Abstract: To examine the effects of acclimation temperature on locomotion performance and behavior of pale chub (Zacco platypus), fishes collected from Wujiang River were acclimated at 15 ℃ and 25 ℃ for three weeks, respectively. After that, the critical and faststart swimming performance and behavior (activity and hiding behavior) were measured. We found that fishes  acclimated under low temperature (15 ℃) had lower critical swimming speed and lower metabolic parameters (e.g.maximum metabolic rate, routine metabolic rate, and metabolic scope) than those acclimated under high temperature (25 ℃) (P<0.05). Furthermore, both the faststart maximum velocity and maximum acceleration, distance moved in 120 ms were lower for fished acclimated under lower temperature (P<0.05), whereas response latency showed no difference between two groups. The behavior exhibited substantial differences between two temperatures as fish acclimated at lower temperature showed decreased spontaneous activity and increased hiding behavior (P<0.05). Our results suggested that pale chub adaptively regulate its swimming performance and metabolic status at low temperature, whereas the behavior compensation mechanism such as decreased spontaneous activity and increased use of shelter as well as the unchanged faststart response latency might be adaptive strategies to cope with potential predators at low temperature.

Key words: hemispherical photograph, Markov matrix., canopy openness, Leaf area index, thinning