以江苏苏北地区主要河流为研究对象,探讨底栖动物不同分类阶元对水生态评价的影响.结果表明,在仅包括软体动物、摇蚊和寡毛类物种水平和属级水平的nMDS排序图上,样点间的相对距离和位置未发生变化.与物种水平相比,属级水平丢失的信息(＜5％)小于科级水平(7％),且分类单元数与物种水平分类单元数呈极显著正相关(r =0.88,P＜0.01).鉴定至属级水平较物种级水平不仅可节省大量的人力、物力和时间,而且可降低鉴定错误的概率；鉴定水平的统一能提高不同地区生态评价结果的可比性.因此,建议在长三角河网地区开展水生态评价时,采用鉴定至属级水平的软体动物、摇蚊和寡毛类较为合适.%The effects of different taxonomie resolutions on water ecological assessment was investigated by using data of benthic macroinvertebrate assemblages collected from 49 river sites in northern Jiangsu Province. The results showed that, based only on data of mollusca, chironomidae and oligochaeta, there were no differences in the location and relative distance among sites on the non-metric multidimensional scaling ordinations (nMDS) at the species or genus level. The information loss was less on the genus level ( <5% ) than on the family level (7 % ) , and the genus-level richness was strongly correlated with that of the species level ( r = 0. 88, P < 0. 01). There was no difference in accuracy of ecological condition assessment between coarse taxonomical level and species level. It costs much less to obtain information from family or genus level instead of species level, and identification errors can be reduced. The consistency of taxonomical resolution among different bioassessment programs increases the potential of inter-regional comparison from different ecological conditions. Our results suggested that the use of genus level in the combination of mollusca, chironomidae and oligochaeta was proper in river bioassessement in the Yangtze River delta.
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