四大家鱼早期生活史阶段的传播模式、途径及其对环境条件的响应机制研究

长江是我国重要经济鱼类四大家鱼的种质资源地，四大家鱼适应江河、湖泊环境，形成特殊的鱼类早期生活史策略——产漂流性卵，鱼卵、仔鱼随水流向下游传播进入育幼场。受水流条件、个体发育状况等因素的影响，四大家鱼早期生活史阶段的传播过程极其复杂。传统的生态调查表明，鱼卵的传播过程是受水流支配的被动过程，但是孵出后的仔鱼在水体中的传播机制仍不清楚。有迹象表明，四大家鱼仔鱼在传播过程中呈现一定的昼夜节律和空间分布规律，这种现象是否与仔鱼的主动行为有关？由此我们提出假说：四大家鱼仔鱼的传播过程为主-被动兼有的行为，且随着发育的逐步完成，主动行为的影响逐渐加强。围绕这一问题，本研究拟采用生态调查和亲缘关系分析的方法，全面详细地对四大家鱼早期生活史阶段的传播模式、传播途径及其对流水环境的响应机制进行研究，揭示四大家鱼早期生活史的生态适应策略，为种群保护和恢复提供理论基础，也为河流管理和生态修复提供技术支撑。

The four major Chinese carps (silver carp Hypophthalmichthys molitrix, bighead carp Aristichthys nobilis, grass carp Ctenopharyngodon idella, and black carp Mylopharyngodon piceus) are the most important commercial freshwater fish in China. The four carp species are found in many Chinese rivers, but the Yangtze River has the largest population. During flood season, the adult fish migrate upstream to spawn. The semi-buoyant eggs and larvae are transported to the floodplains (nurseries) along the river banks, where they find favorable conditions for shelter and feeding. This transport process is regulated by internal factors (ontogenetic) and environment factor, behavioral and physiological changes during development may enable certain stages to actively react to their environment and to temporally and spatially regulate their drift. Many studies showed that the semi-buoyant eggs drift passively in the current, but remain vague about the underlying mechanisms of dispersal after hatch. Spatial (lateral and horizontal) and diel distribution patters of drifting larvae was observed, it was hypothesized that aside from eggs, the early stages of the four major Chinese carps are usually a mixture of active and passive drifters. DNA parentage analysis provides a direct method for measuring larval dispersal for organisms. In the present study, based on DNA parentage analysis and the most common technique in the investigation of the drift of the young stages of fish, the patterns and processes in the drift of early developmental stages of the four major Chinese carps will be studied, which would be important for current protection and future rehabilitation efforts throughout the historic range of the species, and will have implications for river management and restoration projects.