Abstract
Polymetallic nodules provide essential hard substrata for benthic fauna and are widely assumed to enhance biodiversity on abyssal plains. Yet, our understanding of how nodule cover shapes megafaunal communities remains limited and largely restricted to low nodule cover conditions. Using a large image dataset from a nodule-rich abyssal basin in the northwest Pacific (NWP), we characterized megafaunal communities and quantitatively assessed their responses across a broad gradient of nodule cover. A total of 169 morphospecies from 14 phyla were recorded, with holothurians and sponges comprising the dominant taxa. Surprisingly, megafaunal density exhibited a U-shaped response to nodule cover, declining from low to intermediate nodule cover, remaining relatively stable at intermediate levels, and increasing sharply at high nodule cover. Community composition shifted markedly from mobile deposit-feeder dominance at low cover to sessile filter-feeder dominance at high cover. This transition was primarily driven by changes in the relative density of dominant taxa rather than species turnover. Compared with the Clarion–Clipperton Zone (CCZ), the NWP showed lower megafaunal density and distinct assemblage composition but comparable diversity, consistent with large-scale influences of particulate organic carbon flux and carbonate saturation. Our findings reveal a previously unrecognized relationship between megafauna and nodule cover in the NWP nodule province and underscore the need for region-specific management of deep-sea mining.
Acknowledgements
We thank the crew of RV DAYANGYIHAO and the scientists on board for their assistance with data collection. We appreciate Dr. Peng Xu, Dr. Bo Lu, Dr. Yueyun Wang, Dr. Ruiyan Zhang, and Dr. Chen Fang for their consultants on the species annotation. We also thank Dr. Dong Sun for his valuable suggestions on the statistical analyses. Finally, we would like to express our graduate to Beijing Pioneer Hi-Tech Development Corporation Ltd for organizing and supporting the cruises at sea. This work was financially supported by the National Key Research and Development Program of China (2022YFC2804001), Scientific Research Fund of the Second Institute of Oceanography, Ministry of Natural Resources—Specialized Scientific Research Fund of State Key Laboratory of Submarine Geoscience (SGLabZZKT2025-10), and the UN Ocean Decade Programme Digital DEPTH.
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Fang, L., Zhang, D., Shen, C. et al. Pronounced megafaunal community transition driven by polymetallic nodule cover in the Northwest Pacific abyss.
Commun Earth Environ (2026). https://doi.org/10.1038/s43247-026-04042-5
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DOI: https://doi.org/10.1038/s43247-026-04042-5
Source: Ecology - nature.com
