西江流域大型底栖无脊椎动物物种多样性及维持机制

Species diversity and maintenance mechanisms of benthic macroinvertebrate assemblages in the Xijiang River

作为我国第三大河流珠江的主支,西江孕育了丰富且独特的生物多样性。受多重人为压力影响,流域内生物多样性日渐降低。然而,人们对西江底栖动物物种多样性格局及维持机制的认识明显不足。本研究基于历史文献调研和2021–2023年现场调查,系统评估了西江主要水体底栖动物物种多样性,厘定和编撰物种名录,甄别驱动群落结构变化的关键因子及受胁因素,并提出保护对策。结合历史文献和实地调查,共记录大型底栖无脊椎动物5门10纲33目150科437属704种(历史记录506种,2021–2023年调查记录352种),中国特有种占比高达26%。现场调查结果显示,全流域底栖动物的平均密度和平均生物量分别为437.53 ind./m^(2)和38.65 g/m^(2)。全流域的优势种为长足摇蚊属一种(Tanypus sp.)、雕翅摇蚊属一种(Glyptotendipes sp.)、纹沼螺(Parafossarulus striatulus)和河蚬(Corbicula fluminea)。支流、干流和湖泊的底栖动物群落结构差异显著,支流的物种丰富度、Simpson优势度指数和Shannon-Wiener多样性指数均高于干流和湖泊。典范对应分析显示,海拔、电导率、高锰酸盐指数等环境因子和空间因子是影响群落结构的重要因素。方差分解表明,支流和湖泊的群落主要受环境过滤驱动,而干流的群落主要受空间过程(质量效应)的影响。流域内的多重人类活动(航运业、大型水利设施、挖沙业、水体污染、土地无序开发利用和外来种入侵等)严重威胁底栖动物多样性。建议采取相应对策,包括打击过度捕捞、管控挖沙业、恢复湖滨带以维持水文自然节律、控制污染物排放以及科学防控外来入侵种等。

Aims:The Xijiang River,renowned for its rich freshwater biodiversity and endemism,presents an intriguing yet understudied ecosystem.This study aims to elucidate the species diversity patterns and underlying mechanisms maintaining macroinvertebrate communities in this mega river.Drawing from published literature and an extensive field survey conducted from 2021 to 2023,our objectives include compiling a comprehensive species checklist,identifying ecological drivers shaping community structure,and proposing conservation strategies.Methods:Macroinvertebrates were sampled from key water bodies within the Xijiang River,including main stream,tributaries,and plateau lakes from the years 2021 to 2023.One-way ANOVA was employed to analyze species diversity indices across different water bodies.PERMANOVA(permutational multivariate analysis of variance)and PCoA(principal co-ordinates analysis)were used to assess community structure variation,while canonical correspondence analysis and variation partitioning identify potential key factors influencing macroinvertebrate community organization.Results:A total of 704 species from 437 genera,representing 150 families across 10 orders and 5 phyla,were documented(combining 506 historical records with 352 findings from 2021 to 2023).The proportion of species endemic to China reaches as high as 26%of the total number of species.The average density and biomass in the present survey period were 437.53 ind./m^(2) and 38.65 g/m^(2),respectively.Tanypus sp.,Glyptotendipes sp.,Parafossarulus striatulus and Corbicula fluminea emerged as the dominant species.Species richness and diversity indices were highest in tributaries,followed by the main stream and lakes.Canonical correspondence analysis(CCA)revealed that a combination of environmental factors(e.g.,altitude,conductivity and chemical oxygen demand with permanganate)and spatial factors jointly influenced macroinvertebrate community structure.Moreover,variation partitioning highlighted the dominance of environmental factors in tributaries and lakes,while spatial factors predominantly influenced main stream communities.Conclusion:This study presents the most comprehensive inventory of macroinvertebrates in the Xijiang River to date,showcasing its significance as a global biodiversity hotspot.Despite the region’s rich macroinvertebrate biodiversity,anthropogenic pressures have led to a decline in species richness.To safeguard and restore macroinvertebrate diversity and endemism,proactive conservation measures are imperative.Strategies should include curbing overfishing,regulating illicit mining practices,restoring natural hydrological patterns and riparian zones,mitigating point and non-point source pollution,and preventing the encroachment of non-native species.