Applied Time Series Analyses (2000–2017) of Vibrio vulnificus and Vibrio parahaemolyticus (Pathogenic and Non-Pathogenic Strains) in the Eastern Oyster, Crassostrea virginica

Concerns about the health consequences of seafood-born human pathogens are ongoing given their occurrence, prevalence, and ability to cause infections, and sometimes death in humans as well as seafood-associated morbidity and mortality worldwide. An applied time-series (2000–2017) analysis of six reefs examined pathogen-specific annual trends and seasonal patterns in the eastern oyster, Crassostrea virginica, in Galveston Bay (Texas), a subtropical estuary in the Gulf of Mexico. Pearson correlation coefficients showed that temperature had a strong positive correlation with Vibrio vulnificus and V. parahaemolyticus (r = 0.66 and 0.51), but not the pathogenic thermostable direct hemolysin (tdh+) V. parahaemolyticus (r = 0.12). The correlations between Vibrio spp. and salinity showed the opposite trend. A cross-correlation factor analysis revealed the strongest positive correlations (r = 0.41 and r = 0.36, respectively) for high densities of V. vulnificus during high Perkinsus marinus infections with short lags (up to 1 month); this was not the case for total or tdh+ V. parahaemolyticus. These results reveal some of the complexity of interannual and long-term patterns of pathogens in oysters. Given climate change impacts and a growing aquaculture industry, examinations of oyster microbiomes in response to environmental and water quality variables are needed.