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Molecular underpinnings and biogeochemical consequences of enhanced diatom growth in a warming Southern Ocean [Environmental Sciences]
Proceedings of the National Academy of Sciences of the United States of America ( IF 11.1 ) Pub Date : 2021-07-27 , DOI: 10.1073/pnas.2107238118
Loay J Jabre 1 , Andrew E Allen 2, 3 , J Scott P McCain 1 , John P McCrow 4 , Nancy Tenenbaum 5 , Jenna L Spackeen 6 , Rachel E Sipler 6, 7, 8 , Beverley R Green 9 , Deborah A Bronk 6, 8 , David A Hutchins 10 , Erin M Bertrand 11
Affiliation  

The Southern Ocean (SO) harbors some of the most intense phytoplankton blooms on Earth. Changes in temperature and iron availability are expected to alter the intensity of SO phytoplankton blooms, but little is known about how these changes will influence community composition and downstream biogeochemical processes. We performed light-saturated experimental manipulations on surface ocean microbial communities from McMurdo Sound in the Ross Sea to examine the effects of increased iron availability (+2 nM) and warming (+3 and +6 °C) on nutrient uptake, as well as the growth and transcriptional responses of two dominant diatoms, Fragilariopsis and Pseudo-nitzschia. We found that community nutrient uptake and primary productivity were elevated under both warming conditions without iron addition (relative to ambient −0.5 °C). This effect was greater than additive under concurrent iron addition and warming. Pseudo-nitzschia became more abundant under warming without added iron (especially at 6 °C), while Fragilariopsis only became more abundant under warming in the iron-added treatments. We attribute the apparent advantage Pseudo-nitzschia shows under warming to up-regulation of iron-conserving photosynthetic processes, utilization of iron-economic nitrogen assimilation mechanisms, and increased iron uptake and storage. These data identify important molecular and physiological differences between dominant diatom groups and add to the growing body of evidence for Pseudo-nitzschia’s increasingly important role in warming SO ecosystems. This study also suggests that temperature-driven shifts in SO phytoplankton assemblages may increase utilization of the vast pool of excess nutrients in iron-limited SO surface waters and thereby influence global nutrient distribution and carbon cycling.



中文翻译:

南大洋变暖中硅藻生长增强的分子基础和生物地球化学后果 [环境科学]

南大洋 (SO) 拥有地球上一些最强烈的浮游植物繁殖。预计温度和铁可用性的变化会改变 SO 浮游植物大量繁殖的强度,但对这些变化将如何影响群落组成和下游生物地球化学过程知之甚少。我们对罗斯海麦克默多湾的表层海洋微生物群落进行了光饱和实验操作,以检查铁可用性增加 (+2 nM) 和变暖 (+3 和 +6 °C) 对养分吸收的影响,以及两种优势硅藻的生长和转录反应,FragilariopsisPseudo-nitzschia. 我们发现,在没有添加铁的两种变暖条件下(相对于环境 -0.5 °C),群落养分吸收和初级生产力均有所提高。在同时添加铁和加热的情况下,这种效果大于添加效果。Pseudo-nitzschia在不添加铁的情况下(尤其是在 6°C 下)在变暖下变得更加丰富,而Fragilariopsis在添加铁的处理中仅在变暖下变得更加丰富。我们归因于明显的优势Pseudo-nitzschia表明在升温条件下,铁保存光合作用过程的上调,铁经济氮同化机制的利用,以及铁吸收和储存的增加。这些数据确定了主要硅藻群之间的重要分子和生理差异,并为Pseudo-nitzschia在使 SO 生态系统变暖方面发挥越来越重要的作用提供了越来越多的证据。这项研究还表明,温度驱动的 SO 浮游植物组合的变化可能会增加对铁含量有限的 SO 地表水中大量过量营养物的利用,从而影响全球营养物分布和碳循环。

更新日期:2021-07-24
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