| This study surveyed periphytic algae changes in annual period from the section from Yibin to Jiangjin in the upper Yangtze River. Sampling times are November 2013, January, April, and June 2014. We analyzed the composition, species richness, annual change of number, variation of diversity index of periphytic algae, and evaluated the water quality according with the characteristics of diversity of periphytic algae. Based on periphyton biological integrity, a P-IBI system which suits to upper reaches of the Yangtze River was constructed and used to evaluate the water health. Main results were obtained as follows:(1) Total 82 species of periphytic algaes, distributed into 4 divisions and 31 genus, were identified in this study. In the whole year sampling period, the dominant periphytic algal community is Bacillariophyta (79.27%),65 species and 19 genus, and then is Cyanophyta (9.76%) and Chlorophyta (9.76%),8 species and 4 genus of both. Whereas the lowest community is Euglenophyta, only 1 specie and 1 genus. The dominant population are composed by Melosira, Diatoma, Nitzschia, Cyclotella, Synedra, Navicula, Gomphonema of Bacillariophyta, and Oscillatoria of CyanoPhyta. Richness of the total number of periphytic algal species is presented as Gaozhuangqiao> Yangshi> Jiangjin> Jiangan> Baisha, and as autumn> winter> spring> summer. The Diatom quotient suggests that it is oligotrophic water in the surveying river section, but the value presents gradually increasing from upper to lower reaches. These results indicate that the water quality is transiting from a-oligosaprobic to β mesosaprobic during sampling period.(2) The density and biomass of periphytic algae showed increasing trend from upper to lower reaches in protection zone, Jiangjin section reached the highest density and biomass, and the whole surveyed river section reached the highest density and biomass in winter. The Shannon-Weaver diversity indexes and Pielou’s indexes displayed decreasing trend from upper to lower reaches, Gaozhuangqiao reached the highest, followed by Yangshi, Jiangan, Baisha, and Jiangjin. The changes of the Margalef’s indexes showed that Gaozhuangqiao, Yangshi, Baisha, and Jiangjin were intermediate pollution, and Jiangjin was heavy pollution. The similarity index of periphytic algae mostly showed moderate in the surveyed river section and annual period. The results showed that the environment in protection zone is general stable.(3) Through analyzing the range of index value distribution, spearman correlation and judgment ability, we obtained seven indexes that suited to upper reaches of the Yangtze River to build P-IBI system, including periphytic algae taxa number, BacillarioPhyta percentage, Cymbella percentage, Nitzschia percentage, Shannon-Weaver index, periphytic algae biomass, and Motility diatoms percentage. Comparing with the results of different dimensions and the results with community diversity index evaluation, we found that the more reliable method is 95% quantile method in all sampling points in the way of 3-point system and 4-point system. Among all five sampling points, water quality is sub-health in Gaozhuangqiao and Jiangan, general health in Yangshi and Jiangjin, middle of sub-health and general health in Baisha. In general, the trend of water quality is upper reaches better than lower reaches. Taken together, the evaluation result of water quality of Yangtze River upper reaches display positively correlated with DO, WT, pH, conductivity, and altitude, negatively correlated with transparency and COD, and the most correlation factors are conductivity and altitude. |
PDF Full Text Request