温度和重复测定对秦岭细鳞鲑快速启动反应、游泳性能及力竭后代谢特征的影响

在全球气候变暖背景下,冷水性鱼类的温度适应性备受关注。秦岭细鳞鲑(Brachymystax lenok tsinlingensis)是目前世界上分布最南端的两种鲑科鱼类之一,为国家Ⅱ级重点保护水生野生动物。尽管温度是决定该物种生存与分布的关键因子,然而其热生物学相关研究至今鲜见报道。研究考察了驯化温度(6℃、12℃和18℃)和重复测定对秦岭细鳞鲑生态相关的重要指标如快速启动反应、游泳性能及力竭后代谢特征的影响。结果发现:(1)快速启动反应时滞(Latency time,Tlatency)随温度升高而变短(P<0.05),但温度和重复测定对反应率(Reaction rate,R)无显著影响(P>0.05);(2)温度对步法转换速度(Gait transition speed,Ugait)和匀加速游泳速度(Constant acceleration test speed,Ucat)影响显著(P<0.05),重复测定对Ugait和Ucat无显著影响(P>0.05);(3)温度对日常代谢率(Routine metabolic rate, RMR)和最大代谢率(Maximum metabolic rate, MMR)影响显著(P<0.05)、对代谢空间(Metabolic scope,MS)无显著影响(P>0.05),重复测定对MMR和MS均无显著影响(P>0.05);(4)低温驯化方向(6—12℃)生理参数的Q10值较大,而高温驯化方向(12—18℃)生理参数的Q10值较小。研究结果提示:(1)高温下秦岭细鳞鲑快速启动反应更为迅速,但该物种对低强度机械刺激主要采用静息而非逃逸的策略;(2)秦岭细鳞鲑游泳性能对温度变化的敏感性较高,游泳性能的最适温度估计介于12—18℃之间;(3)秦岭细鳞鲑具备较好的代谢恢复与重复运动能力,但总体上游泳性能较弱,可能易受生境水温和水流环境变化的限制。

Effects of temperature and repeat measurement on fast-start, swimming performance and post-exhaustion metabolic characteristics in Brachymystax lenok tsinlingensis

Temperature is one of the most important abiotic factors for ectothermic animals and has been called the "ecological master factor" for fish. In the context of global climate warming, the temperature adaptability of cold-water fish has become a focus of interest and concern. Brachymystax lenok tsinlingensis, a threatened fish in Qinling Mountain region, is a second-class state-protected wild animal in the China Red Data Book of Endangered Animals, and is generally regarded as one of the two southernmost-distributed Salmonid fish worldwide. Remarkably, the lowest elevation at which B. lenok tsinlingensis occurs has risen by about 300 m, likely reflecting shifting thermal ranges in response to changing climate. Although water temperature is crucial for the survival and distribution of B. lenok tsinlingensis, information on the thermal biology of this species remains largely unknown. In this study, we investigated the effects of temperature and repeat measurement on fitness-related parameters(i.e. fast-start, swimming performance and post-exhaustion metabolic characteristics) in B. lenok tsinlingensis. The results showed that:(1) the latency time(Tlatency) of fast-start in B. lenok tsinlingensis became shorter as the temperature increased(P<0.05), but temperature and repeat measurement had no significant effect on the reaction rate(R)(P>0.05).(2) Both gait transition speed(Ugait) and constant acceleration test speed(Ucat) were significantly affected by temperature(P<0.05), while those were not affected by repeat measurement(P>0.05).(3) Temperature had a significant effect on the routine metabolic rate(RMR) and the maximum metabolic rate(MMR)(P<0.05), but had no significant influence on the metabolic scope(MS)(P>0.05). Besides, the MS and MMR were not significantly affected by repeat measurement(P>0.05).(4) The Q10 values of physiological parameters was larger in the direction of low acclimation temperature(6—12℃), and smaller in the direction of high acclimation temperature(12—18℃). The results indicated that:(1) B. lenok tsinlingensis could react more rapidly at high temperature, but it mainly adopted the strategy of "keeping still" rather than escaping in response to the low-intensity mechanical stimulation.(2) The swimming performance of B. lenok tsinlingensis was sensitive to temperature changes, and the optimum temperature for swimming performance was estimated to be between 12℃ and 18℃.(3) B. lenok tsinlingensis showed excellent performance in metabolic recovery and repeat swimming performance, however, due to the relatively weak swimming ability of this species, it may be vulnerable to changes in habitat water temperature and flow environment.