基于鱼类物种状况的长江生态环境质量评估

鱼类是水域生态系统的重要组成部分, 也是水域生态环境良好的指示类群。为合理评估长江生态环境的现状和变化趋势, 文章提出将土著鱼类物种数和珍稀特有鱼类物种数作为评价指标, 并建立了相关的评价基准和等级划分标准。以2010年和2020年为评价年, 评估了长江干流及代表性重点水域的生态环境质量。结果显示, 当前长江上游干流和下游干流的生态环境质量优于中游; 支流赤水河的生态环境质量良好, 大型湖泊鄱阳湖的生态环境质量中等。从时间上看, 随着长江十年禁渔等一系列保护措施的实施, 长江干流的生态环境质量有不同程度地好转。在此基础上, 提出了进一步改善长江生态环境的对策与建议。

ECOLOGICAL ASSESSMENT OF THE YANGTZE RIVER ENVIRONMENT BASED ON FISH SPECIES RICHNESS

Species richness is an important metric for assessing ecosystem health, and the species number is one of the most widely used metrics. Fishes are an important component of freshwater ecosystems. Due to their sensitivity to habitat degradation and other environmental stressors, the use of fish as biological indicators has grown in popularity since the inception of Karr’s Index of Biotic Integrity (IBI) in 1981. Based on the analysis of fish diversity in the Yangtze River, we proposed a fish-based ecological assessment systems for the Yangtze River, including the number of indigenous fish species and the number of rare and endemic fish species. The evaluation grades and scoring criteria of each matric was also provided according to the IBI method. Within this framework, we evaluated the ecological condition of the Yangtze River in 2010 and 2020. The results showed that the current ecological environment of the upper and lower reaches of the Yangtze River is better than that of the middle reach. The evaluation grade of Chishui River was “good”, while the Poyang Lake was “fair”. Overall, the ecological environment of the mainstream of the Yangtze River has improved to varying degrees with the implementation of ecological protection measures such as 10-year fishing ban. On this basis, countermeasures and suggestions for further improving the ecological environment of the Yangtze River have been proposed.