高位池养殖过程凡纳滨对虾携带WSSV情况的动态变化

为了更好地预防对虾白斑综合征(WSS)的暴发,探讨该病毒病的流行规律,笔者针对养殖过程中对虾的携带WSSV情况展开调查。调查于2010年7月-2010年11月广东省汕尾市红海湾养殖场进行,从10口凡纳滨对虾高位养殖池中随机抽取6口进行跟踪采样。收集指标包括对虾生长状况、基本环境指标、浮游微藻种群结构和对虾病毒携带量等。本文重点报道利用实时定量PCR-TaqMan探针法检测6口精养池塘对虾体内WSSV的携带量变化情况,检测结果显示:①1-3号虾池苗种携带WSSV,其波动范围在1.3×103~1.7×104copy/g之间;②对虾在养殖过程中均带毒,鳃组织中的平均病毒携带量(2.3×109copy/g)多于肌肉组织中的平均病毒携带量(3.2×108copy/g),且变化趋势一致,但没有显著性差异(P>0.05);③在整个养殖过程中对虾WSSV携带量总体呈现波动上升的趋势,期间各池出现过数次高值。前期WSSV拷贝数的波动范围在1.3×103~3.0×107copy/g之间,后期上升到1.5×106~1.2×1011copy/g,使得某些池塘养殖对虾WSS暴发。调查结果说明:1)对虾携带WSSV可以进行养殖生长;2)WSSV在对虾体内的含量是变化的,且其变化存在着一定的规律性;3)这种变化规律主要体现在带毒量随着养殖时间的进行及外界水环境中某些主要因子的变化而变化,如:养殖时间越长,带毒量越高;养殖环境中某些关键环境因子的改变,如:温差较大,不良藻相转换,天气骤变等均可引起对虾体内病毒含量较大的波动。鉴此,作者提出,构建并维持良好的浮游微藻的群落结构,注意有害藻相改变时保持养殖水体环境稳定,对环境突变前后都做好应对对虾应激的措施等可以极大程度地减少WSS暴发的可能。本研究通过对WSSV的密切跟踪,旨在更好的反映其在养殖环境下的动态变化规律,以及受各种环境因子影响的情况,从而为预防对虾WSS提供依据和参考。

Variation in WSSV in Litopenaeus vannamei during the period of culture in ponds above sea level

The commercial culture of shrimp has expanded rapidly in China in recent decades and is now one of the most important agricultural industries.However,shrimp production decreased significantly between 1992-1997 due to the outbreak of white spot syndrome(WSS).WSS is of serious concern to shrimp farming throughout the world as mortality can approach 100% within 3-10 d of infection with WSSV.There is currently no effective treatment for this disease.We measured the variation in infection intensity of WSSV carried by shrimp(Litopenaeus vannamei) among six ponds in Hongtai Farm in Shanwei of GuangDong province between July and November 2010.In addition,we measured several environmental indices,water quality indicators,and the population structure of planktonic algae.We used real-time PCR to quantify the number WSSV copies in each shrimp.All the shrimp larvae carried WSSV at concentrations ranging from 1.3×103 to 1.7×104 copies/g.Fur-thermore,the shrimp were infected with WSSV throughout the entire farming period.The mean number of WSSV copies was higher in the gill tissue(2.3×109 copies/g) than in the muscle tissue(3.2×108 copy/g),but the differ-ence was not significant(P>0.05).The number of WSSV copies tended to increase in both tissues throughout the farming period,and was characterized by a number of peaks.During the early rearing period,the number of copies ranged from 1.3×103–3×107copies/g,whereas in the mid and latter stages of rearing the number of copies in-creased to 1.5×106-1.2×1011 copies/g.In some ponds,outbreaks of WSS forced an end to farming.Rapid changes in water temperature,algae population structure,and weather were also associated with changes in the number of WSSV copies in shrimp.Our results suggest that shrimp can be cultured even when infected with WSSV.The in-tensity of infection with WSSV varied temporally and was affected by culture time and environmental factors.We suggest that maintaining the population structure of planktonic algae,keeping water quality constant,and de-creasing stress can significantly reduce the likelihood of WSS outbreak.