Degree

Master of Science (MS)

Department

Biology

Document Type

Thesis

Abstract

Invasive carp (Hypopthalmichthys spp.) is a generalist filter feeder that has established itself across the Mississippi Watershed of the United States and caused harm to native fish species through depletion of a shared resource, causing a decline in zooplankton density and body size. This study analyzes the impact of larval invasive carp on zooplankton community structure between drought and non-drought years and an environmental gradient in the Atchafalaya River Basin. Larval carp and zooplankton density and size were sampled using net tows and correlated with environmental parameters measured in 2023 and 2024. Results showed that zooplankton density and size were impacted by differences between years which may be driven by drought while larval invasive carp did not differ in density or size between years. Piecewise structural equation modelling revealed relationships between larval invasive carp and the zooplankton community, with larval carp density positively associating with rotifer density and larval carp size negatively associating with cladocera density and positively with copepod density. Other indirect relationships were revealed with larval carp density associated with smaller mean zooplankton community size. The inclusion of chlorophyll a concentration as a proxy for phytoplankton biomass through fluorimetry in 2024 allowed for bottom-up processes to explain further variability and revealed more significant relationships between larval carp and the zooplankton community. These results suggest that after accounting for interannual variability, environmental parameters, phytoplankton and interactive effects of zooplankton, larval invasive carp density and size are correlated with shifts in zooplankton community density and size which may influence fish assemblages within the Mississippi Atchafalaya River Basin.

Date

2-6-2026

DOI

https://proquest.com/docview/3347849839

First Committee Chair

Kelly Robinson

First Committee Member

Beth Stauffer

Second Committee Member

Craig McClain

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