锯缘青蟹苗池微生态环境影响因素的初步探讨

通过对锯缘青蟹苗池微生态环境和水质环境的全过程检测,探讨了总菌数、弧菌数及弧菌数/总菌数的消长规律,并对苗种培育阶段涉及的各种外源因素及控制苗池微生态环境的相关手段的有效性作了初步的探讨。结果表明:苗池水体中总菌数在Z1~Z2少量添加水不换水阶段,呈相对稳定状态,进入Z3后总菌数逐渐增加,最高达3.5×106cfu/m l;弧菌数在Z1培育阶段出现2×102cfu/m l激增至5×104cfu/m l的峰值,第二峰值出现在Z5阶段,达6×105cfu/m l;弧菌数/总菌数比值在育苗起始时仅为0.4%,之后迅速升至30%~40%,在Z5阶段,由于弧菌数量急剧上升,达到50%的高比值;NH4-N与COD检测值在育苗过程中变动较大,两者与弧菌数/总菌数比值呈正相关关系。现行育苗方式中对苗池微生态环境产生影响的主要因素是苗种培育密度,海水、饵料的处理方式和抗生素;净化功能菌和蛭弧菌应用于育苗水体具有抑制弧菌繁殖的效果。

An approach to factors affecting the microecological environment in the nursery ponds of mud crab, Scylla serrata

Resting on the examination of microecological enviroment and water quality in the nursery ponds of mud crab Scylla serrata,total counts,vibrio counts,and the depression and growth rhythm of vibrio counts/total counts were studied.A preliminary study was carried out on various exogenous factors and related means to control microecological enviroment in the nursery ponds during the seedling rearing period.The results revealed that the total counts were relatively steady during states Z1-Z2 when adding a small amount of water but without changing water in nursery ponds,while entering into state Z3 the total counts steadily increased with the highest reaching 3.5×10~6 cfu/ml.The vibrio counts occurred at 3×10~2 cfu/ml at Z1,and significantly increased to peak value of 5×10~4 cfu/ml;the second peak appeared at Z5 with a value of 6×10~5 cfu/ml.The ratio of vibrio counts to total counts at the initial seedling rearing state was only 0.4%,and continued to grow rapidly to 30%-40%.At Z5,the ratio reached a high value of 50% due to the sharp raise of vibrio counts.The values of NH_4-N and COD changed greatly during the period of seedling rearing,and the two values bore a positive relationship with the ratio of vibrio counts to total counts.In the way of seedling rearing,the main factors affecting the microecological environment in the nursery ponds are seedling rearing density,seawater,the dealing way of feed and antibiolics.The application of purifying function bacteria and Bdellovibrio to seedling rearing water has an effect of inhibiting the propagation of vibrios.