Li Jin Peng, Dong Shi Kui, Peng Ming Chun, Wu Xuan, Zhou Fang, Yu Yin
China Waterborne Transport Research Institute, Beijing 100088, China.
School of Environment, Beijing Normal University, Beijing 100088, China.
Ying Yong Sheng Tai Xue Bao. 2017 Dec;28(12):4101-4108. doi: 10.13287/j.1001-9332.201712.033.
Benthic macroinvertebrate assemblages are one of the biological groups in aquatic ecosystem most sensitive to the habitat change and degradation, and can be a biological indicator for the aquatic ecosystem change and succession in cascading hydropower dam reservoir. The middle and lower reaches of the Lancang River are key spot for international biodiversity conservation and ecological studies on the effects of cascading hydropower dam exploitation. In this study, the reservoir of Manwan hydropower dam, the first dam in Lancang-Mekong river main stream, was selected as the study site. The benthic macroinvertebrate assemblages were sampled in 2011 and 2016 respectively. Meanwhile, the survey data before impounding (natural river, 1996) and early stage of single dam (1997) were collected to conduct the overall analysis for structure, distribution pattern and evolution of benthic macroinvertebrate assemblages. The results showed that the dominant biological group was gradually changed from the Oligochaeta and Insecta to the Mollusca. Along the longitudinal gradient, the density and biomass of the benthic macroinvertebrate assemblages were remarkably increased in reservoir, especially in the lacustrine zone. As for the functional feeding group, the predator and gatherer-collector changed into filter-collector predominantly in lacustrine zone. With the cascading dams operation, the biotic index indicated that the water quality of reservoir in 2016 was better than in 2011. The evolution of benthic macroinvertebrate assemblages in the Manwan Reservoir was related to the operation of Xiaowan dam in the upper reach, the hydrological regime and siltation in the reservoir, and would continue with dynamic changes with the operation of the cascading hydropower dam.
底栖大型无脊椎动物群落是水生生态系统中对栖息地变化和退化最为敏感的生物群体之一，可作为梯级水电站水库水生生态系统变化和演替的生物指标。澜沧江中下游是国际生物多样性保护的重点区域，也是梯级水电站开发影响的生态研究关键地点。本研究选取澜沧江-湄公河干流上的第一座大坝——漫湾水电站水库作为研究地点，分别于2011年和2016年对底栖大型无脊椎动物群落进行采样。同时，收集了蓄水前（天然河流，1996年）和单坝初期（1997年）的调查数据，以对底栖大型无脊椎动物群落的结构、分布格局和演变进行综合分析。结果表明，优势生物类群逐渐从寡毛纲和昆虫纲转变为软体动物纲。沿纵向梯度，底栖大型无脊椎动物群落的密度和生物量在水库中显著增加，尤其是在湖泊区。就功能摄食类群而言，捕食者和收集者-采集者在湖泊区主要转变为滤食者-采集者。随着梯级大坝的运行，生物指数表明2016年水库水质优于2011年。漫湾水库底栖大型无脊椎动物群落的演变与上游小湾大坝的运行、水库的水文状况和淤积有关，并将随着梯级水电站的运行持续动态变化。
