湟水河上游底栖动物群落结构及其与环境因子间的关系

Community structure of macrobenthos and its relationship with environmental factors in the upper reaches of Huangshui River

[目的]本文旨在揭示湟水河上游底栖动物群落及其与环境因子间的关系,为生态系统多样性保护提出指导意见。[方法]通过改良湟水河底栖动物采样点法,于2018年4—5月和7—8月分2次对湟水河上游干流19个样点的底栖动物群落结构、水化学指标及环境因子进行采集。采用探索性数据分析、主成分分析、典范对应分析等方法对湟水河上游生态环境指标与底栖动物之间的关系进行分析。[结果]采集鉴定出底栖动物42个分类单元,共8980头,隶属于2纲6目28科。主成分排序分析(PCA)表明:对样点贡献度较高的主要环境因子有海拔(alt)、溶解氧(DO)、离源头距离(das)、可溶性磷(SRP)、总氮(TN)、总磷(TP)、铵态氮(NH+4-N)、硝态氮(NO-3-N)等。通过样点组合聚类分析将19个样点区分为4组:第1组为样点1~5、第2组为样点6~11、第3组为样点12~16、第4组为样点17~19。对大型底栖动物分布特征影响的土地利用类型,襀翅目从高到低依次为草地、农地、城市用地;蜉蝣目为农地、城市用地、草地;毛翅目为农地、草地、城市用地;双翅目为城市用地、农地、草地。典范对应分析(CCA)表明:多数物种集中于中、上游样点,对他们贡献度较高的变量有海拔、最大流速(MAX)、平均流速(AVG)等,而下游河流段呈现富营养化状态,仅有少数耐污种出现。[结论]湟水河自上游到下游随着土地利用类型的变化受到不同程度污染和干扰,水体理化指标升高,底栖动物丰富度下降,不同土地利用类型下底栖动物分布特征明显。

[Objectives]The purpose of this paper was to reveal the relationship between macrobenthos community and its environmental factors in the upper reaches of the Huangshui River,and to provide more comprehensive guidance for ecosystem diversity protection.[Methods]The community structure,hydrochemical index and environmental factors of macrobenthos in 19 sample sites in the upper reaches of the Huangshui River were collected in April,May,July and August 2018 by the improved sampling point method of macrobenthos in the Huangshui River.[Results]42 taxa of macrobenthos were collected and identified,a total of 8980 heads,belonging to 2 classes,6 orders,28 families.Principal component analysis(PCA)showed that the main environmental factors with high contribution to the sample were altitude(alt),dissolved oxygen(DO),distance from source(das),soluble phosphorus(SRP),total nitrogen(TN),total phosphorus(TP),ammonium nitrogen(NH+4-N),nitrate nitrogen(NO-3-N).19 sample points were divided into 4 groups by cluster analysis:first group(sample 1-5),second group(sample 6-11),third group(sample 12-16)and fourth group(sample 17-19).The effects of different land use types on the distribution characteristics of macrobenthos ranged from high to lows:Lepidoptera(grassland,farmland,urban),Ephemera(farmland,urban,grassland),Trichoptera(farmland,grassland,urban),and Diptera(urban,farmland,grassland).Canonical correspondence analysis(CCA)showed that most species were concentrated in the midstream and upstream of the samples,and the variables contributing to them were altitude,maximum velocity(MAX),average velocity(AVG).[Conclusions]From the upstream to downstream of the Huangshui River,different degrees of pollution and interference occurred along with the change of land use types.Physical and chemical indexes of water body increased,macrobenthos abundance decreased,the distribution characteristics of macrobenthos were obviously in different land use types.