An Assessment of Fecal Pollution in the St. Lucie Estuary and Indian River Lagoon

Contamination of recreational waters with fecal waste, indicated by the presence of
enterococci, can have consequences for human and ecosystem health. The difficulty in
determining the extent and origin of fecal pollution in dynamic estuarine systems is
compounded by contributions from sources including septic tanks and agricultural runoff.
This study investigated fecal pollution at five sites with variable hydrological conditions
in the St. Lucie Estuary and Indian River Lagoon. The distribution and occurrence of
enterococci was assessed using traditional cultivation. A human-associated microbial
source tracking assay was validated and applied in these estuaries using qPCR. Results
demonstrated a correlation between enterococci concentrations, rainfall, and salinity. The
human-associated assay was sensitive and specific in the lab; however, human fecal
pollution was not detected in the field even though samples contained high levels of
enterococci. This study highlights the importance of expanding the range of water quality
assessment.