College of Life Sciences, Qingdao University, Qingdao, PR China.
PLoS One. 2020 Jul 10;15(7):e0235755. doi: 10.1371/journal.pone.0235755. eCollection 2020.
As a widespread phytoplankton species, the coccolithophore Gephyrocapsaoceanica has a significant impact on the global biogeochemical cycle through calcium carbonate precipitation and photosynthesis. As global change continues, marine phytoplankton will experience alterations in multiple parameters, including temperature, pH, CO2, and nitrogen sources, and the interactive effects of these variables should be examined to understand how marine organisms will respond to global change. Here, we show that the specific growth rate of G. oceanica is reduced by elevated CO2 (1000 μatm) in [Formula: see text]-grown cells, while it is increased by high CO2 in [Formula: see text]-grown ones. This difference was related to intracellular metabolic regulation, with decreased cellular particulate organic carbon and particulate organic nitrogen (PON) content in the [Formula: see text] and high CO2 condition compared to the low CO2 condition. In contrast, no significant difference was found between the high and low CO2 levels in [Formula: see text] cultures (p > 0.05). The temperature increase from 20°C to 25°C increased the PON production rate, and the enhancement was more prominent in [Formula: see text] cultures. Enhanced or inhibited particulate inorganic carbon production rate in cells supplied with [Formula: see text] relative to [Formula: see text] was observed, depending on the temperature and CO2 condition. These results suggest that a greater disruption of the organic carbon pump can be expected in response to the combined effects of increased [Formula: see text]/[Formula: see text] ratio, temperature, and CO2 level in the oceans of the future. Additional experiments conducted under nutrient limitation conditions are needed before we can extrapolate our findings to the global oceans.
作为一种广泛分布的浮游植物，颗石藻通过碳酸钙沉淀和光合作用对全球生物地球化学循环有重大影响。随着全球变化的持续，海洋浮游植物将经历多个参数的变化，包括温度、pH 值、CO2 和氮源，并且应该检查这些变量的交互作用，以了解海洋生物将如何应对全球变化。在这里，我们表明，在 [Formula: see text] 培养的细胞中，升高的 CO2（1000 μatm）会降低颗石藻 G. oceanica 的比生长速率，而在 [Formula: see text] 培养的细胞中则会升高。这种差异与细胞内代谢调节有关，与低 CO2 条件相比，[Formula: see text] 中高 CO2 条件下细胞的颗粒有机碳和颗粒有机氮（PON）含量降低。相比之下，在 [Formula: see text] 培养物中，高 CO2 和低 CO2 水平之间没有发现显著差异（p > 0.05）。从 20°C 升高到 25°C 会增加 PON 的产生速率，而在 [Formula: see text] 培养物中增强更为明显。根据温度和 CO2 条件，观察到与 [Formula: see text] 相比，[Formula: see text] 中细胞的颗粒无机碳产生速率增强或抑制。这些结果表明，未来海洋中[Formula: see text]/[Formula: see text] 比值、温度和 CO2 水平的综合效应可能导致有机碳泵更大的破坏。在我们能够将我们的发现推断到全球海洋之前，还需要在营养限制条件下进行额外的实验。
