不同水培育方式下斜带石斑鱼孵化池水质变化特征

斜带石斑鱼(Epinephelus coioides)为我国南方近海重要网箱养殖海水鱼品种之一,而石斑鱼苗种繁育成败对其养殖规模化有着重要影响。为此,本研究比较了3种不同水培育方式下斜带石斑鱼孵化池水质变化特征。孵化在水泥池中进行,池规格为2.5m×4.0m×1.1m。试验采用益生菌和虾片作为培水材料,益生菌总活菌浓度为1.0×108cells/mL。在孵化前1周,每天同时等量往孵化池中加入益生菌和虾片2次,至试验结束,添加时间分别为早上7:00和下午13:00。处理组1、2、3益生菌日添加量分别为每池160、320、320mL,虾片日添加量分别为每池8、8、16g。每组设2个重复。石斑鱼受精卵孵化后持续培育27d,并分别在孵化后第3、8、13、18、23、27d检测水池中pH值和溶氧、总磷、活性磷、氨氮、硝酸氮、亚硝酸氮含量。结果表明:在孵化后第3d,水体中pH值从8.06下降至7.03,之后又上升至初始值。试验期间,溶解氧水平维持在6.86~7.99mg/L之间。总磷和活性磷水平随培养时间延长而增加。在孵化后第13d,亚硝酸氮水平开始升高,并在孵化后第23d达到峰值(约0.57mg/L)。硝酸氮含量也从孵化后第13d开始上升。各处理组氨氮含量均在孵化后第18d上升至最高值。试验期间,处理组2亚硝酸氮及硝酸氮水平均低于处理组1及处理组2。因此,基于水体亚硝酸氮及硝酸氮为评价指标,斜带石斑鱼孵化池中日添加益生菌及虾片适宜浓度分别为40mL/m3和1g/m3。另外,为避免可能发生的石斑鱼鱼苗亚硝酸盐中毒,应在孵化后第23d往池中注入适当新水。

Response of water quality in concrete grouper Epinephelus coioides nursery ponds under different water breeding regimes

This study compared and discussed response of water quality in concrete nursery ponds (W 2.5 m×L 4.0 m×H 1.1 m) applied for grouper Epinephelus coioides hatching under three different water breeding regimes (group 1, 2, 3). Pepared effective microorganisms (a total active bacterium concentration of 1.0×103 cells/mL solution (EMS) together with shrimp chip (SC) were daily added. Daily addition levels of EMS for group 1, group 2 and group 3 were respectively 160 mL, 320 mL and 320 mL per pond. For SC,aily addition levels were respectively 8 g, 8 g and 16 g per pond. The experiment continued 27 days. Water quality was measured during the whole experimental period, pH values decreased from 8.06 to 7.45 on 3 days after hatching (DAH), and then increased to the initial level. Dissolved oxygen (DO) levels varied at 6.86～7.99 mg/L. Total phosphate (TP) had an increasing tendency with larvae cluture time,and similar results were observed in for Soluble reactive phosphate (SRP). On 13th NO2-N values rapidly rose and reached a peak (about 0.57 rag/L) on 23th. NO3-N values started to increase on 13th. NH3-N values in all groups had a peak on 18th. Overall, daily additions of EMS and SC at concentrations of 40 mL/m3 and 1 g/m3 would be optimal for water breeding of grouper nursery ponds, and new seawater should be exchanged into nursery ponds on 13th.