Determining the Effect of Sediment Resuspension from the Activity of Phenoloxidase in Penaeid Shrimp Post Larvae

Problem statement: Regular sediment resuspension or dredging in coastal zones can induce stress in a postlaval penaeid shrimp, which affects immune response. Phenoloxidase is a significant enzyme in the penaeid shrimp’s immune system which, when used as a biomarker, can serve as an early warning sign in ecological systems. The stress response of shrimp postlarvae from sediment reuspension was analyzed by sediment toxicity test in laboratory. Approach: This study was designed to determine the activity of phenoloxidase with sediment resuspension in two types of postlarval penaeid shrimp, the white shrimp (Penaeus vannamei) (at salinity 17 psu) and the black tiger shrimp (Penaeus monodon) postlarva 10 (at 17 psu and 3 psu). Sediment resuspension varied from 1:40, 1:16, 1:8 and 1:4 v/v (sediment/water) and control water (filtered seawater). Sediment in the experiment was taken from Chanthaburi Estuary, Thailand which may contaminated by several pesticides. After resuspension, 20 of the postlarval shrimp were added to one liter of resuspended water for 96 h. At the end of the test, phenoloxidase activity and shrimp survival were analyzed. Results: The study of black tiger shrimp at salinity 3 psu found that only sediment resuspension at 1:40 was sufficient to increase the activity of phenoloxidase in shrimp postlarvae. All sediment resuspension treatments had higher levels of phenoloxidase activity than in the control group. However, only phenoloxidase activity at 1:40 and 1:16 showed a significantly higher difference to the control group (p<0.05). At 17 psu, in both black tiger shrimp and white shrimp, the levels of phenoloxidase activity were higher in sediment resuspension treatments than in the control group. Conclusion: The phenoloxidase activity showed an early response with sediment resuspension even though the response did not show a clear increase in the order of sediment resuspension treatment.