UCLA

Fecal contamination of coastal waters is known to degrade the environment and poses a health risk to recreational beach users. Fecal indicator bacteria (FIB) are used around the world to assess water quality and characterize fecal contamination. Elevated levels of FIB have been linked to health risks in epidemiological studies. However, some limitations exist with this indicator. FIB cannot be used to identify the specific sources as they originate from both human and animal sources. FIB may also persist and regrow in the environment. In order to effectively remediate the cause of pollution and characterize the hazards at chronically impaired beaches it is necessary to measure indicators that can provide information about the sources of the general fecal pollution. Tracking pollution sources at impaired beaches is critical to ensuring the health of coastal watersheds and reducing the incidence of swimming related illness. Molecular methods have gained popularity to identify and detect sources of fecal contamination using host-associated markers.

The work presented here addresses areas warranting further research in the state of the science of water quality monitoring. In Chapter 2, we demonstrate that host-associated markers exhibit similar limits of detection in different water types and are robust in environmental field applications. Additionally, we provide a cost-benefit analysis and provide water quality managers with information supporting the inclusion of molecular methods in current monitoring practices. This body of work also presents novel methods for rapid and viability-based detection of recent fecal contamination with propidium monoazide (PMA-qPCR) and a field portable method covalently-linked IMS/ATP technique (Cov-IMS/ATP). In Chapters 3 and 4, we present results on optimization and specificity of the Cov-IMS/ATP. We evaluated the performance of Cov-IMS/ATP at three different watersheds for rapid quantification of enterococci, and show this method to be a robust tool in assessing water quality at complex sites. This work also addresses drawbacks of traditional qPCR to quantify viable fecal contamination. We validate the PMA-qPCR method and demonstrate its performance in detecting recent fecal contamination in environmental waters. Use of these methods demonstrates a new framework that can enhance current microbial source tracking studies and water quality monitoring.