Modeling Photosynthesis and Exudation in Subtropical Oceans. Issue 9 (21st September 2021)

• Record Type: Journal Article
• Authors: Wu, Zhen; Dutkiewicz, Stephanie; Jahn, Oliver; Sher, Daniel; White, Angelicque; Follows, Michael J.
• Is Part Of: Global biogeochemical cycles. Volume 35:Issue 9(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-09-21
• Subjects: phytoplankton -- photosynthesis -- exudation -- primary production -- subtropical gyres -- biogeochemical model; Biogeochemical cycles -- Periodicals; Electronic journals; 577.1405
• DOI: 10.1029/2021GB006941
• Languages: English
• ISSNs: 0886-6236

Abstract

Abstract: Marine phytoplankton contributes nearly half of the total primary production on Earth through photosynthesis. Parameterizations of algal photosynthesis commonly employed in global biogeochemical simulations generally fail to capture the observed vertical structure of primary production. Here we examined the consequences of decoupling photosynthesis (carbon fixation) and biosynthesis (biomass building) with accumulation or exudation of excess photosynthate under energy rich conditions in both regional and global models. The results show that the decoupling of these two processes improved the simulated vertical profile of primary production, increased modeled primary production over 30% globally and over 40% in subtropical oceans, improved simulated meridional patterns of particulate C:N:P and increased modeled surface pool of labile/semi‐labile dissolved organic carbon. More generally, these results highlight the importance of exudation, which results from the decoupling of photosynthesis and biosynthesis, as a major physiological process affecting ocean biogeochemistry. Key Points: Decoupling of photosynthesis and biosynthesis improved simulations of primary production Predicted global primary production increased by about 1/3 Model results suggest exudation could contribute ∼ 20% to total dissolved organic carbon fluxes in euphotic layer