Microbial Source Tracking: Advances in Research and a Guide to Application

Abstract

Microbial source tracking (MST) is a still-new and developing discipline that allows users to discriminate among the many potential sources of fecal pollution in environmental waters. As MST continues to transition from the realm of research to that of application, it is being widely used in beach monitoring, total maximum daily load (TMDL) assessment of pollution sources, and any other waters that do not meet designated use criteria as determined by high densities of fecal indicator bacteria (FIB). The main area of research activity in MST focuses on the identification of source-specific genetic markers that can be used to detect contributions from different hosts such as humans, livestock, and wildlife. However, a variety of other accessible approaches can also be used including detailed investigations of the watershed and infrastructure, chemical tracers and leak tests, and increased FIB sampling. This chapter can serve as a guide for decision-making on where, when, and how to deploy MST. Included are discussions of the main drivers of MST and how these have shaped the development of past and present methodological approaches, plus current research initiatives such as community analysis that could usher in yet another new and improved methodological basis for the entire field of MST. Finally, a tiered system is presented as a recommended means to navigate the multiple options for MST analyses that will assist the reader in how best to use MST within the context of more traditional approaches.