Thermal tolerance of juvenile Silurus meridionalis Chen

To understand the effects of different acclimation temperature on the thermal tolerance of juvenile Silurus meridionalis Chen, the juveniles with a mass of 16.9±0.3 g were acclimated at water temperature 10 ℃, 20 ℃ and 30 ℃ for 2 weeks, and their thermal tolerance under a temperature variation rate of 1 ℃·h-1 was evaluated. The results showed that the critical thermal maximum (CTmax), lethal thermal maximum (LTmax), critical thermal minimum (CTmin), and lethal thermal minimum (LTmin) at acclimation temperatures 10 ℃, 20 ℃ and 30 ℃ were 34.13 ℃, 38.22 ℃ and 39.41 ℃, 34.84 ℃, 38.63 ℃ and 39.53 ℃, 4.88 ℃, 5.90 ℃ and 9.80 ℃, and 4.12 ℃, 5.03 ℃ and 8.29 ℃, respectively, i.e., the test parameters all increased with increasing acclimation temperature. The thermal tolerance amplitude at 10 ℃, 20 ℃ and 30 ℃ was 29.25 ℃, 32.32 ℃ and 29.61 ℃, respectively. Within the range of acclimation temperature 10 ℃-20 ℃, the acclimation response ratio (ARR) at high and low temperatures was 0.41 and 0.12; while within the range of acclimation temperature 20 ℃-30 ℃, the ARR was 0.10 and 0.39. The thermal tolerance polygon area of the juveniles within the range of acclimation temperature 10 ℃-30 ℃ was calculated as 617.5 ℃2. It was indicated that the thermal tolerance of S. meridionalis was dependent on acclimation temperature.