摘要:2017年8月对拉萨河流域23个采样点的底栖动物群落和环境因子特征进行了调查，采集到大型底栖动物41属（种），其中水生昆虫35属（种），占85.4%；软体动物2属（种），占4.9%；环节动物3属（种），占7.3%；线形动物1属（种），占2.4%。各点位平均物种数为8种，优势种组成差别较大，优势种主要有四节蜉属（Baetis spp.）、大蚊属（Tipula sp.）、纹石蛾属（Hydopsyche sp.）、短石蛾属（Brachycentrus sp.）、水丝蚓属（Limnodrilus sp.）、摇蚊属（Chironomus sp.）等，各采样点底栖动物平均密度为362只/m²。运用生物多样性指数分析底栖动物的群落结构，Marglef丰富度指数、香农威纳指数和均匀度指数平均值分别为1.18、1.32和0.49，生物多样性指数水平较低。采用均匀度指数法和底栖动物BI指数法进行了水质评价，两种评价结果显示分别有30.3%和56.5%的采样点水质为中污染至重污染状态。典范对应分析结果表明：影响拉萨河流域底栖动物群落的主要环境因子是海拔、化学需氧量、硫化物、pH值、总磷和总氮。



Abstract:The macroinvertebrate community structure and environmental factors were surveyed in 23 sampling sites in the Lhasa River Basin in August 2017. A total of 41 macroinvertebrate species were collected, of which, 35 species (85.4%) were aquatic insects, 2 species (4.9%) were mollusks, 3 species (7.3%) were annelids, 1 species (2.4%) was nematomorpha. The average number of species was 8 from all sites, there were significant differences in the dominant species composition, the main dominant species were Baetis spp., Tipula sp., Hydopsyche sp., Brachycentrus sp., Limnodrilus sp., and Chironomus sp. The average density of macroinvertebrate species was 362 ind/m². The macroinvertebrate community structure was evaluated by using biodiversity indices (including the Margalef species richness index, Shannon-Wiener index, and Pielou index). The level of biodiversity indices were relatively low, and the average value of each index was 1.18, 1.32, and 0.49, respectively. The Pielou index and Biotic Index were used to assess the water quality. The two results of assessment, respectively, showed that 30.3% and 56.5% of sampling sites were moderately polluted or heavily polluted. Canonical correspondence analysis revealed that macroinvertebrate community structure was heavily determined by levels of altitude, COD_Cr, sulfides, pH, TP and TN.





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