The global distribution of macroalgal carbon burial in coastal sediments
- Dongyang Fan
- Carlos M. Duarte
- Faming Wang
- Oscar Serrano
- Dabo Guan
- Junyu He
- Xiaojing Hua
- Yingjie Zhu
- Zhangqi Zuo
- Karen Filbee-Dexter
- Chuancheng Fu
- Marianne Holmer
- Thomas Wernberg
- Ik Kyo Chung
- Hatim Albasri
- Lei Chen
- Yang Liu
- Tao Tang
- Simai Wang
- Xufeng Guo
- Xi Xiao
2026-08-31
Macroalgae play a pivotal role in the global ocean carbon cycle, yet the spatial distribution of their coastal carbon burial, a long-term sink relevant to national inventories, remains poorly resolved. Here, we present a high-resolution (5-arcminute, ~9.2 km at the equator) global assessment of the Macroalgal Carbon Burial Index (MCBI), a measure of how favorable coastal environments are for burying macroalgal carbon. Synthesizing the most comprehensive dataset of sediment accumulation rates ( n = 1617), we identify the depositional environment as a critical constraint on burial, acting independently of macroalgal productivity. High-favorability sinks are geographically rare (<1% of global coastlines), clustering in regions such as the Korea Bay and Okhotsk-Sakhalin region. We further identify coastline complexity as an informative predictor of MCBI (R² = 0.59), enabling low-cost identification of burial hotspots. Notably, we identify a mismatch in conservation: existing marine protected areas cover 23.9% of low-burial coastlines but only 17.1% of primary burial hotspots. Our findings map the global pattern of macroalgal carbon burial and provide a spatially explicit basis for its integration into conservation and management.