Candice Thorstenson

• Coastal ecosystems are highly dynamic regions and extremely important to the livelihoods and health of the people living in coastal regions. Tourism, the aquaculture industry, and human health are all directly tied to the microbial community in these regions. Furthermore, many key aquaculture stocks, such as oysters, may serve as vectors for a variety of foodborne diseases in humans, both at the harvesting area and when imported far inland. Rising sea surface temperatures in the North Atlantic and North Sea have been heavily implicated in the spread and rising abundance of the human pathogenic Vibrio species: Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus in North America and Northern Europe. This study investigates how environmental changes may impact the growth and behavior of these key Vibrio species within the context of the surrounding microbial community. The genetic accessibility of V. cholerae, V. parahaemolyticus, and V. vulnificus environmental strains was initially assessed, and this work resulted in the development of new genetic tools and a rapid fluorescent protein-labelling protocol which worked universally in all tested strains. In a small-scale microcosm investigation, red fluorescent protein-labelled Vibrio clones were co-incubated with a native microbial community under three discrete temperatures. These microcosm experiments indicated that increased temperatures alone do not confer greater competitive fitness to these Vibrio species. Finally, through environmental field sampling for pathogenic Vibrio, two discrete pathogenic Vibrio populations in the North Sea and the North Atlantic, where identified and further characterized, allowing for future speculation on the role these species may play in their respective regions.