Study On The Resource Competitions And Succession Laws Among The Algae In Eutrophication Water

Eutrophication water is a phenomena , which results from excess nutrition accumulation with nitrogen and phosphorus in water ,leading to excess proliferation of alga, deteriorating water and disordering water function. Therefore, its essence is damaging creature diversity , which leads to the system loss of self-maintenance , self-accommodation ability and system balance stability , finally results in the destroying of water co-system and farther intensification of environmental issues. These are main problems of eutrophication. At first we select algae which grow under different level of nutrition (or different development phase in the process of eutrophication) , domesticate , selecte seed, and culture algae at the lab, and then we obtain dependence of each algae on nutrition and understand information of eco-breadth of nutrition of supplied alga through pure culture under different concentration of nutrition. We find out resource utilization, competition between interspecies and confirm the quantity-effect relationship between succession of species and nutrition through mixed culture. The results show that each algae has its eco-breadth of nutrition, overlap exists between these eco-breadth in a degree, And the range of overlap shows the possibility of co-exist, at the same time, many factors have effect on eco-breadth of nutrition and degree of overlap of eco-breadth. At suitable range of nutrition, Hydrodictyon reticulatum can obtain dominance of resource competition atinitial stages, because it has more capability in absortion and utilization of resource than that of Microalga, which reduces the resource utilization of Microalga and restrains overgrowth of Microalga in a degree. At the same time, Hydrodictyon reticulatum can give out a great deal of oxygen by photosynthesis when it grows vigorously, which can increases concentration of dissolved oxygen and improves water quality , and also is beneficial to the improvement of water eco-environment and increase of self-clean of water.Culture solution of Hydrodictyon reticulatum has been separated with membrance of 0.2um,0.45um, and then Microalgae is cultured with the separated solution. The results show that the mechanism that Hydrodictyon reticulatum restrains Microalgae is closely related to the chemical interference to Microalgae from biometabolism of Hydrodictyon reticulatum besides their resource competition. We also find that there are two main functional substances in permeated solution with membrance of 0.45um, one substance is beneficial to other algae, the other can restrain growth of algae. The molecular weight of the inhibitor has intensive distribution, effect of restrain of inhibitor has long time persistence, and is relation to light intension , temperature and so on.. Therefore, our cogonition on these experimental phenomena and laws makes a science base to further reveal the essence of eutrophication and provides an experimental base to implement bio-engeering technology of rebuilding and constructing waiter ecosystem, and also offterstechnologies for the Microalgae controlled by the Hydrodictyon reticulatum.On the other hand, this paper details the study on effects of environmental pollution on the algae growth besides essential nutrition, especially those of dye wastewater in Sunan area on the process of eutrophication, from which we expect to know what the environmental pollution factors overlapping other factors interfere with the competitive relationships of different species and have a certain effects on the succession of water ecosystem species .