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Located in the tropical region, many oysters are widely distributed near-shore in the shallow water along the Gulf of Thailand. Rock oyster, Saccostrea forskali, is commonly found attached to the rocks along the beach. In order to fully utilize them as bioindicators of aquatic pollution, in this study, the genetic diversity and distribution of S. forskali was assessed by using microsatellite markers. A total of 240 S. forskali oyster samples were collected from eight locations in seven provinces along the Gulf of Thailand including Trat, Chanthaburi, Rayong, Chon Buri, Phetchaburi, Prachuap Khiri Khan (two locations) and Chumphon, and were analyzed based on eleven microsatellite loci developed from oyster species. The average number of amplified DNA bands per locus varied between one to four bands. The observed heterozygosity of oyster populations ranged from 0.365 to 0.523 while the expected heterozygosity ranged from 0.537 and 0.597. The genetic differentiation between populations was high, suggestive of isolated populations with very low gene flow. By regular monitoring of the genetic diversities of these S. forskali populations, emerging environment threats could be efficiently detected before more catastrophic damages would occur.
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