PRELIMINARY GENETICS ASSESSMENT OF OYSTER Crassostrea spp. FROM THE EAST COAST AND NORTHERN PENINSULAR MALAYSIA

Crassostrea oysters are among the most well-known oyster species in Malaysia. Several types of oysters can be found in the country, including Crassostrea iredalei, Crassostrea belcheri, Saccostrea cucullata, Ostrea folium, and Hyotissa hyotis. The high commercial demand for Crassostrea oysters has led to the development of its aquaculture, helping to reduce the pressure on wild populations. This study used Crassostrea oyster samples from Kelantan and Kedah, Malaysia, with the aim of identifying the specific species present in these regions using the mitochondrial cytochrome c oxidase subunit I (COI) gene. The study also examined the population genetics of the Crassostrea oysters from these two locations. BLAST results revealed that the samples from Kelantan were identified as Crassostrea iredalei and Crassostrea belcheri, while the samples from Kedah included Crassostrea iredalei and Crassostrea saidii. The analysis showed moderate to high haplotype diversity (h = 0.4–0.8667) and low to moderate nucleotide diversity (π = 0.0006–0.0072). The neighbor-joining and Bayesian phylogenetic trees indicated that the three Crassostrea species are genetically distinct, with the presence of a monophyletic clade consisting of C. madrasensis and M. bilineata. The results of this study have significant implications for Malaysia’s aquaculture industry, population management, and the protection of wild oyster species in the future.