Study On The Conservation Of Bostrychus Sinensis At The Buried Pipe System Of Mangrove Area In Zhanjiang

Mangrove as a natural nursery for marine fishery,its fish diversity conservation has high ecological,economic and social value.The buried pipe network system is a set of innovative mangrove ecological culture mode.Scientific and rational optimization of the conservation density and daily management can improve the utilization of water resources,increase the output of the unit and reduce the cost of production.It is an effective way to take into account the ecological protection and economic development.In this paper,the growth,physiology and biochemistry of Bostrychus sinensis under the different conservation density were analyzed and compared,and the water quality index of the system was monitored in the buried pipe network system in the semidiurnal mangrove area of Zhanjiang.B.sinensis's initial individual body weight?45.39±2.36?g,individual body length?12.51±0.35?cm,the 3 stocking densities were group A(4.3kg·m^-3),B group(5.0kg·m^-3),C group(5.7kg·m^-3),each with 3replicates in the system for conservation period of 80 d.The results showed as follows:1?During the trial,the temperature was 27.7 C³1.0 C,the salinity was 16.8²2.5,and the pH was 7.0⁸.8,which was stable.The growth condition was good.The water quality of the reservoir is in good condition.The survival rate of each group was above94.9%.Experimental study showed that the buried pipeline conservation system suitable for growth of Bostrychus sinensis.2?The final body length,specific growth rate,length gain ratio rate,weight gain ratio and daily weight gain of Bostrychus sinensis in each density group showed no significant difference?P>0.05?,However,the final body mass of group C was significantly lower than that of group A,and the coefficient variation in body mass of group B and group C was significantly higher than that of group A.The results showed that the growth of Bostrychus sinensis in the high-density group was restrained,showing obvious growth retardation and growth dispersion and feed conversion ratio increased.3?There was A significant difference in dissolved oxygen concentration between group C and group A?P<0.05?.The dissolved oxygen concentration decreased with time in each group,and dissolved oxygen concentration decreased to a lower level?<3mg/L?at the 50th day.The ammonia nitrogen concentration of each group was maintained at a relatively stable level,and the ammonia nitrogen concentration of group C was significantly higher than group A from the 50th day?P<0.05?.The change cycles of nitrogen nitrite,inorganic nitrogen and inorganic phosphorus concentration of each group were consistent with the window cleaning cycle?20d?,showing a rising trend.The inorganic nitrogen and inorganic phosphorus concentrationt is more than The Sea Water Quality Standard?sea water limit value at the end of cycle.Starting from the 10th day,the content of inorganic phosphorus in group C was significantly greater than that in group A?P<0.05?,and starting from the50th day,the content of inorganic nitrogen in group C was significantly greater than that in group A?P<0.05?.In view of the rapid deterioration of water quality at the later stage of desilting cycle and the low content of dissolved oxygen.It is suggested to shorten the cleaning period of the window to 15 d,and to add oxygen adding device in the management window.To ensure the safety of aquaculture water quality.4?In terms of nutrition index,liver index and crude fat content in group C were significantly lower than that in group A?P<0.05?,but there was no significant difference in water content and crude protein content?P>0.05?;antioxidant function:before,during and after the trial,the content of antioxidant enzyme SOD in group C was significantly lower than that in group A?P<0.05?,and the content of MDA was significantly higher than that in group A?P<0.05?,indicating that long-term high-density stress resulted in oxidative damage of fish tissues.Non-specific immunity:LZM activity in group C was significantly lower than that in group A?P<0.05?,indicating that in the high-density group,the immunity of Bostrychus sinensis was reduced,and the resistance to disease was reduced.To sum up,long-term high density stress can inhibit the antioxidant and non-specific immune function of fish,and by affecting the body's material metabolism and energy metabolism,the synthesis of nutrients in the body can adversely affect the nutritional status of fish,which is manifested as significant changes in the body's biochemical composition.According to the data of the growth,physiology,biochemistry and water quality obtained from this study,it is suggested that 480 tails of seedling/window should be adopted in the early raising stage of Bostrychus sinensis in the buried pipeline system of the mangrove area,and it is suggested that the individual classification should be carried out in time when a certain growth discrete image appears in the middle period?50 d?,and the management is adjusted accordingly.The load rate of window is to ensure their individual growth and achieve the goal of individual healthy growth.