基于底栖动物群落相似性的黑水河替代生境的研究

The lower reaches of the Jinsha River (hereinafter referred to as "the lower Jinsha") is an important reserve for fish germplasm resources and an important area of concern for the protection of the Yangtze River. In the context of several large cascade hydropower stations in the lower Jinsha gradually being put into operation, the issue of water ecological protection in the region has received extensive attention. In this study, through the analysis of the benthic animal community similarity in three main tributaries (the Heishui River, the Xixi River and the Chishui River) of the lower Jinsha, and combined with the analysis of the impact of environmental factors on their similarity patterns, the possibility of the Heishui River as an alternative habitat for the Jinsha River was explored. The study found that the benthic animals in the three rivers are mainly composed of Ephemeroptera, Trichoptera and Diptera, and Ephemeroptera is the absolutely dominant group in all three rivers. The density, biomass and biodiversity of benthic animals in the Heishui River and the Chishui River are generally higher than those in the Xixi River. The comparison of benthic animal community similarity found that the upstream community structures of the Heishui River and the Chishui River have a higher similarity, and both take the sensitive species of Baetidae as the main dominant group, while showing a lower similarity with the Xixi River which is closer to the Heishui River. Canonical correspondence analysis found that altitude and total nitrogen are the most significant factors affecting the benthic animal community structure (P < 0.05), representing the factors at the regional scale and the characteristics of the local habitat respectively. Although the upstream of the Chishui River is generally more affected by total nitrogen, compared with other regions, its community structure is still more similar to that of the upstream of the Heishui River, which may be attributed to the more similar physical habitats of the two rivers. This indicates that even on a large spatial scale, the local microhabitat still has a strong shaping effect on the benthic animal community. Due to the similarities in benthic animal community, biomass and diversity characteristics between the Heishui River and the Chishui River with a good ecological status, it can be inferred that the Heishui River can act as an alternative habitat and undertake some ecological functions in this region.

金沙江下游(以下简称“金下”)是重要的鱼类种质资源保护区,也是长江大保护关注的重要区域.在当前金下几座大型梯级水电站逐渐投入运行的背景下,区域内的水生态保护问题受到广泛关注.本研究中通过对金下3条主要支流(黑水河、西溪河和赤水河)进行底栖动物群落相似性分析,并结合环境因子对其相似性格局的影响进行了分析,探讨黑水河作为金沙江替代生境的可能性.研究发现,三条河流底栖动物主要由蜉蝣目、毛翅目和双翅目组成,三条河流中绝对优势类群均为蜉蝣目.黑水河和赤水河底栖动物的密度、生物量和生物多样性总体上高于西溪河.底栖动物群落相似性比较发现,黑水河与赤水河的上游群落结构相似性较高,且均以四节蜉科的敏感种为主要优势类群,而与距离黑水河更近的西溪河则表现出较低的相似性.典范对应分析发现海拔和总氮是影响底栖动物群落结构最显著的因子(P<0.05),分别代表了区域尺度的因子和局域生境的特征.虽然赤水河上游总体上受总氮影响较高,但相较于其他地区,其群落结构依然与黑水河上游更为相似,可能归因于两条河流更相似的物理生境.这表明即便在较大的空间尺度上,局域微生境对底栖动物群落仍具有较强的塑造作用.黑水河因与生态状况良好的赤水河在底栖动物群落相似性、生物量以及多样性特征上均较为相似,可以推测黑水河在该区域内可作为替代生境承担部分生态功能.