The Influence Of Cyanobacteria Degradation On The Submersed Plant Population Growth

Eutrophication could lead the outbreak of blue-green algae. Cyanobacteria degradation has the inhibition of aquatic plant growth. In large shallow lake, as Taihu Lake, the blue-green algae often break out in open water, and drift to the shore driving by the wind and lake flow. Based on the survey on the ecological environment and algae nearby the shore of Taihu Lake, after the outbreak of algae in Taihu Lake water plankton species composition, species diversity and eutrophication status. Based on the algae bloom and degradation of submerged plant populations, blue-green algae submerged plant populations. Including:(1) The cyanobacteria degradation growth of submerged plant populations, mainly through the field in situ enclosure experiments and for cyanobacteria stable submerged plant population growth. Add a blue-green algae in the enclosures (calculated amount of water enclosures, shall be calculated by adding fresh weight cyanobacteria); measured enclosures inside and outside the hydration and plant species, plant growth changes. Wild peripheral blocking the acquisition of the experiment, the addition of blue-green algae have a significant effect on the growth of plant populations in the experimental system. Cyanobacteria concentration to100ug·L-1, the entire stock biomass of submerged plants decreased by11.84%, while not a member of the blue-green algae control, submerged plant population biomass increase of53.07percent, the results showed that100ug·L-1cyanobacteria on submerged plants produce inhibition,100ug·L-1of blue-green algae, wild peripheral compartment the Ceratophyllum demersum116.8g reduce to29.7g in the control Ceratophyllum demersum increased from203.6g to242.28g;(2) The submerged macrophytes Hydrilla competitive relationship studies to understand the root submerged macrophytes rootless submerged plant Hydrilla verticillata relationship between species and the competitive relationship between nutrients and illuminance. Manual control simulation, experimental species cultivate cultivate Vallisneria and Hydrilla verticillata, after a certain period of time the conditions are right Vallisneria and Hydrilla verticillata seedling experiment. Controls were divided into three groups:the the single bitter grass, single black algae and plant Hydrilla verticillata and Vallisneria biomass ratio of1:1. Experimental results show that:Vallisneria biomass of single species of Vallisneria experimental system relative rate of change in the planting the Vallisneria experimental system and hybrid experimental system can be drawn. Mixed Vallisneria+the Hydrilla experimental system, Vallisneria negative growth phenomenon, Vallisneria the viability of competition, but Hydrilla verticillata, and the decrease in biomass, black algae biomass increased, so summed hybrid experiments Vallisneria biomass system relative growth rate was negative growth. In the the mixed bitter grass+the Hydrilla experimental system, the growth rate of Hydrilla verticillata, indicating that the competitiveness of the black algae is greater than the pain of grass, and the increase in biomass, the Vallisneria of biomass reduce Conclusion:hybrid Vallisneria+the experimental system of Hydrilla Hydrilla verticillata biomass relative growth rate was positive growth mode。The experimental results can be drawn, the Vallisneria survival competitiveness is far lower than the viability of Hydrilla verticillata, the single bitter grass ecosystem, bitter grass can survive good, Vallisneria and Hydrilla verticillata co-exist in the same ecosystem,the Vallisneria survival competitiveness weaker than black algae, and black algae relative growth rate is very rapid.(3) The cyanobacteria degradation submerged plant grass and Hydrilla population growth, understand cyanobacteria degradation Vallisneria and Hydrilla verticillata competitive relationship. The experimental setup three different ecosystems of the community structure, processing:single Vallisneria; processing: single black algae; processing:Hydrilla+Vallisneria, in accordance with the ratio of1:1biomass cultivation Vallisneria and Hydrilla set a single control for each treatment setting three replicates; experiment, the determination of water TN, TP, TSS, chlorophyll A light; experimental month later, the determination of bitter grass and vanes the Hydrilla fresh weight, dry matter weight, chlorophyll content and biomass. In manual control simulation, adding the cyanobacteria concentration of10ug·L-1, Vallisneria and Hydrilla verticillata experimental system can not survive, blue-green algae to a certain concentration submerged plants will not survive. Opposition peripheral compartment test system based on the experimental results can be simulated Vallisneria and Hydrilla verticillata competition simulation, observation of the relationship between the bitter grass and black algae species and competition between nutrients and illuminance.