Unusual larval abundance of Scyllarides nodifer and Albunea sp during an intrusion of low-salinity Mississippi flood water in the Florida keys in September 1993: Insight into larval transport from upstream

A massive intrusion of low-salinity water (salinity = 31-35) from the Missi ssippi River to the Florida Keys in September 1993 coincided with an unusua l abundance of the phyllosoma larvae (stages IV-VII) of a slipper lobster, Scyllarides nodifer, and the zoeae (stages III-V) of a sand crab, Albunea s p. These species are abundant in the northeastern Gulf of Mexico, but their adults and early stage larvae are not common in the Florida Keys. The infl ux of S. nodifer and Albunea sp. larvae into the Florida Keys is believed t o have originated on the northeastern Gulf of Mexico shelf. The southward t ransport of the larvae within a low-salinity plume from the Mississippi Riv er was apparently caused by anomalous eastward winds moving shelf waters in to the Loop Current, which had extended to within similar to 170 km of the Mississippi Delta. During normal-salinity conditions (salinity > 36) the sp iny lobster Panulirus argus is the most numerous species of phyllosoma larv ae in the coastal waters of the Florida Keys. A wide range of stages of P. argus is present year-round in the Florida Keys, suggesting multiple larval sources upstream possibly in the Yucatan Peninsula and the Caribbean. In c ontrast, the source of S. nodifer and Albunea sp, recruits for the Florida Keys may lie principally in the northeastern gulf. The recruitment success of larvae of gulf origin to the Florida Keys may depend partly on the coinc idence of specific wind and Loop Current transport conditions with an avail ability of larvae for expatriation at the source.