Remote Radar Measurement of Shelf Currents off Key Largo, Florida, U.S.A.

The east coast of the United States is lined by a series of shallow inlet/bays systems that provide essential habitats for a number of important fish species. The strongest currents in these systems are typically found near the inlet where they are dominated by semidiurnal tidal motion. Beam-trawl sampling in the vicinity of Little Egg Inlet in southern New Jersey over several years indicates that the settlement of winter flounder, Pseudopleuronectes americanus, occurs predominantly within small coves just inside the inlet. Because of the strong tidal currents, horizontal motion of pre-settlement larvae is strongly influenced by advection. Based on hydrodynamic surveys of the region, a mechanism is suggested by which coves immediately inside of tidal inlets favour the delivery of estuarine larvae for subsequent settlement. The mechanism involves the filling of the coves with estuarine waters trapped just inside the inlet by flow separation during the flood. As a result, these observations suggest that coves near inlets may provide important settlement habitats for this estuarine species.