淮河流域典型河流夏秋季底栖动物群落特征及其与环境因子的关系

大型底栖无脊椎动物是河流生态系统的重要组成部分,对水生态环境的变化极为敏感,其群落结构特征可有效指示河流水质及生态健康状况.为掌握淮河流域主要河流强人为干扰下水生态健康状况,分别于2014年夏季和秋季对淮河干流及其主要支流上27个站点进行水质、沉积物及底栖动物采样分析,运用统计方法分析了该区域底栖动物组成、优势种、生物多样性、群落结构时空特征以及与环境因子的关系.结果表明两季共获62个分类单元,4297个底栖动物,主要以软体动物门(Mollusca)和昆虫纲(Insecta)为主,其中昆虫纲主要为双翅目(Diptera)、蜉蝣目(Ephemeroptera)和蜻蜓目(Odonata),分别占昆虫纲分类单元数的33.33%、21.21%和18.18%.其次,夏季平均密度为74.21 ind·m~(-2),平均生物量为7.89 g·m~(-2),优势种为米虾属(Caridina)和铜锈环棱螺(Bellamya aeruginosa);秋季平均密度为27.53 ind·m~(-2),平均生物量为1.13 g·m~(-2),优势种则为米虾属、直突摇蚊属(Orthocladius)、四节蜉属(Baetis)和环足摇蚊属(Cricotopus),但t检验差异分析发现,夏秋两季生物密度无显著空间差异(p=0.135),而生物量空间分布则表现出极显著差异(p=0.002).对比发现两季生物丰度的差异主要由软体动物门与甲壳纲(Crustacea)贡献;同时,昆虫纲类丰度分布也表现出季节性,夏季毛翅目(Trichoptera)明显多于秋季,而双翅目和蜉蝣目则显著少于秋季.冗余分析(RDA)发现水温、p H、总氮和沉积物重金属(Cd、Pb、Hg)的梯度变化是该区域底栖动物群落结构变化的主要驱动因子;其次,闸坝运行、边坡固化、岸边植被带及采砂活动等对底栖动物的栖息地与空间分布同样是重大干扰.

The community structure of macroinvertebrate and its relationship to the environmental factors in summer and autumn within typical reaches of Huai River Basin

Being an important component of river ecosystem, benthic invertebrate is sensitive to the changes of water environment and ecological status. The community structure characteristics of invertebrate can effectively indicate the status of water quality and river ecosystem condition. To assess the ecological health of Huai River system which is under strong human disturbances, monitoring on water quality, sediment and benthic invertebrate were conducted at 27 sampling sites in summer and autumn of 2014 in Huaihe mainstream and tributaries. Multivariate analysis methods were used to analyze the composition dominant species, biodiversity, temporal and spatial characteristics of macroinvertebrate assemblages, as well as their relationships to environmental factors. The results showed that 4297 macroinvertebrates of 62 taxa collected within two investigations were mainly composed by Mollusca and Insecta. Insecta mainly consisted of Diptera, Ephemeroptera and Odonata, accounting for 33.33%, 21.21% and 18.18% of the total number in Insecta taxa, respectively. Additionally, the average abundance and biomass of macroinvertebrate were 74.21 ind·m^-2 and 7.89 g·m^-2 in summer with the dominant species of Caridina and Bellamya aeruginosa, and were 27.53 ind·m^-2 and 1.13 g·m^-2 in autumn with the dominant species of Caridina, Orthocladius,Baetis and Cricotopus. The results of t-test showed that there was no significant difference (p=0.135) on spatial distribution of macroinvertebrate density between summer and autumn, while the spatial distribution of the biomass was significantly different (p=0.002). Based on the comparison of two investigations, it was found that the difference in macroinvertebrate abundance was mainly contributed by Mollusca and Crustacea; the individual number of Insecta also appeared the seasonal difference as the number of Trichoptera in summer is significantly higher than that of in autumn, and the numbers of Diptera and Ephemeroptera were obviously lower than that of in autumn. The results of Redundancy analysis (RDA) indicated that the gradient changes of water temperature, pH, total nitrogen, and heavy metals (Hg, Cd, Pb) were the main driving factors for the changes of benthic macroinvertebrate community structure. Furthermore, dam operation, slope solidification, riparian vegetation, and sand mining were major disturbances to habitats and biodiversity of benthic macroinvertebrates.