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

Abstract

A massive intrusion of low‐salinity water (salinity = 31–35) from the Mississippi River to the Florida Keys in September 1993 coincided with an unusual 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 sp. 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 influx of S. nodifer and Albunea sp. larvae into the Florida Keys is believed to have originated on the northeastern Gulf of Mexico shelf. The southward transport of the larvae within a low‐salinity plume from the Mississippi River was apparently caused by anomalous eastward winds moving shelf waters into the Loop Current, which had extended to within ∼170 km of the Mississippi Delta. During normal‐salinity conditions (salinity > 36) the spiny lobster Panulirus argus is the most numerous species of phyllosoma larvae 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 contrast, 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 coincidence of specific wind and Loop Current transport conditions with an availability of larvae for expatriation at the source.