The Investigation On Environmental Factors Of Aquaculture Water And The Study On The Pathogenic Bacteria Of Pelodiscus Sinensis

Nine months'sampling and monitoring analysis about diseases condition and aquaculture water of P. sinensis in Fuping P. sinensis farm were done. Effects of of water quality and community character of phytoplankton in the aquaculture water were discussed; Three strains of bacteria were isolated from the diseased P. sinensis. According to the artifically infection experiment, they were the pathogenic bacteria of P. sinensis. A few of medicines were selected through the drug sensitivity test which can inhibit the pathogenic bacteria effectively; Physiology and biochemistry analysis on the infected blood of P. sinensis showed that there were abnormal changes in blood indexes of diseased P. sinensis, which is helpful to the prevention of P. sinensis's diseases.42 species of phytoplankton were identified, which belongs to 5 phylum,5 class,22 family. Among them, Chlorophyta includes the most,25 species, which belong to 19 genera; Cyanophyta ranked secondly,13 species, which belong to 9 genera. The dominant species of phytoplankton in aquaculture water of P. sinensis was S. quadricanda. Due to the pollution resistance character of S. quadricanda, It could be drawn that the aquaculture water of P. sinensis organic pollution degree was comparatively high. The result of chemical indexes monitoring about the aquaculture water showed that the content of total nitrogen and ammonia nitrogen was comparatively high. Associating that with the diseases condition, we could draw the conclusion that there was positive correlation between the diseases condition and the change of content of total nitrogen and ammonia nitrogen.In the isolation and identification of bacteria, three dominant strains were isolated. They are A. hydrophila, P. aeruginosa, and A. sobria, respectively. According to the artificially infection experiment, they were the pathogenic bacteria of P. sinensis. The drug sensitivity test showed that A. hydrophila was extremely sensitive to gentamicin, erythromycin, ciprofloxacin, and chloramphenicol. Pseudomonas was extremely sensitive to tetracycline, and it's sensitivity to norfloxacin, gentamicin, and ciprofloxacin was comparatively high. A. sobria was extremely sensitive to oxytetracycline and erythromycin. Treating bacteria-infected P. sinensis with the pertinent medicine could have well therapeutic effect in short time.The blood cells of P. sinensis infected by pathogenic bacteria decreased dramatically in number. With reference to enzyme activity:the enzyme activity of AST, ALT, and LDH of diseased P. sinensis were remarkably higher than those of the healthy one.The diseased P. sinensis was stimulate by pathogenic bacteria, which lead to organ lesions, could explain the change of enzyme activity. In the meantime, the endoenzyme had emit could also be the possible reasons for the change. The change of CK enzyme activity was not significant. About protein metabolism:the contents of total protein and albumin decreased, and the contents of urea nitrogen increased significantly. It showed that the immune system of P. sinensis was affected by bacteria, and thus the immune function decreased tremendously. The filtration and reabsorption dysfunction of nephron of diseased P. sinensis resulted in the increase of urea nitrogen contents. As to lipid metabolism:the content of triglyceride of diseased P. sinensis was significantly lower than that of the healthy one. Because the content of triglyceridethe is closely related to the normal function of liver, the liver of diseased P. sinensis was severely damaged. The content of CHOL changed a little. Concerning ion metabolism:the change of contents of Ca2+, Na+, Cl- were not significant. Relatively short sick time might explain this.