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Biogeochemistry in oligotrophic ocean gyres
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Reduced nitrogenase efficiency dominates response of the globally important nitrogen fixer Trichodesmium to ocean acidification
P-M2-03
Ya-Wei Luo* , State Key Laboratory of Marine Environmental Science and College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian 361102, China
Dalin Shi, State Key Laboratory of Marine Environmental Science and College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China
Sven A. Kranz, Department of Earth, Ocean and Atmospheric Science, Florida State University, Tallahassee, FL 32306, USA
Brian M. Hopkinson, Department of Marine Sciences, University of Georgia, Athens, GA 30602, USA
Haizheng Hong, State Key Laboratory of Marine Environmental Science and College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China
Rong Shen, State Key Laboratory of Marine Environmental Science and College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China
Futing Zhang, State Key Laboratory of Marine Environmental Science and College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China
Presenter Email: ywluo@xmu.edu.cn |
| The response of the prominent marine dinitrogen (N2)-fixing cyanobacteria Trichodesmium to ocean acidification (OA) is critical to understanding future oceanic biogeochemical cycles. Recent studies have reported conflicting findings on the effect of OA on growth and N2 fixation of Trichodesmium. Here, we quantitatively analyzed experimental data on how Trichodesmium reallocated intracellular iron and energy among key cellular processes in response to OA, and integrated the findings to construct an optimality-based cellular model. The model results indicate that Trichodesmium growth rate decreases under OA primarily due to reduced nitrogenase efficiency. The downregulation of the carbon dioxide (CO2)-concentrating mechanism under OA has little impact on Trichodesmium, and the energy demand of anti-stress responses to OA has a moderate negative effect. We predict that if anthropogenic CO2 emissions continue to rise, OA could reduce global N2 fixation potential of Trichodesmium by 27% in this century, with the largest decrease in iron-limiting regions. |
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