金沙江下游水电站建设对圆口铜鱼种群生存力影响的遗传随机性分析

In recent years, there has been widespread concern over the long-term effects of habitat fragmentation by damming on fish populations. As an endemic river migratory fish in the upper reaches of the Yangtze River, the migration routes of largemouth bronze gudgeon supplementary stocks below dam have been blocked by the construction and operation of four hydropower stations on the downstream of the Jinsha River. Through studying the losing rate of genetic diversity, reproductive biology parameters, ranges of spawning ground and changes of hydrological parameters, we will calculate the Population Viability and population extinction risk of largemouth bronze gudgeon lived in three different conditions, which are before impoundment of four hydropower stations, two of them impounded and all impounded. In addition, we will identify the key factors affecting largemouth bronze gudgeon population dynamic through sensitivity analysis and correlation analysis. Analyzing the result of three different conditions is expected to reveal the effects to habitat by the construction and the number of hydropower stations on the downstream of the Jinsha River, and studying the key factors will provide a scientific basis for the resources protection and recovery of the population of river migratory fish.

水利工程建设导致的生境破碎对鱼类种群的长期影响，是近年在国内外引起广泛关注的焦点问题。圆口铜鱼作为一种长江上游特有的河道洄游性鱼类，金沙江下游水电站的建设将阻断其补充群体上溯产卵的洄游通道，从而影响到其种群生存。本项目通过研究金沙江下游水电站运行的不同阶段下（电站运行前、部分电站运行、所有电站运行），圆口铜鱼种群的遗传多样性水平和遗传多样性丧失速率，并结合圆口铜鱼繁殖生物学参数、产卵场分布范围和水文参数的改变程度，计算三种状态下圆口铜鱼种群生存力大小、评估种群灭绝风险，并利用灵敏度分析和相关性分析辨识影响圆口铜鱼种群动态变化的关键因子。本研究将从种群生存力的角度具体分析水电站运行的不同阶段对河道洄游性鱼类物种生存的影响，其中，关键因子的分析对长江上游水利开发背景下其他鱼类的物种保护也具有普遍借鉴意义。

水利工程建设导致的生境破碎对鱼类种群的长期影响，是近年在国内外引起广泛关注的焦点问题。本项目选取河道洄游性鱼类——圆口铜鱼作为研究对象，探讨金沙江下游水电站的建设对其种群生存的影响。构建了圆口铜鱼特异性分子标记体系，包含29个多态性微卫星标记和1个线粒体D-loop区的特异性标记。利用这些标记，分析了金沙江下游水电站运行的不同阶段下（电站运行前、部分电站运行）圆口铜鱼种群的遗传多样性水平；并利用年度群体间的遗传多样性水平的变化情况，推算出了所有电站运行后（2020年）圆口铜鱼群体的遗传随机性参数。将这三个阶段设置为Vortex软件中的三个场景，结合圆口铜鱼繁殖生物学参数、基础生物学数据，分别模拟了三个场景下圆口铜鱼种群生存力大小，结果显示电站运行所带来的圆口铜鱼种群遗传多样性的降低，对其种群生存力影响不大。利用灵敏度分析辨识影响圆口铜鱼种群动态变化的关键因子，发现0-1龄的死亡率对种群大小以及种群灭绝影响最大。因此，对于圆口铜鱼，其受精卵需要在一定的流水中漂流孵化并完成早期发育的种类，保留一定长度的流水江段以供其受精卵孵化发育，是保护物种的一个关键。