College of Graduate Studies: Theses & Dissertations

Term of Award

Summer 2026

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Biology

Committee Chair

John Carroll

Committee Member 1

Lisa Brown

Committee Member 2

Stephen Greiman

Abstract

The rapid growth of oyster aquaculture in the Southeastern United States necessitates the validation of post-harvest processing strategies to mitigate the risk of Vibrio spp. infection. This study investigated the efficiency of three cooling methods - Direct Ice Burial, Indirect Ice Cooling, and Ambient Control, on the prevalence and abundance of V. cholerae, V. parahaemolyticus, and V. vulnificus in cultured oysters (Crassostrea virginica) harvested in Georgia. Additionally, the study examined the safety of two different re-submersion periods for oyster safety.

Internal temperature profiles confirmed that while Direct Ice Burial achieved the most rapid cooling (< 10° C in 7.3 ± 1.2 min), the Indirect Ice Cooling protocol successfully reached the safety threshold in 73.7 ± 17.2 min, well within the 2-hour regulatory window. Microbiological analysis (N = 270) revealed that V. cholerae prevalence was significantly influenced by seasonality (p = 0.0039) and cooling method (p=0.0014). Samples subjected to ambient temperature were significantly more likely to harbor V. cholerae (Odds Ratio = 6.32) and V. parahaemolyticus (p = 0.0287) compared to cooled samples. Importantly, there was no significant difference in pathogen detection between Direct and Indirect icing (p = 0.50), validating the use of indirect icing as a viable industry alternative.

A distinct seasonal divergence was observed in the efficacy of tidal re-submersion. A significant interaction between month and re-submersion (p = 0.0129) was detected in September. In this late-season window, extending re-submersion to 14 days from day 10 likely resulted in a secondary re-infection, characterized by elevated V. cholerae detection and the emergence of V. vulnificus. This study recommends the uses of indirect icing protocols but cautions that re-submersion strategies should be seasonally adaptive to prevent pathogen resurgence.

Research Data and Supplementary Material

No

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