Physical Mechanisms Sustaining Silica Production Following the Demise of the Diatom Phase of the North Atlantic Spring Phytoplankton Bloom During EXPORTS
Brzezinski, Mark (University of California, Santa Barbara. Department of Ecology Evolution and Marine Biology)
Johnson, Leah (University of Washington)
Estapa, Margaret L. (University of Maine)
Clevenger, Samantha (Woods Hole Oceanographic Institution)
Roca Martí, Montserrat (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Romanelli, Elisa (University of California, Santa Barbara)
Buck, Kristen N. (Oregon State University)
Jenkins, Bethany D. (University of Rhode Island, Bay Campus)
Jones, Janice L. (University of California, Santa Barbara)

Data:	2024
Resum:	Each spring, the North Atlantic experiences one of the largest open-ocean phytoplankton blooms in the global ocean. Diatoms often dominate the initial phase of the bloom with succession driven by exhaustion of silicic acid. The North Atlantic was sampled over 3. 5 weeks in spring 2021 following the demise of the main diatom bloom, allowing mechanisms that sustain continued diatom contributions to be examined. Diatom biomass was initially relatively high with biogenic silica concentrations up to 2. 25 μmol Si L−1. A low initial silicic acid concentration of 0. 1-0. 3 μM imposed severe Si limitation of silica production and likely limited the diatom growth rate. Four storms over the next 3. 5 weeks entrained silicic acid into the mixed layer, relieving growth limitation, but uptake limitation persisted. Silica production was modest and dominated by the >5. 0 μm size fraction although specific rates were highest in the 0. 6-5. 0 μm size fraction over most of the cruise. Silica dissolution averaged 68% of silica production. The resupply of silicic acid via storm entrainment and silica dissolution supported a cumulative post-bloom silica production that was 32% of that estimated during the main bloom event. Diatoms contributed significantly to new and to primary production after the initial bloom, possibly dominating both. Diatom contribution to organic-carbon export was also significant at 40%-70%. Thus, diatoms can significantly contribute to regional biogeochemistry following initial silicic acid depletion, but that contribution relies on physical processes that resupply the nutrient to surface waters.
Ajuts:	Agència de Gestió d'Ajuts Universitaris i de Recerca 2021/BP-00109
Nota:	Unidad de excelencia María de Maeztu CEX2019-000940-M
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, i la comunicació pública de l'obra, sempre que no sigui amb finalitats comercials, i sempre que es reconegui l'autoria de l'obra original. No es permet la creació d'obres derivades.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Diatom bloom ; Diatoms ; North Atlantic bloom ; Particle export ; Silica cycling
Publicat a:	Global biogeochemical cycles, Vol. 38, Issue 7 (July 2024) , art. e2023GB008048, ISSN 1944-9224

DOI: 10.1029/2023GB008048

22 p, 2.9 MB

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