Utilization of Probiotics to Manage Epizootic Shell Disease in American Lobsters, Homarus americanu

Epizootic shell disease (ESD) in the American lobster, Homarus americanus, has a major impact on the southern New England lobster industry, yet there are no practical tools for managing the disease. The goal of this study was to identify bacterial probiotics that could be used to decrease the severity of ESD in wild lobster populations. Candidate bacterial isolates (n = 24) were previously isolated from lobsters in Narragansett Bay and identified as having probiotic characteristics against ESD-associated bacteria Thalassobius sp. and Aquimarina macrocephali, or the fish pathogen Vibrio anguillarum. Healthy lobster post-larvae were exposed to five of the candidate strains isolated from lobsters and a probiotic bacterial strain isolated from the eastern oyster, Crassostrea virginica (Phaeobacter inhibens S4). After several weeks of treatment, there were no significant differences in molting frequency, mortality, or growth of treated lobsters when compared with the control, indicating the candidate probiotics do not exhibit adverse effects on lobster post-larvae. The effect of selected candidate probiotics (n = 3) on progression of ESD in adult lobsters was tested for three months. Frequent molting due to high disease severity confounded long-term effects of the treatments, and no significant differences were seen in mortality, molting, growth, or disease progression. These results highlight the challenges involved in the development of tools for the management of a chronic disease with a poorly understood etiology. Future research should focus on a better understanding of microbe-microbe-host interactions in ESD, and the effect of environmental conditions on these interactions.