Study On Water Velocity And Polyculture In Recirculating Aquaculture System

In recent years,Recirculating Aquaculture System has been developing vigorously.Researchers at home and abroad have also done a lot of problems for the Recirculating Aquaculture System.However,the studies on the design of the flow rate of the system are too little,which can not provide reliable data support in the actual production.Flow rate is closely related to the control of the object,but domestic and foreign research mostly concentrated in the temperature,breeding density,water dissolved oxygen or other toxicology,etc.,for the culture of the pool of little research,the only study of flow rate is based on changes in flow rate caused by changes in the flow.In this study,the flow rate was changed with the flow constant(ie,the consistency of each cylinder was in and out of the water).The influence of the same flow rate on the juvenile turbot was studied,so as to provide theoretical support for the optimal design and development of Recirculating Aquaculture System.In the Recirculating Aquaculture System for multi-trophic level comprehensive breeding,it not only can improve aquaculture production,reduce farming costs,but also can promote the use of multi-level nutrition to improve feed utilization and reduce the concentration of harmful substances in wastewater.At present,the study on multi-trophic level integrated breeding is mainly concentrated in freshwater or fish,shrimp and other mixed farming,in the seawater Recirculating Aquaculture System of multi-trophic level breeding,although there have been reports of sea cucumber and abalone polyculture,but fish and abalone and sea cucumber,mixed polyculture case has not been reported.In this experiment,the effects of different polyculture combinations on the growth and water quality of each aquaculture object were discussed in order to explore new development direction for Recirculating Aquaculture System culture.In this paper,the velocity distribution in the aquaculture culture system of Recirculating Aquaculture System was modeled and verified by the experiment.The average velocity model related to the radius of the pond,the system inlet and the flow of the flow pump was put forward.At the same time,the effects of different flow rates on the growth and water quality of juvenile turbot(Turbot)were studied at the design flow rate,and the flow rate of the larvae was determined.Based on the multi-layer seawater circulating water culture system,the combination of fish,abalone and ginseng was used to analyze the growth and water quality of the fish.Now summarize the relevant conclusions are as follows:(1)The flow velocity distribution in the circular aquaculture pond increases with the increase of the center distance.Weight of 161.9±18.0 g of turbot larvae,the density of 8.10±0.04 kg /m2 breeding conditions,the fish on the flow rate of the tank has little effect.The increase of flow rate can increase the food intake of juvenile turbot and increase the mortality rate.Appropriate increase of flow rate can increase the specific growth rate of juvenile turbot,but the flow rate is too large to reduce its specific growth rate.The appropriate flow rate can reduce the FCR of the juvenile turbot,and the viscera index,improve the meat rate.Under the condition of flow rate of 0.18 m/s in the culture pond,the feeding rate was the lowest,the coefficient of diets was the lowest,the meat coefficient was the lowest,the mortality rate was the highest and the mortality rate was lower than 0.06 m / s and 0.36 m / s.(2)The concentration of Total Ammonia Nitrogen,Nitrite Nitrogen,Nitrate Nitrogen and COD in water did not change with the change of flow rate,and there was no significant difference under the three flow rate gradients,and the trend was increasing with time.There was no significant difference in the concentration of Unionized Ammonia Nitrogen and Dissolved Oxygen at different flow rates,and the overall trend was decreasing with time.The total concentration of bacteria in the water and the concentration of Vibrio were not significantly affected by the flow rate.The total number of culturable bacteria in the water and the total number of Vibrio were not significantly affected by the flow rate.In the Recirculating Aquaculture System breeding turbot,the water quality is not related to the flow rate in the pond.(3)In the case of the fish,the specific growth rate of juvenile fish was the highest,the viscera coefficient was the lowest;in the case of fish and sea cucumber,the specific growth rate was the lowest,the FCR was the highest;in the case of polyculture of fish,abalone and sea cucumber,the FCR was the lowest and the viscera coefficient was the highest.Comprehensive evaluation point of view,Sebastes schlegeli larvae when the growth rate of juvenile fish the fastest,the highest rate of meat.Abalone and sea cucumber,fish polyculture,the entire experimental cycle in the overall weight loss,mortality is low.The results show that fish,abalone,ginseng polyculture,can not significantly promote the growth of abalone.Compared with the sea cucumber and the fish,the sea cucumber and the fish and the abalone and the abalone polyculture,is more conducive to the growth of sea cucumber,abalone is more suitable for growth.Therefore,the polyculture of Sebastes schlegeli and Apostichopus japonicus and Haliotis discus hannai Ino has a better effect.(4)There were no significant differences in Total Ammonia Nitrogen,Nitrite Nitrogen,Chemical Oxygen Demand(COD),Nitrate Nitrogen,TN,TP and other indexes in the three aquaculture combinations,and showed an increasing trend over time.There was no significant difference in the concentration of Unionized Ammonia Nitrogen in different combinations.There were no significant differences in the total number of cultivated bacteria and the total number of Vibrio in three different breeding combinations,but they showed an increasing trend with time.