基于底栖动物群落相似性的黑水河替代生境的研究

Studies about Heishui River as an alternative habitat for aquatic biodiversity protection basedon macroinvertebrate community similarity

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.

As an important region of the Yangtze River Protection Strategy,downstream of Jinsha River plays a vital role as the reserve of fish germplasm resources.Therefore,protection of local aquatic ecosystem has been paid more attentions,particularly in the context of the operation of cascade hydropower stations.In this study,the similarity of macroinvertebrate community in three main tributaries of Jinsha River(i.e.,Heishui River,Xixi River and Chishui River)and their relationships with the environmental factors were analyzed.The aim of this study was to explore the possibility of Heishui River as an alternative habitat of the Jinsha River.The results showed that Ephemeroptera,Trichoptera and Diptera were the dominant taxa,while Ephemeroptera was the most abundant taxa in all three rivers.The density,biomass,and diversity indices of macroinvertebrate community in Heishui River and Chishui River were all higher than those in Xixi River.A higher similarity of macroinvertebrate community was found between Heishui River and the upper reach of Chishui River,which dominated by the sensitive taxa of Baetidae.In contrast,its similarity with Xixi River,which is close to Heishui River,was relatively lower.Based on the canonical correspondence analysis,elevation and total nitrogen(TN)were identified as the most significant factors(P<0.05)influencing the macroinvertebrate community structure,which represented as the regional and local habitat characteristics.Although the upstream of Chishui River was threatened by nitrogen enrichment,it still demonstrated a higher similarity with Heishui River than the rest region.The possible reason is that Chishui and Heishui rivers have similar physical habitats at the head stream reaches.Our findings highlighted the important roles of micro-habitats in structuring the macroinvertebrate community even at a relatively large spatial scale.Considering the higher similarities in terms of community structure,biomass as well as diversity pattern between the Heishui River and the Chishui River,they could be a potential alternative habitat for the ecological function protection in this area.