ORCID
0000-0001-8819-189X (Mulholland)
Document Type
Article
Publication Date
2024
DOI
10.3389/fmars.2024.1495649
Publication Title
Frontiers of Marine Science
Volume
11
Pages
1495649 (1-13)
Abstract
Biological dinitrogen (N₂) fixation, the energetically expensive conversion of N₂ gas to ammonia, plays an essential role in balancing the nitrogen budget in the ocean. Accumulating studies show detectable N₂ fixation rates below the euphotic zone in various marine systems, revealing new insights of marine N₂ fixation. However, the reported rates are highly variable and frequently fall close to detection limits, raising the question of the ubiquity and significance of N₂ fixation in the global dark ocean. Using highly sensitive isotopic labeling incubation including a set of control incubations, we confirm the occurrence of mesopelagic N₂ fixation in the South China Sea. Interestingly, we consistently observed that ca. 30% of samples show a significant elevation of ¹⁵N in the particulate nitrogen after incubation at most depths (200 - 1000 m). Although this approach does not allow accurate quantification of N₂ fixation rates, our data suggest the occurrence of dark N₂ fixation yet with highly heterogeneous signals in the mesopelagic zone of the South China Sea. A data compilation of reported N₂ fixation in the global dark ocean further reveals that such heterogeneity has also been observed elsewhere, unveiling the ubiquitous heterogeneity in mesopelagic N₂ fixation. Thus, we call for more observations to constrain mesopelagic N₂ fixation budgets and to understand the underlying mechanism for such heterogeneity.
Rights
© 2024 Wu, Wan, Du, Chen, Selden, Benavides, Bonnet, Löscher, Hamersley, Mulholland, Yan and Kao.
This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License. The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Data Availability
Article states: "The original contributions presented in the study are included in the article/Supplementary Material. Further inquiries can be directed to the corresponding author."
Original Publication Citation
Wu, S., Wan, X. S., Du, M., Chen, X., Selden, C. R., Benavides, M., Bonnet, S., Löscher, C. R., Hamersley, R. M., Mulholland, M. R., Yan, X., & Kao, S.-J. (2024). Heterogeneity of nitrogen fixation in the mesopelagic zone of the South China Sea. Frontiers in Marine Science, 11, 1-13, Article 1495649. https://doi.org/10.3389/fmars.2024.1495649
Repository Citation
Wu, Siqi; Wan, Xianhui Sean; Du, Moge; Chen, Xirong; Selden, Corday R.; Benavides, Mar; Bonnet, Sophie; Löscher, Carolin R.; Robert Hamersley, M.; Mulholland, Margaret R.; Yan, Xiuli; and Kao, Shuh-Ji, "Heterogeneity of Nitrogen Fixation in the Mesopelagic Zone of the South China Sea" (2024). OES Faculty Publications. 523.
https://digitalcommons.odu.edu/oeas_fac_pubs/523
Supplementary Material
Included in
Biochemistry Commons, Biogeochemistry Commons, Oceanography and Atmospheric Sciences and Meteorology Commons