The Effect Of Phosphorus, Temperature And Illumination On Interaction Among Alage-flea-grass Co-culture

The whole world has been generally faced with water environment problem-eutrophication. Howeverblue-green alage bloom is the major performance of eutrophic water and it appered frequently. Controllingblue-green alage bloom has been the most complex and difficult problem we have encountered. How canwe control blue-green alage bloom that go with eutrophication? It has been one of the hot issue. Whilebiomanipulation technology and large submerged plant controlling alage technology are the main treatmentmeasures which could control blue-green alage bloom. The threshold value of phosphorus concentrationhas been a principal factor which influenced water-bloom governance. As a result, it is worthwhile andnecessary for us to do systematic research. The temperature and illumination are closely related with waterbloom, so they can influence water-bloom controlling. To solve the environmental probem of blue-greenalage bloom better, we design the co-culture experiment in different phosphorus concentration culturemedium according to the characteristic of domestic eutrophic water. We respectively do pairwise co-cultureexperiment with Microcystis aeruginosa, Daphnia magna and Ceratophyllum demersum. Then we analysethe growth rate of them and the removal rate of total nitrogen and phosphorus. We study the growth rate ofMicrocystis aeruginosa, Daphnia magna and Ceratophyllum demersum when they are co-culture underdifferent temperature, illumination and photoperiod.The main conclusions are as follows:(1) Under the fixed condition of high nitrogen(11mg/L), temperature25℃, light intensity2200lxand photoperiod14h:10h:①Microcystis aeruginosa and Daphnia magna are co-culture in the incubator. When thephosphorus concentration is no more than0.2mg/L, it is avail to grow and breed for Daphnia magna. Daphnia magna was in a dominant position. When the phosphorus concentration was0.5~1.5mg/L, Microcystis aeruginosa presented positive growth, however the growth rate of Daphniamagna is lower than Microcystis aeruginosa.②Microcystis aeruginosa and Ceratophyllum demersum are co-culture in the incubator. When thephosphorus concentration is no more than0.2mg/L, it was in favor of the growth of Ceratophyllumdemersum. The growth rate of Ceratophyllum demersum is highest and it was in a dominant position.When the phosphorus concentration was0.5~1.5mg/L, Microcystis aeruginosa presented positive growthand the growth rate of Microcystis aeruginosa went up with the phosphorus concentration rising. Highphosphorus concentration was advantageous to the the growth of Microcystis aeruginosa. The growth rateof Ceratophyllum demersum bring down with the phosphorus concentration rising.③When Microcystis aeruginosa, Daphnia magna and Ceratophyllum demersum are co-culture in theincubator, both the number of Daphnia magna and biomass of Ceratophyllum demersum rised under allphosphorus concentration. The growth of Microcystis aeruginosa has been effectively inhibited. When thephosphorus concentration was0.2~0.5mg/L, the effect of controlling alage was the best. When thephosphorus concentration was0.5mg/L, the removal rate of total nitrogen and phosphorus than the otherphosphorus concentration.④When the nitrogen concentration of eutrophic water was11mg/L and the phosphorusconcentration was0.2~0.5mg/L, biomanipulation and aquatic macrophyte vegetation restoration can getbetter result to control Microcystis aeruginosa.(2) Under the culture condition of high nitrogen(11mg/L), light intensity2200lx, photoperiod14h:10h and the temperature gradient was15℃,20℃,25℃,30℃, the nitrogen and phosphorusconcentration was the same as (1). Microcystis aeruginosa, Daphnia magna and Ceratophyllum demersum are co-culture in the incubator. The change of phosphorus concentration has less effect on controlling alageunder15℃. When the phosphorus concentration was0.2~1.5mg/L, the growth rate of Ceratophyllumdemersum is higher than Microcystis aeruginosa under15℃. When the temperature was20~25℃, thegrowth rate of Daphnia magna is higher and it was advantageous to the the growth of Ceratophyllumdemersum under0.2mg/L. The effect of controlling alage was better. When the temperature is30℃, thegrowth rate of Daphnia magna was lower. Moreover Microcystis aeruginosa appered positive growth at1.5mg/L.(3) Under the culture condition of high nitrogen(11mg/L), temperture25℃, photoperiod14h:10hand the light intensity gradient was1100lx,2200lx,3400lx,4500lx, he nitrogen and phosphorusconcentration was the same as (1). Microcystis aeruginosa, Daphnia magna and Ceratophyllum demersumare co-culture in the incubator. The light intensity was1100~2200lx, the growth rate of Ceratophyllumdemersum and Daphnia magna was higher than Microcystis aeruginosa under all phosphorusconcentration. The effect of controlling alage was obvious. When the light intensity was3400~4500lx,phosphorus concentration affected biomanipulation and macrophyte vegetation restoration more obviouslythan light intensity. When the phosphorus concentration was0.2~0.5mg/L, the effect of controlling alageis better and it is avail to restore macrophyte vegetation.(4) Under the culture condition of high nitrogen(11mg/L), temperture25℃, the light intensity2200lx and the photoperiod gradient was10h:14h,12h:12h,14h:10h,16h:8h, he nitrogen and phosphorusconcentration was the same as (1). Microcystis aeruginosa, Daphnia magna and Ceratophyllum demersumare co-culture in the incubator. The photoperiod was12h:12h and14h:10h, he growth rate ofCeratophyllum demersum and Daphnia magna was higher than the other photoperiod under all phosphorusconcentration. The growth of Microcystis aeruginosa was inhibiton obviously and the effect of controlling alage is better. When the phosphorus concentration was0.2~0.5mg/L, the effect of controlling alage isbetter and it is avail to restore macrophyte vegetation.