Dynamic Changes Of Phytoplankton Communitystructure And Its Affecting Factors In Three Reservoir Of Guizhou Plateau

As primary productivity in the water body, phytoplankton not only affecting the structure of food chain but also the change of global environmental. Most reservoir in the Guizhou plateau is deep, geographical environment is complex, nutritional status vary, so the habitat of the phytoplankton is special and complex.In order to investigate and analyze the influence of environmental factors on Phytoplankton, this paper researched the relation between phytoplankton community structure and environmental factors in Sanbanxi Reservoir, Wanfenghu Reservoir, Longtan Reservoir of Guizhou Plateau. The main research contents includ structure and dynamics of phytoplankton community; The variation charateristics of environmental factors; The effects of environmental factors on phytoplankton community.Main results and conclusion:(1) There existed 140 species(genus) and 7 phylum phytoplankton in all samples, which were mainly composed of the Chlorophyta, Bacillariophyta and Cyanobacteria. Chlorophyta accounted for the most species amount to 73 species(genus), followed by Bacillariophyta, amount to 36 species(genus), Cyanobacteria were detected in 25 species(genus), followed by Pyrrophyta, Cryptophyta, Euglenophyta, Chrysophyta, accounted for 3, 1, 2, 1 species(genus), respectively. Longtan Reservoir with the largest number of species(genus), in front of 99 species(genus) and 7 phylum, Sanbanxi Reservoir is the least among the three reservoir, in front of 84 species(genus) and 6 phylum, Wanfenghu Reservoir accounted to 98 species(genus) and 7 phylum. The number of phytoplankton in dry season is the fewest, in wet season is the most in Sanbanxi Reservoir and Wanfenghu Reservoir, The number of phytoplankton in Longtan Reservoir is the least in wet period, normal periods and wet period are more.(2)The abundance of phytoplankton was least in the dry season and most in the wet season, which reduces as the depth increases. The abundance of phytoplankton in Wanfenghu Reservoir was the most while Sanbanxi Reservoir was the least. The Dominant Species of phytoplankton is different in different periods. Cyanophyta was most abundant, at Sanbanxi Reservoir and Longtan Reservoir in wet season, while chlorophyta in Wanfenghu Reservoir.(3) The number of phytoplankton species(genus) and abundance are less than normal season and wet season, so the index of Shannon-Weiner is small. The number of Diatom species(genus) and abundance are increasing, so the index of Shannon-Weiner added during normal season. The number of Cyanobacteria and Chlorophyta species(genus) and abundance in the wet period was increased that could cause the index of Shannon-Weiner increasing during dry season. The account of species(genus) is comparatively less, while Dominant species increasing, therefore the index of Shannon-Weiner is minimum in Sanbanxi Reservoir, thing is the reverse in Wanfenghu Reservoir.(4)The phosphorus concentration of Sanbanxi Reservoir was higher and Longtan Reservoir was lower, which significant variety in different period. The total nitrogen concentration was the lowest in Sanbanxi Reservoir, there’s no significant variety in different period. Longtan Reservoir and Wanfenghu Reservoir have higher total nitrogen concentration, there’s significant variety in different period. The N/P ratios in Sanbanxi Reservoir was lower than Wanfenghu Reservoir and Longtan Reservoir.(5) Water temperature is the key environmental factor that impacts the phytoplankton’s species abundance change, succession and vertical distribution in Sanbanxi reservoirs, Wanfenghu reservoirs and Longtan reservoir. But due to the difference of water temperature of three reservoirs, the climatic division might be different. In Sanbanxi reservoir, due to obvious seasonal change, phytoplankton’s seasonal succession and abundance changes significantly; In Wanfenghu reservoir, for high water temperature, phytoplankton abundance were higher in the hydrology period; And in Longtan reservoir, because of high water temperature all the year round, Diatom can also adapt to the high temperature. Total nitrogen(TN), nitrate nitrogen(NO3-N), and nitrate(NO2-N) is the nutrient to influence the dynamic change of phytoplankton community in Guizhou plateau’s deep reservoirs. In Sanbanxi reservoir, phytoplankton abundance, total phosphorus(TP) and orthophosphate show very significant correlation(TP). But in the Longtan reservoir, the phytoplankton abundance, influenced by total phosphorus(TP) and orthophosphate(TP), was not significant.