Abstract
We aimed to clarify environmental factors affecting the distribution patterns of Vibrio vulnificus along the coast of Nagasaki prefecture. V. vulnificus in the Ariake seawater was found to range from 2 to 4 Log MPN/100 mL on average in summer when the water temperature exceeded 25°C. Although this is generally comparable to the bacterial abundance in other coastal waters of Nagasaki, V. vulnificus cells in the western Ariake Sea exceeded 4 Log MPN, reaching 6.4 Log MPN per 100 mL, when the salinity decreased to 3.3-23 psu in the summer of 2006. In a local river that flows into the Ariake Sea (the Funatsu River), V. vulnificus persisted all year round with a relatively high abundance (2-4 Log MPN/100 mL) in the area between the river mouth and the estuarine basin, where the salinity ranged from 8 to 28 psu. From these results, it is suggested that (1) the estuarine basin of local rivers that flow into the Ariake Sea provides V. vulnificus with a stable habitat, and (2) a combination of high water temperature and long-term rainfall in the Ariake Sea in summer creates low-salinity conditions that favor the excessive growth of V. vulnificus.
