Recreational waters are routinely assessed by enumeration of fecal indicator bacteria, such as enterococci, but research suggests viral indicators may be better suited for recreational water quality applications. Somatic and F+ coliphage were proposed as predictors of viral pathogens in recreational waters, but concurrent measurements of enterococci and coliphages and comparisons across different risk-based beach action values (BAVs) are limited. We collected paired measurements of enterococci, E. coli, somatic and F+ coliphage from three Gulf of Mexico beaches. Enterococci (colony forming units: CFU) were enumerated on mEI agar and by qPCR (Entero1a: target sequence [TS]). E. coli was enumerated by qPCR (EC23S587, TS). Coliphages (plaque forming units: PFU) were enumerated using dead-end hollowfiber ultrafiltration and single agar layer assay. The largest correlation observed was between Entero1a and cultured enterococci (r≥0.51, p≤0.0001) and the smallest (r≤0.01, p=1.0) between F+ coliphage and cultured enterococci. Applying equivalent BAVs for culturable enterococci (60CFU/100mL), Entero1a (9658 TS per 100mL) and suggested somatic (14 PFU/100mL) and F+ (3 PFU/100mL) thresholds resulted in the overall greatest agreement in beach advisory status between coliphages and Entero1a (74-82%) and lowest between cultured enterococci and somatic coliphage (65%). This rich data set not only provides valuable insights on the incidence of coliphage and FIB in the Gulf of Mexico but will also provide a foundation for future research on fecal source identification and water quality forecast modeling in sub-tropical marine waters.
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