Genetic Structure and Diversity of the Moon Jellyfish Aurelia coerulea Polyp Population in Jaran Bay, Korea, Revealed by Mitochondrial COI and 16S rRNA Genes

Blooms of the moon jellyfish (Aurelia coerulea) have been responsible for huge economic losses and environmental disruptions in oceans around the world. The mass occurrence of these jellyfish may be highly related to the benthic polyp populations; however, studies supporting this are scarce. Here, we analyzed the genetic diversity and structure of Korean A. coerulea, using two mitochondrial genes, COI and 16S rRNA, in 51 polyps collected from Jaran Bay (South Korea) that is greatly affected by the mass occurrence of the jellyfish. Genetic diversity analysis identified 20 and 9 haplotypes in COI and 16S rRNA genes, respectively. TCS network analysis and haplotype distance matrix revealed a significant genetic structure in both genes. In addition, two distinct haplogroups (A and B) coexisted in Jaran Bay, and a single haplotype (COI-H4 or 16S-H2) dominated. These findings suggest a strong population differentiation among the polyp population that may have an effect on the jellyfish blooms in Jaran Bay.