水位骤降下近岸栖息地和底栖动物变化特征

Impacts of hydropeaking on riparian habitats and macroinvertebrates community structures

本研究于2014年秋对牡丹江中游段两处受电站调峰影响的河段进行野外调查,对6个岸边退水潭进行水质采样和大型底栖动物采集,分析其水质特征和底栖动物群落组成,与相邻天然主河道的栖息地环境因子和底栖动物群落结构进行对比,并通过冗余分析(RDA)研究退水潭中底栖动物分布与主要栖息地环境因子之间的关系。研究表明,退水潭与主河道的水质和底栖动物组成均有显著差异,退水潭处溶解氧含量和pH值显著高于临近河道,氨氮和总氮含量较高。双翅目、半翅目和腹足纲为退水潭中的优势底栖物种,退水潭中底栖动物物种丰度、生物密度、Shannon-Wiener指数和Margalef丰富度均较河道处低。冗余分析表明退水潭中影响底栖动物群落结构的关键环境因子为溶解氧、pH值、总磷等。

The main objective of this study is to quantify the impacts of peaking flows on riparian habitat fragmentation and macroinvertebrate assemblage variations.Field surveys of the Mudan River were conducted in the autumn of 2014.We sampled its macroinvertebrate assemblages and collected the habitat variables in six selected drawdown pools in its two regulated reaches,and made comparison with the data collected in its natural channels.Redundant analysis(RDA)of the physical and chemical habitat variables is used to summarize total variations in the habitat data and to identify the major environmental gradients in the pools.Results indicate substantial differences in the habitat variables and macroinvertebrate assemblages between the pools and river channels.In the pools,dissolved oxygen and pH were significantly higher than the natural river;higher levels of ammonia nitrogen and total nitrogen were found;and diptera,Hemipteran,Gastropoda were dominant.The abundance,taxa richness,Shannon-Wiener index,and Margalef richness significantly decreased in the pools due to habitat isolation.Redundancy Analysis reveals that the key habitat variables affecting macroinvertebrate assemblages in the pools are dissolved oxygen,pH and total phosphorus.