Study Of Carrying Capacity, Litopenaeus Vannamei, In Extensive, Intensive And Super Intensive Water Bodies

In order to make the Litopenaeus vannamei farming industry clean, safe, healthy and low-carbon, sustainable development, the study of the carrying capacity is very important. This research used three years, studied the carrying capacity of Litopenaeus vannamei in different culture water bodies and with different water treatment measures. The results are as follows:1. The carrying capacity of Litopenaeus vannamei juveniles in extensive culture water with low salinity. This study was conducted at six stocking densities: 10,20,30,40,50,60 ind/m², then we detected the water quality of the shrimp ponds, the growth of the Litopenaeus vannamei, the activity of digestive enzymes during the 60d’s culture cycle. The results showed that: the amount of shrimp in unit-water mainly affected the water quality with pH, NH₃-Nm, DO. The turbidity and total phosphorus （TP） has significant differences in different stocking groups （P<0.05）, while the non-ionic ammonia （NH₃-Nm）, dissolved oxygen （DO） content, total nitrogen （TN） and pH have an extremely significant difference （P<0.01）. But in each test group the shrimp can still tolerate the water; DO is the main limiting factor to the carrying capacity. On the other hand, the protease activity of shrimp’s mid-gut gland in different experimental groups also have significantly difference （P<0.05）. With the capacity in unit-mass water growing up, the shrimp’s activities of protease and nitrogen utilization went down. After considering the assessment indicators studied in this research, we concluded that, in extensive culture water with low salinity, the carrying capacity of Litopenaeus vannamei juveniles is 57.5g/m³.2. The carrying capacity of Litopenaeus vannamei in intensive culture water body. This research studied the carrying capacity under five culture factors: stocking densities, aeration, water exchange, microbial agents and disinfectants, in intensive farming water body. The results showed that: After 110d culturing, under the influence of above 5 factors, considering the Nemerow index and biological evaluation, the carrying capacity of Litopenaeus vannamei in intensive farming water body should be around 877.01g/m3. Due to the high survival rate, faster specific growth rate, coupled with lower water pollution index in low stocking density groups, the comprehensive evaluation index in 50 and 100ind/m² is greater than other groups. Intermittent pneumatic not only can reduce water pollution index, but also the amount of shrimp in unit-water. Similarly, water change, addition of microbial agents and disinfectants can also down the water pollution index, but at the same time resulted in lower survival rate of farmed shrimp and the amount of shrimp in unit-water. The influence of stocking density and 4 kinds of water treatment measures to carrying capacity, stocking density>water change> Inflation> Disinfectants> microbial agents. Different amount of shrimp in unit-water caused by different stocking density, water change are two main limited factors to carrying capacity.3. The carrying capacity of Litopenaeus vannamei in super intensive culture water body. Super-intensive farming means recirculating water farming. This reasearch studied the carrying capacity of Litopenaeus vannamei in recirculating water body. The results show that: After 80d culturing, under the influence of four factors: stocking density, bio-filtration, water purification network, advection precipitation, the carrying capacity of Litopenaeus vannamei in recirculating water body is around 592.41g/m³. Lower stocking densities followed with faster growth rate, higher survival rate, and lower amount of shrimp in unit-water. And the effect of faster growth rate and higher survival rate to carrying capacity palyed a predominant role. The comprehensive evaluation index in the 128ind/m² group is larger than other groups. Biological filtering down the water pollution index, while improving the survival rate of shrimp and the amount of shrimp in unit-water. Water purification network not only failed to reduce the water pollution index, but caused lower survival rate of shrimp and the amount of shrimp in unit-water. Advection precipitation can also reduce water pollution index, but has limited impact on shrimp biology. The influence of stocking density and 3 kinds of water cycle management to carrying capacity, stocking density> biological filtration> water purification network > advection precipitation. Different amount of shrimp in unit-water caused by different stocking density, biological filtration water cycle management are two main limited factors to carrying capacity. In specific production process, due to the stocking density effected the amount of shrimp in unit-water greatly, on the other hand the amount of shrimp in unit-water have a great impact on water quality and shrimp growth, so when chossing stocking density and water treatment measures must be strictly based on carrying capacity.