Temporal And Spatial Variations In Rotinfers Community And Their Correlations With Environmental Factors In Shengjin Lake

Shengjin Lake is an important wintering and stopover habitat for migratory birds en route from East Asia to Australia.we examined species composition, the dominant species, density and the temporal and spatial distribution of the rotifer community to understand the rotifer community structure characteristics from February to July 2014 in the upper lake of Shengjin Lake. Each sampling point of water detective quality is T, pH, WH, SD, Chi a, DO, TN, TP, NH3-N, NO3-N, NO2-N, COD and BOD5 The main environmental factors affecting rotifer community structure were analyzed by using Canonical correspondence analysis (CCA) method with focus on the influence of the waterbody environment on the rotifer community and biomass in areas where waterbirds are found. The results may provide some insights into the evaluation of the water environment, rational utilization of fishing resources and environmental protection in Shengjin Lake.1. A total of 17 genera and 31 species of rotifers were identified, including 8 species of Brachionus that accounted for approximately 18.3-86.9% of the total rotifer density, the dominant species being Brachionus angularis, B.calyciflorus, Asplanchna priodonta, and Schizocerca diversicornis. B.calyciflorus, B.angularis, A.priodonta and Polyarthra trigla were observed throughout the survey, with B.angularis always dominant.2. The lowest biomass (11.92 mg/L) and density (14.0 ind./L) were observed in April. The highest biomass (793.10 mg/L) was observed in July,94.7% of which could be attributed to A.priodonta. The highest density (176.0 ind./L) was observed in June, with 36.8%,27.0% and 17.1% attributed to B.forficula, B.angularis and Trichocerca cylindrica, respectively. The Shannon Wiener diversity index varied from 1.49 to 2.31 with an average of 2.03; Pielou evenness index varied from 0.57 to 0.78 with an average of 0.67; Margalef index varied from 0.77 to 1.50 with an average of 1.13. The diversity indices of rotifer community in Shengjin Lake revealed obviously temporal and spatial variations.3. The most significant environmental factors influencing rotifer community were SD, T, WH, pH, SS and nutrient concentration. Pearson correlations revealed that:total rotifer abundance showed a significant positive correlation with Chi a, DO, T and SD (P< 0.01), and their correlation coefficient were 0.454,0.417,0.426 and 0.652; but a negative one with NO2-N (P< 0.01). Also, the total algal biomass presented a positive relationship with BOD, Chi a, T, DO, pH, SD and TP(P< 0.01), and their correlation coefficient wereO.463,0.616,0.344,0.319,0.312 and 0.356; but a negative one with SS (P< 0.05). Canonical correspondence analysis (CCA) and correlation analysis showed that some environmental factors, such as temperature, pH, water depth, SD, and Chi a, had a considerable effect on the lake’s rotifer community structure.4. Through the analysis of the water quality situation and the temporal and spatial characteristics of rotifer density, biomass and diversity index in the upper lake of Shengjin lake, the influence from the droppings of wintering waterbirds on rotifer community structure was deduced. Rotifer density and the nutrient salt content were higher in the areas inhabited by migratory birds. The impact of the droppings of wintering waterbirds on rotifer community structure are discussed.