Jennifer L. Hsieh's MSPH Technical Report Final Defense

Estuaries are susceptible to the impacts of environmental change as enriched by eutrophication, a process which affects an increasing number of estuaries around the world. The alterations in microbial community structure resulting from eutrophication can affect water quality, and the economic resources and recreational uses of estuaries. One naturally occurring group of bacteria, the Vibrio genus, is endemic to estuaries around the world and includes several human pathogens (e.g. V. cholerae, V. parahaemolyticus and V. vulnificus). Pathogenic Vibrio sp. have been shown to cause mild to serious disease globally, and locally in North Carolina (NC). The objective of this study was to describe the ecology of Vibrio sp. in the eutrophying Neuse River Estuary (NRE), NC. Over a 16-month period, water samples were collected bi-monthly and after storm events several sites along the length of the NRE. Vibrio sp. were measured by membrane filtration and plating on thiosulfate citrate bile salts sucrose agar. Additional microbial and physiochemical parameters were measured in situ and in the lab. Results showed clear seasonal and geographic trends in Vibrio sp. populations. Multiple regression analysis revealed a strong dual parameter relationship that depends on temperature and salinity, which can be used as a predictive model for Vibrio sp. concentrations. To improve the specificity of this model for a single species, V. vulnificus, a preliminary QPCR assay incorporating Scorpions. primer probe chemistry and targeting the vvh gene of V. vulnificus was developed. With further quantification, this rapid, specific assay and the salinity and temperature predictive model developed here will provide powerful tools for managers and modelers of estuarine ecosystems.

Committee Members:
Dr. Rachel T. Noble
Dr. Hans Paerl
Dr. Frederic Pfaender

For further information please contact Rebecca Riggsbee Lloyd by email at Rebecca_Lloyd@unc.edu