ARC Centre of Excellence for Coral Reef Studies, James Cook Drive, Douglas 4814, James Cook University, QLD, Australia
ARC Centre of Excellence for Coral Reef Studies, James Cook Drive, Douglas 4814, James Cook University, QLD, Australia.
J Exp Biol. 2019 Aug 23;222(Pt 16):jeb202713. doi: 10.1242/jeb.202713.
Marine heatwaves, which are increasing in frequency, duration and intensity owing to climate change, are an imminent threat to marine ecosystems. On coral reefs, heatwave conditions often coincide with periods of peak recruitment of juvenile fishes and exposure to elevated temperature may affect their development. However, whether differences in the duration of high temperature exposure have effects on individual performance is unknown. We exposed juvenile spiny damselfish, , to increasing lengths of time (3, 7, 30 and 108 days post-hatching) of elevated temperature (+2°C). After 108 days, we measured escape performance at present-day control and elevated temperatures, standard length, mass and critical thermal maximum. Using a Bayesian approach, we show that 30 days or more exposure to +2°C leads to improved escape performance, irrespective of performance temperature, possibly owing to developmental effects of high temperature on muscle development and/or anaerobic metabolism. Continued exposure to elevated temperature for 108 days caused a reduction in body size compared with the control, but not in fish exposed to high temperature for 30 days or less. By contrast, exposure to elevated temperatures for any length of time had no effect on critical thermal maximum, which, combined with previous work, suggests a short-term physiological constraint of ∼37°C in this species. Our study shows that extended exposure to increased temperature can affect the development of juvenile fishes, with potential immediate and future consequences for individual performance.
海洋热浪由于气候变化而变得越来越频繁、持续时间越来越长且强度越来越大，这对海洋生态系统构成了迫在眉睫的威胁。在珊瑚礁上，热浪条件通常与幼年鱼类的繁殖高峰期相吻合，而高温暴露可能会影响它们的发育。然而，高温暴露时间的长短是否会对个体表现产生影响尚不清楚。我们让幼年的棘尾鱼暴露在不同时长的高温环境中（孵化后 3、7、30 和 108 天），温度升高了 2°C。在 108 天后，我们在当前控制温度和升高温度下测量了它们的逃避表现、标准体长、体重和临界热最大值。使用贝叶斯方法，我们表明 30 天或更长时间的 2°C 高温暴露会导致逃避表现的改善，而与表现温度无关，这可能是由于高温对肌肉发育和/或无氧代谢的发育影响所致。与对照组相比，持续暴露在高温下 108 天会导致体型缩小，但在高温暴露 30 天或更短时间的鱼中则不会。相比之下，任何时长的高温暴露都不会对临界热最大值产生影响，这与之前的工作相结合，表明该物种的短期生理限制约为 37°C。我们的研究表明，延长暴露在高温下会影响幼年鱼类的发育，对个体表现产生直接和未来的潜在影响。
