Phosphorus availability modifies carbon production in Coccolithus pelagicus (Haptophyta)

Gerecht, A. C. and Å upraha, L. and Edvardsen, B. and Langer, G. and Henderiks, J. (2015) Phosphorus availability modifies carbon production in Coccolithus pelagicus (Haptophyta). Journal of Experimental Marine Biology and Ecology, 472. pp. 24-31. ISSN 0022-0981 DOI 10.1016/j.jembe.2015.06.019

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Abstract

The coccolithophore Coccolithus pelagicus (Wallich) Schiller fixes CO2 into particulate organic carbon (POC) through photosynthesis and into particulate inorganic carbon (PIC) in the form of calcite. To examine the role of phosphorus (P) availability in the production of POC and PIC, C. pelagicus subsp. braarudii (Gaarder) Geisen et al. was grown in semi-continuous cultures at three initial phosphate concentrations (P-replete, 1, and 0.5 μM P). Reduced P-availability (1 and 0.5 μM P) decreased POC production, while PIC production only decreased when phosphate concentrations became growth limiting (0.5 μM P). This decrease has not been observed previously in batch cultures, highlighting the inadequacy of the batch culture approach with regard to determining carbon production. The reduction in growth rate by 50\% at 0.5 μM P was accompanied by a doubling in cell volume (and POC). PIC production was halved, resulting in a lowered PIC to POC ratio. The average number of coccoliths per cell (and PIC content) remained the same among treatments, despite the significant change in cell size. Our data suggest that POC production in C. pelagicus is more sensitive towards a moderate reduction in phosphorus availability than PIC production. Once phosphorus availability limits cell division, however, phosphorus resources are invested into POC rather than PIC production. This reduces cell density and sinking rates, indicating that coccoliths do not act as ballast for reaching deeper nutrient-rich layers under nutrient limitation.

Item Type: Article
Uncontrolled Keywords: 2015AREP; IA70; weekly list
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Journal of Experimental Marine Biology and Ecology
Volume: 472
Page Range: pp. 24-31
Identification Number: 10.1016/j.jembe.2015.06.019
Depositing User: Sarah Humbert
Date Deposited: 16 Jan 2016 19:23
Last Modified: 16 Jan 2016 19:23
URI: http://eprints.esc.cam.ac.uk/id/eprint/3519

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