LOWER VIBRIO VULNIFICUS CONCENTRATIONS OBSERVED IN SUSPENDED, FARMED OYSTERS THAN IN WILD, ON-BOTTOM OYSTERS IN EASTERN NORTH CAROLINA

In North Carolina (NC) and throughout the United States (US), shellfish aquaculture is growing rapidly in an attempt to meet increasing seafood demands. Shellfish, including oysters, are filter-feeders and can concentrate bacteria from the water column, including two human pathogens, Vibrio vulnificus and Vibrio parahaemolyticus. Due to roughly 50% of commercial oysters being consumed raw, these bacteria pose a serious risk to consumers and a problem to the growing oyster industry in NC. Oysters can be harvested from the wild or they can be farmed, in which case they are grown using a variety of aquaculture systems. With increases in farmed oyster production, few studies have been conducted to determine whether oyster aquaculture grow-out methods (e.g. floating bags, floating/submerged cages) influence Vibrio concentrations in oyster meats. Of these few studies, none have been conducted in NC. In this study, we compared the total Vibrio, total and potentially pathogenic V. vulnificus, and total and potentially pathogenic V. parahaemolyticus concentrations of wild (on-bottom) and farmed (suspended) oysters harvested during the summer season of 2018. This study found that total V. vulnificus and potentially pathogenic V. vulnificus concentrations were lower in suspended oysters (unpaired t-test, p=0.0334). Over the short duration of this study, confirmed V. parahaemolyticus concentrations were not substantially different in wild on-bottom versus suspended oysters (unpaired t-test, p=0.2202). In addition to our intended study results, this study has added to a growing body of literature that shows the proportion of potentially pathogenic V. parahaemolyticus found in NC waters and across all types of oysters in NC is very low (less than 1% in this study). Additionally, aside from few discrepancies, culture methods were accurate for quantifying Vibrio concentrations, although the range of values observed was high on certain dates and molecular methods were necessary for evaluation of potential pathogenicity. Although this study found some interesting patterns, the results would be best supplemented by another study with a larger geographical range and longer period of study.Master of Scienc