The Influence of Circulation Variability on Postlarval Brown Shrimp (Penaeus aztecus) Recruitment

Abstract

A parametric study with a calibrated and verified computer model has shown that changes in the direction of seaward atmospheric frontal passages as slight as ten degrees can significantly influence the nature of surface flow off Sabine Pass and Galveston Entrance. These computations and an array of interdisciplinary field observations reveal the sensitivity of the shelf's nearshore waters to external forcing. Abrupt restriction of transport into Sabine Lake and Galveston Bay by the development of seaward plumes is possible during several day episodes whose timing can influence recruitment of brown shrimp (Penaeus aziecus ) postlarvae. Postlarvae attempt to enter estuaries from the shelf over a late March--early April spring tide interval each year in order to reach an environment necessary for their development into adults. Redistribution over the inner portion of the shelf at this time by a transient, wind-forced alongshore or offshore component of the Texas Current can physically alter their chances to gain the life-sustaining embayments or to be swept away, back onto the shelf. This study provides an initial estimate of the sensitivity of critical processes to atmospheric forcing. Dynamic evolution of submesoscale physical features and their spatial and temporal phasing with respect to biological processes have the potential to be dominant factors in penaeid recruitment variability.