Effects of probiotics on the dynamic of bacteria in marine shrimp pond

In the Shenzhen East Sea Aquaculture Company, the effects of probiotics on the dynamic of heterotrophic bacteria and vibrio in semi-enclosed intensive marine shrimp aquaculture system were studied during the adult aquaculture period of Penaeus monodom from May to July, 2001. The results show that heterotrophic bacteria and vibrio density in water of experimental ponds, where probiot-ics were used, are obviously higher than that in control pond where no probiotics were used, and their dynamic characteristics are al-most the same. During the prophase of shrimp culture, the heterotrophic bacteria and vibrio density in water kept in a relatively low lev-el, while at the middle and final phase, both increased rapidly, especially in the control pond, the vibrio density even exceeded the threshold of 100×10² CFU · mL^-1, that was considered to cause disease problem easily. There are no obvious differences for hetero-trophic bacteria and vibrio density in sediment between experimental ponds and control ponds, and their dynamic variation characteristics are almost similar, but there are some differences between experimental ponds and control pond. In experimental ponds, there were two peaks of individual density appeared in the prophase or middle phase and near the harvest time, while in control pond, the peak of individual density appeared at middle phase. It is obvious that the application of probiotics can depress the increase of heterotrophic bacteria, especially vibrio in shrimp pond water are more significant than that in sediment.