梯级开发背景下生境大小及其分隔对鱼类物种迁徙-灭绝动态研究

Cascade hydropower stations built cause habitat heterogeneity lowering, habitat fragmentation and barrier effects on fish population dynamics, community succession, behavioral characteristics, genetic diversity and d a variety of comprehensive cumulative factors lead to extinctions process of species , are focus of attention at home and abroad in recent years. Whether the reduce of the natural habitat area due to habitat fragmentations and gene flow barriers because of the barrier effects can impact on the fish migration, and ultimately lead to the extinction of the species, are still important issues faced by the cascade hydropower stations running. Domestic research on the integrated ecological effects existed by the cascade hydropower stations is still a lack of integrity and the combination of multi-scale researches. This study is intended to focus on the local populations living in the tributary estuaries, selecting 13 tributaries sampled from genetics, individual, population, community and landscape scales to study the laws of the fish migrate among different habitats ,focusing on the situations of fish genes' hinder among the different tributaries though the lateral migration process caused by the reservoir operation, exploring the effect mechanisms of different sizes and the different degrees of habitat separation on the migratory of the fish stocks - extinction dynamics and their impact levels, as well as the adaptation mechanisms exerted by these external and Internal stresses faced by the fishes embodying different types of ecology under the background of cascade Hydropower development, aiming to provide theoretical and technical support for fish conservation under the context of cascade Hydropower development.

梯级电站修建所引起的生境异质性降低、生境破碎以及阻隔效应对鱼类种群动态、群落演替、行为学特征、遗传多样性的影响以及多种因素综合累积所引起的物种灭绝过程，是近年来国内外关注的焦点问题。生境破碎化导致的自然生境的减小以及阻隔效应所引起的基因交流障碍是否对鱼类的迁徙产生影响，并最终导致物种的灭绝，仍然是梯级电站运行所面临的重要问题。目前国内对梯级电站所引起的综合生态效应的研究仍缺乏整体性和多尺度的结合。本研究拟以集群在支流河口的局部种群为研究对象，选取13条支流从遗传学、个体、种群、群落以及景观尺度上进行采样，研究鱼类在不同生境之间进行迁徙的规律，重点了解水库运行对鱼类在不同支流的横向迁徙过程之间的遗传阻碍情况，探讨梯级电站开发背景下不同生境大小和不同分隔程度对鱼类种群迁徙-灭绝动态的影响机制及其影响程度以及不同类型鱼类对这些胁迫所形成的适应机制，为梯级电站开发背景下的鱼类保护提供理论和技术支撑

生境破碎化导致的自然生境的减小以及阻隔效应所引起的基因交流障碍是否对鱼类的迁徙产生影响，并最终导致物种的灭绝，仍然是梯级电站运行所面临的重要问题。本项目围绕这一问题开展了内容，获得的主要结果如下：.（1）库区上游与干流连通的支流自然流水生境的鱼类群落结构会受到下游梯级开发蓄水运行的明显影响；.（2）5个环境变量包括平均水温、海拔、底栖无脊柱动物生物量、建坝情况和沿岸带植被覆盖率能够有效地影响长江上游14条支流河口及其上游江段鱼类群落结构的空间分布，鱼类群落结构在14个采样江段的分布首先和主要受到水温和海拔差异的影响；.（3）3种不同生活史类型鱼类的遗传多样性和遗传结构的研究表明：在长江上游干流梯级水电开发后的较短时间内，水电开发对广适性鱼类瓦氏黄颡鱼和喜流水性、较长距离产卵迁徙鱼类中华金沙鳅的遗传多样性和遗传结构影响有限，但对喜流水性、短距离产卵迁徙鱼类中华纹胸鮡的遗传多样性和遗传结构的影响较为明显；.（4）支流是许多干流栖息鱼类重要的产卵生境，产卵迁徙对长江上游部分支流鱼类群聚结构的变动造成了明显的影响；在长江上游干支流严重水电开发背景下，干支流连通性的完整对长江上游鱼类物种多样性的维持具有重要的意义； .（5）支流河口及其上游自然流水生境面积的大小与鱼类的物种多样性成对数关系，维持支流河口及其上游江段1~2 km2的自然流水生境面积能够有效维持该区域较高丰富度的物种；.（6）相较之非自然河流生境的库区江段以及夹在下游水库和上游大坝之间的自然河流生境江段，下游分布有水库而上游无大坝分布的自然河流生境江段受水电开发的影响最小；.（7）在生境面积大于1.00 km2且溶解氧大于11.02 mg/L的采样江段，其分布的特有鱼类种类数较多，而在生境面积处于0.35 km2~1.00 km2 之间且溶解氧处于7.41~7.81 mg/L之间的采样江段，其分布的特有鱼类种类数最少；生境面积、总磷、溶解氧和沿岸带植被覆盖率对特有鱼类在不同江段的种类数分布起最重要的作用。