Iron Availability Influences the Tolerance of Southern Ocean Phytoplankton to Warming and Elevated Irradiance
Iron Availability Influences the Tolerance of Southern Ocean Phytoplankton to Warming and Elevated Irradiance
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DOI：
10.3389/fmars.2019.00681
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发表时间：
2019-11-01
影响因子：
3.7
通讯作者：
Ellwood, Michael J.
中科院分区：
文献类型：
--
作者：
Andrew, Sarah M.;Morell, Hugh T.;Ellwood, Michael J.
南大洋通过生物和物理过程吸收了约 40% 的海洋碳。在南大洋，浮游植物的生长受到低铁 (Fe) 和光照供应的限制。南大洋气候模型预测表明，由于人为二氧化碳排放量的增加，未来温度、水下辐照度和铁供应可能会同时发生变化。这些环境特性对浮游植物生理学的个体影响已得到广泛研究，利用南大洋浮游植物进行的培养研究表明，温度和铁将在未来条件下的生长过程中发挥关键作用。为了探索南大洋浮游植物对这些环境变化的潜在反应，我们在两种光和铁组合以及一系列温度下培养了触生植物南极棕囊藻和硅藻弯曲角毛藻、无刺长鼻藻和南极海链藻。我们的研究表明，南大洋主要浮游植物的热响应曲线是多种多样的，在5摄氏度时测得最高生长率（隔离地点的年温度范围目前为1-4摄氏度）。变暖对光系统 II (PSII; F-v/F-m) 的光化学效率、PSII 的功能吸收截面 (sigma(PSII))、碳氮比和细胞叶绿素 a 浓度具有物种特异性影响。铁的可用性通过提高生长上限并随后增加每个物种栖息的热生态位来提高物种耐受温暖条件的能力。
The Southern Ocean is responsible for approximately 40% of oceanic carbon uptake through biological and physical processes. In the Southern Ocean, phytoplankton growth is limited by low iron (Fe) and light supply. Climate model projections for the Southern Ocean indicate that temperature, underwater irradiance and Fe supply are likely to change simultaneously in the future due to increasing anthropogenic carbon dioxide emissions. The individual effects of these environmental properties on phytoplankton physiology have been extensively researched, and culturing studies using Southern Ocean phytoplankton have shown that temperature and Fe will play a key role on setting growth under future conditions. To explore the potential responses of Southern Ocean phytoplankton to these environmental changes, we cultured the haptophyte Phaeocystis antarctica and the diatoms Chaetoceros flexuosus, Proboscia inermis, and Thalassiosira antarctica under two light and iron combinations and over a range of temperatures. Our study revealed that the thermal response curves of key Southern Ocean phytoplankton are diverse, with the highest growth rates measured at 5 degrees C (the annual temperature range at the isolation sites is currently 1-4 degrees C). Warming had species-specific effects on the photochemical efficiency of photosystem II (PSII; F-v/F-m), the functional absorption cross-section of PSII (sigma(PSII)), carbon:nitrogen ratio and cellular Chlorophyll a concentrations. Iron availability increased species' ability to tolerate warmer conditions by increasing the upper limit for growth and subsequently increasing the thermal niche that each species inhabit.