【作者】 段学花；

【导师】 王兆印；

【作者基本信息】 清华大学 ， 水利工程， 2009， 博士

【摘要】 本文通过野外调查和野外试验研究了河流水沙条件对底栖动物的生态影响,并以底栖动物为指示物种对河流生态进行评价。选取我国32条河流的64个断面进行底栖动物调查采样和鉴定分析,研究了底质、河床演变和水质污染对底栖动物的影响。共开展3项野外试验,通过更换河床底质研究了不同粒径的底质对底栖动物的影响,通过人工隔离河边水域研究了栖息地破碎的影响,分析了底栖动物物种数与采样面积之间的关系。底栖动物多样性随底质粒径增大而发生规律性变化,且不同类型底质中的优势类群不同。卵石河床中的生物多样性最高,沙质河床中的生物多样性最低。底质的稳定性、孔隙率和空隙大小对底栖动物群落亦影响显著,而外观形状和表面糙度对底栖动物结构组成和密度影响不大。河床底质中生长水生植物对底栖动物生存有利。水质污染导致底栖动物多样性降低,敏感物种消失。随着总氮浓度的增加,撕食者、刮食者和捕食者比例不断降低,牧食收集者比例不断增加。以底栖动物为指示物种对水质进行了生物评价,并与理化分析进行对比,二者结果基本一致。从河床演变的角度,探讨了河床稳定性对底栖动物的影响。根据河床演变特征,将河流分为稳定型、侵蚀下切型、淤积抬升型和强烈走沙型。稳定型河流,动物密度大,物种丰富,多样性高;侵蚀下切型河流,动物密度和物种丰度较低;淤积抬升型河流,动物密度和物种丰度更低;强烈走沙型河流,物种丰度和密度均非常低,甚至为零。总结出了不同河床演变条件下的典型底栖动物群谱。水生栖息地隔离使得底栖动物物种丰度、密度和生物多样性明显下降,且隔离程度越强,降低越显著;动物结构组成也发生变化。综合主要物理条件和化学条件对底栖动物的影响,提出了简单易用的底栖动物生物栖息地适宜度指数计算公式。生物多样性指数和物种丰度与栖息地适宜度指数呈非线性正相关关系。此外,提出了东江流域受损河段的生态修复方略,综合分析了长江流域的底栖动物分布。更多还原

【Abstract】 The ecological impacts of water and sediment transportation on macroinvertebrate communities in rivers are studied through field investigations and experiments. Macroinvertebrates are used as indicator species in the assessment of river ecology. Macroinvertebrate samples were taken from 64 sampling sites on 32 rivers in China. Various species of macroinvertebrates were identified from the samples and they were compared and analyzed for the effects of substrate, fluvial process, and water pollution. Three field experiments were conducted to study the effects of substrata replacement with sediment of different sizes, the effects of aquatic habitat fragmentation by isolating riparian waters from the river, and the relation between the number of species in the samples and the sampling area.Biodiversity of macroinvertebrates varies with grain size of substrata, and different benthic organisms dominate in different types of substrata. Cobble substrate has the highest biodiversity, and sand substrate has the lowest biodiversity. The macroinvertebrate assemblage is also significantly affected by the stability, porosity, and interstitial dimension of the substrata, while it is rarely affected by the shape and the surface roughness of the sediment particles. Aquatic plants are favorable for macroinvertebrate assemblages. The effect of streambed substrate on macroinvertebrates is well understood, integrating both the results of the field investigations and the experiment.Water pollution results in a decrease of macroinvertebrate biodiversity and disappearance of intolerant species. Shredder, scraper and predator reduce following the increase in the concentration of total nitrogen. Collector-gatherer increases with the increased nitrogen. Because the macroinvertebrate communities are affected by pollution, water quality may be assessed by using macroinvertebrates as indicators. The results show that water quality assessment using macroinvertebrates as an indicator agrees with water chemistry analysis.The effect of fluvial process on the distribution of macroinvertebrates is studied. The rivers, according to their fluvial conditions, are classified as streams with a stable channel bed, degrading or aggrading channel beds, or intensive bed load motion. The compositions of macroinvertebrate fauna for the four types of rivers are very different. Stable streambeds provide the best habitat for benthic communities and have the highest biodiversity. Benthic communities are stressed in incised channels and the biodiversity is lower. In streams undergoing siltation habitats are seriously impaired and the biodiversity is even lower. In streams with strong bed load movement there are hardly any macroinvertebrates colonizing. This dissertation also presents the pedigrees of the benthic fauna in the four types of rivers.The taxa richness, density and biodiversity of macroinvertebrates greatly decrease in the isolated plots due to the habitat fragmentation. The smaller the isolated habitat plot, the more the biodiversity decreases. Habitat fragmentation also results in a succession of macroinvertebrate communities. A Habitat Suitability Index for macroinvertebrates (HSIm) is proposed in this dissertation, integrating the effects of the primary physical (including biotic and abiotic) and chemical conditions. The biodiversity index value and taxa richness increase non-linearly with the HSIm.Moreover, ecological restoration strategies for the impaired reaches of the East River basin are suggested in the dissertation. Macroinvertebrates distribution in the Yangtze River basin is studied.更多还原