Temporal And Spatial Variation Of Phytoplankton Community Structure And Water Quality Assessment In Lake Anhui Taiping

Lake Taiping is one of the largest artificial lakes in Anhui province. It has been listed as one of the national key protection lakes in 2014, which indicates that the environmental protection of Lake Taiping has risen to national strategies. The investigation about phytoplankton of Lake Taiping is not much and mostly is basic research, the relationship between environmental factors and phytoplankton community structure was not analyzed. Therefore, a total of 10 investigations were conducted in this study from November 2012 to October 2014, including phytoplankton species、abundance、biomass、dominant species、diversity index and part of water quality index, and the relationship between environmental factors and phytoplankton community structure has been analyzed, including correlation analysis、regression analysis and cluster analysis, using ecology index and water quality index to evaluate water quality of Lake Taiping. The main results are as follows:1、In this study, a total of 150 phytoplankton species belonging to 109 genera were identified(include species and varieties), Chlorophyta is comprised of 46 genera and 80 species, Bacillariophyta is comprised of 28 genera and 29 species, Cyanophyta is comprised of 20 genera and 23 species, Euglenophyta is comprised of 5 genera and 5 species, Dinophyta and Chrysophyta is comprised of 4 genera and 5 species, Cryptophyta is comprised of 2 genera and 3 species. Xanthophyta didn’t appear in the microscopic examination, Volvox appeared 3 times.The number of phytoplankton species is high in autumn and low in winter. The number of phytoplankton species decreases from H1 to H5 sampling sites and from upper to lower.The average of abundance is 212.81×10~4cells/L, varies between 58.11~641.60×10~4cells/L. The average of biomass is 1.04mg/L, varies between 0.44~1.89mg/L. The abund ance is high in summer and low in spring, the biomass is high in autumn and low in winter. The abundance and biomass decrease from H1 to H5 sampling sites and from upper to lower. There are algal blooms of Lake Taiping in the summer of 2013, which leading to a sudden jump in abundance in September 2013.The dominant species add up to 17 belonging to 4 phyla, Bacillariophyta and Cyanophyta has 6 species, Chlorophyta has 3 species, Cryptophyta has 2 species. One species of them is O-slight pollution indication algae, 4 species of them are Ppolysaprobic pollution indication algaes, 12 species of them are β-moderate pollution indication algaes, which focus on Cyanophyta and Bacillariophyta, Cryptomonas erosa and Chroomonas acuta did’t become dominant species in 2014. The dominant species is low in winter and it’s horizontal change is small.The average of index H’ is 2.27, varies between 1.10~3.54, did’t having significant change from upper to lower. The average of index d is 2.27, varies between 1.50~2.97, slowly decreasing from upper to lower. Index H’ and d is high in autumn and low in winter, becoming maximum in H1 sampling site and minimum in H5 sampling site. The average of index J is 0.59, varies between 0.34~0.79. Index J is low in winter and it’s spatial variation isn’t obvious.2、The average of phytoplankton chlorophyll a is 5.90 mg/m~3, varies between 3.03~14.28mg/m~3. There are two peaks of chlorophyll a in September 2013 and October 2014. Chlorophyll a is high in summer and low in spring and winter. Chlorophyll a slowly rised from the upper to the middle and slowly declined from the middle to the lower, showing into inverted "V" shaped.3、In Lake Taiping, the water depth varies between 9.1~53.0m, transparency varies between 1.5~6.2m, the temperature varies between 7.5~28.3℃, dissolved oxygen varied between 3.95~11.31mg/L.4、Correlation analysis indicates that, the number of phytoplankton species is significantly negative related with transparency and extremely significant positive related with temperature, the number of dominant species is significantly negative related with dissolved oxygen, abundance and biomass is extremely significant positive related with temperature and Chlorophyll a, abundance and biomass is extremely significant negative related with transparency and dissolved oxygen.Regression analysis indicates that, abundance and biomass is extremely significant positive related with temperature and extremely significant negative related with transparency, changes in water quality will directly affect the changes in phytoplankton, and cause complex changes in ecosystem and ecological process in Lake Paiping.Cluster analysis indicates that, phytoplankton community structure is similar between summer and autumn, phytoplankton community structure is similar in H1、H2、H3 and H4、H5 sampling sites, phytoplankton community structure is similar between close depth level.5、Compared to 2013, the appearance of Volvox and the decrease of the number of Cryptophyta indicates that the water quality of Lake Taiping is on the rise in 2014. Ecology index indicates that the water quality is light to moderate pollution and oligotrophic to mesotrophic. The water quality indexes indicate that Lake Taiping is I type water and mesotrophic condition. Each standard evaluation results are relatively consistent, the water quality of Lake Taiping is light to moderate pollution and oligotrophic to mesotrophic.