硅藻在南大洋次极地边缘地带的低效转移
英国国家海洋学中心Martin, A. P.研究团队在研究中取得进展。他们报道了硅藻在南大洋次极地边缘地带的低效转移。该研究于2024年11月28日发表于国际一流学术期刊《自然—地球科学》杂志上。
南大洋是气候变化的高度脆弱区域，通过生物碳泵在调节全球营养循环和大气二氧化碳方面，发挥着至关重要的作用。硅藻是光合作用活跃的浮游生物，具有致密的蛋白石骨架，是这一过程的关键，因为它们的外骨骼被认为可以增强颗粒有机碳向深海的转移，使它们成为碳储存的主要载体。然而，相互矛盾的观察模糊了硅藻、蛋白石和颗粒有机碳通量之间的机制联系，特别是在通量损失最大的过渡带。
研究人员报道了来自南大洋亚极地不同区域的春季通量的直接测量结果，表明在亚极地边缘地带的大片地区，碳被有效地转移到深海，尽管不是通过硅藻。相反，蛋白石被保留在海洋表面附近，这表明硅藻浮力调节和食草动物改变等过程可以抵消硅藻骨架的压载作用。
他们的研究结果强调，在南大洋最大的生物群系的地表水中，硅藻的存在并不能保证它们作为通过亚极地过渡带有效碳转移载体的重要性。气候变化驱动的浮游植物群落组成变化对生物封存碳库的影响，可能比目前预测的要小。
附：英文原文
Title: Inefficient transfer of diatoms through the subpolar Southern Ocean twilight zone
Author: Williams, J. R., Giering, S. L. C., Baker, C. A., Pabortsava, K., Briggs, N., East, H., Espinola, B., Blackbird, S., Le Moigne, F. A. C., Villa-Alfageme, M., Poulton, A. J., Carvalho, F., Pebody, C., Saw, K., Moore, C. M., Henson, S. A., Sanders, R., Martin, A. P.
Issue&Volume: 2024-11-28
Abstract: The Southern Ocean, a region highly vulnerable to climate change, plays a vital role in regulating global nutrient cycles and atmospheric CO2 via the biological carbon pump. Diatoms, photosynthetically active plankton with dense opal skeletons, are key to this process as their exoskeletons are thought to enhance the transfer of particulate organic carbon to depth, positioning them as major vectors of carbon storage. Yet conflicting observations obscure the mechanistic link between diatoms, opal and particulate organic carbon fluxes, especially in the twilight zone where greatest flux losses occur. Here we present direct springtime flux measurements from different sectors of the subpolar Southern Ocean, demonstrating that across large areas of the subpolar twilight zone, carbon is efficiently transferred to depth, albeit not by diatoms. Rather, opal is retained near the surface ocean, indicating that processes such as diatom buoyancy regulation and grazer repackaging can negate ballast effects of diatoms’ skeletons. Our results highlight that the presence of diatoms in surface waters of the Southern Ocean’s largest biome does not guarantee their importance as vectors for efficient carbon transfer through the subpolar twilight zone. Climate change-driven shifts in phytoplankton community composition may affect biologically sequestered carbon pools less than currently predicted.
DOI: 10.1038/s41561-024-01602-2
Source: https://www.nature.com/articles/s41561-024-01602-2
来源：科学网 小柯机器人
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