底栖动物完整性指数评价西苕溪溪流健康

Stream Health Assessment Using a Benthic-Index of Biotic Integrity in Xitiaoxi Stream,Zhejiang Province,China

根据浙江安吉县西苕溪的64个底栖动物样点数据,对36个生物参数的分布范围、Pearson相关性和判别能力进行分析,确定B-IBI指数由总分类单元数、EPT分类单元数、鞘翅目%、前3位优势分类单元%、（纹石蛾科/毛翅目）%、滤食者%和BI指数构成.用比值法统一参数量纲,采用直接累加、变异系数权重法和熵值权重法分别计算B-IBI值并进行B-IBI健康标准的准确性检验,结果表明,熵值权重法的准确性（92.9%）优于直接累加（85.7%）和变异系数权重法（78.5%）.建立了评价西苕溪健康的B-IBI标准：B-IBI〉0.69健康,0.52-0.68亚健康,0.35-0.51一般,0.18-0.34差,B-IBI〈0.17极差.B-IBI指数与栖境指数（r=0.62,p〈0.01）、水温（r=-0.64,p〈0.01）和海拔（r=0.64,p〈0.01）显著相关.

Stream macro-invertebrate assemblages were collected from 64 stream sites in Xitiaoxi Stream,Anji County,Zhejiang Province,China.Thirty-six candidate metrics were evaluated stepwise by distributing range analysis,discriminatory power analysis,and Pearson＇s correlation analysis.The B-IBI was composed of seven metrics： total taxa,EPT taxa,Coleoptera %,three dominant taxa,Hydropsychidae（Trichoptera） %,filterers %,and Biotic Index（BI）.The ratio scoring method was used to transform the value of each metric into a uniform score.A variability coefficient method and an entropy method were used to calculate the weight value of each metric of the B-IBI.The measurement accuracy of the health criteria for the B-IBI derived from all sample data was better than that from only reference data.The entropy method had a higher accuracy（92.9%） than the sum total score method（85.7%） and the variability coefficient method（78.5%） in discriminating stressed and reference sites.The B-IBI health criteria for Xitiaoxi Stream were： B-IBI〉0.69=healthy,0.52-0.68=sub-healthy,0.35-0.51=goodfair,0.18-0.34=fair,B-IBI〈0.17=poor.The Pearson＇s correlation analysis between B-IBI and chemical-physical variables showed that the B-IBI strongly corresponded with the habitat quality index（r=0.62,p〈0.01）,water temperature（r=-0.64,p〈0.01）,and altitude（r=0.64,p〈0.01）.Our results suggest that the B-IBI is a good indicator in stream health assessment and should be used in water resource management in China.