澜沧江梯级开发下鱼类支流生境替代效果

作为干流高坝水电开发导致鱼类生境丧失的一种补偿措施,支流替代生境近年来被广泛应用于受工程影响河段的土著鱼类保护,但替代支流发挥怎样的保护效果及干流对其的影响仍不清楚。以实施了澜沧江梯级生境替代的支流基独河与罗梭江为研究对象,并选择了邻近的对照支流,通过对鱼类调查数据的分析对比,揭示了各支流鱼类种类组成与群落结构的差异特征,初步阐明了梯级开发下鱼类支流生境替代效果以及干流工程建设对其的影响。结果表明：澜沧江支流替代生境对干流鱼类具有明显的保护作用,支流生境修复后鱼类物种丰富度明显提高,罗梭江土著鱼类、特有鱼类物种数分别增加了12种、7种,基独河则是7种、2种,替代生境能为澜沧江土著鱼类、部分濒危特有鱼类和洄游鱼类提供完成生活史的关键栖息地。干流对支流生境替代保护有着重要影响,罗梭江、基独河与邻近干流鱼类群落的Bray-Curtis相似性分别为21.76%、10.73%,支流河口段保持“河相”是支流生境替代保护效果可持续的关键。综合考虑生境替代保护的效益与投入,建议今后开展此类保护措施时优先选择库尾河相区的支流。

Effects of fish habitat substitution in tributaries under the cascade hydropower development of Lancang River

As a compensation for the loss of fish habitat caused by the development of high-dam hydropower in the mainstream, tributary habitat substitution has been widely used to protect native fish in the river affected by the projects. However, what kind of protection effect of substitution tributary plays and the impact of the mainstream on it remain unclear. In this work, the Jidu River and Luosuo River were selected as the research objects, and the neighboring tributaries were selected as the control groups. Through analysis and comparison of the fish survey data, the differences of fish species and community structures in each tributary were revealed, and the effects of tributary habitat substitution and the influence of the mainstream on it were investigated. Results showed that the tributary habitat substitution had obvious protection effects on the mainstream fish. The fish species richness was significantly improved after the restoration of the tributary habitats. The number of native fish and endemic fish species increased by 12 and 7 respectively in the Luosuo River, while the corresponding increments were 7 and 2 species in the Jidu River. The tributary habitat substitution could provide the key habitat for the native fishes, some endangered endemic fishes, and migratory fishes of Lancang River to complete their life history. The mainstream had important influences on the substitution tributaries. Bray-Curtis similarity of fish communities in Luosuo River and Jidu River were 21.76% and 10.73%, respectively. Maintaining the "riverine zone" in the tributary estuary was the key to the sustainable protection. Considering the benefit and investment of tributary habitat substitution, it is recommended that the tributaries in the reservoir tail should be given priority when carrying out such protection measures in the future.