东江河流生态评价及其修复方略

本文通过对大型无脊椎底栖动物状况的调查对东江河流水生态状况进行了分析,并在此基础上提出了生态修复方略。从上游到河口选12个点采集底栖动物样本,发现东江流域底栖动物生物多样性在上游和中游保持在较高水平,而到下游则迅速降低到零。对增江湾、西枝江牛轭湖等处的取样进行分析并探讨改善东江生态的方法。针对不同生态应力提出了3种生态修复方略:1.创造多样性的生物栖息地,开发和形成一系列类似增江湾那样的缓流滞流区,把已经隔离的牛轭湖和江边湖泊湿地重新与江水连通;2.调整大坝运用方式,采取大坝泄放的流量逐渐增加和减少的方式,给生物发出流速增大和降低的信号,使其得以准备和躲避;3.稳定岸坡、控制侵蚀、保护和发育河边植被。

Assessment of ecological system in East River and corresponding ecological restoration strategies

The stream ecology of the East River is investigated by using the benthic macro-invertebrates as indicator.Samples were taken from 12 selected sites with different environmental conditions from upper reaches to lower reaches.It is found that the biodiversity and bio-community index of benthic invertebrates maintain a relatively high level respectively in the upper reaches and middle reaches of the river,but they are reduced to nearly zero in the lower reaches.The analysis on samples obtained from the Zengjiang Bay and Xizhijiang Oxbow Lake indicates that the major ecological stress is loss of habitats due to reclamation and separation of riparian water from the river.The restoration strategies are suggested accordingly.The strategies include: 1.creating multiple habitats with high habitat diversity,such as riparian lakes,wetlands,backwater and sluggish flow zones and reconnect separated lakes with the river;2.adjusting the operation scheme of the upstream reservoir to mitigate the impact induced by instantaneous fluctuation of flow discharge;3.stabilizing river banks,controlling river erosion and protecting the riverside vegetation.