Equatorial upwelling of phosphorus drives Atlantic N2 fixation and Sargassum blooms

作者：Jonathan Jung, Nicolas Duprey, Alan Foreman, Juan Pablo D’Olivo, Carolin Pellio, Yeongjun Ryu, Erin L. Murphy, Baseerat Romshoo, Diego K. Kersting, Gabriel O. Cardoso, Tanja Wald, François Fripiat, Carlos Jiménez, Eberhard Gischler, Paolo Montagna, Carlos Alonso‐Hernández, Miguel Gómez-Batista, Christina Treinen-Crespo, José D. Carriquiry, Maria Rosabelle Ong, Nathalie F. Goodkin, Reia Guppy, Hedy M. Aardema, Hans A. Slagter, Lena Heins, Isabella Hrabě de Angelis, Aaron L. Bieler, Maayan Yehudai, Trevor P. Noël, Kendon James, Denis Scholz, Chuanmin Hu, Brian B. Barnes, Andrea Pozzer, Christopher Pöhlker, Jos Lelieveld, Ulrich Pöschl, Hubert Vonhof, Gerald H. Haug, Ralf Schiebel, Daniel M. Sigman, Alfredo Martínez‐García · 发表于：Nature Geoscience · 年份：2025 · DOI：10.1038/s41561-025-01812-2 · 被引用次数：9 · 研究领域：Marine and coastal plant biology、Coral and Marine Ecosystems Studies、Marine and coastal ecosystems

Abstract The Great Atlantic Sargassum Belt first appeared in 2011 and quickly became the largest interconnected floating biome on Earth. In recent years, Sargassum stranding events have caused substantial ecological and socio-economic impacts in coastal communities. Sargassum requires both phosphorus (P) and nitrogen (N) for growth, yet the primary sources of these nutrients fuelling the extensive Sargassum blooms remain unclear. Here we use coral-bound N isotopes to reconstruct N 2 fixation, the ultimate source of the ocean’s bioavailable N, across the Caribbean over the past 120 years. Our data indicate that changes in N 2 fixation were primarily controlled by multidecadal and interannual changes in equatorial Atlantic upwelling of ‘excess P’, that is, P in stoichiometric excess relative to fixed N. We show that the supply of excess P from equatorial upwelling and N from the N 2 fixation response can account for the majority of Sargassum variability since 2011. Sargassum dynamics are best explained by their symbiosis with N 2 -fixing epiphytes, which render the macroalgae highly competitive during strong equatorial upwelling of excess P. Thus, the future of Sargassum in the tropical Atlantic will depend on how global warming affects equatorial Atlantic upwelling and the climatic modes that control it.