title: Multiple environmental controls on phytoplankton growth strategies determine adaptive responses of the N : P ratio.
abstract: The controls on the 'Redfield' N : P stoichiometry of marine phytoplankton and hence the N : P ratio of the deep ocean remain incompletely understood. Here, we use a model for phytoplankton ecophysiology and growth, based on functional traits and resource-allocation trade-offs, to show how environmental filtering, biotic interactions, and element cycling in a global ecosystem model determine phytoplankton biogeography, growth strategies and macromolecular composition. Emergent growth strategies capture major observed patterns in marine biomes. Using a new synthesis of experimental RNA and protein measurements to constrain per-ribosome translation rates, we determine a spatially variable lower limit on adaptive rRNA:protein allocation and hence on the relationship between the largest cellular P and N pools. Comparison with the lowest observed phytoplankton N : P ratios and N : P export fluxes in the Southern Ocean suggests that additional contributions from phospholipid and phosphorus storage compounds play a fundamental role in determining the marine biogeochemical cycling of these elements.
authors.affiliation: Earth System Science, College of Life and Environmental Sciences, University of Exeter, Laver Building, North Park Road, Exeter, EX4 4QE, UK.
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Daines
authors.forename: James R
authors.initials: JR
authors.lastname: Clark
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Lenton
mesh_terms: D000222:Adaptation, Physiological; D004777:Environment; D008954:Models, Biological; D009584:Nitrogen / Q000737:chemistry* / Q000378:metabolism; D010758:Phosphorus / Q000737:chemistry* / Q000378:metabolism; D010839:Phytoplankton / Q000254:growth & development / Q000502:physiology*; D012335:RNA, Ribosomal / Q000378:metabolism; D012623:Seawater / Q000737:chemistry*
chemical_list: D012335:RNA, Ribosomal; D010758:Phosphorus; D009584:Nitrogen
keywords: Biogeochemistry; N/P; Redfield ratios; biogeography; marine; microbial; phytoplankton; stoichiometry; traits