Algae Community Epiphyticed To Typical Submerged Plants And Their Phosphorus Stagnant Effect

Caohai is a unique plateau grass-type lake.With the social and economic development of Caohai,Caohai Lake District is facing a large amount of pollution from production and life,which brings ecological risks to the ecological environment of Caohai.This paper analyzes the submerged aquatic plants and their epiphytic biofilms in Caohai in different seasons,and observes the dynamic changes of their algae community structure;In this paper,the SMT（Standards Measurements and Testing）classification method is used to extract and analyze the different forms of phosphorus in the biofilms of different submerged plants in Caohai,discuss the influencing factors of phosphorus species migration and transformation in the biofilms of Caohai,and provide reasonable suggestions for eutrophication.The main results are as follows:（1）The water quality of Caohai in 2017 and 2018 was in a medium nutrition state.The comprehensive nutritional status of water quality in July and November 2018 is still in the middle nutritional status,but the water temperature,pH,ammonia nitrogen and chlorophyll a in July are higher than in November.（2）There are spatiotemporal differences in algae communities in submerged plant biofilms.The main dominant species have changed,but they are all in a rich state.In November 2017,81 species of 6 algae,8classes,17 orders,29 families,65 genera were obtained.The algae in the attached biofilm of Caohai in July 2017 was identified,and 52 species of5 genera,7 classes,13 orders,46 genera were obtained.According to the identification of algae in the submerged plant biofilm collected from Caohai in November 2018,52 species of algae in 5 phylums,7 classes,13orders,46 genera were obtained.The dominant species of epiphytic algae obtained from the three samplings are different;the cyanophyta dominated the submerged plant biofilms collected in 17 and 18 years.The abundance of attached algae in July 2018 was generally greater than in November 2017 and November 2018;（3）In November 2017,algae was identified and 19 functional groups M,S1,L₀,L_M,MP,G,N,B,J,D,X1,F,A,P,W1,W2,Y,X2,H1;13 functional groups:S1,L₀,M,F,X1,D,W1,G,MP,P,N,J,F in July2018;S1,L₀,M,F in November 2018,X1,B,D,W1,G,MP,P,N,J,F have a total of 14 functional groups.Algae functional groups that dominate the dominant biofilm in different submerged plants are different.（4）Analyze the relationship between attached algae and water environmental factors by RDA.In November 2017,there was a significant correlation between Microcystis and total nitrogen,and Oscillatoria and Total phosphorus（TP）,nitrate nitrogen（NO₃^-）had a positive correlation.Chloroccum（Chloroccum）has a significant positive correlation with Total nitrogen（TN）.In July 2018,there was a significant positive correlation between the genus Melosira,Navicula and Pseudanabaena and the environmental factors TP,TN,DO,etc.In November 2018,Chlorella,Oscillatoria and Pseudanabaena were significantly positively correlated with TP,TN and NH⁺₄.（5）Through correlation analysis,we obtain leaf shape dimension and algae abundance(cells·cm^-2),biomass per unit area(ug·g^-1),biomass per unit mass(ug·cm^-2)There is an obvious positive correlation,indicating that the difference in plant stem and leaf structure affects the photosynthesis of attached algae,resulting in the distribution and colonization of algae in the epiphytic biofilm.（6）A large amount of phosphorus was retained in the submerged plant biofilm,and the total phosphorus content eluted from the surface of the three submerged plants in July reached 0.39¹.472 g·kg^-1.The total phosphorus content range obtained in December It is between 0.286¹.775 g·kg^-1.In general,the content of phosphorus in submerged plant biofilms in July and November showed inorganic phosphorus（IP）>calcium phosphorus（Ca-P）>organic phosphorus（OP）>Fe/Al iron-aluminum combined trend（NaOH-P）.（7）The leaf shape dimension will affect the distribution of iron（Fe）,manganese（Mn）,calcium（Ca）,total phosphorus and the content of each phosphorus form in the biofilm attached to submerged plants.The algal biomass(ug·g^-1)of different phylums is related to the distribution of total phosphorus and the content of each phosphorus form.Among them,algal biomass(ug·g^-1)and organic phosphorus（OP）are in 0.5,0.01<p≤0.05)were significantly correlated at the level.