Assessment Of Ecosystem Health Of Upper Yangtze River In Yibin To Jiangjin Using Plankton-index Of Biotic Integrity

In this study, annual variety of plankton was investigated from Yibin to Jiangjin section of Yangtze River, between November 2013 to June 2014. Five sampling section were selected and 4 sampling times (November 2013, and January, April, and June 2014) represented each seasons. Species composition, density, and biomass of plankton were analyzed, and were used to Shannon-Wiener, Pielou, and Margalef index analysis to evaluate water quality. The method of Box line chart and Pearson correlation analysis were employed to select the evaluation index and standard that fit to the biotic integrity of phytoplankton (P-IBI) or zooplankton (Z-IBI). And then P-IBI and Z-IBI were used to evaluate health of the surveyed river. The main results are as follows:1. In total,95 phytoplankton species, belonging to 6 phyla and 38 genera, were obtained in total samples. Among them, the main algae are bacillariophyta and green algae phyla,67 species (71% of total) distributing into 22 genera are bacillariophyta, and 18 species (19% of total) distributing into 10 genera are green algae. Also included some minor algae phyla, cyanophyta (2 species and 2 genera), euglenophyta (2 species and 1 genera), pyrrophyta (2 species and 2 genera), and cryptophyta (4 species and 1 genera). The annual average density and biomass of phytoplankton is 30.39×104 ind/L and 0.158 mg/L, respectively. The range value of Shannon-Wiener, Pielou, and Margalef index of phytoplankton are 1.99-4.32,0.43-0.91, and 2.52-4.40, respectively. The result indicated that most of the sampling points is in the light pollution or pollution-free state, and only a few sample points is in pollution state.Meanwhile, thirty-one zooplankton species were obtained in total, most species are rotifer (65% of total species), and cladocera is the second zooplankton group (19% of total species). The annual average density and biomass of zooplankton is 7.4 ind/L and 0.0159 mg/L, respectively. The range value of Shannon-Wiener, Pielou, and Margalef index of zooplankton are 0.94-3.03,0.28-0.95, and 0.95-2.22, respectively. Similarly as phytoplankton, this result indicated that most of the sampling points is in the light pollution or pollution-free state, and only a few sample points is in pollution state.2. Following index selection, Shannon-Wiener index, Pielou index, Margalef index, percentage of bacillariophyta, density of phytoplankton were screened to fit with P-IBI model. Three points method,4 points method, and ratio method were employed to evaluate P-IBI index of the five sampling points. River health of 3 points method analysis show that, Yang Shi in January, Gaozhuang Qiao in June, and Jiang an in June and November, is sub-health; Jiang an and Degan in January and April is fare; the other sampling point and sampling time is health. River health of 4 points method analysis show that, Jiang an and Degan in January is fare; Jiang an, Baisha, and Degan in April is sub-health; the other sampling point and sampling time is health. Whereas, river health of ratio method analysis show that, Jiang an and Degan in January is fare; Jiang an, Baisha, and Degan in April is sub-health; Gaozhuang Qiao in June and Jiang an in November is sub-health; the others are health.3. The index of Shannon-Wiener index, Pielou index, Margalef index, density ratio between phytoplankton and zooplankton, were selected to fit with Z-IBI model analysis. Also 3 points method,4 points method, and ratio method were used. Three points method analysis show that, the river health is fare at Yangshi in November; sub-health at Gaozhuang Qiao and Degan in April, Jiang an in June, Gaozhuang Qiao, Degan, Jiang an and Baisha in June; poor at Gaozhuang Qiao in June; and the others are health. Four points method analysis show that, the river health is sub-health at Yangshi in November; worse at Gaozhuang Qiao in June; others are health. Ratio method analysis show that, the river health is sub-health at Gaozhuang Qiao and Degan in April and November, at Jiang an in June, and at Yangshi in November; worse at Gaozhuang Qiao in June; others are health.Take together, the river health state is health at Gao Zhuangqiao and JiangAn, Yang Shi, Bai Sha, and degan is in the transition from health to sub-health. And the river health is becoming worse from upstream to downstream.