Elimination of White Spot Syndrome Virus (WSSV) Using The Biofloc System

Abstract

Intensified aquaculture farming requires more supplementary protein feed to increased production level. However, high level of protein in the feed also accompanies adversary effects such as nitrogenous wastes, which may affect on the growth performance and survival rates. Even though they are exposed to a little bit above the critical ammonia levels over time, fish are more susceptible to the various pathogens resulting in increased chance of disease outbreaks. Increased nitrite concentration has negative effects on the growth and survival of fishes as well as other aquatic organisms. Adding of carbonaceous materials increase C/N ration which favors the growth of microbial protein by reducing the ammonia from the culture system. Nitrogen compound covalently bond with carbon and produce flocs of protein molecules, flocculated together and form a floating mass called bioflocs. These bioflocs may be used for water quality improvements, fish nutrients as well as antimicrobial agents. Considering the potential application of bioflocs, experiments have been conducted to verify the effect of bioflocs on reduction of White Spot Syndrome Virus (WSSV) particle. Bioflocs were prepared under laboratory condition in the rectangular tank with sea water. Commercial feed was given constantly as source of additional carbohydrates and water was vigorously aerated by aerator. After the preparation of bioflocs, hepatopancreas from infected shrimp (Litopenaeus vannamei) was inoculated. Water was taken from the tank on Ist and 3rd day and copy number of WSSV/ng was measured by Real time PCR. The resulted show that copy number of WSSV in bioflocs tank decreases dramatically. After 1th day, copy number of WSSV was 752,616 and decreased to 34,929 on 3rd days. Findings of this experiments showed that bioflocs have effect on the reduction of WSSV particles from the culturetanks.