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155107 - Enhanced silica export in a future ocean triggers global diatom.pdf (8.37 MB)

Enhanced silica export in a future ocean triggers global diatom decline

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posted on 2023-05-21, 16:03 authored by Taucher, J, Lennart BachLennart Bach, Prowe, AEF, Boxhammer, T, Kvale, K, Riebesell, U
Diatoms account for up to 40% of marine primary production and require silicic acid to grow and build their opal shell. On the physiological and ecological level, diatoms are thought to be resistant to, or even benefit from, ocean acidification. Yet, global-scale responses and implications for biogeochemical cycles in the future ocean remain largely unknown. Here we conducted five in situ mesocosm experiments with natural plankton communities in different biomes and find that ocean acidification increases the elemental ratio of silicon (Si) to nitrogen (N) of sinking biogenic matter by 17 ± 6 per cent under pCO2 conditions projected for the year 2100. This shift in Si:N seems to be caused by slower chemical dissolution of silica at decreasing seawater pH. We test this finding with global sediment trap data, which confirm a widespread influence of pH on Si:N in the oceanic water column. Earth system model simulations show that a future pH-driven decrease in silica dissolution of sinking material reduces the availability of silicic acid in the surface ocean, triggering a global decline of diatoms by 13–26 per cent due to ocean acidification by the year 2200. This outcome contrasts sharply with the conclusions of previous experimental studies, thereby illustrating how our current understanding of biological impacts of ocean change can be considerably altered at the global scale through unexpected feedback mechanisms in the Earth system.

Funding

Australian Research Council

History

Publication title

Nature

Volume

605

Pagination

696–700

ISSN

0028-0836

Department/School

Institute for Marine and Antarctic Studies

Publisher

Nature Publishing Group

Place of publication

Macmillan Building, 4 Crinan St, London, England, N1 9Xw

Rights statement

© The Author(s) 2022, corrected publication 2022. This article is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0) License, https://creativecommons.org/licenses/by/4.0/ which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Repository Status

  • Open

Socio-economic Objectives

Assessment and management of pelagic marine ecosystems

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