Microbial Source Tracking of Bacterial Contamination in Recreational and Aquaculture Waters – A Root Cause Public Health Tool Towards Improved Water Quality.

Participatory Science
Oral Presentation

Presented by S. Esenther
Prepared by S. Esenther1, M. Pascucilla2
1 - Institute at Brown for Environment and Society, 85 Waterman St, Providence, Rhode Island, 02912, United States
2 - East Shore District Health Department, 688 East Main Street, Branford, Connecticut, 06437, United States


Contact Information: [email protected]; 617-651-5987

ABSTRACT

Closure of recreational beaches and shellfish beds is currently determined by a simple fecal indicator bacteria threshold. Bed closure is initiated by water samples that exceed the threshold, or precipitation events statistically likely to correlate with exceedant bacteria levels, neither of which provide information about the root causes of contamination. This method simplifies routine administration but may be insufficient to provide the identifying information necessary to understand patterns of fecal contamination and to direct mitigation efforts in chronically impaired waters. Here, we demonstrate the utility of microbial source tracking (MST) to identify the species source of fecal indicator bacteria entering the waters of recreational beaches, shellfish beds, and kelp farms from outfalls in Branford, CT. Contrary to the previous assumption that leaky sewage disposal systems in the town were primarily responsible for the high levels of contamination, preliminary results indicate that dog and avian bacteria also enter the waters in high concentrations at these outfalls. These findings have initiated efforts, in collaboration with the Civic Association of Short Beach, to add water-tight trash cans for canine waste at local beaches and to improve education on proper waste disposal among residents. Given anticipated increases in the magnitude and frequency of extreme precipitation events with climate change, recreational and aquaculture waters will likely face increasing bacterial contamination from precipitation-induced runoff in the coming years. The use of MST and other technologies will likely become increasingly important tools to understand and minimize waterborne bacteria contamination, a critical step to protecting public health in a changing climate. Further, given the mounding success of this MTS as a public health water quality tool method, both EPA and states should consider reviewing this laboratory methodology for approved use.