Coastal organisms reside in highly dynamic habitats. Global climate change is expected to alter not only the mean of the physical conditions experienced but also the frequencies and/or the magnitude of fluctuations of environmental factors. Understanding responses in an ecologically relevant context is essential for formulating management strategies. In particular, there are increasing suggestions that exposure to fluctuations could alleviate the impact of climate change-related stressors by selecting for plasticity that may help acclimatization to future conditions. However, it remains unclear whether the presence of fluctuations alone is sufficient to confer such effects or whether the pattern of the fluctuations matters. Therefore, we investigated the role of frequency and initial conditions of the fluctuations on performance by exposing larval sea urchin Heliocidaris crassispina to either constant or fluctuating pH. Reduced pH alone (pH 7.3 vs 8.0) did not affect larval mortality but reduced the growth of larval arms in the static pH treatments. Changes in morphology could affect the swimming mechanics for these small organisms, and geometric morphometric analysis further suggested an overall shape change such that acidified larvae had more U-shaped bodies and shorter arms, which would help maintain stability in moving water. The relative negative impact of lower pH, computed as log response ratio, on larval arm development was smaller when larvae were exposed to pH fluctuations, especially when the change was less frequent (48- vs 24-h cycle). Furthermore, larvae experiencing an initial pH drop, i.e. those where the cycle started at pH 8.0, were more negatively impacted compared with those kept at an initial pH of 7.3 before the cycling started. Our observations suggest that larval responses to climate change stress could not be easily predicted from mean conditions. Instead, to better predict organismal performance in the future ocean, monitoring and investigation of the role of real-time environmental fluctuations along the dispersive pathway is key.

中文翻译：

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时间变异性调节pH值对幼虫海胆发育的影响：主题文章：生物力学与气候变化

沿海生物栖息于高度动态的栖息地。预计全球气候变化不仅会改变所经历的自然条件的平均值，而且还会改变环境因素波动的频率和/或幅度。了解与生态相关的环境中的响应对于制定管理策略至关重要。尤其是，越来越多的建议认为，承受波动可能会通过选择可帮助适应未来条件的可塑性来减轻与气候变化有关的压力源的影响。但是，目前尚不清楚仅存在波动是否足以产生这种影响，或者波动的模式是否重要。因此，鸡血吸虫保持恒定或波动的pH值。单独降低pH值（pH 7.3 vs 8.0）不会影响幼虫死亡率，但会降低静态pH处理中幼虫臂的生长。形态变化可能会影响这些小生物的游泳力学，几何形态分析进一步表明总体形状发生变化，使酸化的幼虫具有更多的U形体和较短的臂，这将有助于维持流动水中的稳定性。当幼虫暴露于pH波动时，尤其是当变化频率较低时（48-vs 24-h周期），较低的pH（以log响应比计算）对幼虫臂发育的相对负面影响较小。此外，与保持初始pH值为7的幼虫相比，经历初始pH下降的幼虫（即在pH 8.0开始循环的幼虫）受到的负面影响更大。骑车开始前3。我们的观察结果表明，从平均条件很难预测幼虫对气候变化压力的反应。相反，为了更好地预测未来海洋中的生物表现，监测和调查实时环境波动沿分散路径的作用至关重要。