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.

大气二氧化碳浓度持续升高正驱动海水碳酸盐体系发生改变，导致海水pCO2升高、pH值降低（即海洋酸化）。既往针对海洋生物的研究多聚焦于生物体对pCO2升高的短期生理响应，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造成的影响，对新环境的驯化与适应是亟需探讨的关键议题。本研究针对嗜冷海冰硅藻*Nitzschia lecointei*，探究了其在3种pCO2水平（280、390与960 µatm）下经过194天长期驯化（约60个无性世代）后的生理响应。驯化147天后，研究人员在pCO2为960 µatm的处理组中检测到小幅生长抑制。既往短期实验未能在*N. lecointei*中观测到高pCO2条件下的生长变化，这一结果凸显了实验时长在气候变化研究中的重要性。此外，长期驯化处理对该硅藻的碳代谢产生了显著影响，使得细胞释放的溶解有机碳（DOC）水平升高。与此同时，易分解有机碳的释放刺激了该系统中的细菌生产力。本研究得出如下结论：针对海洋酸化的长期驯化对*N. lecointei*具有重要意义，且在高CO2环境下，该生物体的碳过度消耗与溶解有机碳分泌现象可能会有所增强。