| In this paper, the algae assemblages from six sampling sites were investigated in spring, summer and autumn of 2014 and 2015 in Xinhua Lake. Physical and chemical indicators of water were also monitored during the same period at the sampling sites. With the composition of algal species and cell density in different sampling sites were examined, we analyzed the diversity of algae in the study areas. The relationship between the algae community structure and evironmental factors was studied using RDA and MDS method. Through the analysis of diversity index of the algae composition structure of Xinhua Lake, the water quality of Xinhua Lake was preliminarily assessed, which will provide basic information for lake protection.1. Through the preliminary study, 146 taxa of algae, belonging to 6 phyla, 8 classes, 13 orders, 29 families, 58 genera were identified. The main groups of algae were diatoms and chlorophyta. The average cell density of algae in the two years was 52.25 × 106 ind. / L. The species of algae were abundant. The normal algae were 28 taxa and dominant species were 33 taxa, which most of them were diatoms and chlorophyta. And the dominant species were obviously different at different sampling sites.2. Shannon-Wieaver index, Margalef index, Pielou index, Simpson index and Diversity threshold index were comprehensively used in the assessment of water body quality. Shannon-Wieaver indexranged from 1.698 to 3.100; Margalef index ranged from 1.496 to 3.896; Pielou index ranged from 0.324 to 0.873; Simpson index range from 0.642 to 0.945; Diversity threshold index ranged from 3.178 to 4.094. The comprehensive evaluation of the results showed that water body quality in Xinhua Lake were moderate pollution.3. The physical and chemical indicators in each sampling site were monitored. The analysis results shows that the average water temperature was 23.96?. The water is alkaline because of the average p H was 8.96; the average value of electrical conductivity was 3787.78 ?s/ cm; the average value of dissolved oxygen was 6.48 mg/ L; the average value of biological oxygen demand was 16.9 mg/ L, the average value of chemical oxygen demand was 115.10 mg/ L, the average value of the total phosphorus concentration was 0.53 mg/ L, the average value of the total nitrogen concentration was 3.27 mg/ L, the average value of NH3-N concentration was 0.63 mg/ L. The total phosphorus concentration and total nitrogen concentration in Xinhua Lake were higher because of the serious agricultural pollution; we concluded that the water of Xinhua Lake was polluted in some extent.4. Principal component analysis and redundancy analysis methods were used to explore the relationship between the algae and environmental factors in Xinhua Lake, the results showed that:WT, DO, COD, TP, TN and p H were the main environmental factors for affecting the change of the algae community structure in the Xinhua Lake.5. Cluster analysis and multidimensional scaling analysis(MDS) was based on algae of sampling sites. The results showed that: there were some differences in the algae community composition among the different sampling sites. The Stress index was less than 0.1 in MDS, so that the ordination grap can accurately explain the similarities of algae communities between different sampling sites. |
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