黄河兰州段鱼类多样性与保护

兰州市是黄河唯一穿城而过的省会城市, 是黄河流域综合治理与高质量发展的重要区域, 了解其鱼类多样性现状及变化趋势对黄河流域水生态保护尤为重要。本文于2020年7-10月对黄河干流兰州段及其4条支流(庄浪河、大通河、湟水河和宛川河)开展了鱼类多样性、分布及影响因素调查, 以Shannon-Wiener多样性指数、Pielou均匀度指数、Simpson优势度指数、Cody和Routledge指数、Bray-Curtis相异性系数对黄河兰州段5条河流鱼类群落进行评估, 同时通过相对多度(relative abundance, RA)判定优势种, 利用非度量多维标度排序(non-metric multidimensional scaling, NMDS)展示物种空间分布格局。本次调查获得鱼类20种, 隶属于4目6科15属。其中, 国家II级重点保护野生动物1种, 受威胁鱼类4种, 中国特有鱼类7种, 黄河特有鱼类4种。区系组成属青藏高原区高原西北亚区, 其中鲤形目种类占绝对优势, 优势种为东方高原鳅(Triplophysa orientalis)、粗壮高原鳅(T. robusta)、鲫(Carassius auratus)和麦穗鱼(Pseudorasbora parva)。庄浪河和黄河干流的α多样性较高。β多样性分析结果表明, 黄河干流与庄浪河、大通河、湟水河和宛川河间的鱼类物种明显不相似; 大通河与湟水河之间以及黄河干流与宛川河之间的鱼类物种组成相似性较高。NMDS分析表明, 黄河兰州段鱼类被划分为地理空间上相近的4个地理群。水利设施建设、外来物种和水体污染可能影响了黄河兰州段鱼类多样性和分布。本研究为黄河兰州段鱼类多样性保护和科学管理以及黄河流域生态保护和高质量发展提供了基础调查数据。

Fish diversity and conservation in the Lanzhou reach of the Yellow River

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.