Master of Science (MS)


Renewable Natural Resources

Document Type



Research on blue crab diseases, parasites, and symbionts has been sporadic in the Gulf of Mexico. Understanding the prevalence of diseases, parasites, and symbionts is important for managers to set informed regulations for the commercial industry and to understand the impacts of environmental disasters on aquatic animal health. The objective of this research was to determine the prevalence of Lagenophrys callinectes, Urosporidium crescens, Hematodinium perezi, Loxothylacus texanus, reo-like virus (RLV), shell rot, and Vibrio spp. in crabs collected from four coastal locations and four shedding facilities in 2013 and the beginning of 2014. Additionally, I determined the prevalence of white spot syndrome virus (WSSV) in the wild populations. I also recorded infections by non-Vibrio bacteria and by Ameson michaelis. H. perezi, L. texanus, WSSV, and RLV were detected by polymerase chain reactions. Shell rot and U. crescens were detected by gross visual detection. L. callinectes and A. michaelis were identified by microscopy and Vibrio spp. and non-Vibrio spp. bacteria were detected by standard microbiological culture techniques and biochemical testing. No samples were infected with H. perezi, L. texanus, or WSSV. Based on the low salinities sampled, these results were expected for H. perezi and L. texanus. Shell rot and Vibrio spp. were moderately prevalent in the wild and captive crabs, but infections were more common in the captive crabs. U. crescens was never found in crabs from Lake Pontchartrain, the lowest salinity field site. It was also rare in crabs from the low salinity shedding facilities, indicating that this hyperparasite may be limited to moderate to high salinities. L. callinectes was ubiquitous with over 90% prevalence in wild and captive crabs. Reo-like virus infections were found in wild and captive crabs in the summer of 2013, and A. michaelis was present in two shedding facility pre-molt crabs. Overall, Louisiana’s blue crab nearshore populations appear to be healthy with no parasitization by the two most ecologically and economically detrimental parasites, H. perezi and L. texanus. However, in the future, RLV needs to be extensively studied because it is also capable of decimating blue crab populations.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Anderson, Julie