Microbial Source Tracking in Coastal Recreational Waters of Southern Maine: Relationships Between Enterococci, Environmental Factors, Potential Pathogens, and Fecal Source

Coastal water quality has been an issue for centuries. Fecal pollution of these waters represents a significant public health concern, as a variety of fecal sources can harbor human pathogens that range from bacteria and viruses to protozoa. Anthropogenic activities have exacerbated water quality through development such as housing, sewage infrastructure, and agriculture have increased fecal pollution sources and transport pathways, ultimately leading to increased pollution loading at the coast. For decades, federal, state and local municipalities have been using fecal indicator organisms to assess coastal water quality to assess public health risks. This thesis focuses on key factors that may influence enterococci concentrations, the fecal indicator for coastal recreational waters, and its relationship to fecal-borne bacterial pathogens to better understand its effectiveness as an indicator of public risk from fecal pollution. Results presented here come from three field sampling studies conducted during 2015--2016 where a combination of applied and basic research objectives were explored. Significant findings indicate that concentrations of enterococci are influenced predominantly by particle-associated enterococci and mammal fecal source concentrations across freshwater and estuary/marine environments. Other ecosystem-specific characteristics, such as sediment and freshwater transport, are also significant factors under some conditions. The relationship between fecal contamination and potential pathogens is water-type and location specific, with storm water having the highest detection of fecal potential pathogens across a diverse data set. Moreover, bird feces represent a significant source of fecal-potential pathogens, as this fecal source significantly correlated to fecal potential pathogen abundance. Overall, the results highlight the dynamic nature of enterococci as a fecal indicator across different ecosystems. Ultimately, concentrations observed in the water are reflective of a combination of factors where potential health significance is location and water-type specific.