The Vibrio-HAB Connection: Investigating Interactions Between HAB Species and Pathogenic Vibrio Species

            Bacteria belonging to the genus Vibrio are abundant in coastal estuaries. These species include several that are human pathogens, such as Vibrio cholerae, the causative agent of cholera, as well as V. vulnificus and V. parahaemolyticus, which are responsible for the majority of sea-food borne illness and fatalities in the US. Several studies have demonstrated an increase in Vibrio abundance and illnesses with increased eutrophication, rising temperatures and salinities in coastal regions around the world. Changes in global weather patterns associated with climate change have been correlated with outbreaks of Vibrio-related diseases, and suggest that these outbreaks will increase in frequency and duration in the coming years.  Studies have also demonstrated a direct correlation between Vibrio and algal abundance, and the growth and survival of Vibrio spp. is thought to be enhanced in the rich microenvironment produced during algal blooms. Other studies suggest that attachment to algal cells during a bloom provides Vibrio with a refuge from predation.  These interactions may be species-specific, however, as some algal species have demonstrated inhibitory effects on Vibrio in laboratory cultures and mesocosm experiments.  This project will investigate species-specific interactions between algal blooms and Vibrio populations in Delaware’s inland bays (DIB).  Our objectives are to: (1) Examine changes in abundance of Vibrio spp. during algal blooms in the DIB, (2) Evaluate particle attachment by Vibrio spp. during algal blooms, and (3) Investigate the effects of Vibrio attachment on algal toxicity. The results of our research will improve pathogen forecasting efforts and benefit local, state and federal agencies by contributing to the development of algal indices to assess human health risks.

Investigators:  This project is funded by a grant from DE Sea Grant to Kathryn J. Coyne ( and by DE-EPSCoR to Kathryn J. Coyne ( and Fidelma Boyd (UD, Dept. of Biology).

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