Biological invasion is a major driver of biodiversity loss and ecosystem disruption, with non-native aquatic species threatening ecological integrity and economic stability. The Qinling Mountains, located in central China, serve as a crucial barrier between temperate and subtropical climate zones, and separate the Yellow and Yangtze River basins. This study investigates the role of these geographical barriers in regulating the distribution and invasion risk of non-native aquatic species. We identified 27 non-native species in Shaanxi Province based on occurrence records compiled from field survey conducted between 2012 and 2024 (and from 2019 to 2024 in the Yellow River mainstream of the Shanxi–Shaanxi Gorge), including 13 high-risk species, such as Trachemys scripta elegans, Procambarus clarkii, Sander lucioperca, and Hypomesus olidus. Using the Aquatic Species Invasiveness Screening Kit and species distribution models, we identified the Hanjiang River in the Yangtze basin and Weihe River estuary in the Yellow River basin as high-risk areas for these species. Mean annual temperature was the primary environmental factor influencing species distribution, with species adapted to cooler conditions predominantly found north of the Qinling Mountains, while those preferring warmer climates are more common in the south. Our findings highlight the Qinling Mountains as both a physical and climatic barrier, limiting cross-basin dispersal and creating distinct invasion patterns. However, human activities such as inter-basin water-transfer projects, damming, and aquaculture practices have gradually weakened the barrier’s effectiveness, facilitating the spread of invasive species. We recommend prioritizing monitoring efforts in cross-basin water-transfer regions, focusing on high-risk species adapted to both cooler and warmer climates, and incorporating environmental DNA (eDNA)-based monitoring in recipient areas of inter-basin water-transfer projects for early detection and control to minimize ecosystem damage.

Wuzhizhou Island (WZZ) is one of the most mature tourism islands on the coast of the South China Sea, and its surrounding waters are rich in tropical coral reef fishes. Tourism could affect marine biodiversity, especially the coral reef fish community. In order to understand the species diversity of fish surrounding WZZ, environmental DNA (eDNA) samples were collected from six sampling sites around the island, located in the core and non-core tourism areas, respectively, from 2022 to 2023. In total, 188 fish species, belonging to 124 genera, 63 families and 17 orders, were detected using eDNA method. The Perciformes contained the highest number of species (n = 130, 69.15% of total number). Compared to traditional fishing nets, eDNA could provide more information on fish species. The results indicated that species richness and Margalef’s index were higher at the sampling sites in the core area of tourism of WZZ, which maybe relevant to tourism-based provisioning. By contrast, the Shannon–Wiener index, Pielou’s index and dominant species of fish did not display significant differences between core and non-core tourism areas. On the basis of the results of the β-diversity index, the differences in fish communities had a closer relationship to geographical location. Furthermore, there were obvious differences in fish communities in different seasons, which may be attributed to the influence of ocean currents.