Host and Water Microbiota are Differentially Linked to Potential Human Pathogen Accumulation in Oysters

Oysters play an important role in coastal ecology and are a globally popular seafood source. However, their filter feeding lifestyle enables coastal pathogens, toxins, and pollutants to accumulate in their tissues, potentially endangering human health. While pathogen concentrations in coastal waters are often linked to environmental conditions and runoff events, these do not always correlate with pathogen concentrations in oysters. Additional factors related to oyster hosts and the microbial ecology of pathogenic bacteria likely play a role in accumulation but are poorly understood. In this study, we investigated whether microbial communities in water and Pacific oysters (Crassostrea gigas) were linked to accumulation of potentially pathogenic bacteria. To accomplish this goal, we measured environmental variables, quantified fecal indicator bacteria (FIB), Vibrio parahaemolyticus, and Vibrio vulnificus, and characterized associated water and oyster microbiomes using metabarcoding (16S rRNA profiling) across a natural environmental gradient in Newport Bay, CA over 4 weeks.