ORCID ID

0009-0004-2007-1129

Date of Award

5-2026

Degree Type

Dissertation

Degree Name

Ph.D.

Degree Program

Biological Sciences

Department

Biological Sciences

Major Professor

Boyle, Kelly S. ; Rieucau, Guillaume

Second Advisor

Lailvaux, Simon

Third Advisor

Rees, Bernard

Abstract

The life histories of many Louisiana fishes are closely tied to the timing, magnitude, and duration of the Mississippi River flood pulse, which regulates the ecological connectivity and productivity of adjacent floodplain habitats. Anthropogenic modifications such as levee construction and water-control structures have disrupted these natural hydrologic linkages, altering habitat quality and community structure across the Lower Mississippi River Basin. This dissertation used high-resolution imaging sonar to investigate how fish assemblages, species, and collectives respond to changes in floodplain connectivity within the Richard K. Yancey Wildlife Management Area prior to hydrologic restoration. In the first chapter, I applied imaging sonar to characterize the floodplain-associated fish assemblage abundance, size-class distribution, and seasonal use of floodplain habitats. Results demonstrated size-class-dependent responses to inundation level, with greater detections during high-water connected periods, underscoring the role of the flood pulse in structuring assemblage dynamics. The second chapter focused on gars, an easily identifiable fish family within imaging sonar datasets. Gars exhibited size-dependent occupancy patterns mediated by seasonal inundation level, highlighting the importance of low water habitats as nursery and refuge when disconnected from the main channel. The third chapter examined collective tendencies of floodplain-associated schooling fish to floodplain connectivity. Quantifying school area, alignment, and nearest-neighbor distance revealed that fish modulated group structure and cohesion in response to changing water levels and habitat conditions. The fourth chapter experimentally tested the influence of perceived predation risk on schooling behavior using visual background manipulations. Schools exposed to higher perceived risk formed larger groups, while variation in collective tendencies was consistently driven by inundation level and site-specific hydrology. Together, these studies demonstrate that floodplain-associated fishes exhibit strong ecological and behavioral plasticity in response to the dynamic hydrology of the Mississippi River flood pulse.

Rights

The University of New Orleans and its agents retain the non-exclusive license to archive and make accessible this dissertation or thesis in whole or in part in all forms of media, now or hereafter known. The author retains all other ownership rights to the copyright of the thesis or dissertation.

Download

Share

COinS