洞庭湖水系梯级开发影响下的鱼类多样性及生物响应

The Dongting Lake water systems are the important fish habitats and spawning sites of Yangtze River, and could be an important and valuable maintaining or providing for the fish diversity of the Yangtze River. The development of cascade hydropower changes the hydrological situation and habitat of natural stream channels and has a significant effect on the fish diversity. As such, it would be so significant to learn how to assess the ecological risk of the cascade hydropower development and protect the fish resources. In our study, by taking the fishes in Yuanshui River as the research objectives, researches will be conducted by the combination of field investigation and indoor experiments. The research contents include the fishes fauna composition, resource quantities, body length, weight, age structure, genetic diversity, foods composition and reproductive trait; at the same time, the Bighead crap and Yellow catfish are used as the target species in laboratory experiment. The numerical relationship are studied with the target fishes physiological and ecological response (energy metabolism, hematology indices and movement) to the key water environment factors(current velocity and water temperature), based on actual measuring data, different statistical analysis and mathematics methods. The research results will provide support for the river optimum management and reservoir ecological operation.

洞庭湖水系是长江鱼类重要的栖息地和产卵场，对长江鱼类多样性的维持或补充有着重要作用。水电梯级开发改变了天然河流的水文情势和生境，进而对此生境下的鱼类多样性产生重大影响。因此，了解水电梯级开发对鱼类多样性影响及鱼类的生物响应规律，对于科学评价水电梯级开发造成的生态风险和鱼类资源保护具有重要意义。本课题以长江中游通江湖泊—洞庭湖分支水系—沅水鱼类为研究对象，通过野外调查监测和室内实验，系统分析在梯级开发影响下沅水鱼类的区系组成、资源量、体长、体重、年龄结构、种群遗传多样性、饵料食物组成及繁殖特性；同时，以鳙、黄颡鱼为主要实验对象，基于实测数据，通过各种统计分析和数学方法，建立目标鱼类生理生态指标（能量代谢、血液指标、运动）与关键水环境因子（流速、水温）的量化响应关系，为河流优化管理和水库生态调度提供支持。

洞庭湖水系梯级开发背景下，因河流的水文情势和生境改变，鱼类多样性和生物学响应亦可能发生变化。本课题系统研究了梯级开发影响下沅水鱼类的多样性及其生物响应规律，对于科学评价水电梯级开发造成的生态风险和鱼类资源保护具有重要意义。主要研究内容及结果如下：.1.区系组成：沅水梯级开发影响下现有鱼类102种（不含引进种），沅水最大梯级五强溪水库库区鱼类67种；与水库建成前比较：沅水鱼类减少33种，降幅24.44%，库区鱼类减少46种，降幅达40.71%。.2.种群遗传结构：对光泽黄颡鱼、大鳍鱯和4个鲫品系群体的分子遗传多样性研究表明，沅水两个江段光泽黄颡鱼群体遗传差异不明显，而五强溪水库同一大鳍鱯群体至少存在两个种群的分化；洞庭湖水系两个养殖鲫（洞庭青鲫、彭泽鲫）群体之间和两个野生鲫（二、三倍体鲫）群体之间均有较近的亲缘关系，养殖群体的遗传多样性明显低于野生群体。.3.饵料食物组成：鲫、鲇、黄颡鱼三种常见鱼在五强溪水库库区与下游入湖口的饵料食物种类组成均存在差异。.4.繁殖特性：对沅水常见鱼类䱗繁殖期内繁殖力和卵径变化研究表明，䱗的繁殖批次较多，不同繁殖期的分批繁殖力、繁殖次数不一样，䱗的沅水种群跟湖泊种群都具有较大的个体繁殖力；鲫、鲇、黄颡鱼的个体繁殖力在沅水不同江段也有明显差异。.5.生物响应：对沅水不同水库大眼鳜的5种血清免疫酶活性测定结果表明，大眼鳜群体的非特异性免疫功能以桃源水库的最强，凌津滩水库次之，五强溪水库最低；对沅水常见鱼类鲫、大眼鳜和黄颡鱼幼鱼的趋流游泳行为及运动生理指标研究表明，在不同流速下，三种鱼的呼吸频率、摆尾频率、趋流率、耗氧率、游泳状态等表现出不同的变化或行为特征。.6.洞庭湖水系鱼类资源与染色体研究：洞庭湖水系沅水、澧水和资江现有鱼类120种，隶属8目23科76属；完成洞庭湖水系46种（品系）鱼的染色体图谱及22种（品系）鱼的核型分析。