A Study On Tolerance Value Of Benthic Macroinvertebrates And Biotic Index In Jiangsu Province

Tolerance value of benthic macroinvertebates reflected the ability of organism topollution. Biotic index was calculated from tolerance value was widely used in waterquality bioassessment.Based on data obtained from Qinghuaihe river (Nanjing city), 26 sampls, Nanxi River(Changzhou city), 30 samples and Taihu Lake, 64 samples, tolerance values of benthicmacroinvertebrate taxa which had more than 5 times occurrences in total 119 samples wascomputed according to the method of Leanat 1993. The values of macroinvertebrate taxawith less than 5 times occurrences however were referenced from published papers.Tolerance values of 112 benthic taxa were finally gotten. Among them, four taxa inEphemeroptera, ten taxa in Trichoptera, 6 taxa in Odonata, 7 taxa in Coleoptera, 44 taxa inDiptera, 4 taxa in Crustacea, 31 taxa in Mollusca, 1 taxa in Nematoda, and 13 taxa inAnnelida. Using a sample of sites from the entire population, the 5th percentile of the BIfrom the population of sites was determined. Statistic analysis with SPSS, any values belowthe 5th percentile were considered as "excellent", and values above the 5th percentile, wasquardisected for different water quality ratings. Bio-assessment criteria of BI for streamwas preliminary determined, there is,＜5.48, Excellent; 5.48～6.53, Good; 6.54～7.59,Good-fair; 7.60～8.64, Fair;＞8.64, Poor.The correlation analysis between BI(only Taihu Lake) and chemical factors (onlyTaihu Lake) showed that BI had high correlation with Conductivity, TP, TN, NH₃-N andChlorophyll.