| In recent years,with the vigorous development of shrimp aquaculture in Jiangsu Province,the traditional high-input and high-output culture mode has brought a huge burden to the aquaculture water environment,and the phenomenon of excessive nitrogen and phosphorus in aquaculture waters has become increasingly serious.How to solve the problem of excessive nitrogen and phosphorus in shrimp culture water and treat the culture tail water so that it can meet the current standards is the focus of the text research.In this paper,starting from the source of shrimp feed,the feeding method of shrimp feed was improved to slow down the degree of eutrophication of water body and reduce the pressure for the treatment of tail water for follow-up culture.Then,through the water quality purification of shellfish and microalgae,the culture water body was biologically purified,and finally the shrimp and shellfish culture system was constructed to provide model reference for actual culture.The specific research is as follows:1.Using the method of experimental ecology,three experimental groups were set up,namely,chilled feed group(Diet1 group),combined feed group(Diet3 group)and 1:1mixed feeding group(Diet2 group),to study the effects of different feeding methods on the growth,digestive enzymes,body composition and aquaculture water quality of Exopalaemon carinicauda..The purpose is to grasp the current situation of water environment and culture output under the common mixed mode of Exopalaemon carinicauda,and to provide scientific reference and theoretical basis for ecological and healthy culture.The results showed that:(1)the growth performance of Exopalaemon carinicauda in the mixed feeding group(Diet2 group)was significantly higher than that in the single feeding group(Diet1 group and Diet3 group)(P<0.05),while there was no significant difference between the single feeding group(Diet1 group and Diet3 group)(P>0.05).(2)From Diet1 group to Diet3 group,the dietary protein level decreased gradually,while the protease activity of Exopalaemon carinicauda decreased gradually and the amylase activity increased gradually.There was no significant difference in lipase activity among the three feeding groups(P>0.05).(3)The crude protein content of the Diet2 group was significantly higher than that in Diet3 group(P<0.05),but not significantly different from that in Diet1 group.and the difference between the Diet1group and the Diet1 group was not significant(P>0.05).The water content in mixed feeding group was significantly lower than that in single feeding group.There was no significant difference in crude fat content and ash content among the experimental groups(P>0.05).(4)With the progress of the experiment,the content of COD,ammonia nitrogen,nitrite,nitrate,inorganic nitrogen and inorganic phosphorus in the aquaculture water environment of Exopalaemon carinicauda all showed an upward trend.At the end of the experiment,the water quality indexes showed the rule of Diet1>Diet2>Diet3.It can be seen that the artificial compound feed has little environment pollution,and it has become a trend to replace chilled feed.However,Trapped in the nutrition conditions,it cannot completely replace the chilled feed,so it will continue to be fed on the form of"chilled feed+artificial feed"for a long time in the future,The problem of excessive nitrogen and phosphorus in culture water will continue to exist.therefore,the culture water quality needs to be treated by filtered shellfish to ensure that the tail water of white shrimp culture meets the current discharge standards.2.Using ecological method and response surface method to study the filtration rate of Meretrix.The experimental results showed that:(1)in a certain range,the water filtration rate of the clam larvae increased with the increase of salinity,temperature and algal density;beyond a certain range,the water filtration rate decreased with the increase of salinity,temperature and algal density.(2)under the same conditions,there was no significant difference in water filtration rate between the clam larvae of red-shell color breeding strain and the wild population,but the growth rate of the red-shell color breeding was significantly higher than that of wild population.(3)according to the results of BBD model optimization by response surface method,the optimal filtration rate conditions for clam larvae of the red shell color breeding strain were as follows:salinity was 21.82,the temperature was 27.40?,and the algal density was 9.96×10~4 ind/m L.The predicted filtration rate was 1.62 m L/(per·min).(4)the water quality was tested under the optimal filtration rate obtained by the BBD model optimization,and the results showed that the clam could significantly reduce the contents of TSS,Chl.a and COD in the water(P<0.05),but had no significant elimination effect on the inorganic nitrogen and inorganic phosphorus in water(P>0.05).It is necessary to cooperate with microalgae to eliminate inorganic nitrogen and inorganic phosphorus in water.3.Using the method of experimental ecology and response surface CCD model,four experimental groups were set up,namely,no clam without algae group(group O),clam without algae group(group A),clam without algae group(group B)and clam with algae group(group AB),and three replicates were set up for each experimental group.According to the CCD model,13 experimental groups were set up with the density(A)and the density of microalgae(B)as the influencing factors.The synergistic effect of clams and microalgae on the removal of inorganic nitrogen and inorganic phosphorus in water was investigated.The experimental results showed that(1)in clear water state(algae-free)environment,the elimination effect of the clam on inorganic nitrogen and inorganic phosphorus was not significant(P>0.05),it needed to cooperate with microalgae to significantly reduce the contents of inorganic nitrogen and inorganic phosphorus(P<0.05).(2)the optimal proportion of clam and microalgae was:221 ind/m~2of clam and 1.92×10~6 cell/m L of microalgae,and the maximum daily elimination rates of inorganic nitrogen and inorganic phosphorus in the water were 6.93%and 8.60%respectively.4.Through the construction of the series culture model of"Exopalaemon carinicauda-Meretrix"in Lusi,Jiangsu Province,and using the ecological method,the water quality index of the series culture system of shrimp and shellfish was monitored continuously for 30 days.it can purify the tail water of white shrimp culture to a certain extent and achieve the purpose of energy saving and emission reduction.Therefore,the shrimp and shellfish pond culture system has a certain feasibility,which can provide a reference for the green and healthy culture of Exopalaemon carinicauda with spine tail in the future. |
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