Data from: Long-term acclimation to elevated pCO2 alters carbon metabolism and reduces growth in the Antarctic diatom Nitzschia lecointei

Increasing atmospheric CO2 levels are driving changes in the seawater carbonate system, resulting in higher pCO2 and reduced pH (ocean acidification). Many studies on marine organisms have focused on short-term physiological responses to increased pCO2, and few on slow-growing polar organisms with a relative low adaptation potential. In order to recognize the consequences of climate change in biological systems, acclimation and adaptation to new environments are crucial to address. In this study, physiological responses to long-term acclimation (194 days, approx. 60 asexual generations) of three pCO2 levels (280, 390 and 960 µatm) were investigated in the psychrophilic sea ice diatom Nitzschia lecointei. After 147 days, a small reduction in growth was detected at 960 µatm pCO2. Previous short-term experiments have failed to detect altered growth in N. lecointei at high pCO2, which illustrates the importance of experimental duration in studies of climate change. In addition, carbon metabolism was significantly affected by the long-term treatments, resulting in higher cellular release of dissolved organic carbon (DOC). In turn, the release of labile organic carbon stimulated bacterial productivity in this system. We conclude that long-term acclimation to ocean acidification is important for N. lecointei and that carbon overconsumption and DOC exudation may increase in a high-CO2 world.大气二氧化碳浓度升高正驱动海水碳酸盐体系发生变化，导致海水二氧化碳分压（partial pressure of carbon dioxide, pCO2）升高、pH值降低（即海洋酸化）。当前海洋生物相关研究多聚焦于生物体对升高pCO2的短期生理响应，针对生长缓慢、适应潜力相对较低的极地生物的相关研究则较为匮乏。为明晰气候变化对生物系统的影响，探究生物对新环境的驯化与适应机制至关重要。本研究以嗜冷海冰硅藻莱科特菱形藻（Nitzschia lecointei）为研究对象，探究了其在3个pCO2梯度（280、390与960 µatm）下经过194天（约60个无性繁殖世代）长期驯化后的生理响应。培养至147天时，在960 µatm pCO2处理组中检测到小幅生长抑制现象。此前的短期实验未能在莱科特菱形藻中观测到高pCO2对生长的影响，这一结果凸显了实验时长在气候变化相关研究中的重要性。此外，长期高pCO2处理显著影响了该硅藻的碳代谢过程，导致细胞释放更多溶解性有机碳（dissolved organic carbon, DOC）。而易降解有机碳的释放会进一步促进该系统内细菌的生产力。本研究最终得出结论：长期驯化适应海洋酸化对莱科特菱形藻至关重要，在高二氧化碳世界中，碳过度摄取与溶解性有机碳分泌现象可能会显著增加。