Science Inventory

Occurrence of recreational water quality monitoring general fecal indicator bacteria and fecal source identification genetic markers in gray seal scat

Citation:

Paar, John, J. Willis, L. Sette, S. Wood, A. Bogomolni, M. Dulac, M. Sivaganesan, AND O. Shanks. Occurrence of recreational water quality monitoring general fecal indicator bacteria and fecal source identification genetic markers in gray seal scat. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, Netherlands, 934:173220, (2024). https://doi.org/10.1016/j.scitotenv.2024.173220

Impact/Purpose:

Fecal pollution remains a challenge for water quality managers across the United States. When present, fecal waste can pose a serious public health risk and can lead to severe economic burdens, especially in communities that rely on clean and safe water. Fecal pollution can originate from numerous sources such human and agricultural animal waste practices. In response to this nationwide need, the U.S. EPA ORD maintains an active research program to develop, validate, implement, and provide technical support for tools to characterize fecal pollution sources in environmental waters. An often-overlooked potential source of fecal pollution is local wildlife. Information covered in this manuscript was prepared based on Region 1 RARE project objectives (ORD.0.0.0 - Temporary ORD Product for all non-RAP and Ancillary Research, ORD.0.0.0.300).

Description:

The number of gray seals (Halichoerus grypus) observed along the United States Northwest Atlantic region has been increasing for decades. These colonial animals often haul-out on beaches seasonally in numbers ranging from a few individuals to several thousands. While these larger aggregations are an important part of gray seal behavior, there is public concern that haul-outs could lead to large amounts of fecal waste in recreational areas, potentially resulting in beach closures. Yet, data to confirm whether these animals contribute to beach closures is lacking and minimal information is available on the occurrence of key water quality monitoring genetic markers in gray seal scat. This study evaluates the concentration of E. coli (EC23S857), enterococci (Entero1a), and fecal Bacteroidetes (GenBac3) as well as six fecal source identification genetic markers (HF183/BacR287, HumM2, CPQ_056, Rum2Bac, DG3, and GFD) measured by qPCR in 48 wild gray seal scat samples collected from two haul-out areas in Cape Cod (Massachusetts, U.S.A.). Findings indicate that FIB genetic markers are shed in gray seal scat at significantly different concentrations with the Entero1a genetic marker exhibiting the lowest average concentration (−0.73 log10 estimated mean copies per nanogram of DNA). In addition, systematic testing of scat samples demonstrated that qPCR assays targeting host-associated genetic markers indicative of human, ruminant, and canine fecal pollution sources remain highly specific in waters frequented by gray seals (>97 % specificity).