The Performance of Mangrove (Rhizophora apiculata) Leaf Extract to Treat Vibriosis (Vibrio harveyi) in Mud Crab (Scylla serrata)

Abstract

Mud crabs (Scylla serrata) is one of the most economic crabs in Central Java. However, mortality was reached 80% during fattening due to bacterial infection. Meantime, mangrove leaf contain bacteriostatic and bactericidal such as saponin, flavonoid, tanin, alkaloid, steroid, terpenoid and phenol that might effective to control bacterial infection. This study was carried out to observe the performance of mangrove leaf extract to treat vibriosis in mud crabs at various concentration in vitro and in vivo. In vitro study demonstrated that mangrove leaf extract at concentration of 300 mg/l to 900 mg/l were able to prevent Vibrio harveyi growth and formed clear ring between 11.37–13.67 mm. Forty eight mud crabs at body weight of 4011±253 g were injected with a bacterial V. harveyi at density of 106 CFU/ml in between the leg join. Then immersed into mangrove leaf extract at concentration of 0 mg/l, 300 mg/l, 600 mg/l, 900 mg/l for 30 minutes. Post injection of bacterial Vibrio crabs showed clinical signs such as wide apart of swimming and walking legs, blackened carapace, white spots, and red spots. Immersion of mangrove leaf extract post injection could improved survival rate, healing and histopathological features of experimental crabs. Therefore, it can be concluded that the use of mangrove leaf extract at 900 mg/l demonstrated best survival rate, histopathological feature and recovery after 14 days post infection.