larval tracking model. Our results show that larval delivery to the surf zone is higher at the more dissipative beach than at the more reflective beach, and this is consistent with the larval recruitment study by Shanks et al. (2010). Also, two possible factors for the successful onshore larval transport on an intermediate beach, turbulent-dependent sinking behavior and buoyancy of larvae, are not always necessary in the case of a reflective beach.