流溪河大型底栖动物群落结构及其影响因素

为了探究流溪河大型底栖动物的群落结构特征和关键影响因素,于2016年4月(平水期)、7月(丰水期)和11月(枯水期)对流溪河的14个采样断面进行了生态调查,共鉴定出133种大型底栖动物,隶属于55科127属。大型底栖动物平均密度和生物量分别为213 ind./m²和20.02 g/m²,寡毛类和水生昆虫的密度占优势,软体动物的生物量占优势。此外,结果表明流溪河大型底栖动物群落结构具有明显的时空变化。在空间方面,从上游至下游大型底栖动物种类数呈现逐渐减少的趋势,并且支流的大型底栖动物种类数高于干流；从上游至下游大型底栖动物密度和生物量变化无规律,支流大型底栖动物的密度明显高于干流,而生物量却明显低于干流；上游的大型底栖动物Shannon-Wiener多样性指数和Margalef丰富度指数均高于下游,支流的大型底栖动物Shannon-Wiener多样性指数和Margalef丰富度指数均高于干流,而Pielou均匀度指数是支流低于干流。在时间方面,平水期至枯水期大型底栖动物种类数呈现逐渐增加的趋势；密度分布为平水期＞枯水期＞丰水期,生物量分布规律与密度相似；Shannon-Wiener多样性指数和Margalef丰富度指数均为枯水期最高,平水期最低。流溪河大型底栖动物群落可划分为干流群落和支流群落,群落间物种组成存在显著性差异。综上结果表明:流溪河支流大型底栖动物群落结构较干游更加稳定,下游断面群落受到了较大程度的干扰,生态环境质量状况较差,影响大型底栖动物群落结构的主要因素为有机质、总磷和溶解氧。

Macrozoobenthos Community Structure and Environmental Determinants of the Liuxi River

In order to explore the community structure characteristics and key influencing factors of macrozoobenthos in the Liuxi River,14 sampling sections of the Liuxi River were investigated in April (normal flow period),July (high flow period) and November (low flow period) 2016.A total of 133 taxa belonging to 55 families and 127 genera were recorded.The mean density and biomass of macrozoobenthos were 213 ind./m² and 20.02 g/m²,respectively.The density of oligochaetes and aquatic insects were on predominance,and the biomass of molluscs was on predominance.Furthermore,results showed that temporal and spatial variations of the macrozoobenthos community structure were obvious in the Liuxi River.Spatially,the taxa number decreased gradually from the upper reach to the lower reach,and the taxa number in branches was significantly higher than that in the main stem.There is no regularity in the density and biomass of macrozoobenthos from the upper reach to the lower reach.The density of macrozoobenthos in branches was significantly higher than that in the main stem,while the biomass was significantly lower than that in the main stem.The Shannon-Wiener index and Margalef index in the upper reach were higher than those in the lower reach,and those indices in branches were higher than those in the main stem,while the Pielou evenness index was lower in branches than that in the main stem.Temporally,the taxa number of macrozoobenthos increased gradually from normal flow period to low flow period.The density in normal flow period ranked first,low flow period second,and high flow period third,and the distribution of the biomass had a similar tendency with density among seasons.The Shannon-Wiener index and Margalef index were the highest in low flow period and the lowest in normal flow period.The macrozoobenthos community could be divided into the main stem community and branch community.The taxa composition among the communities had significant differences.The results showed that the macrozoobenths community structure in branches was more stable than that in the main stem.The communities along the lower reach were greatly disturbed and the quality of the ecological environment was poor.The main factors affecting the macrozoobenths community structure were organic matter,total phosphorus and dissolved oxygen.