SGER: Identifying Sources of Fecal Contamination and the Prevalence of Human Pathogens in Water, Sediments, and Shellfish of Lake Pontchartrain in Response to Floodwater Pumping

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ABSTRACTOCE-0554768This project is one of several coordinated marine environmental studies funded through a Small Grant for Exploratory Research (SGER) for rapid response to a natural disaster: the flooding of New Orleans by Hurricane Katrina. This effort by scientists at the NSF-NIEHS Center for Ocean and Human Health (COHH) at the University of Hawaii is part of a larger collaborative study with Louisiana State University at Baton Rouge, and with the NSF-NIEHS Centers for Oceans and Human Health at the University of Miami and the Woods Hole Oceanographic Institution. Shortly after Hurricane Katrina made landfall in the Gulf Coast Region, widespread flooding in the New Orleans area resulted in sewage overflows and contamination of floodwaters. Shortly thereafter, these floodwaters were pumped continuously into Lake Pontchartrain without treatment, resulting in the spread of contaminants into the Lake, which ultimately discharges towards the Gulf of Mexico. Working collaboratively, the multi-institutional research team will investigate the extent to which the waters in Lake Pontchartrain and vicinity have been contaminated with chemical contaminants, pathogenic microbes, and harmful algal bloom (HAB) organisms. The study will document the levels and spread of biotic and abiotic contaminants along with HAB organisms, information which will be useful for subsequent modeling efforts.With SGER funding through this award, investigators at the University of Hawaii will document the presence, abundance, and fate of selected human pathogens (Vibrio spp, Staphylococcus aureus, viruses) and sewage indicators (Bacteroides, FRNA coliphages) in water, sediments, and shellfish in Lake Pontchartrain in the weeks and months following floodwater pumping. Data on microbial pathogens will be placed in the context of changes in abundance and diversity of the total microbial community. The data will allow discrimination of contamination from sewage- vs. non-sewage-borne pathogens and an overview of the ecological impacts on the lake microplankton.Bacterial pathogens in water and sediments will be assayed as colony-forming units on selective media. Pathogens in oysters will be assayed following physical enrichment from tissue homogenates using magnetic bead technology. Identity of the cultivated strains obtained will be verified by biochemical tests and their relative pathogenicity assessed by molecular detection of selected virulence-associated genes. Epifluorescence microscopy and molecular fingerprinting will be used to determine the abundance and composition of the total microbial community.The primary broader impact of this rapid-response study is that it will provide much needed information in the aftermath of a natural disaster. The microbes released by the sewage can potentially impact a large area including Lake Pontchartrain, and subsequently the Gulf of Mexico. There are significant human populations and fisheries in both these areas that can experience acute and chronic disease from these chemical, microbial, and HAB organism exposures now and in the future. From a basic science and public health perspective, it is important to investigate the mechanisms by which and the extent to which these contaminants have migrated.