Theses and Dissertations

ORCID

https://orcid.org/0000-0002-4628-5713

Issuing Body

Mississippi State University

Advisor

Hanson, Larry A.

Committee Member

Petrie-Hanson, Lora

Committee Member

Peterman, Ann E. (Beth)

Committee Member

Ross, Matthew K.

Date of Degree

12-9-2022

Document Type

Graduate Thesis - Open Access

Major

Veterinary Medicine Science

Degree Name

Master of Science (M.S.)

College

College of Veterinary Medicine

Department

Veterinary Medical Science Program

Abstract

Microcystin-LR is a hepatotoxin produced by cyanobacteria. Aeromonas hydrophila and Edwardsiella piscicida infections are leading causes of losses in market-sized channel catfish (Ictalurus punctatus). These older fish should have natural immunity in place and a predisposing factor is likely a prerequisite for these disease outbreaks. While microcystin-LR rarely causes mortality in warm-water aquaculture, we believe it may be a predisposing factor that leads to bacterial disease outbreaks during the summer months due to its ability to damage the liver. Our study investigated microcystin-LR’s effects on channel catfish susceptibility to these pathogens. We found that a sublethal dose of microcystin-LR induced substantial damage to multiple immune organs. In our challenges with both the toxin and bacteria, we saw a significant increase in mortality of fish. Our findings suggest that microcystin-LR increases channel catfish susceptibility to Aeromonas hydrophila and Edwardsiella piscicida infections.

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