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 (NH3) (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 NH3 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).