青海湖裸鲤生态鱼道的适宜性研究

Naked carp of Qinghai Lake (Gymnocypris przewalskii) is the national level 2 protected animal and a unique highland migratory species. However, due to climate change and human influence, such as construction of barrages, migration routes of the naked carp have been impaired severely. Massive mother fishes died because of the barriers on the rivers or diversion channels. To restore the migration route of the naked carp, fishpasses are extensively developed on the migration rivers. Unfortunately, the actual effectiveness and suitability of the fishpasses are low and requires improvement. This present study is fully aware of the ecological demand of naked carp migratory and their food resources, and therefore attempts to propose an ecological fishpass type imitating the natural step-pools system. The ecological suitability of the step-pool system for the naked carp will be studied by applying field investigation, theory modeling, laboratory and field experiments. In the field investigation, the natural habitat conditions of the naked carp in its migration rivers will be measured. A model will be proposed to study the adaptability of the naked carp to the physical and chemical parameters of the habitats. Laboratory experiments will be performed to study the migratory behavior and response to the hydrodynamic conditions of the naked carp. The key design elements of the step-pool-system fishpass will be determined according to the results of field investigation and laboratory experiments. The hydraulic characteristics and stability of the step-pool-system will be studied by flume tests. The actual effectiveness and suitability of the step-pool-system fishpass will then be tested and evaluated in the migration river during the migratory season of the naked carp.

青海湖裸鲤为国家二级保护动物，作为高原特有洄游鱼种，受气候变化及拦河坝建设等影响，其洄游通道大规模丧失，亲鱼大规模死亡丧生。为修复裸鲤洄游通道，已建大量鱼道工程，但其实际过鱼效果及对裸鲤的适宜性亟需改善。本项目考虑青海湖裸鲤洄游的生态需求，尽可能地减少阻隔，提出模仿天然阶梯-深潭系统的生态鱼道型式，并研究其对裸鲤的生态适宜性。拟从青海湖裸鲤自然洄游通道中栖息地的河流水动力条件及生态条件出发，提出适宜性模型研究裸鲤对洄游通道的地貌、水环境、水生态条件相关的理化因子的适应性规律。结合裸鲤洄游习性及对水动力条件响应的试验研究，提炼满足裸鲤生态适应性及洄游习性的阶梯-深潭鱼道的关键要素。通过室内水槽试验测量阶梯-深潭鱼道的水力学及稳定性特征。并通过洄游季节的现场试验检验优选的关键要素组合下阶梯-深潭鱼道的过鱼效果，论证模仿天然阶梯-深潭系统的生态鱼道对裸鲤洄游的适宜性。

青海湖裸鲤作为高原特有洄游鱼种，受气候变化及拦河坝建设等影响，其洄游通道大规模丧失。虽然部分入湖河流已建鱼道工程，但其实际过鱼效果及对裸鲤的适宜性亟需改善，且现有研究关注青海湖裸鲤洄游过程对环境适应性非常有限，制约了青海湖裸鲤资源恢复。本研究的主要目的为建立裸鲤对栖息地环境条件的生态适应性模型，揭示青海湖裸鲤洄游对洄游通道栖息地条件的适应性。综合考虑裸鲤对生态因子的适应性模型、裸鲤洄游习性、阶梯-深潭系统的生态水力学和地貌学优势，研究阶梯-深潭型生态鱼道对裸鲤洄游的适宜性。.主要研究成果包括：.（1）系统调研了高原水生态特征及与河流物理栖息地演变的关系，构建了河流地貌-水动力-水生食物网协同研究模型，揭示了水动力过程对河流生物完整性的影响规律与作用机制。模型应用于裸鲤洄游通道的栖息地生态特征和食物资源特征研究，发现河型变化产生的废弃河道对于河流食物网的结构和功能起显著改善作用。.（2）基于青海湖裸鲤资源的历史数据、不同时期裸鲤开发强度、种群保护和恢复策略等的系统调研，构建了耦合密度依赖的青海湖裸鲤种群结构演变模型，发现提高裸鲤卵苗和幼鱼的存活率、提高起捕年龄、保障亲鱼群体的产卵活动是裸鲤种群恢复的关键。.（3）研发了深度融合基于无人机的摄影测量和人工神经网络技术的新方法，实现野外直接采集高分辨率的裸鲤鱼群分布大数据。使用新的识别方法获取青海湖裸鲤密度的时空分布特点，研究水力地貌环境对青海湖裸鲤分布的影响，发现较高裸鲤空间密度出现在大水深静水条件或高流速动水条件，且流速比水深对鱼群空间分布的影响更大。.（4）研发了基于阶梯-深潭稳定性和生态适宜性的生态鱼道设计技术。通过水槽试验，人工构造单个阶梯-深潭模型并使用非恒定升水过程，揭示了阶梯-深潭地貌、流态、消能率和稳定性在洪水条件下的具体相互作用机制。结合试验测量和数值模拟，获取阶梯-深潭单元高分辨率三维水动力特性。