Date of Award
Engineering and Applied Science
Earth and Environmental Sciences
Lorenz, O. Thomas
McCorquodale, J. Alex
Quantifying the impacts of restoration on coastal waterways is crucial to understanding their effectiveness. Here, I look at the impacts of multiple restoration projects on urban waterways within the city limits of New Orleans, LA, with an emphasis on the response of fishes. First I report the effects of two projects designed to improve exchange down estuary on the hydrologic characteristics of Bayou St. John (BSJ). Within BSJ, flow is dominated by subtidal wind driven processes. Removal of an outdated flood control structure did not appear to alter exchange in BSJ, but removal combined with sector gate openings did. I also refined a three dimensional hydrodynamic model of this system to have accurate predictions of velocity and elevation. Temperature and salinity were difficult to constrain with this model. Solutions of this model were used to compare flow metrics, along with linearly interpolated temperature, and other variables to Red Drum (Sciaenops ocellatus) activity and movement patterns. Relationships between Red Drum activity and velocity suggested a response to subtidal, wind driven flow. Overall, high Sedentariness, a measure of inactivity, was found suggesting high levels of site fidelity. Higher mean Sedentariness during the night was also found. I also used a pseudo-BACI design to analyze the fish assemblage response to removal of an outdated flood control structure and the impacts of sector gate openings on fish guild species richness in BSJ. Limited differences were found when comparing fish assemblages before and after removal, but these differences were likely due to a decrease in salinity not restoration efforts. No significant differences in Freshwater or Estuarine fish guild species richness was observed for any of the control or impact sites. Marine fish species richness was found to be higher immediately following sector gate openings at the site closest to the structure, suggesting an initial pulse of young marine organisms is provided via these events. The findings here can be used to optimize management of exchange flow in coastal impounded waterways.
Smith, Patrick W., "Response of Fishes to Restoration Projects in Bayou St. John located within the City of New Orleans, Louisiana, including Hydrological Characterization and Hydrodynamic Modelling" (2015). University of New Orleans Theses and Dissertations. 2110.