Study On Quality Improvement And Purification Of Oyster Under Industrialized Temporary Cultivation Mode

In recent years,with the rapid development of China’s economy,industrial emissions of pollutants overload,exhaust emissions do not meet the standard and other human factors,resulting in serious pollution in coastal areas.Oysters are favored by people for their advantages of high protein,low fat,delicious and nourishing.However,due to the filter feeding characteristics of oysters,the accumulation of pollutants by oysters is particularly serious,including but not limited to heavy metal pollution and microbial pollution.With the development of many years,factory recirculating aquaculture has been applied to a variety of aquaculture quality,its significant advantages are water saving,land saving,reduce manpower,etc.,has become a consensus of people,but also become an important part of the development of aquaculture industry.This study mainly focused on the purification and quality improvement of coastal oysters(Pacific oyster Crassostrea Gigas),and conducted several experiments with the mode of factory temporary cultivation,aiming to study the advantages and effects of factory temporary cultivation on the purification and quality improvement of oysters,and to provide a new method for the purification of oyster temporary cultivation.The main results of this study are as follows:(1)Study the purification method of oyster in temporary cultivation mode.The pollutants mainly include the total number of bacteria and the concentration of heavy metal Cd.In all experiments,the breeding parameters were set as: water temperature(15±2)℃;The circulating water salinity is 22±1.The circulating water volume is(1500±100)L/h;Dissolved oxygen(6.5±0.8)mg/L;Shellfish water ratio 1:5.The temporary cultivation of oysters with factory circulating water can strictly control the temperature of temporary cultivation and inhibit the growth of bacteria.Under the reasonable use of ultraviolet ozone combined with sterilization,the survival rate of oysters can be guaranteed at95% and the removal rate of total bacteria can reach 43%.The removal rate of heavy metal Cd by the combined diet of chitosan + algae + soybean reached 46% under the mode of purifying temporary cultivation.However,in the factory circulating water mode,the removal rate of heavy metal Cd was 55%after 15 days of temporary cultivation,and reached the food hygiene standard.In the stratified temporary culture experiment,the highest removal rate of heavy metal Cd in oyster body reached 40%.(2)The quality improvement of oyster by bait in temporary rearing mode was studied.The results of water temporary rearing experiment showed that the combined diet consisting of chitosan,soybean and algae significantly increased the total sugar of oyster(P < 0.05),which increased by 36% after 15 days of temporary rearing.The combined diet of soybean and algae had little effect on the increase of total sugar in oyster,and the increase rate of total sugar was 15% after 15 days of temporary cultivation.The combination of the temporary cultivation mode of industrial circulating water and the combined diet significantly increased the fatness of oyster(P < 0.05).The average fatness of oyster after 15 days of temporary cultivation increased by 6.18%.The temporary cultivation mode of factory circulating water promoted the feeding and quality improvement of oyster.The total sugar increased by 50% and the average feeding rate of oyster reached 40% after 15 days of temporary cultivation.