Over 10,000 US water bodies are impaired under section 303(d) of the Clean Water Act due to fecal contamination, as evidenced by fecal indicator bacteria. Agricultural practices, including land spreading of approximately 1.6 billion kg of poultry litter (soiled bedding) per year as a fertilizer, were the leading probable source of water quality impairments in the US in 2008. Poultry litter (bedding contaminated with feces) contains pathogens which can impact environmental waters when constituents of land-applied poultry run off during storms. Degraded water quality leads to regulatory action (impairment), eutrophication, altered ecosystem structure, and fish kills due to the planned application, and in some cases mismanagement, of poultry litter as a fertilizer. Microbial source tracking methods can be used to more accurately determine the source of impairment to water bodies, and to circumvent known issues and inadequacies in fecal indicator bacteria-based pathogen monitoring and fecal pollution source identification. Detection of microorganisms specific to one animal's feces, a.k.a. a marker, in receiving water enhances environmental stewardship by allowing watershed managers to investigate and remediate only the most likely sources of fecal pollution. Development and validation of rapid methods to conclusively determine whether land-applied poultry litter is in runoff is a crucial need for watershed management across the U.S. These methods are widely sought by regulatory agencies and others concerned with water quality beach advisories/closures, TMDL formulation, and remediation of contaminated waterways. This research will critically evaluate 1) a poultry litter marker gene?s correlation with pathogens and fecal indicator bacteria originating from poultry feces and litter and 2) the fate, transport and inactivation of the marker gene and human pathogens under environmentally relevant conditions. Specific studies will be conducted to determine the correlation and survival of poultry litter associated pathogens, fecal indicator bacteria, and the poultry litter marker derived from the 16S rRNA gene of Brevibacterium sp. LA35. These studies will be conducted in soiled poultry litter and feces, in laboratory mesocosms simulating environmental exposure, and in field-scale, simulated rainfall runoff studies. At the completion of this project the research will have critically evaluated the value of the poultry litter marker gene as a tool to identify poultry litter contamination in water bodies, as well as the marker's utility in assessing risk to humans from exposure to water containing poultry litter and its associated pathogens.
The completed study is expected to have a significant positive impact on the efficacy of monitoring of water bodies for poultry litter contamination and human pathogens originating from runoff contaminated by poultry litter. This research will lead to the development of a tool that allows accurate measurement and modeling of non-point source pollution from land-applied poultry litter, including better estimates of human health risk from such contamination. In the long term, this research will provide water quality managers with a rapid and quantitative tool for identifying pollution sources and for determining appropriate poultry litter application rates to agricultural fields, which will ultimately lead to lower public exposure to human pathogens as a result of poultry litter management.
