Optimal temperature and thermal tolerance of postlarvae of the freshwater prawn acclimated to different temperatures.

In this study, the optimum temperature and thermal tolerance of postlarvae of the commercially important freshwater prawn were determined after acclimation to six different rearing temperatures (19 °C, 22 °C, 24 °C, 26 °C, 28 °C, and 30 °C) during a 45 day-culture period. Best growth parameter values were obtained within the temperature range of 24 °C to 28 °C, where the optimum temperature for growth was found to be at 26 °C (weight gain 81.70%; specific growth rate 1.33 %/day) but had not significant effect ( > 0.05) on survival (64%-71%) of postlarvae. Increasing the acclimation temperature significantly ( < 0.05) increased both the critical thermal maximum (CTMax: from 33.82 °C to 38.48 °C) and minimum (CTMin: from 9.27 °C to 14.58 °C). The thermal tolerance interval increased ( < 0.05) from 24.55 °C to 25.48 °C in postlarvae acclimated at 28 °C but decreased ( < 0.05) to 23.90 °C in those acclimated at 30 °C. The acclimation response rate was lower for CTMax and higher for CTMin. The current (12.48 °C) and future (9.48 °C) thermal safety margins were like those reported for other tropical crustaceans. A thermal tolerance polygon over the range of 19-30 °C resulted in a calculated area of 242.25 °C. The presented results can be used for aquaculture activities and also to help to protect this species against expected climate warming impacts.