Investigating coastal microbial communities
Joyner, Jessica Lee
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Coastal development and maintaining the integrity of coastal ecosystems is a global issue, especially with the global population growing. In the Florida Keys, over 60,000 people live on a small archipelago (356 km2). This dense population in close proximity to the only U.S. barrier reef has attracted much attention in research for the impacts on the health of coastal ecosystems. This dissertation investigates the level of water contamination and the coral health along the entire reef tract. In the remote Dry Tortugas National Park there is limited access and during peak activity, visitors swimming or wading introduced detectable levels of human enteric bacteria. This study confirms the introduction of enteric bacteria in coastal environment throughout the Florida Keys, which threatens the coral reef ecosystem. Serratia marcescens is one enteric bacterium that causes disease, white pox disease acroporid serratiosis, in the threatened coral species, Acropora palmata. The bacterial community of A. palmata was investigated to describe their healthy and disease states communities. These communities were highly diverse and responded to large environmental events, such as a Saharan dust storm. Overall, the bacteria Order Rhodobacterales increased in diseased coral lesions but neither S. marcescens nor its parent Order Enterobacteriales were specifically associated with disease lesions. An advanced molecular assay was developed to specifically detect this bacterium throughout the Florida Keys. When three years of A. palmata samples and reef water were screened for S. marcescens there was only a 9% detection rate. However, it was more likely to detect the bacterium in the coral mucus than the water. Coral mucus is capable of concentrating and supporting the growth of introduced bacteria, like S. marcescens. The issue of the Florida Keys high population density and its influence on the coral reef resource is improving because local government agencies are upgrading the wastewater management. This improvement has dramatically improved the coastal water quality and minimized sewage contamination on the coral reef. However, complete etiologies of white pox disease along with other coral diseases are still illusive. More detailed monitoring and efforts are needed to identify pathogens.