The effect of monsoon on the distribution of fecal coliform and Escherichia coli (E. coli) in cultured oysters (Crassostrea iredalei), surrounding waters and sediments of Setiu Lagoon, Terengganu, South China Sea

Abstract

Trus study was carried out to study the levels of fecal contamination in Setiu Lagoon and the monsoon effects as well as to determine whether the cultured oysters in the lagoon are safe for human consumption. Three sampling trips were conducted which were on g th September 2007 (Southwest Monsoon), 21 51 October 2007 (Inter-Monsoon) and 29 th December 2007 (Northeast Monsoon). Six sampling stations were established around the oyster cages in the lagoon. Total coliform, fecal coliform and Escherichia coli (E. coli) counts in surrounding waters, sediments and cultured oysters (Crassostrea iredalei) were estimated by using Multiple Test Tube Fermentation Method. The enumeration of positive fecal coliform bacteria was made by referring to the Most Probable Number (MPN) chart. Mean for the total coliform, fecal coliform and E. coli counts in the surrounding waters of Setiu Lagoon were 30.667 MPN.lOOmL- 1 , 165.167 MPN.IOOmL- 1 and 90.167 1 MPN.lOOmL- respectively. The mean of total coliform, fecal coliform and E. coli counts in the sediments were 1.072 MPN.g- 1 , 9.472 MPN.t 1 and 5.044 MPN.g- 1 respectively. Then, mean for the total coliform, fecal coliform and E. coli counts in the oysters were 1 , 14.572 MPN.g- 8.511 MPN.g- 1 and 7.317 MPN.g- 1 respectively.