水电开发对鱼类种群分布及生态类型变化的影响——以溪洛渡至向家坝河段为例

Distribution characteristics and ecological types changes in fish communities under hydropower development from Xiluodu to Xiangjiaba reach

梯级水库修建后自然河流形成了河相段和湖相段,而河流生境的改变对鱼类种群空间分布和生态类型变化产生了重要影响。为探究金沙江梯级水电开发对鱼类资源的影响,结合2018年5月渔获物和文献记载水库修建前后的渔获物数据,分析了鱼类群落组成及变化,优势物种及群落多样性特点,以及鱼类在河相、湖相段生态类型的变化。结果表明,梯级水库建设后溪洛渡至向家坝鱼类的种类数减少,随着水库的运行该减少趋势放缓,而大型鱼的种类数占比呈增长趋势。受生境变化的影响,鱼类优势物种发生变化,水库河相段和湖相段生态类型差异较大。生态类型组成上以缓流型、生活于水流中下层、产卵初始水温高于18℃等生态类型占优。研究表明,高坝大库的运行会造成鱼类种群以生态需求为目标,形成明显的空间分布和群落结构特征,而梯级水库建设导致的水动力条件差异是鱼类群落生态类型差异的内在驱动力。

Natural rivers are divided into the riverine and lacustrine zones owing to the construction of cascade reservoirs.However,changes in habitat conditions have significant effects on the spatial distribution of fish and changes in ecological types.Changes in fish species composition,dominant species,community diversity and variation in fish ecological types between riverine and lacustrine zones were used to evaluate the effects of fish habitat.Data were obtained from the fishery survey in May 2018 and previous literature.The results showed that the number of fish species decreased and the rate of decrease slowed,whereas the proportion of big fish species increased after the construction of cascade reservoirs.The dominant species were constantly changing under the influence of habitat changes,and the ecological types of fish in the riverine and lacustrine zones were different.The species that inhabit the slow-flow zone,the middle and lower layers of water flow,and require initial spawning water temperature higher than 18℃were the dominant ecological types.Finally,the study showed that because of fish autecology,there were distinct patterns in fish spatial distribution and community structure characteristics affected by the operation of high dam reservoirs.The riverine and lacustrine zones caused by the hydrodynamic variation of cascade reservoir construction were the internal driving force for the changes in fish community ecological types.