Project not complete

Microbial water quality indicators are found in high concentrations in sewage, and are thus used to determine whether or not a water body is safe for recreational purposes. Recently, concerns have been raised about the appropriate use of microbial indicators to regulate recreational uses of water bodies. This is particularly true for water bodies located in tropical and subtropical environments, due to the potential for microbial re-growth in these latitudes, and the fact that studies used to set national guidelines were not conducted in tropical and subtropical environments.

The primary goal of this study is to evaluate the relationship between human health and the physical and microbial characteristics of a coastal body of water and its shoreline. This goal is addressed by measuring human health effects and microbial water quality at a recreational beach site within a subtropical climate, and by developing a predictive, coupled model of hydrodynamic characteristics and microbial fate that can be used to distinguish impacts from sewage sources versus re-growth of microbes. Each of these sources could possibly result in different health effects as observed at the beach site. Substantial pilot data have been collected for the subtropical study site chosen for this research. These pilot data, as well as the literature, indicate that exposure to contaminated recreational marine waters may result in human health effects, and that the shoreline sediments are one likely source of indicator microbes.

Human health is evaluated in the project through an epidemiologic study that randomly assigns exposure to water or beach with coordinated individual environmental sampling and repeated follow-up of reported human health effects. Water quality is evaluated through two sets of environmental measurements. The first phase of the environmental assessment focuses on identifying the distribution and sources of enterococci (the current, federally-recommended indicator microbe) within the study site, and correlations with suspended sediment concentrations. The data gathered from this intensive sampling effort will be used to develop source functions for an enterococci fate model to be coupled with a hydrodynamic oceanographic model developed for the area. The second phase of environmental measurements will focus on the analysis of multiple microbes coincident with times that participants participate in the epidemiologic study. Microbe measurements will include traditional (enterococci, Escherchia coli, fecal coliform) and non-traditional (Clostridium perfringens, coliphage) microbial indicators, as well as direct measurement of microbial pathogens (Staphylococcus aureus, enterovirus, Norwalk virus, hepatitis A, Cryptosporidium parvum, and Giardia lamblia).

A primary goal of this research is to develop a rapid (same day), accurate high throughput and sensitive molecular test for the identification of pathogenic microorganisms in marine and freshwater environments. The Remote Sensing Core and the Genomics Core will participate in this interdisciplinary collaborative research study.

The results from the coupled hydrodynamic and microbial fate model will be compared with the pathogen and human health data for the purposes of predicting beach closures due to health hazards. Ultimately, the human, environmental and oceanographic data will be used to develop a predictive model with broad applicability to beaches in the tropics and subtropics with appropriate modifications for local conditions. The final result will be the improvement of recreational water quality monitoring in tropical/subtropical marine environments, and an increase in public confidence in the results from microbial water quality monitoring and modeling.