Isolation of the 2019 Bonnet Carré Spillway Effects on the Habitat Suitability of Brown Shrimp (Farfantepenaeus aztecus) and Blue Crab (Callinectes sapidus) Using a Modeling Approach

Author

Mallory Dyson, University of Southern MississippiFollow

Date of Award

12-2025

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

School

Ocean Science and Engineering

Committee Chair

Dr. Scott Milroy

Committee Chair School

Ocean Science and Engineering

Committee Member 2

Dr. Kim de Mutsert

Committee Member 2 School

Ocean Science and Engineering

Committee Member 3

Dr. Jerry Wiggert

Committee Member 3 School

Ocean Science and Engineering

Abstract

In 2019, an unprecedented flood year, the Bonnet Carré Spillway (BCS) was opened on two separate occasions (February 27^th to April 11^th, and May 10^th through July 27^th) diverting a volume 6 times the volume of Lake Pontchartrain into the surrounding coastal waters of Louisiana, Mississippi, and Alabama. The goal of this research was to determine the spatio-temporal influence of these freshwater releases on two economically and ecologically important species (Farfantepenaeus aztecus and Callinectes sapidus) with variable responses to salinity and temperature depending on the age class. The Habitat Suitability Index (HSI) model framework was utilized in this study in conjunction with (1) combined-effects calculation schemes using catch per unit effort (CPUE) data and (2) hydrodynamic model (msbCOAWST) output to determine if there was a significant impact from the 2019 BCS diversions.

The geometric mean was determined to be the best combined-effects model for estimating habitat suitability model values when considering salinity, temperature, and depth in combination (SxTxD and SxT) The results for brown shrimp and blue crabs indicated that there was a consistent significant impact from BCS outflows in response to salinity across all age classes and all critical ecological periods, while impacts in response temperature were more variable, with significantly impacts on the younger age classes (larvae) and more developed blue crabs (juvenile and adult male). The significant impacts were primarily seen in Louisiana and Mississippi in response to salinity and temperature for both species, with few significant impacts seen in Alabama.

ORCID ID

https://orcid.org/0000-0003-3350-5876

Copyright

Mallory Dyson 2025

Recommended Citation

Dyson, Mallory, "Isolation of the 2019 Bonnet Carré Spillway Effects on the Habitat Suitability of Brown Shrimp (Farfantepenaeus aztecus) and Blue Crab (Callinectes sapidus) Using a Modeling Approach" (2025). Master's Theses. 1158.
https://aquila.usm.edu/masters_theses/1158