Water pollution influencing contamination of Vibrio bacteria in the coastal aquaculture area of Chanthaburi and Trat Provinces

Abstract

Since 1982, the Eastern coastal area of Thailand has been developed from the Eastern Seaboard Project (ESP) to the Eastern Economic Corridor (EEC). The marine ecosystem of Chanthaburi and Trat Provinces was polluted by anthropogenic activities such as agriculture, transportation, tourism, fisheries, and urban communities. This study aims to investigate the marine environmental quality and the contamination of the Vibrio bacteria (V. cholerae, V. parahaemolyticus and V. vulnificus) in the coastal aquaculture area of Chantaburi and Trat Provinces. Environmental sampling areas were designated at seven stations eastward from Tamai to Klongyai districts (about 150 km long stretch). The physicochemical parameters, including temperature, salinity, conductivity, pH, dissolved oxygen (DO), NH3, and major anions e.g. NO2-, PO43- of seawater samples were measured at designated stations. Marine samples, including cockles (Anadara granosa), mussels (Perna viridis), oysters (Saccostrea cucullata) and white shrimp (Litopenaeus vannamei) were collected from aquaculture areas located in the estuarine ecosystem with simple random sampling. Our studies revealed that major inorganic substance concentrations followed this consequence order PO43- > NH3 >NO2-. The physicochemical properties indicated that seawater quality has been varied within the marine quality standard class III for aquaculture. The prevalence of V. parahaemolyticus and V. vulnificus showed in all bivalve samples were detected at 0.36 to 4.30 MPN/g and below the detection limit (0.3 MPN/g), respectively, whereas V. cholerae was not detected. This study also concluded that the periods of environmental sampling did not significantly influence the seawater quality and the level of Vibrio contamination. However, the difference of infection rates for V. parahaemolyticus and V. vulnificus depended on the marine species.