Inferring the impact of large-scale aquaculture of Haliotis discus hannai in northern and southern China using EST-SSR markers

Abstract

The Pacific abalone Haliotis discus hannai originated in cold waters, but as an economically important aquaculture shellfish in China, there has been a large-scale transfer of fish to Fujian Province in southern China for culture. Our goal was to clarify the current status of the genetic structure of Pacific abalone in China. In this study, eighteen polymorphic EST-SSR loci were successfully developed based on the hemolymph transcriptome data of Pacific abalone, and thirteen highly polymorphic EST-SSR loci were selected for the genetic variation analysis of six populations collected from Zhangzhou in Fujian Province (ZZ), Dalian in Liaoning Province (DL), Rongcheng in Shandong Province (RC), and the Changshan Archipelago, including Nanhuangcheng Island (NH), Daqin Island (DQ), and Tuoji Island (TJ). The results showed that the average number of observed alleles was 8.0769 (RC)-11.3848 (DQ) in each population. The number of observed alleles in the DQ, NH, and TJ populations was significantly higher than that in the RC population. If the NH and TJ cultured populations of the Changshan Archipelago were excluded, then compared with the DQ wild population, the number of alleles in the cultured population decreased by 22.79%. The pairwise Fst values and analysis of molecular variance (AMOVA) revealed significant population differentiation among most populations, with the RC and ZZ cultured populations exhibiting the largest population differentiation (Fst = 0.1334). The UPGMA phylogenetic tree and structural analysis divided the six populations into two groups (group 1: NH, DQ, and ZZ; group 2: DL, TJ, and RC), and there was no relationship between geographical distance and genetic distance. These results may reflect the large-scale culture from north to south in China and the exchange of juveniles between hatcheries. Different breeding conditions have led to a higher degree of genetic differentiation between the RC and ZZ populations. In conclusion, this study provides valuable information on the genetic structure of Pacific abalone populations in China and contributes to the management and restoration of Pacific abalone.