Microbiological Quality of the Shellfish-growing Waters and Mussels in Changseon, Namhae, Korea

A sanitary survey was conducted to evaluate the water quality and mussel (Mytilus edulis ) conditions oftwo administrative shellfish growing waters: those designated as shellfish growing water for export, andadjacent waters on the east coast of Changseon Island, Namhae, Korea. In all, 1,656 seawater and 166mussel samples were collected at 46 stations for seawater and five stations for the shellfish from January2007 to December 2009. Both seawater and mussels were examined for total coliforms and fecal coliforms.The standard plate count and most probable number of Escherichia coli were also determined for the shellfishsamples. The range of the geometric means and the estimated 90th percentiles of fecal coliform for seawatersamples at each station were <1.8 4.1 MPN/100 mL and <1.8 22.3 MPN– – /100 mL, respectively. The sanitaryconditions for both shellfish growing areas, the designated shellfish growing area and adjacent area inChangseon, met the 'Approved area' criteria of the United States National Shellfish Sanitation Program.The range of E. coli detected in mussels in these areas was <20 500 MPN/100 g; and o– nly 3 of 166samples exceeded 230 MPN/100 g, the European standard for the consumption of raw bivalves. Therefore,the mussel farms in the Changseon area are classified as 'Class A' according to criteria set in EuropeanCommunity regulations. However, the levels of E. coli in mussels in parts of the designated shellfish growingarea and adjacent area exceeded the bacterial limits after rainfall exceeding 45 mm. Further studies areneeded to fully define the conditions leading to a temporary closure to harvest after a rainfall event.