Coastal waters undergo dynamic changes in seawater carbonate chemistry due to natural and anthropogenic factors. Despite this, our current understanding of how coastal phytoplankton respond to fluctuating pH is limited. In the present study, we investigated the physiological responses of two coastal diatoms and to seawater acidification and diurnally fluctuating pH under natural solar irradiance. Seawater acidification did not significantly impact the growth, maximum and effective quantum yield of PSII, and photosynthetic rates of the two species. However, it did increase the maximum relative electron transport rate of by 11%. Overall, fluctuating pH had neutral or positive effects on both species. It enhanced the light-saturated photosynthetic rate of by 20% compared to cells grown under seawater acidification condition. Results from the short-term pH exposure experiment revealed that the photosynthetic rates of both species remained unaffected by acute pH changes, indicating their tolerance to varying pH. Nevertheless, it is crucial to consider dynamic pH when predicting changes in primary production in coastal waters, given the interplay of various environmental drivers.

中文翻译：

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动态光照条件和海洋酸化场景下两种海洋硅藻对昼夜pH波动的耐受性

由于自然和人为因素，沿海水域的海水碳酸盐化学性质发生动态变化。尽管如此，我们目前对沿海浮游植物如何响应 pH 值波动的了解还有限。在本研究中，我们研究了两种沿海硅藻在自然太阳辐照度下对海水酸化和 pH 值昼夜波动的生理反应。海水酸化并没有显着影响PSII的生长、最大和有效量子产率以及两个物种的光合速率。然而，它确实将最大相对电子传输速率提高了 11%。总体而言，pH 值波动对这两个物种均产生中性或积极影响。与海水酸化条件下生长的细胞相比，其光饱和光合速率提高了20%。短期 pH 值暴露实验的结果表明，两个物种的光合速率均未受到 pH 值急剧变化的影响，表明它们对 pH 值变化的耐受性。然而，考虑到各种环境驱动因素的相互作用，在预测沿海水域初级生产变化时考虑动态 pH 值至关重要。