应用O/E模型评价淮河流域典型水体底栖动物完整性健康的研究

Application of O/E model for measuring the biological integrity of macroinvertebrates in the Huai River Basin

本研究尝试采用我国已有的季风气候区底栖动物观测值(O)/期望值(E)比值模型,在无足够数量参照样点的情况下,建立淮河流域O/E指数健康评价指标体系,评价淮河流域典型水体底栖动物物种组成完整性现状.于2014年夏季(8月)和秋季(11月)分别调查了淮河流域20和25个典型水体的底栖动物和水质指标.O/E模型评价结果表明,监测点位在PC(Probabilities of Capture)>0和PC≥0.5条件下,夏季和秋季的物种期望丰富度分别约为25和9.所有25个点位中,仅1个点位为健康,其余为一般或较差;模型控制自然梯度后O/E0和O/E50值均没有显著的季节性差异(p=0.565和0.229).环境胁迫因子(TN、EC、CODCr和p H)和土地覆盖数据(水体比例、湿地比例、裸地比例、森林比例和草地比例)对秋季O/E50和O/E50-null的解释量高于夏季,TN是能够解释淮河流域典型水体夏季O/E指数变异最多的环境因子,p H和CODCr是能够解释秋季O/E指数变异最多的环境因子.研究表明,在缺少有效参照点位构建评价指标体系的情况下,在淮河流域应用已经构建的季风气候区底栖动物O/E指数模型进行健康评价是比较可靠的方法.

In the absence of a sufficient number of high quality reference sites,we attempted to use the well-developed macroinvertebrate-based Observed /Expected（ O / E） models of Chinese monsoonal streams and rivers to calculate O / E index and assess the integrity of macroinvertebrate assemblages in the Huai River basin. We collected macroinvertebrate and water samples from 20 and 25 sites in summer（ August） and autumn（ November） 2014,respectively. We found that the expected taxa richness were 25 and 9 with PC ≥ 0 and PC ≥ 0. 5,respectively,insignificantly related to the season.Modeled O / E values with natural variation adjustment were higher than their related null O / E counterparts with no natural variation adjustment. Neither O / E0 nor O / E50 showed significant variation between seasons（ p = 0.565 and 0.229,respectively）. The variation of modeled and null O / E50 in autumn explained by environmental stressors（ e. g.,TN,EC,CODCrand p H） and land cover（ e. g.,water bodies,wetland,bareland,forest,and grassland）variables were higher than those in summer. TN was the most selected variable that can explain variation of O / E values in summer; however p H and CODCrwere the most selected variables in autumn. The health conditions of integrity of macroinvertebrate assemblage of all sites were in fair or poor class,except there was only one site in health class. Our results indicated that applying the well-developed macroinvertebrate-based O / E models of Chinese monsoonal streams and rivers is one relative robust method to assess the integrity of macroinvertebrate assemblages in the Huai River.