Bay Monitoring: Bacteria Sampling – Fecal coliform & Enterococci

Fecal coliform is a type of bacteria that is used to indicate the presence of possible sewage contamination and disease causing bacteria, viruses and pathogens. There are several reasons why testing for fecal coliform is important. In the State of Rhode Island fecal colifom is currently the standard for determining the heath of shellfish beds in Narragansett Bay and their accessibility to shellfishing. Shellfishing is a multi-million dollar industry in Rhode Island and the health of the shellfish beds is crucial not only for shellfishermen but for the consumer as well. Elevated fecal coliform can also be indicative of potential pollution within the bay coming from wastewater contamination, onsite septic systems, domestic and wild animal waste, and storm runoff. Evaluation of fecal coliform is also used to help determine the effectiveness of the NBC CSO Abatement Project.

Enterococci are a type of bacteria that are indicative of potential human fecal contamination and are the best indicator in salt water for the possible occurrence of digestive illnesses at swimming beaches. The State of Rhode - Department of Health tests for Enterococci on a regular basis at state beaches to determine potential health effects for beach goers. If elevated levels of enterococci are detected, beaches are closed to swimming.

The NBC began monitoring for fecal coliform in 2003 and for enterococci in 2006. Twenty locations in the Upper Narragansett Bay are sampled twice/month for fecal coliform and 25% of locations are analyzed for enterococci; please see map below for locations. On board the R/V Monitor, water samples are taken from 0.5 m below the water surface into sterile bottles, kept in 4oC for preservation and are brought to the NBC laboratory to be analyzed using the multiple-tube fermentation process (Standard Method 9221 E EPA method). The Idexx Entrolert Method is used for Enterococci analysis.