Vibrio bacteria are widely distributed in estuarine and coastal aquatic systems across the globe and not only play vital roles in nutrient cycling but are also important human pathogens. V. vulnificus is especially important in the United States as it is responsible for a majority of deaths seafood-related deaths. This study examined dynamics among total Vibrio, V. vulnificus, plankton populations and environment parameters in the Neuse River Estuary. Size fractionation was used to crudely partition zooplankton from phytoplankton. While there was substantial variation in total Vibrio concentrations, the ≥180μm fraction, containing primarily large phytoplankton and zooplankton, exhibited more rapid growth over the course of the experiment compared to fractions containing smaller organisms and control treatments. Responses of V. vulnificus were also tested, but results showed that dynamics are complex and highly variable. Further exploration of the species-specific nature of these relationships is necessary to improve understanding of Vibrio ecology.