长江葛洲坝江段鱼类时空动态对水文条件需求的量化

Sustainable management of water resources requires changing of dam operations to maintain river ecosystems. To restore habitat quality of fish species, it is essential to understand the hydrological requiremnts of the fish species when conduct the re-operation for this species. The existing studies directed toward those requirements by using the methods of environment flow and weighted usable area. However there are information gaps between those study and fish needs. The lacks of information on spatiotemporal changes in fish species hindered those in-depth studies. In this study, we take the Coreius genes and Chinese sturgeon as the targeted species and the lower reach of the Gezhouba Dam on the Yangtze River as study area. We combine the fisheries acoustics, geostatistics, hydrology and hydraulics together and aim to document real-time spatiotemporal changes in targeted fish that associated with hydrological conditions, from which we expect to acquire the dynamic requirement of the fish species for the hydrological conditions. To this end, five following steps will be conducted in this study: 1) Hydroacoustic species identification are conducted by using multi-frequency detection. 2) Geostatistical simulation are used to map the 2D and 3D spatial distributions of fishes, during which the uncertain variation in the fish spatial distributions are quantified and improved by the interpolation of Co-Kriging method. 3) The quantified spatial distributions of fishes and the hydrological and hydraulic elements are coupled together to get the real-time spatiotemporal distributions of fishes that associated with hydrological conditions. 4) The time series analysis (TSA) is used to gain the 3D real-time dynamics of the responses of the fish to the changes in the hydrological and hydraulic elements. 5) Differentiation of the inflexion in the change curve of TSA, from which we are able to acquire fish species' response threshold to the hydrological conditions, thereafter acquire the requirement of the fish species for the hydrological conditions. Knowledge of those hydrological and hydraulic requirements of the targeted species is critical to re-operating the Three Gorges Dam and Gezhouba Dam,furthering an ecological restoration of aquatic resources on the Yangtze River.

如何实施生态调度改变水库的调控模式，以适应坝下鱼类等水生生物栖息环境的需求，已成为国际学术界关注的热点问题之一。针对鱼类的生态调度需明确鱼类栖息繁殖对水文条件的适应范围与幅度。然而目前该问题成为了生态调度有效实施的瓶颈。国内外围绕生态流量与鱼类栖息适宜面积地进行了大量的研究。由于鱼类生态数据的欠缺，相关研究无法考虑到水文条件变化下的鱼类时空动态性，从而制约了研究的深入。本研究拟长江葛洲坝江段的铜鱼属和中华鲟为目标种，在渔业声学、地统计学、水文水动力学交叉研究的基础上，实现鱼类与水文条件要素在时空上的"实时"耦合动态。在野外调查和模型演算的基础上，通过目标鱼类空间分布的构建、目标鱼类/水文条件时空耦合、关键水文条件变化下鱼类群落时空的动态、鱼类时空动态对关键水文条件响应的范围与幅度，这一连续的研究过程中，实现目标鱼类对关键水文条件需求的量化，为三峡工程的生态调度提供技术指标与参数。

基于鱼类生态需求的生态调度，需明确鱼类的生态习性及其对调度运行导致的水文要素的适应幅度。本研究基于渔业声学、地统计学、鱼类生态学和水文学等多学科的交叉研究，以葛洲坝坝下江段2种类型产卵场（四大家鱼和中华鲟）为研究对象，研究了四大家鱼、中华鲟以及坝下江段鱼类群落关键生活史阶段对水文条件的响应，在此基础上对其繁殖、栖息的条件进行量化。首先，针对当前渔业声学应用过程中目标信号的种类判别的瓶颈，本项目基于宽频信号的受控试验，初步获得了12种鱼类在90-170KHz范围内的频谱规律，并建立了鱼类目标强度和鱼类体长的换算关系。其次，通过对四大家鱼等产漂流性卵鱼类的繁殖群体在产卵场的时空动态渔业声学调查及其对水文条件的响应，证实了生态调度的涨水过程刺激了亲鱼聚集于产卵场进行繁殖，导致了涨水过程中鱼类的聚集与高密度分布。针对中华鲟的繁殖需求，本研究基于中华鲟繁殖的水流、水温、泥沙等数据，引入了水温过程作为制约中华鲟自然繁殖的关键因子。中华鲟发生2次繁殖、1次繁殖和未繁殖从年度的最高水温下降至繁殖适宜水温（20℃）时间分别为65.2±9.6d、78.8±12.7d和91±13.5d。中华鲟自然繁殖行为的发生时间与水温过程 “滞后”存在显著线性相关。三峡工程秋季蓄水造成的坝下水温过程的“滞后”，与鱼类繁殖时期需求的刺激条件的匹配发生“错位”，为影响鱼类自然繁殖行为发生的一个关键因素。针对坝下江段鱼类群落结构，采用多变量分析的方式进行鱼类群落结构变化与非生物因素的响应关系研究，三峡水库蓄水以及坝下江段渔业捕捞共同作用导致了坝下江段鱼类群落结构的变化。基于项目研究成果完成SCI论文5篇，其中正式发表2篇。相关研究成果可为三峡工程-葛洲坝的联合调度提供技术指标与参数。