title: Microbial source tracking in shellfish harvesting waters in the Gulf of Nicoya, Costa Rica.
abstract: Current microbial water quality monitoring is generally limited to culture-based measurements of fecal indicator bacteria (FIB). Given the many possible sources of fecal pollution within a watershed and extra-intestinal FIB reservoirs, it is important to determine source(s) of fecal pollution as a means to improve water quality and protect public health. The principal objective of this investigation was to characterize the microbial water quality of shellfish harvesting areas in the Gulf of Nicoya, Costa Rica during 2015. In order to achieve this objective, the specificity and sensitivity of 11 existing microbial source tracking (MST) PCR assays, associated with cows (BacCow), dogs (BacCan, DogBac), domestic wastewater (PMMoV), general avian (GFD), gulls (Gull2), horses (HorseBac, HoF), humans (HF183, HPyV), and pigs (PF), were evaluated using domestic wastewater and animal fecal samples collected from the region. The sensitivity of animal-associated assays ranged from 13 to 100%, while assay specificity ranged from 38 to 100%. The specificity of pepper mild mottle virus (PMMoV) and human polyomavirus (HPyV) was 100% for domestic wastewater, as compared to 94% specificity of the HF183 Bacteroidales marker. PMMoV was identified as a useful domestic wastewater-associated marker, with concentrations as high as 1.1 × 105copies/ml and 100% sensitivity and specificity. Monthly surface water samples collected from four shellfish harvesting areas were analyzed using culture-based methods for Escherichia coli as well as molecular methods for FIB and a suite of MST markers, which were selected for their specificity in the region. While culturable E. coli results suggested possible fecal pollution during the monitoring period, the absence of human/domestic wastewater-associated markers and low FIB concentrations determined using molecular methods indicated sufficient microbial water quality for shellfish harvesting. This is the first study to our knowledge to test the performance of MST markers in Costa Rica as well as in Central America. Given the lack of wastewater treatment and the presence of secondary sources of FIB, this study highlights the importance of an MST toolbox approach to characterize water quality in tropical regions. Furthermore, it confirms and extends the geographic range of PMMoV as an effective tool for monitoring domestic wastewater pollution.
authors.affiliation: University of South Florida, College of Marine Science, 140 7th Avenue South, St. Petersburg, Florida, USA. Electronic address: esymonds@mail.usf.edu.
authors.forename: E M
authors.initials: EM
authors.lastname: Symonds
authors.affiliation: University of South Florida, Department of Integrative Biology, 4202 E. Fowler Avenue, Tampa, FL, USA. Electronic address: suzanneyoung@mail.usf.edu.
authors.forename: S
authors.initials: S
authors.lastname: Young
authors.affiliation: University of South Florida, Department of Civil & Environmental Engineering, 4202 E. Fowler Avenue, Tampa, FL, USA. Electronic address: verbylam@mail.usf.edu.
authors.forename: M E
authors.initials: ME
authors.lastname: Verbyla
authors.affiliation: St. Petersburg College, Natural Sciences Department, 2465 Drew Street, Clearwater, FL, USA. Electronic address: shannon.mcquaig@stpetecollege.edu.
authors.forename: S M
authors.initials: SM
authors.lastname: McQuaig-Ulrich
authors.affiliation: Fundación MarViva, Apartado 020-6151 Santa Ana, San José, Costa Rica. Electronic address: erick.ross@marviva.net.
authors.forename: E
authors.initials: E
authors.lastname: Ross
authors.affiliation: Fundación MarViva, Apartado 020-6151 Santa Ana, San José, Costa Rica. Electronic address: jorge.jimenez@marviva.net.
authors.forename: J A
authors.initials: JA
authors.lastname: Jiménez
authors.affiliation: University of South Florida, Department of Integrative Biology, 4202 E. Fowler Avenue, Tampa, FL, USA. Electronic address: vharwood@usf.edu.
authors.forename: V J
authors.initials: VJ
authors.lastname: Harwood
authors.affiliation: University of South Florida, College of Marine Science, 140 7th Avenue South, St. Petersburg, Florida, USA. Electronic address: mya@usf.edu.
authors.forename: M
authors.initials: M
authors.lastname: Breitbart
mesh_terms: D000818:Animals; D002417:Cattle; D003364:Costa Rica; D004285:Dogs; D004926:Escherichia coli; D005243:Feces / Q000382:microbiology; D005260:Female; D006736:Horses; D006801:Humans; D012758:Shellfish; D013552:Swine; D014871:Water Microbiology; D014876:Water Pollution; D060753:Water Quality
keywords: Bacteroidales; Enteric viruses; Enterococcus; Escherichia coli; Fecal pollution; Pepper mild mottle virus