Regulating Effects Of The Chlorella Vulgaris And Ipomoea Aquatica On Aquatic Environmentand Growth Characterization Of Penaeus Vannamei Cultured In Pond

The P.vannamei is one of the important shrimp species cultured in China,but germplasm degeneration,the deterioration of water quality and frequency of diseases has seriously affected the health development of the industry in recent years.In order to solve the above problems,the community analysis of phytoplankton in P.vannamei culturing ponds around typical reclaimed tidal area of Hangzhou bay was analyzed to ensure the relationship between the farming yield and phytoplankton community.Meanwhile,the effects of C.vulgaris and I.aquatica transplantion on water quality,growth characterization of P.vannamei were analyzed to exploit better regulating technology.1.Phytoplanktons of 8 phyla,59 genuses and 84 species were collected from the aquaculture ponds of Pinghu-Siji,Xiaoshan-Tianhe and Cixi-Longwu,including 35 species of Chlorophyta accounted for 41.7%,19 species of Bacillariophyta accounting for 22.6%,16 species of Cyanophyta accounting for 19%,other accounting for 16.7%.Merismopedia tenuissima,Microcystis,Phormidium tenu and Nostocales were the dominant species.The water quality survey results showed that CODMn,TN,and DP were the main over-factors in the experimental ponds of P.vannamei that were bred in Hangzhou Bay.It was indicated the output of P.vannamei was positively correlated with Chlorophyta biomass and was negatively correlated with Bacillariophyta biomass.It maybe one of the effective regulating method through increasing Bacillariophyta content in water to increase output of P.vannamei.2.The best nitrogen source and carbon source were screened based on medium BG-11 to optimize C.vulgaris growth condition.It was indicated that NH4 Cl and Na HCO3 were respectively best nitrogen source and carbon source.The best C/N was 18:1.The sole best nitrogen source and carbon source replacement could promote C.vulgaris to NR and extracellular CA syntheses,but the coupling was inhibited to the NR activity of C.vulgaris and independent to the activity of CA.3.Results of growth regulation of C.vulgaris are as follows.The best nitrogen source of C.vulgaris was ammonium chloride（P<0.05）,and the fastest growing rate of C.vulgaris was 0.05（mg/L）of ammonium chloride.The best carbon source of C.vulgaris was sodium bicarbonate（P<0.05）,and the growth speed of C.vulgaris was accelerated with the decrease of sodium bicarbonate concentration,but low concentration of carbon was not conducive to the stable growth of chlorella for a long time.Results of the carbon to nitrogen ratio’s experiment showed that the high concentration of nitrogen could inhibit the growth of chlorella,and the effect of high concentration carbon source on the growth of C.vulgaris was significantly worse than that of low concentration carbon（P<0.05）.The best ratio of carbon to nitrogen（C/N）was18:1.The best carbon source and nitrogen source promoting C.vulgaris to NR and extracellular CA were sodium bicarbonate and ammonium chloride.And the carbon-nitrogen ratio of sodium bicarbonate and ammonium chloride was antagonistic to the activity of NR enzyme of C.vulgaris,but independent effect to the activity of CA.The results showed C.vulgaris can effectively remove TN,DP,NH₄⁺-N,NO₃^--N and NO₂^--N in the aquaculture waters of P.vannamei,the maximum removal about TN and DP were 67.13% and 63.95% respectively,while C/N regulated by sodium bicarbonate inhibited C.vulgaris to removal the nitrogen and phosphorus.The growth characteristics of P.vannameis showed that the body weight,survival rate and specific growth rate of P.vannamei were increased by 29.09%,5.33% and 0.37% respectively compared with the control group.The immune enzyme activity of P.vannamei analysis showed that the SOD activity and GSH content in the C.vulgaris group increased by 6.64% and 76.82% respectively compared with the control group.4.The effect on physicochemical indexes of water quality showed that inoculation of C.vulgaris,cultivation of I.aquatica,and coupling of both could effectively remove TN、TP、NH₄⁺-N and NO₂^--N from the cultured water of P.vannamei.The cultivation of I.aquatica had the best removal effect of TP,NH₄⁺-N and NO₂^--N,and the removal rates were 74.76%,70.06% and 55.19% respectively.The coupling treatment had the best removal of water TN,and the removal rate was 49.66%.Secondly,the effect on the growth characteristics of P.vannamei showed that the regulation of C.vulgaris and I.aquatica could promote the specific growth rate and survival rate of P.vannamei,and the coupling effect was the best,which was 0.66% and 27.27% higher than that of the control group.Thirdly,the results of immune-related enzymes from liver pancreas in P.vannamei showed that both C.vulgaris and I.aquatica could effectively promote the activities of hepatopancreas immune-related enzymes.Among them,I.aquatica had the great effect on the activity of CAT,GST and GSH content from liver pancreas of P.vannamei.Compared with the control group,it increased by 128.84%,235.39% and 426.26% respectively.The coupling group had the best effect on SOD activity and GSH content from liver pancreas of P.vannamei,and reached the significant level,which was 52.75% and 1376.69% respectively higher than that of the control group.5.The results about water showed that the contents of TN,DP,NH₄⁺-N,NO₃^--N and NO₂^--N in the each treatment ponds of P.vannamei culture were significantly lower than the control group（P<0.05）,among which the removal rate of I.Aquatica was the best,for 47.69%.The best removal rate about NH₄⁺-N and NO₃^--N were in the coupling group between I.aquatica and C.vulgaris,60.05% and 54.64% respectively,the worst removal rate in the C.vulgaris group.The growth characteristics of P.vannamei showed that the increasing weight and SGR of P.vannamei were the largest in the coupling treatment ponds for 0.135±0.006（g/d）and（8.34±0.76）%,the daily gain and SGR of P.vannamei in the I.aquatica treatment ponds were for 0.131±0.021（g/d）and（8.045±0.961）%,the C.vulgaris treatment ponds for 0.125±0.017（g/d）and（7.745±1.205）%.The results about the immunological enzyme activity of P.vannamei showed that the activity about SOD,GST,CAT and GSH content of P.vannamei in each treatment ponds were significantly higher than the control pond.However,the activity about immune enzymes of P.vannamei in the C.vulgaris treatment ponds was significantly lower than that of I.aquantica and coupling treatment.In summary,the inoculation of C.vulgaris and the cultivation of I.aquantica all can effectively improve the culture environment of the P.vannamei culture,promote its growth,the SR and immunity.