title: Increased iron availability resulting from increased CO2enhances carbon and nitrogen metabolism in the economical marine red macroalga Pyropia haitanensis (Rhodophyta).
abstract: Ocean acidification caused by rising CO2is predicted to increase the concentrations of dissolved species of Fe(II) and Fe(III), leading to the enhanced photosynthetic carbon sequestration in some algal species. In this study, the carbon and nitrogen metabolism in responses to increased iron availability under two CO2levels (390 μL L-1and 1000 μL L-1), were investigated in the maricultivated macroalga Pyropia haitanensis (Rhodophyta). The results showed that, elevated CO2increased soluble carbonhydrate (SC) contents, resulting from enhanced photosynthesis and photosynthetic pigment synthesis in this algae, but declined its soluble protein (SP) contents, resulting in increased ratio of SC/SP. This enhanced photosynthesis performance and carbon accumulation was more significant under iron enrichment condition in seawater, with higher iron uptake rate at high CO2level. As a key essential biogenic element for algae, Fe-replete functionally contributed to P. haitanensis photosynthesis. Increased SC fundamentally provided carbon skeletons for nitrogen assimilation. The significant increase of carbon and nitrogen assimilation finally contributed to enhanced growth in this alga. This was also intuitively reflected by respiration that provided energy for cellular metabolism and algal growth. We propose that, in the predicted scenario of rising atmospheric CO2, P. haitanensis is capable to adjust its physiology by increasing its carbon and nitrogen metabolism to acclimate the acidified seawater, at the background of global climate change and simultaneously increased iron concentration due to decreased pH levels.
authors.affiliation: School of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
authors.forename: Binbin
authors.initials: B
authors.lastname: Chen
authors.affiliation: School of Environment and Energy, South China University of Technology, Guangzhou 510006, China; Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, South China University of Technology, Guangzhou 510006, China. Electronic address: dhzou@scut.edu.cn.
authors.forename: Dinghui
authors.initials: D
authors.lastname: Zou
authors.affiliation: Institute of Hydrobiology, College of Life Science and Technology, Jinan University, Guangzhou, 510623, China.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Yang
mesh_terms: D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000494:pharmacology*; D057231:Climate Change; D007501:Iron / Q000493:pharmacokinetics*; D009584:Nitrogen / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology; D000461:Rhodophyta / Q000187:drug effects / Q000378:metabolism*; D012623:Seawater / Q000737:chemistry; D012624:Seaweed / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D002245:Carbon Dioxide; D002244:Carbon; D007501:Iron; D009584:Nitrogen
keywords: CO(2) rising; Global change; Iron availability; Metabolism; Photosynthesis; Pyropia haitanensis