Effect of different mangrove-to-pond area ratios on influent water quality and WSSV occurrence in Penaeus monodon semi-intensive farms using the greenwater culture technique

White spot syndrome virus (WSSV) has been affecting the shrimp industry worldwide for two decades now. It continues to bring economic losses to affected farms. Despite the many studies on its epidemiology, there is no proven treatment or control measure. Diseases, like the WSSV, results from the interaction of three factors: host, pathogen and environment. The environment plays an important role in disease development and determines the health or the immune capacity of the shrimp. High mangrove-to-pond area ratio (MPR) is reported as a protective factor against WSSV. This study investigates if mangroves affect the physicochemical properties of the water and soil as well as the prevalence of infectious agents like the WSSV by monitoring farms with different MPR (0:1, 1:1, 4:1). Results showed that quality of influent water was not significantly better in farms with high MPR. Significantly higher available sulfur was observed in MPR-4; significantly higher percentage green vibrios in the soil in MPR-0. WSSV was detected in farms with MPR-1 and MPR-4 but did not result in an outbreak, suggesting that the presence of mangroves could prevent WSSV outbreak.The study was funded by the Government of Japan under the Trust Fund granted to SEAFDEC AQD (GoJ TFD FH0206) and by RESCOPAR of the Wageningen University, The Netherlands. Gratitude is due to the shrimp farm owners and managers for the permission to get samples from the farms; to Mr. Mark Anthony Quiocson for the exemplary assistance during the conduct of the study; and to Dr. Marc Verdegem for the tutorial in data analysis