eDNA Detection and Invasion Risk Assessment of Alien Aquatic Vertebrates in the Pearl River Estuary

The Pearl River Estuary (PRE) is highly vulnerable to alien species invasion due to intense anthropogenic activities in southern China. However, the invasion risk of alien aquatic vertebrates in the PRE remains unclear. In this study, 12 environmental DNA (eDNA) samples were collected from the PRE to reveal the composition and distribution of alien aquatic vertebrates using a vertebrate-universal primer set, and to assess their invasion risks using the Aquatic Species Invasiveness Screening Kit (AS-ISK). We identified a total of nine alien aquatic vertebrate species, including one amphibian (Aquarana catesbeiana) and eight fish species (Coptodon zillii, Oreochromis niloticus, Gambusia affinis, Cirrhinus mrigala, Labeo rohita, Pterygoplichthys pardalis, Ictalurus punctatus, and Neosalanx taihuensis). Notably, six of the nine alien species were detected at eight or more sampling sites, indicating their wide distribution in the PRE. Moreover, all nine alien species were classified as high risk based on AS-ISK, suggesting potential damage to local ecosystems and the aquaculture industry. Our study can help inform policy decisions for the prevention and control of alien aquatic vertebrates in the PRE.