Can intense storms affect sinking particle dynamics after the North Atlantic spring bloom?

Romanelli, Elisa; Giering, Sarah Lou Carolin ORCID: https://orcid.org/0000-0002-3090-1876; Estapa, Margaret; Siegel, David A.; Passow, Uta. 2024 Can intense storms affect sinking particle dynamics after the North Atlantic spring bloom? Limnology and Oceanography. https://doi.org/10.1002/lno.12723

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Text © 2024 The Author(s). Limnology and Oceanography published by Wiley Periodicals LLCon behalf of Association for the Sciences of Limnology and Oceanography Limnology Oceanography - 2024 - Romanelli - Can intense storms affect sinking particle dynamics after the North Atlantic.pdf - Published Version Available under License Creative Commons Attribution Non-commercial No Derivatives 4.0. Download (1MB) | Preview

Abstract/Summary

The sinking of large particles (i.e., marine snow) has long been recognized as a key pathway for efficient particulate organic carbon (POC) export to the ocean interior during the decline of spring diatom blooms. Recent work has suggested that particles smaller than marine snow can also substantially contribute to POC export. However, a detailed characterization of small and large sinking particles at the end of blooms is missing. Here, we separately collected suspended and small and large sinking particles using Marine Snow Catchers and assessed their biogeochemical composition after the North Atlantic spring bloom in May 2021. During the 3 weeks of sampling, when four intense storms (maximum wind speeds 37–50 kt) created high turbulent kinetic energy dissipation rates and deepened the mixed layer, we observed two distinct sedimentation events. At first, sinking particles were dominated by small (diameter < 0.1 mm), slowly sinking ( 18 m d−1), particles rich in silica that carried a moderate POC flux (< 6 mmol C m−2 d−1) to 500 m depth. Once the storms ceased, the volume of large (diameter > 0.1 mm), fast-sinking (> 75 m d−1), carbon-rich marine snow aggregates (not fecal pellets) increased exponentially and POC fluxes at 100 m depth were more than fourfold greater (30 ± 12 mmol C m−2 d−1) than those during the previous event. The aggregates consisted of a mixed post-bloom plankton community. Our data suggest that the storms shaped the timing, type, and magnitude of POC flux at the end of this spring phytoplankton bloom.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1002/lno.12723
ISSN:	0024-3590
Date made live:	12 Nov 2024 16:41 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/538365

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