Semester of Graduation

Spring 2026

Degree

Master of Oceanography and Coastal Sciences (SOCS)

Department

Oceanography and Coastal Sciences

Document Type

Thesis

Abstract

Since 1986, biologists with the Louisiana Department of Wildlife and Fisheries (LDWF) sampled fish communities in coastal Louisiana. I compared abundance data for fish species in the Lake Pontchartrain estuary in the context of the seven most recent diversions in Louisiana’s Bonnet Carré Spillway (BCS), a well-observed Mississippi River diversion. The BCS redirects an average of 14 km3 of river water (roughly 4 trillion gallons) per opening into the Lake Pontchartrain estuary, temporarily augmenting the temperature, nutrient, and potentially faunal characteristics that typically define this system. Because spillway openings are irregular, the diversions themselves vary in magnitude, timing, duration, and water characteristics, complicating the effects on the present biota. I hypothesized that BCS diversions cause a chain reaction that leads to increased ecosystem productivity, ultimately increasing finfish populations. I used negative binomial generalized linear models to analyze environmental variables during and after BCS openings and compared them to the same conditions in years without openings, as well as comparing fish abundance on a long-term scale to detect any lagged effect of spillway openings that appear within a year of the diversion. My results found that BCS effects on nutrient concentrations and plankton abundance appear limited, and that inclusion of a highly abundant, planktivore species changes the perceived interactions between trophic levels during opening events. In the months following BCS openings, the finfish declined in abundance relative to pre-spillway observations but return to normal levels around the twelfth month. Along with my analyses, I published the LDWF data set using RStudio’s Shiny package to create a web resource on which the data could be hosted. Not only does this resource include a public way to view and download the data, but it also allows users to visualize it and uses Louisiana’s fish populations to educate K-12 students on ecology and data science.

Date

4-15-2026

Committee Chair

Stephen R. Midway

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

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Available for download on Wednesday, February 24, 2027

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