Aim: Lanzhou is the only provincial capital city that the Yellow River passes through. It has played an important role in comprehensive management and high-quality development of the Yellow River basin. It is necessary to understand the status of and changes in fish species diversity to protect this aquatic ecosystem in the future.
Methods: To comprehensively document the pattern of fish diversity in the Lanzhou reach of the Yellow River, we probed the distribution of fish species using field surveys from July to October in 2020. The indices of Shannon-Wiener, Pielou, Simpson, Cody, Routledge, and Bray-Curtis were applied to evaluate the main streams and four tributaries in Lanzhou County. Relative abundance (RA) was calculated to determine the dominant species, and non-metric multidimensional scaling (NMDS) was used to show the spatial distribution pattern of the species.
Results: A total of 20 species, including four threatened species, one national class II protected wildlife species, seven Chinese endemic fish species, and four of the Yellow River’s endemic fish species were collected. These species belonged to 15 genera, 6 families, and 4 orders. Triplophysa orientalis, T. robusta, Carassius auratus and Pseudorasbora parva are the dominant fish species in this area. The fish fauna was dominated by fishes that are widespread in the Northwest Qinghai-Tibetan subregion. Omnivorous, demersal, and settlement fish were the predominant ecological types. Also, the Zhuanglang River and the Yellow River had a higher diversity of fish species than the Datong River and the Wanchuan River. The beta diversity analysis showed that the habitats of the Yellow River were different from those of the Zhuanglang River, the Datong River, the Huangshui River and the Wanchuan River, and that the fish species differentiated somewhat in these rivers. Moreover, the fish composition dissimilarity between the Zhuanglang River, the Yellow River, the Huangshui River, and the Wanchuan River was high. The NMDS method was applied to the collected data and four separate groups with small geographic distance were identified.
Conclusion: Water conservancy facilities construction, alien fish, and water pollution may affect the diversity and distribution of fish in the Lanzhou reach of the Yellow River. This study assessed available baseline information to ensure the protection and scientific management of freshwater fish diversity in the Lanzhou reach of the Yellow River. This information will be useful for the ecological protection and high-quality development of the Yellow River basin.