Environmental factors influencing the distribution of fecal coliform bacteria in Bandon Bay, Thailand

The presence of fecal coliform bacteria (FCB) and deteriorated water quality are prevalent problems in various coastal ecosystems leading to public health concerns. Here, we evaluated the contamination of FCB and its member, Escherichia coli, in the Tapi-Phumduang River system and Bandon Bay in Thailand, and the accumulation of FCB in oysters cultured therein. The results show significantly higher FCB and E. coli in river water than in seawater, substantiating the role that the river serves as a conduit for bacterial delivery to the bay. FCB discharged from the river to the bay during low tide was approximately 4-fold higher than during high tide. The concentrations of FCB in seawater (<79 MPN/100 mL) and oysters (<187 MPN/100 g) from the Bandon Bay are within regulatatory limits. Statistical analysis shows that various environmental parameters including salinity, turbidity, and DSi are strongly correlated with bacterial pollutants in river water, whereas bacterial pollutants in bay water are strongly correlated with salinity, pH, dissolved oxygen, total nitrogen and dissolved silicate. Hence, salinity and turbidity can be used as proxies for bacterial pollution monitoring in the river, and salinity is a good proxy for indicating bacterial contamination in Bandon Bay. Thus, these two proxies may assist in a rapid assessment of bacterial pollution in aquatic environments.