Cai Ting, Feng Yuanyuan, Wang Yanan, Li Tongtong, Wang Jiancai, Li Wei, Zhou Weihua
School of Oceanography, Shanghai Jiao Tong University, Shanghai, China.
Key Laboratory of Marine Ecosystem Dynamics, Ministry of Natural Resources, Hangzhou, China.
Front Microbiol. 2022 Jun 21;13:851149. doi: 10.3389/fmicb.2022.851149. eCollection 2022.
Marine diatoms are one of the marine phytoplankton functional groups, with high species diversity, playing important roles in the marine food web and carbon sequestration. In order to evaluate the species-specific responses of coastal diatoms to the combined effects of future ocean acidification (OA) and warming on the coastal diatoms, we conducted a semi-continuous incubation on the large centric diatom sp. (30 μm) and small pennate diatom (15 μm). A full factorial combination of two temperature levels (15 and 20°C) and pCO (400 and 1,000 ppm) was examined. The results suggest that changes in temperature played a more important role in regulating the physiology of sp. and than CO. For sp., elevated temperature significantly reduced the cellular particulate organic carbon (POC), particulate organic nitrogen (PON), particulate organic phosphate (POP), biogenic silica (BSi), chlorophyll a (Chl ), and protein contents, and the C:N ratio. CO only had significant effects on the growth rate and the protein content. However, for the smaller pennate diatom , the growth rate, POC production rate, and the C:P ratio significantly increased with an elevated temperature, whereas the cellular POP and BSi contents significantly decreased. CO had significant effects on the POC production rate, cellular BSi, POC, and PON contents, the C:P, Si:C, N:P, and Si:P ratios, and sinking rate. The interaction between OA and warming showed mostly antagonistic effects on the physiology of both species. Overall, by comparison between the two species, CO played a more significant role in regulating the growth rate and sinking rate of the large centric diatom sp., whereas had more significant effects on the elemental compositions of the smaller pennate diatom . These results suggest differential sensitivities of different diatom species with different sizes and morphology to the changes in CO/temperature regimes and their interactions.
海洋硅藻是海洋浮游植物功能群之一，具有高度的物种多样性，在海洋食物网和碳固存中发挥着重要作用。为了评估沿海硅藻对未来海洋酸化（OA）和变暖共同作用的物种特异性响应，我们对大型中心硅藻（约30 μm）和小型羽纹硅藻（约15 μm）进行了半连续培养。研究了两个温度水平（15和20°C）和pCO₂（400和1000 ppm）的全因子组合。结果表明，温度变化在调节硅藻的生理方面比CO₂发挥了更重要的作用。对于大型中心硅藻，温度升高显著降低了细胞颗粒有机碳（POC）、颗粒有机氮（PON）、颗粒有机磷（POP）、生物源硅（BSi）、叶绿素a（Chl）和蛋白质含量以及C:N比。CO₂仅对生长速率和蛋白质含量有显著影响。然而，对于较小的羽纹硅藻，生长速率、POC生产率和C:P比随温度升高而显著增加，而细胞POP和BSi含量显著降低。CO₂对POC生产率、细胞BSi、POC和PON含量、C:P、Si:C、N:P和Si:P比以及沉降速率有显著影响。OA和变暖之间的相互作用对两种硅藻的生理大多表现为拮抗作用。总体而言，通过两种硅藻的比较，CO₂在调节大型中心硅藻的生长速率和沉降速率方面发挥了更显著的作用，而对较小的羽纹硅藻的元素组成有更显著的影响。这些结果表明，不同大小和形态的硅藻物种对CO₂/温度变化及其相互作用具有不同的敏感性。
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