Phytoplankton Communities And Their Response To Water Quality In Beipan River Cascade Reservoir

Phytoplankton are important primary producers in the water,the community composition and diversity can be sensitive not only reflect the effects of environmental factors change on aquatic ecosystems,can be further predict and inferring the development trend of water ecological status,to promote effective protection and sustainable development of water resources reservoir has important scientific significance.An investigation into water quality and phytoplankton communities of three cascade reservoir?Shannipo,Guangzhao and Dongjing reservoirs?in Beipanjiang river basin was conducted in July 2016?dry season?and December?rain season?in Guizhou Province,to analyze the environmental character,phytoplankton biological character and their relation.The investigation also used multiple methods to comprehensively analyze the water environment quality and the nutritional status of water environment in those three reservoirs.The species composition and community characteristics of phytoplankton were analyzed.Phytoplankton clustering was carried out in three cascade reservoirs by using phytoplankton function grouping.Correlation analysis and redundancy analysis?RDA?were used to explore the interrelation between physicochemical factors and phytoplankton.The water environment quality and nutritional status of the three reservoirs were comprehensively analyzed from environmental factors and biological perspectives.The results are as follows:1.Characteristics of water environment.The average concentration of Chl.a was increase in turn among Shannipo,Guangzhao and Dongjing reservoirs,and had a significant or very significant positive correlation with SD,TN and NH₄⁺-N?P<0.05 or P<0.01?,while had a significant or very significant negative correlation with SD,COD_Mnn and DO,which indicates that total nitrogen,ammonia nitrogen content and water temperature are affecting many of cascade reservoirs.A main factor,and Chl.a of the impact and the reservoir;In addition,both the Guangzhao reservoir and the Dongjing reservoir have significant negative correlation with TP and COD_Mn?P<0.05?,indicating that TP and COD_Mn affect the Chl.a content of the two reservoirs respectively.2.The phytoplankton species composition.A total of 97 species in 68genera,7 phylum of phytoplankton were identified in the three reservoirs,there were 60 species in 41 genera in Shannipo reservoir,75 species in 56genera in Guangzhao reservoir,77 species in 55 genera in Dongjing reservoir.In Shannipo reservoir,most species was Bacillariophyta,In Guangzhao and Dongjing reservoirs species were composed by Cyanophyta.3.Characteristics of phytoplankton community.The density of phytoplankton in Shannipo,Guangzhao and Dongjing reservoirs increased in turn,which showed that the period of rain season was greater than that of dry season.The phytoplankton community of the Shannipo reservoir is composed of diatomaceous green algae,and the main advantage of the water period is the Trechelomonas oblonga,which is the Microcystis pseudo filamentosa.The phytoplankton community of the Guangzhao reservoir is a green algal diatom type,and the main advantage of the water period is the Eudorina elegans,and the dry season is Pandorina morum.The phytoplankton community of Dongjing reservoir is composed of cyanobacteria cyanobacteria,and the main advantage of the water period is the Cosmarium leave Rab..The phytoplankton diversity results show that the phytoplankton community structure of Dongjing reservoir is the most complex and stable in the three cascade reservoirs,and the diversity of phytoplankton community in the Guangzhao reservoir is the simplest.4.The phytoplankton community characteristic.A total of 35 species of phytoplankton were detected in the three cascade reservoirs,which showed that the abundant in rain season was higher than that in dry season.A total of functional category 33 kinds of the Shannipo reservoir,to adapt to the in functional groups in the nutritional and broad spectrum is given priority to,redundancy analysis?RDA?analysis results show that the water temperature and TN is the most important environment influence its function groups of variables;There are 35 kinds of functional groups in the Guangzhao reservoir,which are mainly used to adapt to the functional groups of the nutritive and nutritive environment.RDA show that TN and COD_Mn are the most important environmental variables that affect their functional groups.There are 32 functional groups in Dongjing reservoir,which are dominated by rich nutrition groups,and RDA show that water temperature and COD_Mn are the most important environmental variables that affect their functional groups.5.Water environmental evaluation.Use single factor evaluation method?types water quality as the standard and comprehensive evaluation to assessment environment quality,the pollution level of Shannipo,Guangzhao and Dongjing reservoirs are mildly polluted in rain season,but the chroma of TN;serious pollution in dry seasons,TN,TP and NH₄⁺-N concentrations were over the surface water quality standard?.Use TSI to evalute the nutritional status of aquatic environment,the three reservoirs both show the medium nutrition level.6.Combined water environment evaluation result shows that the comprehensive ecological characteristics of three reservoirs exhibit,in which Shannipo reservoir and Guangzhao reservoir have different levels of nitrogen and phosphorus pollution,are all in the nutrition state,Shannipo reservoir biodiversity tends to simplification,deal with the comprehensive improvement of the reservoir water environment to work,to carry out the necessary repair measures;The Guangzhao reservoir should strengthen the supervision and prevention measures;There are nitrogen pollution in Dongjing reservoir,which should strengthen the regulation of surrounding life and the emission measures of breeding pollutants,combine prevention and repair,and pay attention to the protection of reservoir water source.