永定河流域大型底栖动物群落分布格局及其影响因子

Distribution pattern of macroinvertebrate community and its relationships with environmental factors in the Yongding River Basin

人类干扰造成了全球河流生态系统的普遍退化。流域尺度的水生生物分布特征及其影响因素研究对于河流生态系统的保护与恢复具有重要意义。本研究以永定河流域大型底栖动物群落为研究对象,分别于2017年春季(3月)、夏季(7月)、秋季(11月)开展全流域尺度的大型底栖动物调查。研究表明:永定河流域以摇蚊科为主,优势类群包括直突摇蚊属、摇蚊属、雕翅摇蚊属以及多足摇蚊属。聚类分析表明,大型底栖动物群落结构存在显著的空间差异性,按照群落相似性可分为2组:组1主要包含桑干河和东洋河水系,以直突摇蚊为主要优势种;组2主要包含洋河、妫水河以及永定河干流部分河段,以雕翅摇蚊为主要优势种。单因素方差分析表明,组2生物量、Shannon指数、Margalef指数、Pielou均匀度指数以及物种丰富度均显著高于组1,指示了该区域内更好的生态状况。大型底栖动物的季节差异显著,夏季的密度、生物量和各多样性指数均显著低于春季和秋季。典范对应分析显示,影响永定河大型底栖动物空间分布的环境因子主要包括水温、铵氮、pH、溶解氧和总磷。从水文因子的角度,流量和流速与主要生物参数存在显著相关性。组2中流速和流量与大型底栖动物密度和EPT%存在显著的正相关关系,表明急流生境有利于EPT(蜉蝣目、襀翅目、毛翅目)敏感类群的生存;但流量和流速与多样性指数呈负相关关系,表明过高流量和流速的生境条件不利于大型底栖动物多样性的维持。总之,水环境因子、水文因子都显示出了对大型底栖动物群落结构和多样性特征的影响,表明永定河流域生态系统受到多类型人为活动的影响。减少水质污染、适度恢复部分河段的流量是永定河流域生态系统修复的重要环节。

Human disturbances have altered global stream ecosystems in multiple ways. Understan-ding spatio-temporal dynamics of aquatic organism composition and their relationships with environmental factors play an important role in revealing changes in the structure and function of river ecosystems. The macroinvertebrates and environmental parameters were sampled in the Yongding River Basin at spring(March), summer(July), and autumn(November) in 2017. The results showed that chironomids were the dominant group in the Yongding River Basin, including Orthocladius, Chironomus, Glyptotendipes, and Polypedilum. Results of the cluster analysis showed significant spatial variations of macroinvertebrate community. Sampling sites were clustered into two groups based on the similarities of macroinvertebrate composition in the Yongding River. Sampling sites belonging to group 1 mainly located in the Sanggan River and Dongyang River, with Orthocladius sp. being the dominant species. Sampling sites belonging to group 2 mainly located in the Yang River, Guishui River and main section of the Yongding River, with Glyptotendipes sp. being the dominant species. The biomass, Shannon index, Margalef index, Pielou evenness index and taxa richness of group 2 were significantly higher than those of group 1. Higher values of biological indices indicated better ecological condition of the stream ecosystem. The density, biomass and diversity indices of summer were significantly lower than those of both spring and autumn. Results of Canonical correspondence analysis(CCA) showed that the spatio-temporal distribution of macroinvertebrate in the Yongding River was mainly influenced by water temperature, ammonium, pH, dissolved oxygen, and total phosphorus. From the perspective of hydrological characteristics, flow velocity and flow capacity were significantly correlated. The significant positive correlations between hydrological parameters of velocity and capacity and biological indices of density and EPT% in group 2 indicated the preference of fast flow to sensitive taxa of EPT(Ephemeroptera, Plecoptera, and Trichoptera). The negative correlations between flow capacity and biodiversity indices implied the adverse effects of high flow on macroinvertebrate biodiversity. Our results confirmed that the composition and biodiversity of macroinvertebrate were affected by both water environment and hydrology, which reflected the multiple human activities in aquatic ecosystems of the Yongding River. It is important to control water contamination and sustain environmental flow at the specific reaches for the restoration of Yongding River.