Lethal low dissolved oxygen concentrations for postlarvae and early juvenile Penaeus setiferus at different salinities and pH

Abstract

This study was undertaken to determine the effect of salinity and pH on tolerance to low dissolved oxygen concentration in postlarval (PL 12

18 mg met weight) and early juvenile (720 mg wet weight) Peneaus setiferus. Lethal levels of dissolved oxygen were determined in animals at four combinations of salinity and pH (36 and 15 ppt salinity and pH 6 and 8). For postlarvae, the 48-h LC50 for dissolved oxygen was 1.27 mgO(2)/L at 15 ppt and pH8, and was significantly lower than that obtained in the other combinations of salinity and pH (P < 0,05). For juveniles, the 72-h LC50 was 1.16 mg/L at 15 ppt and pH 8, and was significantly lower than that obtained in the other combinations of salinity and pH (P < 0.05). A significant interaction between salinity and pH was observed. These results suggest that the intensive culture of P. setiferus may be conducted at moderate salinity, where shrimp appear to be more tolerant of low concentrations of oxygen than at higher salinities.