The Research On Three Methods Inhibiting The Growth Of Spirogyra

In recent years,the ecological enviroment has undergone a series of changes due tothe irrational exploitation of natural resources and pollution caused by industrial andagricultural production,which changed the ecosystem structure and function, causedgrowing phenomenon of water eutrophication and algae abnormal proliferation, as wellas the massive death of fish,these all interfered freshwater and marine ecologicalbalance, destructed the freshwater and marine fisheries resources and harmed to humanhealth. Eutrophication has become the puzzle of water pollution control in the worldtoday, the control of harmful algae become one of the important subjects ineutrophication control area.The dominant species of algae boom in fresh water changedwith the seasons: in spring and autumn were green algae(such as Chlorella), in summerwas cyanobacteria(mainly Microcystis spp.), the main species of red tide algae wereAlexandrium tamarense,Chattonella marina, Heterosigma akashiwo and Skeletonemacostatum. General chemistry, physical, and biological methods used to inhibit thegrowth of algae were difficult to control, and high cost, harmful to the ecology, thus thedevelopment of efficient, safe algal-inhibition method become a research focus ineutrophication control areas.Using allelochemicals control algae boom was high efficiency, fast, easy to control,selective, and has no secondary pollution, thus filtering the new high efficiencyalgaecide has become a hot research.The found of allelopathy and allelochemicalsprovides a new thread to solve the water pollution problem, control the harmful algaeeffectively and restore the ecological environment. At present, the research on theallelopathy of aquatic plant in domestic and international has been extensively studied,dozens of species of aquatic plants was discovered having allelopathic algicidaleffect.But these are mainly for the unicellular algae, the study on harmful filamentousalgae are relatively rare, these unicellular algae blooms was known as "water bloom",algal blooms of filamentous algae was commonly known as "moss", large population offilamentous algae was harmful to water and aquatic organisms. The terrestrial plantshave large biomass and abundant secondary metabolites, a variety of them has a goodability in inhibiting the algae, which was expected to become another hotspot in thefield of algal-inhibition. Therefore, looking for terrestrial plants which secrete algicidalactive substances and separating the allelopathic substances has a good prospect,whichprovide a refenrence for builing a scientific model of water ecological regulation, developing new and efficient algicide and making full use of plant resources in theresearch and application of the water environment.To sum up, algal allelopathic, which has good value, is a hot topic of currentresearch, so compared to the traditional algicidal agent, developing ecological andsafety of products have a high value. The quantitative analysis of the impact of decaySpirogyra on the aquatic ecosystem, especially on water quality and submerged aquaticplant growth was first made in this paper, then on the basis of the study on the inhibitingeffect of Spirogyra using traditional chemical algicide-copper sulfate, then theinhibitory effects on Spirogyra by the allelochemicals exteacted from aquatic plant-hydroxybenzoic acid and the toxicity of it were sudied, at last the inhibitory effects onSpirogyra by some terrestrial plant extracts and the toxicity were mainly sudied.Themain research and conclusions are as follows:1. The impact of decay Spirogyra on water quality and Ceratophyllum demersumgrowthThe result showed that decay Spirogyra increased the conductivity, total nitrogen,total phosphorus, ammonia nitrogen and phosphate content of the water body, whichshowed that the water are contaminated; on the other hand, the decay Spirogyra affectthe germination of submerged plants, which caused great harm to the submerged plants,thus the research on controling Spirogyra has great significance in the water ecologicalenvironment construction.2. The inhibitory effect of Spirogyra using chemicals copper sulfate and its toxicity tozebra fish.The results showed that the copper sulphate reduced the chlorophyll content andprotein concentration of Spirogyra, indicating that the synthesis of chlorophyll andprotein in Spirogyra were inhibited; The SOD increased under stress and then decreased,showing that the Spirogyra was compelled, and remove excess reactive oxygen by SOD;the content of MDA increased, explaining that the plasma membrane of Spirogyra wasseverely damaged; The CAT decreased indicating that the stress has exceeded thethreshold of clean-up of hydrogen peroxide; The results showed that Spirogyra growthwas inhibited by copper sulfate. Toxicity test results indicate that copper sulfate is ahighly toxic substances, so finding a low toxicity and environmental way inhibitingSpirogyra is a urgent need.3. The inhibitory of Spirogra using aquatic plant allelochemicals-hydroxybenzioc acidand and its toxicity to zebra fishThe results show that the hydroxybenzoic acid showed a good algicidal effectwithout destroying Ceratophyllum demersum when it is in the0.2g/L concentration, thisconcentration was in the range of safe concentration63.78mg/L, toxicity experimentsshowed it is low toxicity, thus applying hydroxybenzoic acid in the inhibition ofSpirogyra has potential valu,but it remains to be further researched and analysed.4. Using terrestrial plants inhibiting the growth of SpirogyraThe analysis and preliminary study showed the three terrestrial plant extracts havecertain inhibition effect. The results indicated that camphor, camphor leaves, willowbranches, willow, pine, pine needles have certain inhibition on Spirogyra: visual effectsshowed that the color of Spirogyra turned yellow and became decay; under microscopic observation the spiral structure of chloroplast disintegrated, indicating the synthesis ofchloroplast was hindered; Detecting of physiological index showed that theallelochemicals in the three types of branches, reduced the chlorophyll and solubleprotein contents significantly: compared with the controlled group, the chlorophyllcontent of willow leave group decreased by23%, followed by camphor branch, pineleave, willow branch, camphor leave, pine branch group; the largest deline of solubleprotein content was the group treated with willow leave, then was group treated by pineleave,camphor branch, willow branch, pine branch and camphor leave;the MDA, SOD,CAT levels rised, the most significant inhibition effect of Spirogyra was willow leaves;Further research was needed for selecting terrestrial plants secreting high algicidalactive substances and separating the allelochemicals,the inhibition on harmful algae byterrestrial plants has a good application prospect.