Study On The Interaction Among Flea-Algae-Grass Cultured In Different Nitrogen And Phosphorus Concentration

The bio-manipulation technology is a multiple measure containing comprehensive management to control water blooms. Phosphorus concentration threshold or range is an important parameter of effecting this technology, so it is very important to be studied systematically. In order to better apply the technology to control lake environment problem of water bloom, in this paper pursuant the domestic eutrophic water characteristics, to made different concentrations nutrients solutions to study the growth among Ceratophyllum, Daphnia and Chlorella in different environments (light incubator and small plastic pots indoors), and the effect of temperature and light on the role of interactionamong the three.The main conclusions are as follows:(1) On high nitrogen conditions (10.50mg/L), Daphnia and Chlorella in the incubator communist culture, the phosphorus concentration less than 0.1mg/L, Daphnia was dominant; When phosphorus concentration between 0.1 and 2.0mg/L Chlorella was on outbreak trends. Ceratophyllum and Chlorella were cultured, the phosphorus concentration less than 0.1mg/L, Ceratophyllum was dominant; when the phosphorus concentration was greater than 0.1mg/L the number of Chlorella began to increase. On low nitrogen conditions (0.50mg/L), Daphnia and Chlorella in the incubator Communist culture, and the phosphorus concentration less than 0.5mg / L, Daphnia have a good inhibitory effect on removal Chlorella. Ceratophyllum and Chlorella were cultured, and the phosphorus concentration less than 0.5mg/L, Ceratophyllum and Chlorella could be stable coexistence and no significant inter-suppression phenomenon; phosphorus concentration to be 2.0mg/L, the Chlorella inhibited the growth of Ceratophyllum.(2) Ceratophyllum, Daphnia and Chlorella communist culture in the incubator, when the phosphorus concentration is less than 2.0mg/L, Daphnia and Ceratophyllum had significant inhibition to Chlorella; phosphorus concentrations ranged from 0.1 to 0.5mg / L, Ceratophyllum grew better; phosphorus concentration of being 0.5mg / L corresponding to the best effect removal of nitrogen and phosphorus; on high nitrogen conditions (10.50mg / L) have certain inhibition on the growth of the three .(3) In eutrophic water, the phosphorus concentration is between 0.1 and 0.5mg/L, and nitrogen concentration is the two kinds of concentration of 10.5mg/L and 0.5mg/L, to control Chlorella was better.(4) Ceratophyllum, Daphnia and Chlorella communist culture in the incubator, it was small the effect on controlling the number of algae to change the phosphorus concentration under low temperature . when phosphorus concentration is nomore than 2.0mg / L, the growth rate of C. demersum were higher than Chlorella. The temperature between 25 and 35℃and phosphorus concentration is less than or equal to 0.1mg / L, the growth of Ceratophyllum was better.(5) Ceratophyllum, Daphnia and Chlorella communist culture in incubator, the light intensity between 1000 and 2200lx, with the phosphorus concentration increased (0.05 to 2.0mg/L), the growth of C. demersum and Daphnia was higher than Chlorella in different degrees, the effect on controlling algae and restoration of aquatic vegetation was more obvious; the light intensity between 3400 and 5300lx, the effects of phosphorus concentration factor on bio-manipulation is greater than light element, and phosphorus concentrations between 0.10 and 0.50mg/L is more effective to control the algae growth, more conductive to reconstruction Ceratophyllum population.(6)The experiments of the co-culture of C. demersum and Chlorella in simulative natural water, of which the nitrogen concentration between 2.92 to 12.60mg/L and the phosphorus concentration between0.06 and 0.85mg/L, showed that the growth of C. demersum was not obvious, even presented the negative growth. The density of Chlorella began to decrease obviously ten days later, but in the whole experimental period Chlorella always inhibit Ceratophyllum in certain extent, and the growth rate of Chlorella much higher than Ceratophyllum. The nitrogen and phosphorus removal was weak in the co-culture of C. demersum and Chlorella.(7)The results showed when Daphnia and Chlorella were cultured in a simulated natural water ,Daphnia predation on removal Chlorella was significant ,and the removal of nitrogen and phosphorus was better than co-culture of C. demersum and Chlorella, and the removal of phosphorus was better than nitrogen.(8)The experiments of Ceratophyllum, Daphnia and Chlorella communist culture in a simulated natural water showed that nitrogen concentration in the range of 3.15 and 23.92mg/L, phosphorus concentrations ranged from 0.07 to 0.64 mg / L, the growth rates of Daphnia and Ceratophyllum are higher, Chlorella growth could be maintained at a lower level, and the improvement of water quality is better; with increasing the concentration of nitrogen and phosphorus ,Ceratophyllum populations presented negative growth, and the number of Daphnia decreased.(9)High nitrogen and low nitrogen conditions, when phosphorus concentration less than 0.1mg / L Daphnia magna were dominate, the effect was not well on the control of Microcystis aeruginosa.Phosphorus concentrations higher than 0.5mg / L, is not conducive to growth and reproduction of Daphnia magna. High nitrogen, high phosphorus conditions on the growth of Microcystis aeruginosa is better than low nitrogen, high phosphorus conditions. It had no significant effect on Daphnia magna.