Abstract
Dark CO2 fixation by bacteria is believed to be particularly important in oligotrophic ecosystems. However, only a few studies have characterized the role of bacterial dissolved inorganic carbon (DIC) fixation in global carbon dynamics. Therefore, this study quantified the primary production (PP), total bacteria dark CO2 fixation (TBDIC fixation), and heterotrophic bacterial production (HBP) in the warm and oligotrophic Red Sea using stable-isotope labeling and cavity ring-down spectroscopy (13C-CRDS). Additionally, we assessed the contribution of bacterial DIC fixation (TBDIC%) relative to the total DIC fixation (totalDIC fixation). Our study demonstrated that TBDIC fixation increased the totalDIC fixation from 2.03 to 60.45μgCL-1d-1 within the photic zone, contributing 13.18% to 71.68% with an average value of 33.95±0.02% of the photic layer totalDIC fixation. The highest TBDIC fixation values were measured at the surface and deep (400m) water with an average value of 5.23±0.45 and 4.95±1.33μgCL-1d-1, respectively. These findings suggest that the non-photosynthetic processes such as anaplerotic DIC reactions and chemoautotrophic CO2 fixation extended to the entire oxygenated water column. On the other hand, the percent of TBDIC contribution to totalDIC fixation increased as primary production decreased (R2Combining double low line0.45, p<0.0001), suggesting the relevance of increased dark DIC fixation when photosynthetic production was low or absent, as observed in other systems. Therefore, when estimating the total carbon dioxide production in the ocean, dark DIC fixation must also be accounted for as a crucial component of the carbon dioxide flux in addition to photosynthesis.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3613-3624 |
| Number of pages | 12 |
| Journal | Biogeosciences |
| Volume | 20 |
| Issue number | 17 |
| DOIs | |
| State | Published - Aug 31 2023 |
Bibliographical note
Acknowledgements: This work was supported by the King Abdullah University of Science and Technology (KAUST). We would like to express our deepest gratitude to each and every person involved in this study and the King Abdullah University of Science and Technology, who made this research possible. First and foremost, we would like to express our gratitude to and thank all participants who generously shared their time and experiences enclosed in this research, including all crew members and scientific leaders of the vessels and cruises involved in this study. In addition, we would like to thank the Coastal & Marine Resources Core Lab (CMR) team at the King Abdullah University of Science and Technology (KAUST), who were behind the possibility of conducting the outdoor setup of the coastal experiments. We also extend our appreciation to Mongi Ennasri, who provided the support and assistance throughout the samples analyses in the Picarro CRDS. The support of each and every one of these individuals and organizations enabled us to collect and analyze the data and to disseminate our findings. We would like to express our appreciation and gratitude to the associate editor and the reviewers for their contributions to the improvement of this paper. Their expertise, meticulous attention to detail, and thoughtful feedback have played a crucial role in refining and strengthening the content of this work. We are sincerely grateful for their time, dedication, and commitment to advancing scholarly knowledge in this field.ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Earth-Surface Processes