Flows, salinity, and some implications for larval transport in south Biscayne Bay, Florida

A numerical model was developed to describe the currents, residence times, salinity patterns, and larval transport in a South Florida lagoonal system. Model forcing included tides, wind, and freshwater inflows prescribed from 4 yrs of recorded observations. Physical and biological performance tests were applied to two hindcasts. Computed tidal currents agreed with observations to within 0.01 m s⁻¹. Transports in ocean inlets explained 87% of observed variance over a 45-d period. The average difference of computed salinities, expressing the effects of model advective fields, and historic salinity data from 54 locations was less than 2 psu. Computed residence times varied widely from several months in the more enclosed Barnes Sound, to on the order of a month in the western parts of South Biscayne Bay, and to near zero in the vicinity of the ocean inlets. The hydrodynamic model was also coupled to one for the Lagrangian drift dynamics and recruitment of post-larval pink shrimp to study both passive-particle and behaviorally-mediated drift of population cohorts. Simulations of drift trajectories of pink shrimp larvae and shrimp spatial abundance distributions were in agreement with settlement patterns of live shrimp larvae from synoptic sampling surveys carried out over the last 25 yrs. The coupled models could be used to evaluate ecosystem effects and risks to coastal marine resources from a regional redistribution of surface and groundwater.