Environmental temperature is one of the most significant factors for aquatic ectotherms because it affects their physiological and metabolic processes, as well as their growth, reproduction, survival and distribution patterns. Therefore, the aim of this study was to determine the effects of different acclimation temperatures (AT : 20, 23, 26, 29 and 32°C ± 1°C) on the thermotolerance, thermal window and thermal metabolic scope of postlarvae (PL) and juveniles (J) of Macrobrachium rosenbergii . A total of 250 PL (0.023 ± 0.008 g) of M. rosenbergii were acclimated for a week at five temperatures (50 PL per AT). Subsequently, for each acclimation temperature , the endpoint of maximum (CTmax ) and minimum critical temperature s (CTmin ) was determined using the dynamic method . Using the CTmax and CTmin values, the thermal window a rea was calculated, and the optimal temperature was determined through the thermal metabolic scope. At the end of the previous experiments, the PL were kept for one month at 26°C until they reached the juvenile stage (0.255 ± 0.151 g) and then they were acclimated for 21 days at five temperatures (40 J per AT) and the experimental stages were carried out.
Thermal tolerance of postlarvae and juveniles was significantly affected by acclimation temperatures. The postlarvae were slightly more thermotolerant (CTmax : 35.9-41.1°C, CTmin: 13.1-17.9°C) than the juveniles (CTmax : 35.4-41.2°C, CTmin: 15.5-18.3°C) in the acclimation temperature range of 20-32°C. The thermal window of the postlarvae was slightly wider (209°C2) than that of the juveniles (180°C2). The postlarvae and juveniles acclimated to 26 and 29°C achieved higher aerobic performance, respectively. Therefore, these were the optimal temperatures to optimize and maximize culture at both stages. Under a climate change scenario, the cultivation of postlarvae and juveniles of M. rosenbergii could likely be negatively affected.