Abstract: A total of 100 Penaeus monodon samples were collected from five locations (Sanya, Shenzhen, Yangjiang, Zhanjiang, and Beihai) in the coastal waters of South China, and PCR technique was used to amplify the mtDNA 16S rRNA of the 100 individuals. The PCR products were purified and sequenced. 440 bp nucleotide sequences of partial 16S rRNA were obtained (some of the marginal sequences were excluded), and 19 haplotypes and 28 variable sites were detected. A high percentage (69.0%) of A+T base composition in the 19 haplotypes was observed. The pairwise distances among the 19 haplotypes ranged 0.002-0.033. The median-joining network of the 19 haplotypes did not distinguish distinctly into five-location groupings of haplotypes. All the haplotypes were scattered throughout the network. Among the 19 haplotypes, the haplotype 7 was ancestral haplotype, and the other 18 haplotypes were originated from haplotype 7, according to the distribution of haplotypes in five locations and median-joining network of 19 haplotypes.

Key words: Watershed, Wetland landscape, Fragmentation process