2025-12-16 カリフォルニア大学サンタバーバラ校（UCSB）
＜関連情報＞
- https://news.ucsb.edu/2025/022298/stormy-ocean-voyage-yields-insights-global-carbon-cycle
- https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025GB008676
現場粒子画像を用いた北大西洋春季ブルームの終息期における海洋雪の動態の評価 Assessing Marine Snow Dynamics During the Demise of the North Atlantic Spring Bloom Using In Situ Particle Imagery
D. A. Siegel, A. B. Burd, M. L. Estapa, E. Fields, L. Johnson, U. Passow, E. Romanelli, M. A. Brzezinski, K. O. Buesseler, S. J. Clevenger, I. Cetinić, L. Drago, C. A. Durkin, R. Kiko, S. J. Kramer …
Global Biogeochemical Cycles Published: 19 November 2025
DOI:https://doi.org/10.1029/2025GB008676
Abstract
The ocean’s biological pump, a critical component of the Earth’s carbon cycle, transports organic matter from the surface ocean to depth and is dominated by sinking particles, often in the form of marine snow-sized (diameter ≥0.5 mm) aggregates. Controls of sinking particle carbon export are thought to be driven largely using ecological processes that create and transform sinking particles. We diagnose the importance of both biotic and abiotic processes in the dynamics of marine snow and other suspended particles using image-based determination of their size distribution. These observations were made during the demise of the North Atlantic spring bloom in May 2021 as part of the Export Processes in the Ocean from RemoTe Sensing-North Atlantic (EXPORTS-NA) field campaign. We show that intense storm events generated high turbulent mixing rates in the upper ocean that impacted the abundance, size distribution, porosity and sinking of marine snow. Mixed-layer turbulence levels both created and destroyed marine snow and the sequence of entrainment and detrainment of the mixed layer induced by repeated storm forcings enhanced the vertical transport of aggregates to depth. Evidence of biological transformations was also observed at mesopelagic depths, both for the consumption of particulate matter and in the creation of smaller particles from larger ones, likely due to interactions with zooplankton. Collectively, these results illustrate the complex interplay of physical and biological processes regulating the dynamics of marine snow and suggest their inclusion in predictive models of the ocean’s biological pump.
Plain Language Summary
The ocean’s biological pump is a critical component of the Earth’s carbon cycle, transporting roughly 10 Gigatons of organic carbon from the ocean’s surface layers to its interior, where it is sequestered from the atmosphere for months to millennia. The dominant pathway for the biological pump is via the sinking of organic particles and marine snow, which are amalgamations of largely detrital materials larger than one-half of a millimeter in diameter. Here, we address the dynamics of marine snow and other suspended particles using in situ imagery observations of their size distribution during the demise of the North Atlantic spring bloom. We show the important roles that turbulence in the ocean surface layer has on the creation and destruction of marine snow as well as their transport to depth. We also quantify the interactions of sinking marine snow below the ocean surface layer with zooplankton, both consuming sinking organic matter and creating smaller particles from marine snow. Our results demonstrate the interplay of physical and biological processes controlling the dynamics of marine snow.
Key Points
- Marine snow is highly ephemeral in the ocean’s mixed layer, responding rapidly to changes in turbulence due to the passage of storms
- Entrainment and detrainment processes transport marine snow below the mixed layer, allowing them to grow, and lead to their rapid sinking
- In the mesopelagic zone, sinking marine snow was consumed and fragmented into smaller particles, likely by zooplankton
