|其他题名: ||Impacts of small hydropower plants on macroinvertebrate communities in the Xiangxi River, Three-Gorge Region|
于2005年9月对香溪河干流3个小水电站对河流底栖动物的影响进行调查研究，每个水电站按影响情况设4个样点，各样点采样3次。共采集到2121条底栖动物，分属14目38科64属，平均密度为655ind/m2，其中蜉蝣目(Ephemeroptera)为主要类群。蜉蝣目的四节蜉属(Baetis spp.)出现频率达97.2%，密度占总密度的50.8%，是香溪河流域的优势分类单元。优势功能摄食类群为刮食者，相对丰度达56.0%。底栖动物群落结构的变动用EPT物种数、总个体数、香农指数、均匀度指数和优势种百分比五个指标来衡量，并用裂区实验设计(Split Plot Experiment Design)方差分析研究差异的来源及大小。结果表明，样点间差异最大，电站的地理位置有一定的影响，而微生境的差异不明显。应用MRPP法(Multi-Response Permutation Procedures)对样点相似性进一步分析表明，样点间差异显著，而不同电站间差异并不明显。非度量多维尺度法(Non-metric multidimensional scaling, NMDS)分析也同样表明了不同样点间的分化比不同电站间的分化明显。同时，NMDS还表明了这种分化与流速、溶解氧和水温的变化是分不开的。因此，根据上述分析结果，有必要对小电站的修建进行管理控制。另外，结果还说明，适当改善电站影响区的水流状况，可以减轻小水电站对河流的不利影响。
从2005年12月至2006年5月对香溪河一典型电站——苍坪河电站上的5个样点进行电站对河流底栖动物时间动态影响的研究。整个调查过程中共采集到12756条底栖动物，分属于13目45科85属。其中水生昆虫是绝对优势类群。蜉蝣目的四节蜉属(Baetis spp.)、毛翅目的舌石蛾属(Glossosoma sp.)和蜉蝣目的高翔蜉属(Epeorus spp.)为优势分类单元，相对丰度分别为48.6%、8.2%和6.5%。从时间动态上看，这三种优势类群代表了三种时间分布方式，既四节蜉属(Baetis spp.)在1月份出现峰值，舌石蛾属(Glossosoma sp.)则在整个冬季都有较为明显的优势，而高翔蜉属(Epeorus sp.)在各月之间分布稳定。总密度与生物量在1月份最大，然后逐渐降低，5月份最小。收集者(GC)是香溪河主要的功能摄食类群，在各月间一直保持较为明显的优势，而滤食者(FC)和捕食者(PR)具有一定的季节稳定性，在维持整个生态系统营养、能量流通稳定中起着关键作用。群落差异的效应分析表明，样点与时间的差异对群落的变化都起了重要作用，说明人为干扰与自然的变动都影响着底栖动物的群落组成，而自然变动的影响更为明显。从群落指标的变异系数上看，多数指标从1月到5月有逐渐变小的趋势。理化因子、流量与降雨量在一定程度上反映了香溪河的季节动态，并最终影响着河流底栖动物群落结构上的变化。特别是群落指标的变异系数有随河道流量增加而逐渐减小的趋势。
选择香溪河底栖动物的丰富度指数(Richness measures)、群落组成指数(Composition measures)、耐污指数(Tolerance measures)、营养指数(Trophic measures)、生态型指数(Habitat measures)等共28个参数作为构建香溪河底栖动物生物完整性电站影响指数的候选参数。通过对候选参数的分布范围分析、判别能力分析、各参数间的Pearson相关分析，及参数与环境因子的回归分析，最终得到由10个参数构成的基于香溪河底栖生物完整性的电站影响指数，包括EPT分类单元数、毛翅目百分数、摇蚊科幼虫相对百分数、BI值、滤食者百分数、刮食者百分数、收集者百分数、捕食者百分数、粘附者百分数和均匀度指数。通过对各核心参数的赋分，计算得到香溪河各采样点的电站影响指数值。利用四分法对各采样点的健康状况进行评估，结果显示，电站对香溪河总体健康状况影响不大，大部分样点健康状况为“良”（共计49个样点），占样点总数的81.7%，“优秀”的样点7个，占样点总数的11.7%，“差”的样点4个，占样点总数的6.6%。B-IBI指数在5个样点间的差异显著，样点1与样点4的健康状况要好于其它3个样点。
于2005年12月至2006年5月，对香溪河干流一典型引水型电站——苍坪河电站取水对坝下河段底栖动物栖息地的影响及河道的最小生态需水量进行调查研究，利用加权可利用宽度法(Weighted Usable Width)分别计算了香溪河底栖动物三个主要的目(蜉蝣目、襀翅目和毛翅目)的各断面加权可利用宽度，并对各断面结果进行比较。结果表明，电站引水坝的取水使下游河段部分地出现干涸，三个目的加权可利用宽度显著减小。根据底栖动物加权可利用宽度与流量的回归关系，计算出香溪河底栖动物主要类群的最小生态需水量为3.8m3/s。|
|英文摘要: ||Based on the long-term survey of macroinvertebrate communities in the Xiangxi River system, several researches were carried out: 1) The variation and spatial scales of macroinvertebrate communities caused by small hydropower plants (SHPs). 2) Impacts of the cascaded SHPs on the spatial patterns of the macroinvertebrate communities. 3) A temporal patterns of the macroinvertebrate communities under the impact of a typical SHP named Cangpinghe (CPH). 4) Construction of useful macroinvertebrate metrics for analyzing the Xiangxi river ecosystem health. 5) The impacts of small hydropower plants on macroinvertebrate habitat and the ecological water requirement of Xiangxi River. The main results are as follows:
1. The ecological impact of SHPs on the spatial distribution of macroinvertebrate assemblages was investigated in three cascade SHPs of the Xiangxi River, and the variation caused by SHPs and the natural changes also were compared in this research. Four sites (site 1 is about 100 m upstream the dam, as the reference site, site 2 is just upstream the dam, site 3 locates about 50 m upstream the outlet, which is several kilometers downstream the dam, and site 4 locates just downstream the outlet.) in each SHP and three samples for each site were selected. 2121 macorinvertebrates were collected and mean dencity was 655 ind/m2. Five biotic indices (Ephemeroptera, Plecoptera and Trichoptera (EPT) richness, abundance, Shannon-Wiener index, evenness, and percentage of the dominant species) were analyzed by means of split plot experiment design ANOVAS across different stations, sites, and samples. Significant variation occurred mainly at the site scale. Station scale also has some influences and no significant differences in sample scale. Multi-Response Permutation Procedures (MRPP) also showed that compositions of the macroinvertebrate among four different sites varied significantly and no significant difference among the stations. Non-metric multidimensional scaling (NMDS) presented much clearer separation of communities among sites than among stations, and it also indicated that velocity, dissolved oxygen, and water temperature were the most important factors affecting the macroinvertebrate communities. This study highlights the fact that some necessary measures should be conducted to control the constructions of SHPs. The results also showes that improving the river hydraulic condition could lighten impacts of SHPs.
2. The influence of SHPs on the spatial distribution of macroinvertebrate assemblages was investigated in five cascade SHPs of the Xiangxi River during October of 2005. Five sites (site 1 is about 100 m upstream the dam, as the reference site, site 2 is just upstream the dam, site 3 is just downstream the dam, which is a lentic pool, site 4 is about 50 m upstream the outlet and several kilometers downstream the dam, and site 5 is just downstream the outlet.) in each SHP was selected for sampling. A total of 4656 macroinvertebrates were collected and mean density was 658 ind/m2. The characteristics of macroinvertebrate community structures were analyzed by using richness, abundance, dominant species and functional feeding groups. The results suggested that the construction of the SHPs had no significant impact on the water chemistry, but physical variables (such as velocity and water depth) varied significantly among five sites. All the characteristics of the macroinvertebrate community were affected by the construction more or less, especially the density, filter-collecters (FC) percent and predators (PR) percent which were significantly affected by the stations. According to Hierarchical agglomerative clustering, site 3 was the most severely impacted site which had different taxa composition. Site 2, 3, and 5 had different abundance with site 1 and 4. The results suggested that the sites down of the dam had most different community structures, which meant that obstructing the water completely was harmful for the protection of the macroinvertebrate diversity of the river.
3. Five sites in a typical plant CPH were set just like the sites in October 2005 and sampled for every month from December 2005 to May 2006 to explore the temporal variations of the macroinvertebrate communities under the impact of SHP. A total of 12756 benthic macroinvertebrate individuals, representing 13 orders 45 families and 85 genera, were recorded during the sampling time. Aquatic insects were the most dominant group and constituted about 91.8% of the total taxa. Baetis spp. (Ephemeroptera), Glossosoma sp. (Trichoptera) and Epeorus sp. (Ephemeroptera) were the main taxa and relative abundance were 48.6%, 8.2% and 6.5% respectively. According to the temporal variation, these three groups presented three kinds of temporal distributions. Baetis spp. expressed the highest abundance in January; Glossosoma sp. expressed the high abundance in the whole winter; Epeorus sp. evenly distributed in every month. The density and biomass of the macroinvertebrate communities were the highest in the January and then declined. For the functional feeding groups, gatherer-collectors (GC) were the dominant group. Filter-collectors (FC) and Predators (PR) kept constantly in different months. According to factorial ANOVA, both the temporal impact and the SHP impact were significant and the temporal impact was seemed more important for the variance of the macroinvertebrate communities. The Coefficient of Variation (CV%) of most community metrics showed a declined trend from January to May. The physi-chemical factors, discharge and precipitation varied according to the temporal variation and influenced the fluctuation of the macroinvertebrate communities, especially the change of the Coefficient of Variation.
4. We selected 28 metrics belonged to richness, composition, tolerance and intolerance, functional feeding groups and habitat index of macroinvertebrates in the research area influenced by SHPs of the Xiangxi River as the candidate metrics. EPT taxa, Trichoptera%, Chironomidae%, BI value, Filterers%, Scrapers%, Gatherers%, Predators%, Clingers%, Evenness index were selected as the benthic metrics to assess the biological condition. All of these ten metrics had significant differences (one-way ANOVA, p<0.05) among five sites, which suggested that these metrics were able to distinguish the differences between reference sites and degraded sites. Pearson Correlations analysis also showed that there were low correlations among these metrics. It indicated that little redundant information was included in the further analysis. These metrics fluctuated according to physical metrics among the different sites. General regression analysis showed that they were negatively or positively related physical variables. All of these results confirmed that the metrics selected were suitable and useful for analyzing the impacts of the SHPs. Then the B-IBI was calibrated and constituted. According to the result, the biotic integrity of the Xiangxi river were not severely impacted by the SHPs. The biotic structure of 93.4% sampling sites were excellent or good and only 6.6% sampling sites were fair. There were significant differences among five sites, and site 1 and 4 were better then the other three sites.
5. A typical small hydropower plant “Cangpinghe” was investigated monthly for researching the impacts of small hydropower plants on macroinvertebrate habitat and the ecological water requirement of Xiangxi River. The weighted usable widths (WUW) were calculated for three dominant orders of the macroinvertebrate (Ephemeroptera, Plecoptera and Trichoptera) at each cross section and necessary comparisons were conducted among each cross section. The results showed that the divertion of the water current caused part of the downstream channel dried up and the WUW of the three orders of the macroinvertebrate declined significantly between the upstream channel and the downstream channel. According to the relationship between the WUW and the river discharge, it was calculated that the minimum ecological water requirement for the main group of the macroinvertebrate in Xiangxi River was 3.8 m3/s.|
|Appears in Collections:||中科院水生所知识产出（2009年前）_学位论文|
|File Name/ File Size