Cheng Ruli, Luo Yang, Zhang Yufeng, Li Qinghua, Li Yingwen, Shen Yanjun
Laboratory of Water Ecological Health and Environmental Safety, School of Life Sciences Chongqing Normal University Chongqing China.
Ecol Evol. 2023 Jul 7;13(7):e10275. doi: 10.1002/ece3.10275. eCollection 2023 Jul.
Freshwater ecosystems are under great threat from humans, among which habitat heterogeneity is the most obvious, being one of the important reasons for the decline of fish diversity. This phenomenon is particularly prominent in the Wujiang River, where the continuous rapids of the mainstream have been divided into 12 mutually isolated sections by 11 cascade hydropower reservoirs. Based on the fact that conventional survey methods are more harmful to the ecological environment, the efficient and noninvasive environmental DNA metabarcoding (eDNA) approach was used in this study to conduct an aquatic ecological survey of the 12 river sections of the mainstream of the Wujiang River. A total of 2299 operational taxonomic units (OTUs) were obtained, corresponding to 97 species, including four nationally protected fish species and 12 alien species. The results indicate that the fish community structure of the Wujiang River mainstream, which was originally dominated by rheophilic fish species, has been changed. And there are differences in fish species diversity and species composition among the reservoir areas of the mainstream of the Wujiang River. The fish species in the area have gradually declined under the influence of anthropogenic factors such as terraced hydropower and overfishing. The fish populations consequently have demonstrated a tendency to be species miniaturized, and the indigenous fish are severely threatened. In addition, the fish composition monitored by the eDNA approach was found to be close to the fish composition of historical information on the Wujiang River, indicating that eDNA approach may be used as a complementary tool to conventional methods in this basin.
淡水生态系统正面临着来自人类的巨大威胁，其中栖息地异质性最为明显，这是鱼类多样性下降的重要原因之一。这种现象在乌江尤为突出，乌江干流连续的急流被11座梯级水电站分隔成12个相互隔离的河段。基于传统调查方法对生态环境危害更大这一事实，本研究采用高效、非侵入性的环境DNA宏条形码（eDNA）方法，对乌江干流的12个河段进行了水生生态调查。共获得2299个可操作分类单元（OTU），对应97个物种，其中包括4种国家保护鱼类和12种外来物种。结果表明，乌江干流原本以喜流性鱼类为主导的鱼类群落结构已发生改变。乌江干流库区的鱼类物种多样性和物种组成存在差异。受梯级水电、过度捕捞等人为因素影响，该区域鱼类物种逐渐减少。鱼类种群因此呈现出物种小型化的趋势，本土鱼类受到严重威胁。此外，通过eDNA方法监测到的鱼类组成与乌江历史信息中的鱼类组成相近，这表明eDNA方法可作为该流域传统方法的补充工具。
