Study On Influence Of Temperature And Lighton The Growth Of Several Dominant Algae Inyangtze River Estuary

In recent years,with the existing water sources in the upper reaches of Huangpu River tends to saturation,the pollution load is high,the degree of eutrophication is serious,and the cyanobacteria bloom frequently in summer,which is not suitable for further development.The diversion of water source of Shanghai to the water source of Yangtze Estuary,form the “Two rivers simultaneously,multi-source complementary,urban and rural integration” pattern.At present,water sources of the Yangtze Estuary facing pollutants and pollutant discharge amount of terrigenous input near the upstream brings the problem of increasing,resulting in the Yangtze Estuary in source water nutrients especially nitrogen and phosphorus concentration increased,the possibility of algae bloom increased,which brings potential risks for the normal water supply reservoir area of the Yangtze Estuary.This study to investigate the water source of the Yangtze Estuary phytoplankton combining with indoor experiments,the dominant algae separated from in the Yangtze Estuary as the research object,study the influence of different temperature and light on the algae growth and the competition between different algae,provide theoretical basis for water source water bloom control and prevention.The results are as follows:1.The dominant algae in the Yangtze Estuary mainly include 6 species of Bacillariophyta,4 species of Chlorophyta,2 species of Cyanophyta.12 kinds of algae were isolated from the Yangtze Estuary.Select 4 dominant algae: Pseudanabaena mucicola,Cyclotella meneghiniana,Fragilaria capucina,Ankistrodemus falcatus,and buying Microcystis aeruginosa from Institute of Hydrobiology Chinese Academy of Sciences to expand training.By the method of single factor experiment,the growth and competition of the algae are studied under different temperatures and light conditions.2.Pseudanabaena mucicola is the dominant specie throughout the year in the water source of Yangtze Estuary.Experiment show Pseudanabaena mucicola issuitable to grow under the 20~25?,and it can grow better under low temperature.At the same time,high temperature has certain inhibition on the growth of the alga.Pseudanabaena mucicola is more suitable for growth in the 60~120 ?mol/(m2.s).Strong light has certain inhibitory effect on Pseudanabaena mucicola growth.With Ankistrodemus falcatus culture together,Pseudanabaena mucicola is the dominant alga.With Microcystis aeruginosa culture together,Pseudanabaena mucicola is the dominant at low temperatures and low light conditions.At the same time,Microcystis aeruginosa can promote the growth of Pseudanabaena mucicola.3.Because of the large amount of sediment in the Yangtze Estuary and the low light intensity,no Microcystis aeruginosa is found to be the dominant specie.Experiment shows that,the best growth of Microcystis aeruginosa at 30?.At 10?,Microcystis aeruginosa is limited by temperature significantly,but it did not grow completely.Microcystis aeruginosa is also suitable to growth in the high light.The 90?mol/(m2.s)is a threshold of Microcystis aeruginosa growth,when more than 90?mol/(m2.s),the light has little effect on the growth of Microcystis aeruginosa.At the same time,Microcystis aeruginosa growth cycle is long,and it can maintain relatively fast growth in the longer time,environmental capacity has a high ceiling,This may help explain why microcystis bloom sudden outbreak and exist in the summer in the some areas.With Pseudanabaena mucicola culture together,when the high temperature and high light,Microcystis aeruginosa occupy the dominant position.4.Cyclotella meneghiniana is the dominant specie throughout the year in the water source of Yangtze Estuary.Experiment shows that Cyclotella meneghiniana is high temperature alga.However,the alga can still for low rate of growth at low temperature.Cyclotella meneghiniana is suitable to grow in the medium light,and the alga grow well in the light of 60~120 ?mol/(m2.s).Cyclotella meneghiniana can grow at a higher specific growth rate when the environment is suitable,and it is great help to have the dominant position in the competition.5.Fragilaria capucina is the dominant specie during the winter and spring in the water source of Yangtze Estuary.Experiment shows that,the temperature and light have little effect on the growth of Fragilaria capucina.under the temperature gradient of experiment,the algae the growth rate of change in between 0.25~0.30 d-1.In the low temperature environment,Fragilaria capucina still can grow at a rapid rate of growth.When the light intensity is greater than 60 ?mol/(m2.s),the light has little effect on the Fragilaria capucina.In the light of 20 ?mol/(m2.s),the alga still grow ata faster rate.6.Ankistrodemus falcatus is the dominant specie during the spring and summer in the water source of Yangtze Estuary.Experiment show that,Ankistrodemus falcatus is a high temperature alga.The 20? is a threshold value for the explosive growth of Ankistrodemus falcatus.Ankistrodemus falcatus is also a high light alga.however,under the low light condition,Ankistrodemus falcatus can still grow at a lower rate.The growth cycle of alga is relatively long,and it can maintain a rapid growth,environmental capacity has a high ceiling,but with Pseudanabaena mucicola culture together,the algae is at a disadvantage.