LAUSR

The increasing demand for slipper oyster ( Crassostrea iredalei ) has propelled farmers to expand oyster cultivation areas in the Philippines, chiefly for local consumption and feasibly for export overseas. Being filter feeders, oysters can accumulate pathogens from their surrounding waters, which can cause foodborne diseases once consumed. Monitoring oyster farming areas for microbiological quality and levels of heavy metals is therefore crucial. In the current study, the microbiological quality of oysters and culture waters of the major oyster farming areas in Cogon and Palina rivers and Cabugao bay, located in Roxas City and municipality of Ivisan, Capiz Province, Western Visayas, Philippines, respectively, were examined monthly during the wet (May to October) and dry (November to April) seasons over a period of 12 months. Regardless of the sampling period, high levels of fecal coliforms in the water and Escherichia coli in oysters were noted, clearly illustrating that these oyster growing areas would comply with the lower Class B standard and 'Prohibited' areas under the European Union and United States classification systems, respectively.  Moreover, while Salmonella was erratically detected in oysters, V. cholerae and V. parahaemolyticus count were not detected and within acceptable limit, respectively. The levels of heavy metals in oyster's meat were also determined twice, i.e. during the wet (July) and dry (March) seasons. Zn and Cu were the most abundant metals detected while the levels of Pb, Cd, Hg, and Cr were below the regulatory limits set by the European Union and United States Food and Drug Administration, respectively. Taken together, these oyster culture areas studied should be urgently rehabilitated to improve oysters' poor microbiological quality. Additionally, depuration or relaying of oysters harvested from these sites is imperative to ensure quality and safety.