Abstract：
Natural temperature variation in many marine ecosystems is stochastic and unpredictable, and climate change models indicate that this thermal irregularity is likely to increase. Temperature acclimation may be more challenging when conditions are highly variable and stochastic, and there is a need for empirical physiological data in these thermal environments. Using the hermaphroditic, amphibious mangrove rivulus (Kryptolebias marmoratus), we hypothesized that compared with regular, warming diel thermal fluctuations, stochastic warm fluctuations would negatively affect physiological performance. To test this, we acclimated fish to: (1) non-stochastic and (2) stochastic thermal fluctuations with a similar thermal load (27-35°C), and (3) a stable/consistent control temperature at the low end of the cycle (27°C). We determined that fecundity was reduced in both cycles, with reproduction ceasing in stochastic thermal environments. Fish acclimated to non-stochastic thermal cycles had growth rates lower than those of control fish. Exposure to warm, fluctuating cycles did not affect emersion temperature, and only regular diel cycles modestly increased critical thermal tolerance. We predicted that warm diel cycling temperatures would increase gill surface area. Notably, fish acclimated to either thermal cycle had a reduced gill surface area and increased intralamellar cell mass when compared with control fish. This decreased gill surface area with warming contrasts with what is observed for exclusively aquatic fish and suggests a preparatory gill response for emersion in these amphibious fish. Collectively, our data reveal the importance of considering stochastic thermal variability when studying the effects of temperature on fishes.
摘要：
许多海洋生态系统中的自然温度变化是随机且不可预测的，气候变化模型表明这种热不规则性可能会增加。当条件是高度可变和随机的并且在这些热环境中需要经验生理数据时,温度适应可能更具挑战性。使用雌雄同体，两栖红树林（Kryptolebiasmarmoratus）我们假设与常规相比，变暖diel热波动，随机的温暖波动会对生理表现产生负面影响。为了测试这个，我们使鱼类适应：1）非随机和2）具有相似热负荷的随机热波动（27°C-35°C），和3)在循环低端的稳定/一致的控制温度(27°C)。我们确定在两个周期中繁殖力都降低了，在随机热环境中繁殖停止。适应非随机热循环的鱼的生长速率低于对照鱼。暴露于温暖，波动周期不会影响出现温度，只有规则的diel周期会适度增加临界耐热性（CTmax）。我们预测，温暖的diel循环温度会增加g表面积。值得注意的是,与对照鱼相比，适应任何一种热循环的鱼的g表面积减少，层内细胞质量（ILCM）增加。随着变暖，g表面积的减少与仅在水生鱼类中观察到的情况相反，这表明在这些两栖鱼类中出现的准备g反应。总的来说，我们的数据揭示了在研究温度对鱼类的影响时考虑随机热变异性的重要性。
