基于环境DNA技术的黄河流域下游山区河流大型底栖动物群落多样性特征及其影响要素分析

河流生物群落组成由多种环境因子共同作用形成,但其影响机制尚不清楚。本研究基于环境DNA技术,选择黄河流域下游4条山区河流(锦绣川、锦阳川、锦云川和三川汇合后河流)的10个样点开展大型底栖动物监测。结果发现:不同溪段水质状况有所差异,锦云川盐化程度(以电导率EC表征)和营养盐浓度较高,锦阳川抗生素浓度较高,锦绣川水质较好。山区河流大型底栖动物群落组成差异明显,锦绣川以水生昆虫为主,软体动物占比较低。其中,昆虫纲的大蚊(Tipula abdominalis)、天角蜉(Uracanthella punctisetae)和寡毛纲的顠体虫(Aeolosoma sp.)是造成锦绣川与其他河流大型底栖动物群落结构差异的关键物种。冗余分析和变差分解分析结果表明,盐化、营养盐和抗生素均会对大型底栖动物群落组成产生影响。其中,EC的解释率为22.86%,营养盐中的TP、NH₃-N和TN的解释率分别为20.12%、13.25%和7.81%;此外,盐化可与营养盐和抗生素通过耦合效应对大型底栖动物群落组成产生影响,贡献率分别为21.60%和16.20%;抗生素与营养盐的贡献率为19.60%。逐步判别回归模型结果显示,Margalef指数(d)受盐化(EC)和营养盐(NH₃-N和NO₃^--N)的共同影响;随着河流中EC浓度升高,d 与NH₃-N之间的正响应关系及其与NO₃^--N之间的负响应关系显著增强。因此,多环境因子对水生生物的影响不容忽视,在大型底栖动物生物多样性保护中应关注各类环境因子的影响贡献。

Distribution patterns of macroinvertebrate community diversity and their impact factors analysis in mountainous rivers at lower Yellow River Basin based on environmental DNA technology

Biological community composition in rivers is driven jointly by multiple environmental factors, however, the mechanism is largely unknown. For this, an eDNA-based technology was used to investigate macroinvertebrate community composition and biodiversity at 10 sampling sites from 4 mountainous rivers (Jinxiuchuan, Jinyangchuan, Jinyunchuan and rivers after their confluence) at lower Yellow River Basin. Results showed that the water quality varied in different rivers. For example, the concentrations of dissolved salt and nutrients were higher in Jinyunchuan and antibiotics was higher in Jinyangchuan. Compared with the other two rivers, the Jinxiuchuan had better water quality. The community composition of macroinvertebrates in the mountainous rivers exhibited significant difference. Jinxiuchuan was dominated by aquatic insects with small proportion of molluscs. Among these organisms, Insects (Tipula abdominalis and Uracanthella punctisetae) and Oligochaeta (Aeolosoma sp.) were the key species that contributed greatly to the differences in community composition of macroinvertebrates between Jinxiuchuan and other rivers. Redundancy analysis (RDA) and variance partitioning analysis (VPA) revealed that salinization, nutrients and antibiotic significantly affected the changes of macroinvertebrate community composition. Of these factors, electrical conductivity (EC) were the most important factors for driving the macroinvertebrate community composition changes with a contribution rate of 22.86%, followed by TP (20.12%), NH₃-N (13.25%) and TN (7.81%). In addition, the contribution rates from the coupling effects of salinization with nutrient and antibiotics was 21.60% and 19.60%, respectively, and nutrients and antibiotics was 16.20%. Stepwise regression models showed that Margalef index (d) was jointly affected by salinization (EC) and nutrients (NH₃-N and NO₃^--N). As EC concentration increased, the positive response relationship between d and NH₃-N, and the negative response relationship between d and NO₃^- were enhanced. Therefore, the coupling effect of multi-environmental factors on aquatic organisms should not be ignored, and more attention should be paid on the contribution rate of various environmental factors in the biodiversity protection of macroinvertebrates.