Fish larvae recruitment to Texas bays through Aransas Pass

2012-2014 - $188,533

Scott A. Socolofsky, Kuang-An Chang
Coastal and Ocean Engineering Division,
Zachry Department of Civil Engineering,
Texas A&M University, College Station, Texas

Scott A. Holt
University of Texas at Austin Marine Science Institute, Port Aransas, Texas.

Abstract

This project applies hydrographic measurements in the Aransas Pass bays system to quantify current patterns important for recruitment of red drum (Sciaenops ocellatus) larvae to bayside nurseries.  Red drum remains largely passive in the water column during transport from offshore spawning areas to estuarine grass beds.  Hydrographic measurements proposed here will test the hypotheses that 1.) Larvae are supplied to the bays behind Aransas Pass primarily by tidal currents that are most strongly influenced by bathymetry (during spawning, flood tides are common at night when the winds are generally calm) and 2.) Larvae are captured bayside of Aransas Pass by secondary currents induced by the wind (secondary circulation transports the larvae to the channel and basin edges during the morning, before the diurnal ebb tide).  Field measurements will include Lagrangian drifters, towed and moored acoustic current profilers, and density structure profilers, including high-resolution measurements of the turbulence microstructure.  Predicted recruitment patterns from the field data will be compared to historical bayside settlement data for red drum larvae to evaluate the importance of these physical mechanisms on larval transport.  In addition to the field measurements, an empirical model predicting the importance of tide to wind-driven currents under the influence of local topography and bathymetry will be developed.  This modeling tool will be disseminated to coastal community managers to identify and guide decisions that will affect recruitment of red drum larvae to Texas bays.