Environmental Effects on the Microbial Community of Homarus americanus Afflicted with Epizootic Shell Disease



Andrews, Jamal

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The American Lobster, Homarus americanus, is a commonly harvested shellfish on the North-East coast of the United States whose populations are currently threatened by epizootic shell disease (ESD). The main sign of the disease is the appearance of lesions on the lobster's shell and has a high mortality rate. The exact etiology of ESD has not been fully established, but one proposed infectious agent is the bacterium Aquimarina homaria. This chitinoclastic bacterium is found in high abundance in lesions of diseased lobsters. A study done in the Buzzards Bay region also revealed a higher prevalence of the disease in contrast to the Outer Cape Cod region. The Buzzards Bay region has a higher average temperature than the surrounding region suggesting that temperature may play a possible role in Homarus americanus' succeptibility to ESD. The current study evaluates bacterial dysbiosis, or imbalance of bacterial population, as a possible contributor of ESD by examining bacterial populations on both healthy and diseased lobsters kept at various temperatures for two months. Polymerase Chain reaction (PCR) was conducted on lobster shell samples to amplify the 16S rRNA sequences from bacterial communities. The sequence data were then analyzed using Quantitative Insights into Microbial Ecology (QIIME) software, the Ribosomal Database Bayesian Classifier (RDP11), and Linear discriminant analysis Effect Size (LEfSe). We report a difference in the compositions of bacterial populations between healthy and diseased lobster shells as well as the lesion. In addition, we show that temperature of the environment influences bacterial populations in both healthy and diseased lobsters.



Homarus americanus, Next-Gen sequencing, Epizootic Shell Disease, American Lobster