三疣梭子蟹与凡纳滨对虾混养实验研究

采用海水陆基围隔实验方法探讨三疣梭子蟹和凡纳滨对虾混养的适宜配比和水环境的变化,并比较其养殖效果.实验中对虾6个放养密度分别为0,15,45,75,105,135 尾/m~2;三疣梭子蟹的密度为6尾/m~2.实验结果表明,经过60 d的养殖,混养组梭子蟹的成活率、规格和净产量均优于梭子蟹单养组,其中,混养对虾密度为45尾/m~2组(45.71%,43.22 g/ind,1 191 kg/hm~2)最高,其次是75尾/m~2组(44.58%,39.13 g/ind,1 050 kg/hm~2),梭子蟹单养组(35.13%,32.87 g/ind,693 kg/hm~2)最低.混养6尾/m~2密度梭子蟹条件下,对虾的养成规格和成活率与对虾密度呈负相关.实验后期各混养组水体中总氨氮、亚硝酸盐、硝酸盐和总氮含量均显著高于单养组,且随对虾放养密度增高显著上升.水体总氨氮含量各混养组在养殖50 d后均超过500 μg/L.本实验表明:三疣梭子蟹与凡纳滨对虾混养的最佳配比为三疣梭子蟹6尾/m~2,对虾45～75尾/m~2.

Studies on the Effects of Polyculture of Litopenaeus vannamei with Portunus trituberculatus

The study was designed and conducted to optimize the structure of polyculture for shrimp Litopenaeus vannamei with crab Portunus trituberculatus, and to compare their ecological efficiencies and water quality parameters. The experiments were conducted with land-based enclosures (5×5 m) setting in an earthen pond, in which crabs were stocked at a density of 6 ind·m~(-2) with shrimps at six different densities of 0, 15, 45, 75, 105 and 135 ind·m~(-2) respectively. The results showed that all the poly-culture treatments were superior to crab mono-culture treatment in survival rate, final size and net production. The highest survival rate, final size and net production of shrimp were 45.71%, 43.22 g·ind-1 and 1 191 kg·hm~(-2) for the treatment of 45 ind·m~(-2), followed by 44.58%, 39.13 g·ind-1 and 1 050 kg·hm-2 for the treatment of 75 ind·m~(-2), and the lowest were 35.13%, 32.87 g·ind~(-1) and 693 kg·hm~(-2), which occurred in crab mono-culture treatment during the experimental duration of 60 d. The final size and survival rate had negative correlation with their stocking density. The concentrations of TAN, NO_2-N, NO_3-N and TN in poly-culture were higher than those in crab mono-culture significantly, and the concentrations of those were increased with the shrimp stock density significantly at the end of the culture period. The concentration of TAN in all poly-culture treatment was above 500 μg/L after 50 d. The treatment giving the best culturing benefit was crabs at 6 ind·m~(-2) and shrimps at 45-75 ind·m~(-2).