Study On Fouling Characteristics And Prawn Tolerance In Shrimp Pond

China already leads the production of prawn in the world for many years,and the prawn aquaculture has been developed into a pillar in the aquaculture industry.In the tank with intensive prawns,bio solids will increase the bio chemicals oxygen demand,produce the additional ammonia that predispose fish to bacterial gill disease and other infections if these bio solids cannot be removed efficiently.Therefore,the efficiency of the bio solid removal influences the water quality in the tank and is the key point for a successful aquaculture.Through the model test,we systematically explored the elements of hydraulic driving(jet velocity,jet position),pool conditions(bottom surface roughness,bottom slope),and the density of sewage and other factors on the aquaculture ponds.The results can be used to guide tank design and hydraulic driving conditions in order to remove the bio solids quickly and completely.At the same time,in industrial culture of Litopenaeus vannamei,flow magnitude and the corresponding action duration in the culture pond usually should be adjusted according to the endurance swimming ability together with the waste distribution.To this end,laboratory study was conducted to measure the endurance swimming time of Litopenaeus vannamei in the vertical circulation flume under five flow velocity levels so as to assess its endurance swimming ability.The results of the study showed that:(1)the greater the flow velocity,the better the effect of fouling.The closer the jet position is to the collection port,the better the collection effect.The smoother the bottom of the pool,the less dirt and the better the dirt collection effect.(2)The flow field in the cross section of the shrimp culture pond has a circulation formation,and the velocity of the cross section decreases first and then then decreases.If the boundary is not considered,the flow velocity in the middle of the pool is more stable.(3)During the growth stage around 3.6 g,the flow magnitude in the pond should be controlled less than 34.9 cm/s,and the flow action duration should be decided based on the cure of cumulative fatigue percentage and swimming time as measured in this study.(4)Considering all kinds of factors,it is suggested that the bottom of the pond be as smooth as possible in the construction of the aquaculture pond;adjust the bottom slope of the pool properly to control the breeding density and bait amount of the shrimp.For the large particles,the hydraulic driving device is as close to the pollution port as possible and increases the flow rate as much as possible to ensure the healthy growth of the shrimp.Control the driving time,get better pollution effect.