1 APPLICATION OF MICROBIAL SOURCE TRACKING (MST) METHODS IN ASSESSMENT OF THE SOURCES OF FECAL POLLUTION IN TRIBUTARIES

Microbial source tracking (MST) methods designed to discriminate between human versus animal fecal material were applied to the assessment of surface water quality of seven tributaries of St. Johns River in Duval County, FL. The goal was to collaborate with local agencies and stakeholders to develop and evaluate a methodology for assessing the source(s) of fecal pollution. In this study, indicator organisms (IOs) were quantified by standard membrane filtration methods in river waters and sediments. Florida state standards for IO concentrations in recreational waters were frequently exceeded (57.7% and 83.9 % of samples) for fecal coliforms and enterococci, respectively. Although no regulatory standards exist for IO concentrations in the sediments, the majority of samples contained high levels of all the indicators. Four library-independent MST methods were employed at specific sites based on an adaptive, decision tree-based approach, in which results from previous sample events were used to determine subsequent sampling strategies. The MST methods relied on polymerase chain reaction (PCR) assays targeting human-associated (esp gene of Enterococcus faecium, and 16S rRNA genes of Ent