Effects of Salinity on Acute Toxicity of Ammonia and Oxygen Consumption Rates in Common Prawn, Palaemon serratus (Pennat, 1777)

Palaemon serratus juveniles (0.18 ± 0.06 g) were exposed to different concentrations of ammonia in a series of acute toxicity tests by the static renewal method at four salinity levels (10, 20, 30, and 40 ppt) at 29 C and at a pH of 8.0. Oxygen consumption rate ( OCR ) was also measured. The mortality rate increased with increasing concentrations of ammonia and longer exposure times. High salinity levels clearly increased the tolerance of shrimp to total ammonia nitrogen ( TAN ) and unionized ammonia ( NH 3 ) ( P < 0.05). The safe level for P. serratus was estimated to be 2.1, 3.5, 3.8, and 8.5 mg/L for TAN and 0.13, 0.21, 0.24, and 0.53 mg/L for NH 3 at 10, 20, 30, and 40 ppt salinity levels, respectively. OCR of P. serratus increased with increasing salinity and TAN concentrations. This study clearly indicated that there is a relationship between an increment in salinity or TAN and the OCR of P. serratus juveniles ( P < 0.05).