赤水河支流盐井河连通性恢复对鱼类群落及生境因子的影响OA

Aiming at the ecological barrier caused by the river-crossing road in the lower reaches of Yanjing River,a first-class tributary of the Chishui River,a connectivity restoration project was carried out through fishway reconstruction and barrier removal.Based on three rounds of monitoring data,the response characteristics of habitat factors,fish population dynamics and ecological functions were analyzed.The results showed that after the implementation of the project,the dissolved oxygen(DO)content in the water body increased significantly by 27.8%,the water flow velocity(V)increased by 30.5%,and the turbidity(TUR)decreased by 40.5%,with the convergence of hydrological characteristics in each section enhanced.The fish resources were restored,and the species and quantities of endemic fish in the upper Yangtze River as well as short-distance migratory fish increased remarkably.The community diversity indices(Shannon,Margalef and Pielou)all showed a significant upward trend(P<0.05),and the functional diversity indices(Fric,FEve,FDiv)also presented an increasing trend,indicating that the utilization efficiency of fish niche space was optimized.The female-to-male ratio decreased successively from the upper reaches to the lower reaches,and the proportion of individuals with gonadal development at stages Ⅳ-Ⅵ increased from 59%to 93%,with a significant aggregation feature of fish in the middle and late stages of gonadal development in the middle and upper reaches.The Habitat Suitability Index(HSI)revealed that connectivity restoration had a significant improvement effect on the habitats of Acrossocheilus monticola and Xenocypris davidi,and the mid-slope area(between the project sections)became a highly suitable habitat section.This study demonstrated that the connectivity restoration project effectively promoted the improvement of water environmental quality,the optimization of fish community structure and the natural recovery of reproductive habits in the Yanjing River by optimizing hydrological processes and improving habitat quality,which provides scientific support and technical demonstration for the ecological protection and restoration of the mainstream and tributaries of the Chishui River.