流速对封闭循环水养殖大菱鲆生长、摄食及水质氮素的影响

Effects of flow rate on the growth, feed intake and water nitrogen in a closed recirculation aquaculture system of turbots (Scophthatmus maximus L.)

在封闭循环水高密度养殖条件下(平均密度14.1 kg/m2±0.51 kg/m2),设置4个流速梯度(200,400,600,800 L/h,分别以A～D组表示),挑选相近体质量(200.3g±7.6 g)的大菱鲆进行42 d养殖试验,每个梯度设置3个重复,每个重复55尾鱼,研究流速对封闭循环水养殖大菱鲆生长、摄食以及水质氮素的影响。试验结果表明:(1)大菱鲆(Scophthatmus maximus L)特定生长率、增质量率、摄食量随流速增大先快速上升后缓升趋稳,饲料系数则相反。B、C、D 3组特定生长率、摄食量分别显著高于A组30.77%～52.31%、17.30%～22.05%;饲料系数则显著低于A组13.83%～22.34%;(2)养殖水体中总氨氮、非离子氨及亚硝酸氮浓度随流速的增大先快速下降后缓降趋稳。B、C、D 3组水质总氨氮氨浓度均显著低于A组53.70%～79.07%;(3)根据流速对特定生长率、水体总氨氮二者的影响,得出养殖的生态适宜流速为625 L/h。再结合流速对水循环动力的影响,得出养殖的生态经济适宜流速为480 L/h。

Effects of flow rate on the feed intake, growth and water quality of turbot culture were investigated in a closed recirculation aquaculture system. Fish with a mean initial weight of 200.3 g±7.6 g were reared at four different flow rates （200, 400, 600, 800L/h） in 400 L tanks for 42 days. Six hundred and sixty fish were randomly allotted in four treatment groups with three replicates for each treatment at a stocking density of 14.1 ＋ 0.51 kg/m2. Feed intake, specific growth rate and weight gain rate were increasing rapidly first and then slowly with the increase of flow rate, while food conversion rate showed a reverse pattern. The specific growth rate of group B, C, and D were significantly higher than group A by 30.77%-52.31%, while feed conversion rate ws lower than group A by 13.83%-22.34%. Concentrations of total ammonia nitrogen （TAN）, unionized ammonia nitrogen （UIA-N）, and ni- trite （ NO2 -N） were decreased rapidly first and then slowly with the increase of flow rate. The ammonia nitrogen of group B, C, and D were significantly higher than group A by 53.70%-79.07%. The optimal ecological flow rate was calculated to be 625 L/h, based on the specific growth rate with total ammonia nitrogen in water. Another optimal ecological economical flow rate was calculated to be 480 L/h, based on the specific growth rate with power consumption and TAN in water.