Diel vertical migration exposes zooplankton to fluctuating environmental conditions. In our study, we investigated the physiological costs of diel temperature fluctuations of vertical migration in the neritic marine copepod Centropages typicus, and checked whether the direct effects of fluctuating temperature on copepod performance may differ from those of average temperature conditions (Jensen’s inequality). We determined the rates of egestion, egg production, and respiration of copepods exposed to four temperature regimes including one treatment that simulated diel vertical migration (DVM, 10 h at 14 °C and 14 h at 19 °C) and three treatments with constant temperature (14, 17 and 19 °C). We found that the physiological performance of C. typicus was not significantly different between fluctuating (DVM) and average (17 °C) temperature conditions, thus indicating that differences between varying and average temperature effects might not emerge in migrant zooplankton exposed to thermal variations of moderate magnitude (5 ºC). The copepods exposed to fluctuating temperature mimicking vertical migration (DVM) showed better performance (e.g. higher egg production) than those exposed to constant depth conditions (14 °C); however, no significant differences were detected when compared to constant surface conditions (19 °C). Our study indicates that neritic marine copepods experiencing daily moderate temperature fluctuations through vertical migration may not suffer physiological costs due to temperature associated with this behaviour. In this sense, these animals might have physiological mechanisms to compensate diel temperature fluctuations, which would represent a particularly relevant preadaptation to cope with the increased thermal variability predicted in future climates.

Diel 垂直迁移使浮游动物暴露于波动的环境条件。在我们的研究中，我们调查了浅海海洋桡足类Centropapages typicus中垂直迁移的昼夜温度波动的生理成本，并检查了温度波动对桡足类性能的直接影响是否可能不同于平均温度条件（詹森不等式）。我们确定了暴露于四种温度条件下的桡足类的排卵、产蛋率和呼吸速率，包括一种模拟昼夜垂直迁移的处理（DVM，14°C 下 10 小时和 19°C 下 14 小时）和三种恒温处理（14、17 和 19 °C）。我们发现C. typicus的生理表现波动 (DVM) 和平均 (17 °C) 温度条件之间没有显着差异，因此表明在暴露于中等幅度 (5 ºC) 热变化的迁徙浮游动物中，变化和平均温度效应之间的差异可能不会出现。与暴露于恒定深度条件（14°C）的桡足类相比，暴露于模拟垂直迁移（DVM）的波动温度下的桡足类表现出更好的性能（例如更高的产蛋量）；然而，与恒定的表面条件 (19 °C) 相比，没有检测到显着差异。我们的研究表明，通过垂直迁移经历每日适度温度波动的浅海海洋桡足类可能不会因与这种行为相关的温度而遭受生理成本。在这个意义上说，