2012—2019年松花江干流底栖动物群落变化及其对水环境因子的响应

底栖动物是水生态系统的重要组成部分,其群落特征通常用来评价水生态环境质量。研究了2012—2019年松花江干流水生态环境质量状况、变化趋势,并应用冗余分析(RDA)探究底栖动物群落结构特征与水环境因子之间的响应关系。结果表明:8年间共鉴定出底栖动物246个分类单元,隶属于4门、9纲、25目、58科、69属,其中水生昆虫的EPT物种为99个分类单元,占总物种数的40.24%;水生昆虫的其他物种为68个分类单元,占总物种数的27.64%;软体动物为36个分类单元,占总物种数的14.63%;环节动物为25个分类单元,占总物种数的10.16%;甲壳动物为18个分类单元,占总物种数的7.32%。底栖动物密度总体呈上升趋势,种类组成总体有所增多,其中环节动物、软体动物和甲壳动物有向水生昆虫转变的趋势,群落结构相对稳定且主要以水生昆虫占比最多,底栖动物密度平均值为5.97×10³个/m²,变化范围为2.86×10³~8.98×10³个/m²,优势科(属)主要为小蜉属Ephemerella、小寡脉蜉属Oligoneuriella、扁蜉属Heptagenia、等蜉属Isonychia、纹石蛾科Hydropsychidae、缺叉多距石蛾属Polycentropus、摇蚊科Chironomidae和圆田螺属Cipangopaludina等。生物指数评价结果多数为"中等"及以上,评价结果趋于稳定,且下游评价结果好于上游。松花江干流的水环境质量变化阶段性明显,溶解氧含量升高,氨氮呈下降趋势,其余指标呈波动变化。冗余分析(RDA)结果表明:影响松花江干流底栖动物群落结构变化的主要环境因子是随时间推移而变化的,其中溶解氧、生化需氧量、化学需氧量、总磷、氨氮和总氮等指标是影响该监测区域底栖动物群落分布的重要环境因子。

Changes of Macroinvertebrate Community and Their Responses to Environmental Factors in the Mainstream of the Songhua River from 2012 to 2019

As a necessary link in the food chain of aquatic ecosystems,macroinvertebrate communities are often used for water ecological environment quality assessment.The correlation between macroinvertebrates and environmental factors in the mainstream of the Songhua River from 2012 to 2019 was analyzed.Meanwhile,the status and trend of the water ecological environment were also discussed.The results showed that a total of 246 taxa,belonging to 69 genera,58 family,25 orders,9 classes and 4 phyla were identified.There were 99 taxa of aquatic insect EPT species,accounted for 40.24%;68 taxa of other aquatic insects,accounted for 27.64%;36 taxa of molluscs,accounted for 14.63%;25 taxa of annelids,accounted for 10.16%,and 18 taxa of crustaceans,accounted for 7.32% of the total.The abundance and richness of macroinvertebrates were increasing by year.The proportion of molluscs,arthropods,and annelids gradually decreased,while the aquatic insects increased.The community structure was relatively stable,and aquatic insects were the dominant taxa.The abundance varied from 2.86×10³ to 8.98×10³ind./m²,with the mean of 5.97×10³ ind./m².The dominant family (genera)were Ephemerella,Oligoneuriella,Heptagenia,Isonychia,Hydropsychidae,Polycentropus,Chironomidae,and Cipangopaludina.The majority of the biodiversity index evaluation results were "moderate" or above,and the evaluation results had been stable over the past eight years,with downstream results better than upstream.Moreover,the physico-chemical water quality monitoring results showed an improvement of the water quality in the mainstream of the Songhua River.The content of dissolved oxygen increased year by year,with the downward trend of ammonia nitrogen,and other indicators not significant changed.Relationship between macroinvertebrates and environmental factors was revealed using the redundancy analysis (RDA),which found the key environmental factors that drove the succession of macroinvertebrate community structure was changed with time.DO,BOD₅,COD,TP,NH₃-N and TN were main environmental variables affecting macroinvertebrates community structure.