Effects Of Water Temperature And Nutrients On Characteristics Of Filamentous Algae Growth

The eutrophication has become an urgent problem to be solved in the world.The outbreak of cyanobacterial blooms not only damages the health of lake and reservoir ecosystems,but also seriously threatens the safety of drinking water and harms human health.In recent years,filamentous algae have became dominant algae species in many places and accompanied by blooms,which seriously threatened the safety of water supply.Therefore,in this study,the common dominant filamentous algae species Cylindrospermopsis raciborskii,Pseudoanabaena sp.and Aphanizomenon flos-aquae were selected as the research objects during the outbreak of cyanobacterial bloom.By measureing the algae density,Chlorophyll a concentration,photosynthetic activity,TN concentration changes,APA acivity,this paper study the growth physiological response characteristics of three filamentous algae to the change of water temperature and nutrient concentration under pure culture conditions.It is conducive to a deep understanding of the suitable growth and conditions of filamentous algae and it can provide a certain theoretical basis for early warning and management of cyanobacterial blooms.The results shows that:(1)Under the water temperature range of this experiment(15 ℃,20 ℃,25 ℃,30 ℃),the water temperature has a significant effect on the growth of three filamentous algae(P<0.01)and they can survive well.The consumption and utilization of DTN and SRP of three filamentous algae will be promoted by increasing the water temperature.The optimal growth water temperature of Cylindrospermopsis raciborskii is 30 ℃ and it is suitable for growth at high water temperature and it is easy to obtain advantages.Tthe suitable growth water temperature of Pseudoanabaena sp.is 25～30 ℃,and it has a wide range of water temperature adaptation.The optimal water temperature of the Aphanizomenon flos-aquae is25 ℃,and it can also achieve advantages at a lower water temperature of 15 ℃,we should be pay attention to algal blooms monitoring in winter waters.(2)When the water temperature increased from 15 ℃ to 30 ℃,the photosynthetic activity of Cylindrospermopsis raciborskii is less affected by the temperature change.When the water temperature is lower than 20 ℃,the photosynthetic activity of Pseudoanabaena sp.is be inhibited.The photosynthetic activity of Aphanizomenon flos-aquae was also inhibited when the water temperature is higher than 30 ℃.(3)Under the nitrogen concentration range of this experiment(0.5～5.0 mg/L),the nitrogen concentration had no significant effect on the photosynthetic activities of the three filamentous algae.The Cylindrospermopsis raciborskii can get nitrogen fixation to resist nitrogen deficiency environment at the nitrogen concentration of 0.1mg/L,and the unit mass of algae cells can contribute 0.114±0.048 mg of nitrogen to the system.Pseudoanabaena sp.can not grow in a low-nitrogen environment at a nitrogen concentration of less than 0.1mg/L,but improving the nitrogen concentration will promote its growth.Aphanizomenon flos-aquae has a wide range of suitable nitrogen concentration for growth.Nitrogen fixation will be appeared when the nitrogen concentration is less than1.0 mg/L,and the unit mass of algal cells can contribute 0.07±0.034 mg～0.13±0.048 mg nitrogen to the system.(4)Under the phosphorus concentration range of this experiment(0.02～0.2 mg/L),the phosphorus concentration has a significant effect on the growth of the three filamentous algae.The larger the phosphorus concentration,the better the growth.However,the growth of Pseudoanabaena sp.will be inhibited when the phosphorus concentration is higher than0.2 mg/L.In addition,the phosphorus concentration has little effect on the photosynthetic activity for Pseudoanabaena sp,while the increase of phosphorus concentration will promote the photosynthetic activity of Cylindrospermopsis raciborskii and Aphanizomenon flos-aquae.(5)This three filamentous algae can produce APA to resist the phosphorus-deficient environment.The Cylindrospermopsis raciborskii,Pseudoanabaena sp.and Aphanizomenon flos-aquae will have a phosphorus stress when the phosphorus concentration are below 0.05 mg/L,0.02 mg/L and 0.10 mg/L.And they have different demand for phosphorus,the Aphanizomenon flos-aquae mostly,Cylindrospermopsis raciborskii followed and then Pseudoanabaena sp..