Date of Award

5-2024

Degree Type

Honors College Thesis

Academic Program

Marine Biology BS

Department

Marine Science

First Advisor

Kim de Mutsert, Ph.D.

Advisor Department

Marine Science

Abstract

Coastal ecosystems, known for their abundant natural resources and role in environmental processes, are facing challenges posed by climate change, pollution and anthropogenic activities. Among these challenges is the expansion of hypoxic zones, characterized by low dissolved oxygen (DO) levels, which poses a significant threat to benthic organisms and oyster fisheries. This research investigates the interaction between hypoxia and pH dynamics, intensified by freshwater input, and the biomineralization of Eastern oysters (Crassostrea virginica). To explore these dynamics, experimental trials were conducted in 24 tanks, simulating normoxic, hypoxic, and fresh hypoxic conditions, to assess the impact of hypoxia on pH levels and the growth of juvenile oysters. The experimental setup included 30-day trials with controlled salinity, temperature, and DO levels, replicating conditions observed in the Mississippi Sound. Results revealed significant difference in dry shell weight during hypoxic conditions indicating shell erosion, although pH was not lower during hypoxia as expected. It can be concluded based on the data that dissolved shell material acted as a buffer and increased the pH. The analysis of biological parameters, including weight, size, and condition index, illustrates the potential ramifications of shell dissolution under hypoxic conditions. Significantly lower dry shell weight in hypoxic and fresh hypoxic conditions further substantiate the hypothesis of pH-driven shell erosion. This study illustrates the susceptibility of oysters to increased fluxes of freshwater, and the impacts events such as climate change and the opening of the Bonnet Carré Spillway can have on coastal ecosystems.

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