This present paper studied the technological characteristics of seawater treated by sand filtering, net filtering and reserve-water disinfection.The results showed that after treatment the average filtering ratio of phytoplankton was 89.98%,and that of zooplankton was 89.5%; that it can isolate the other species of shrimp and crab by the filtering net of more than 40 mesh,and it was difficult for Copepoda to pass through the filtering net of more than 60 mesh,so it can block the horizontal disseminate pathway of WSSV; and that 6×10-6 of the efficient chlorine can kill Copepoda but most aquatic creatures were dead in the water treated by 10×10-6 of the efficient chlorine, and it can transfer algae after killing the harmful creatures by using bleaching powder when there was reserve water. The result of water culture for 4 days, in out-seawater and the water treated with sand filtering or net filtering of 60 mesh or 6×10-6of efficient chlorine, showed that the species and quantity of plankton were the most by out-sea-water culture, and it reduced respectively in the water treated by filtering with 6 mesh,sand filtering and 6×10-6 of efficient chlorine.
White spot syndrome virus (WSSV) is the causative agent of white spot syndrome (WSS) of cultured penaeid shrimps. WSS breaks out and prevails in cultured penaeid shrimps in many countries and regions of the world, especially in southeast Asia. WSSV is the virus most severe damaging to the cultured penaeid shrimps in the world. At the present time, the control of the outbreaks of WSSV will recover and develop the penaeid shrimp cultures in China and even in the world.
In 1991, WSS was found in cultured Penaeus monodon in Shantou, Guangdong Province, China.And in 1992, the WSS was broke out in cultmed penaeid shrimps in Shantou and Fujian Province.However, it rapidly extended to all coastal areas in China in 1993, caused enormous economic losses.Until 1999 the penaeid shrimp cultures in China was still unrecovered.
WSS spreaded to the east of Guangdong Province in 1992 and to the west in 1993. Since 1995,due to adoption of new culture patterns and techniques, the yield of cultured penaeid shrimps inGuangdong has increased.……
