乌溪江梯级水库的营养特征及水生态健康评价

Nutritional characteristics and aquatic ecosystem health assessment in cascade reservoirs of Wuxijiang

大量梯级水电开发对河流生态系统的健康状况产生重要影响。以乌溪江梯级水库为研究区域,2017年6—11月对上游湖南镇水库和下游黄坛口水库的营养特征及浮游植物组成进行了调查,并应用生物完整性评价指数对水库水生态系统进行健康评价。结果表明,乌溪江梯级水库氮、磷、有机物含量较低,处于贫营养状态。调查期间共鉴定浮游植物8门152种,其中蓝藻门和绿藻门的密度较高,下游黄坛口水库的浮游植物密度低于上游湖南镇水库。生物完整性指数评价结果显示,乌溪江梯级水库生物完整性较高,处于一般到亚健康状态,该指数受水温影响明显,水温低时黄坛口水库的健康状况较好,水温高时湖南镇水库的健康状况较好。

Extensive cascading hydropower dam exploitation may profoundly affect the river ecosystem health. The nutritional characteristics and community structure of phytoplankton in upstream Hunanzhen reservoir and downstream Huangtankou reservoir in Wuxijiang cascade reservoirs from June 2017 to November 2017 were investigated, and the assessment of the reservoir aquatic ecosystem health was performed by Index of Biological Integrity（ IBI） method. The results indicated that nitrogen, phosphorus and organic matter contents of Wuxijiang cascade reservoirs were low, the nutritional level was poor. The 152 taxa of phytoplankton belonging to 8 phyla were identified, the densities of cyanobacteria and chlorophyte were high, and the phytoplankton density in downstream Huangtankou reservoir was lower than that in upstream Hunanzhen reservoir. The IBI assessment result showed that Wuxijiang cascade reservoirs were in relatively high biological integrity, and at normal to sub-health level. The IBI index was significantly affected by the water temperature, suggesting that the good health level was found in Huangtankou reservoir with low water temperature, but in Hunanzhen reservoir with high water temperature.