梯级小水电干扰下的河流鱼类群落构建机制—以金沙江黑水河为例

The cascaded development and operation of small-sized hydropower plants has dramatically changed the processes of river fish community assembly rules both regionally and globally. However, the knowledge about the mechanism of river fish community response to the operation of small-sized hydropower plants remain yet limited. In present study, fish resources investigations and habitat environmental variables will be carried out in the Heishui River, within rich species diversity and low anthropogenic activities, aiming to test the spatiotemporal variations processes of fish assemblages, functional biodiversity traits and nestedness patterns under the cascaded exploitation context of the small-sized hydropower plants in different scales. Firstly, we will depict the spatiotemporal patterns of fish communities and driving environment factors linked to the variations of fish distribution in the stress context of small-sized hydropower plants. Secondly, fish community functional biodiversity response to the operation of small-sized hydropower plants will be illustrated in the micro-habitat context. Finally, we will establish the quantitative relationships between fish community and nestedness patterns based on above studies in different spatiotemporal scales, to provide the reference for fish habitat alternative protection and the case for fisheries resources management. Meanwhile, these systematic and stereoscopic scientific probes will remarkably enrich the knowledge about the relationships between fish community biodiversity and cascaded small-sized hydropower plants. These results could provide significant implications for river ecosystem health assessment and location optimization of fish alternative habitat.

梯级小水电的开发和运行已显著改变河流鱼类群落稳态的构建过程。而对河流鱼类群落构建对梯级小水电干扰下的响应机制的研究非常匮乏，尤其在功能多样性和嵌套机制方面。本项目拟选取物种多样性较丰富和人为扰动较小的金沙江支流黑水河为研究区域，以鱼类群落为研究对象，在流域和微生境尺度下开展鱼类群落时空格局过程、功能多样性特征和嵌套形成机制对小水电开发和运行响应的研究。首先，以小水电运行干扰为背景，从流域尺度描述鱼类群落结构时空格局过程及驱动格局变化的环境因子；其次，在微生境尺度下，阐明鱼类功能多样性特征变化对小水电运行的响应；最后，在系统了解关键环境因子的基础上，构建鱼类群落在时空格局条件下的嵌套模型，为河流鱼类替代生境保护及渔业资源管理提供参考。同时，本研究整合功能多样性和嵌套格局的方法探讨河流鱼类群落构建对梯级小水电干扰下的响应机理，可以为河流生态系统健康评价及鱼类栖息地替代生境优化选址提供科学支撑。

“干流开发，支流保护”的支流栖息地替代生境保护是减缓水利工程梯级开发引发生态环境效应的一种有效和重要措施。按项目的研究计划，选取金沙江下游生境完整及其生物多样性丰富的典型支流---黑水河、鲹鱼河、龙川江等断面进行了鱼类的定量调查采集，同时监测不同水文条件下鱼类的物种组成、多样性和水体的理化因子（水温、溶氧量、电导率、pH值、水深、叶绿素等）等特征。通过解析栖息地生物多样性组成、环境质量、生境特征及其与环境因子关系，阐明黑水河鱼类群落在不同河段受水利工程影响的生态环境响应。研究以筛选重要栖息地河流和关键保护物种为目标，具体为以物种和功能多样性、栖息河流生境比对、支流生境支流评价体系构建为基础，提出以金沙江下游鱼类多样性较高和支流保护潜力较大的黑水河为保护河段，通过分析黑水河梯级水电蓄水前后鱼类多样性物种和功能组成的差异，提出以栖息地生境模型进行河流内保护区和关键物种优先级的筛选方法。重点研究了支流栖息地生境质量评价体系的构建及其群落构建机制，同时提出了从功能视角分析受水电干扰下鱼类群落构建机理的新思路，进一步优化生物多样性保护的维度。项目的开展促进流域小水电开发背景下鱼类生态与环境水利学在国内外的应用和发展。