Effects of different thermal acclimations on metabolic rate of Brond-snout Chondrostoma regium

The whole-body metabolic rates, which are known as indicatives of the physiological functions of an organism are influenced by biotic and abiotic factors. In this study, the effect of temperature on metabolic capacity of Chondrostoma regium was estimated following thermal tolerance range, which was obtained between 1.9 - 31.7 ̊C. To address that, 56 fish weighing 20.77±1.35 g were exposed different temperature treatments, including 3.5-4.5 ̊C as acute low temperature, 5.5-6.5 ̊C for 24 h and 5.5-6.5 ̊C for a week as low temperature treatment, 30-31 ̊C as acute high temperature, 29-30 ̊C for 24 h and 28-29 ̊C for a week as high temperature and a control treatment (22-23 ̊C). Metabolic rate, including standard metabolic rate, maximum metabolic rate and aerobic scope were determined for each individual fish by intermittent flow respirometer. The results indicate that standard and maximum metabolic rate was elevated (P<0.05) in all high temperature treatments as compared with control while aerobic scope didn't show any significant changes. On the other hand, all metabolic parameters (standard metabolic rate, maximum metabolic rate and aerobic scope) were reduced (P<0.05) in low treatments when compared with control treatment. Based on the present results, it could be concluded that increase in water temperature act as a loading stressor and decrease in temperature act as a limiting stressor to C. regium.