Mechanism of control of luminous vibriosis in shrimp-finfish integrated water system

The disease due to luminous bacteria has been a major problem of the shrimp (Penaues monodon) industry. Different technologies have been introduced to prevent the occurrence of luminous bacteria in shrimp ponds. In the Philippines, one of the techniques that have been reported to work against luminous bacteria is the green water culture system. A green water culture system is an innovative technique wherein shrimp are cultured in water where microalgae such as Chlorella sp. grow abundantly. The present study determined how the different components of the green water culture system, such as Chlorella sp. and tilapia (Oreochromis hornorum), candidate alternative species for polyculture with shrimp such as GIFT tilapia (O. niloticus), milkfish (Chanos chanos), grouper (Epinephelus coioides), sea bass (Lates calcarifer), rabbitfish (Siganus guttatus) and snapper (Lutjanus argentimaculatus), and other factors such as shrimp biomass and feeding, affected the growth of luminous bacteria in a simulated shrimp culture environment. The possible factors involved and the mechanisms on how the green water culture system work against luminous bacteria were identified. This study shows that the direct inhibitory action of the presence of different tilapia hybrids, sea bass, red snapper, grouper and rabbitfish alone is one of the major factors that make the green water culture system or finfish integrated shrimp culture system effective in the control of luminous V. harveyi bacteria in the water. On the other hand, the presence of Chlorella sp. alone is not an important factor in the control of luminous bacteria in a simulated shrimp culture system. Increasing the shrimp biomass also increased the luminous bacteria, total and presumptive Vibrio counts, and decreased the efficiency of fish to control growth of luminous bacteria. Feeding on the other hand improves the efficiency of tilapia in controlling the growth of luminous bacteria.