呼玛河冷水性鱼类栖息地影响因子调查与量化评估

In an allusion to the lack of field measurement data in the research on the current fish habitat, the Huma River - which is one of the best water ecology-protected environments in the northeast region of our country and is also an importance spawning ground for rare cold water fishes like salmon - was selected to be the object of study, the field investigation on main habitats of cold-water fishes in the Huma River was carried out, and the field investigation and sampling analysis on the hydrologic and water-quality factors of habitat, the fish habitat conditions, the plankton, zoobenthos and other aquatic organisms were made. On the basis of the statistic analysis of findings, the habitat suitability curve relative to the hydrologic factors including the depth and flow rate of the water during the different periods, e.g., spawning, fattening, overwintering migration and so on, was created for target species. On the basis of PHABSIM model, the individual habitat simulation model of each habitat was constructed respectively and was coupled with the distributed hydrologic model of drainage basin, the space-time overall evaluation was made for the changes of cold water fishes in the Huma River under the different programs, the calculation results of ecological water requirement for the quasi-original ecological rivers in the northeast region was put forward. Through the project implementation, the more complete and accurate field measurement data of the habitat of cold water fishes in the Huma River are collected to a large extent to prompt the research on the river ecological water requirement based on the habitat and support the protection and recovery of suitable habitat for the cold-water fishes of our country.

针对鱼类栖息地影响因子研究中实测资料不足的问题，选择我国东北地区水生态现状最好的河流之一、大马哈鱼等珍稀冷水性鱼类重要产卵场的呼玛河作为研究区，开展呼玛河冷水性鱼类栖息地影响因子的实地调查，对主要栖息地水文水质要素、鱼类栖息状况、浮游底栖等其他水生生物进行实地调查和采样分析。基于调查结果，建立起目标物种产卵、育肥、越冬洄游等不同时期相对于水深、流速等水文要素的适宜度曲线，并探索总结冷水性鱼类适宜栖息地与溶解氧、浮游生物、底栖动物等水生态要素之间的相关性。分别构建各栖息地生境模拟模型，并与流域分布式水文模型相耦合，对不同方案下呼玛河冷水性鱼类栖息地变化情况进行量化评估，提出呼玛河作为东北地区准原生态河流的生态需水计算结果。力图通过项目实施，得到较为全面的呼玛河冷水性鱼类栖息地影响因子调查结果，促进基于栖息地的河流生态需水研究，并支撑我国冷水性鱼类适宜生境的保护与恢复工作。

项目开展了3次呼玛河冷水性鱼类栖息地的实地调查，获得了呼玛河主要鱼类栖息地的水文、水质和水生态要素实测资料。通过调查，得到了维持具有一定水深和流速的连续洄游通道远比保护恢复某一具体产卵场更加重要的结论。在此基础上，通过开展鱼类栖息洄游适宜水文条件的室内外实验，获得了鱼类洄游最小刺激流速和适宜流速范围、鱼类洄游最小水深、鱼类栖息最小DO浓度及其物理影响因素等重要参数，建立了目标物种适宜栖息地与各影响因子之间的定量关系，促进了具有物理机制的河流生态流量计算方法研究，支撑了冷水性鱼类适宜生境保护和恢复。取得的关键数据成果如下：. （1）根据对于典型冷水性鱼类瓦氏雅罗鱼的原位实验，证明鱼类上溯过程中具有自主选择适宜流速条件的意识，0.15m/s流速是雅罗鱼上溯的最小刺激流速；中等及以下体型雅罗鱼的适宜流速阈值为0.2m/s -0.6m/s，水深阈值为0.1m，但体型较大、活力较强的成鱼可在较短范围内的极浅河段快速窜行。. （2）鱼类洄游适宜水文条件室内实验结果表明：0.2m/s是刺激成年草鱼洄游的最小流速阈值，0.4-1.0m/s是成年草鱼洄游的适宜流速范围，1.2m/s是成年草鱼洄游的最大流速阈值。对鲤鱼而言，适宜度在流速0.3m/s开始上升，整体呈单峰值分布，存在明显的上升-下降分布趋势，以0.45-0.9m/s间流速条件最为适宜，1.1m/s是最大流速阈值。鲫鱼洄游对于流速的敏感性较低，流速0.3-0.8m/s适宜度较好且相差不大，而此范围之外流速条件基本不适宜刺激持续洄游。此外，通过水深对比实验综合判断，表明成年草鱼洄游的最小水深阈值是0.3m。. （3）水体中DO及其物理影响因素实验表明：维持水体中鱼类正常生存的最小DO阈值是2.5mg/L； 0.25m水深下流速达到0.2m/s溶解氧分层现象消失，0.5m、1m水深下流速超过0.25m/s溶解氧分层现象消失。对于III类水体而言，流速达到0.05m/s，DO浓度相比于静止水体增加超过50%，饱和度达到90%左右。流速0.05m/s以下，流速对于溶解氧浓度的影响占主导地位；流速超过0.05m/s，水温的影响占主导地位，水温越高，DO浓度越低，但水温对于DO饱和度的影响并不显著。