1. Marine Sciences Research Center, Stony Brook University, Stony Brook, New York 11794-5000, USA
2. IMEDEA (CSIC-UIB), Instituto Mediterráneo de Estudios Avanzados, Esporles 07190, Mallorca, Islas Baleares, Spain
3. College of Marine Studies, University of Delaware, 700 Pilottown Road, Lewes, Delaware 19958, USA
4. Wrigley Institute of Environmental Studies and Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, USA
5. Romberg Tiburon Center, San Francisco State University, 3152 Paradise Drive, Tiburon, California 94920, USA

Correspondence to: Sergio A. Sañudo-Wilhelmy¹ Email: ssanudo@notes.cc.sunysb.edu

Abstract

The Redfield ratio of 106 carbon:16 nitrogen:1 phosphorus in marine phytoplankton¹ is one of the foundations of ocean biogeochemistry, with applications in algal physiology², palaeoclimatology³ and global climate change⁴. However, this ratio varies substantially in response to changes in algal nutrient status⁵ and taxonomic affiliation^{6, 7}. Here we report that Redfield ratios are also strongly affected by partitioning into surface-adsorbed and intracellular phosphorus pools. The C:N:surface-adsorbed P (80–105 C:15–18 N:1 P) and total (71–80 C:13–14 N:1 P) ratios in natural populations and cultures of Trichodesmium were close to Redfield values and not significantly different from each other. In contrast, intracellular ratios consistently exceeded the Redfield ratio (316–434 C:59–83 N:1 intracellular P). These high intracellular ratios were associated with reduced N₂ fixation rates, suggestive of phosphorus deficiency. Other algal species also have substantial surface-adsorbed phosphorus pools, suggesting that our Trichodesmium results are generally applicable to all phytoplankton. Measurements of the distinct phytoplankton phosphorus pools may be required to assess nutrient limitation accurately from elemental composition. Deviations from Redfield stoichiometry may be attributable to surface adsorption of phosphorus rather than to biological processes, and this scavenging could affect the interpretation of marine nutrient inventories and ecosystem models.

MORE ARTICLES LIKE THIS

These links to content published by NPG are automatically generated.