Campos D F, Val A L, Almeida-Val V M F
Laboratory of Ecophysiology and Molecular Evolution - Brazilian Institute for Research of the Amazon- Manaus, Brazil.
Laboratory of Ecophysiology and Molecular Evolution - Brazilian Institute for Research of the Amazon- Manaus, Brazil.
J Therm Biol. 2018 Feb;72:148-154. doi: 10.1016/j.jtherbio.2018.02.002. Epub 2018 Feb 5.
The metabolism of fishes is profoundly affected by environmental factors such as temperature, oxygen concentration, and pH levels. Also, biotic elements, for instance, activity levels of species, have been suggested to affect the energy demand, driving their capacity to support environmental challenges. The present work aims to investigate the effects of the lifestyle and swimming activities levels of fishes living in Amazon forest stream on the aerobic metabolism and thermal tolerance. Intermittent flow respirometry was used to measure routine metabolic rate and thermal maximum metabolic rate with a thermal ramp methodology. Critical thermal tolerance, thermal aerobic scope, and thermal factorial aerobic scope were calculated for twelve species belonging to different families. Our findings showed a correlation between routine and thermal maximum metabolic rate and, between metabolic rate and activity levels. Species belonging to Characidae and Crenuchidae families have high resting metabolic rates, which decrease their factorial aerobic scope and reduce their abilities to cope with warming events. Therefore, these species have low thermal tolerance. Instead, species from families Rivulidae and Cichlidae showed opposite metabolic results and larger thermal windows. We hypothesize that these responses are related to an evolutionary trade-off between lifestyle and energetic requirements and warming will favor species with low activity performance.
鱼类的新陈代谢受到温度、氧气浓度和pH值等环境因素的深刻影响。此外，生物因素，例如物种的活动水平，也被认为会影响能量需求，进而影响它们应对环境挑战的能力。本研究旨在调查生活在亚马逊森林溪流中的鱼类的生活方式和游泳活动水平对有氧代谢和热耐受性的影响。采用间歇流呼吸测定法，通过热梯度法测量常规代谢率和热最大代谢率。计算了12个不同科鱼类的临界热耐受性、热有氧范围和热因子有氧范围。我们的研究结果表明，常规代谢率和热最大代谢率之间以及代谢率和活动水平之间存在相关性。脂鲤科和溪脂鲤科的鱼类具有较高的静息代谢率，这降低了它们的因子有氧范围，并削弱了它们应对变暖事件的能力。因此，这些物种的热耐受性较低。相反，魣脂鲤科和丽鱼科的鱼类则表现出相反的代谢结果和更大的热窗口。我们推测，这些反应与生活方式和能量需求之间的进化权衡有关，变暖将有利于活动表现较低的物种。
