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Iron, nitrogen, phosphorus and zinc cycling and consequences for primary productivity in the oceans
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- By John A. Raven, Plant Research Unit, Division of Environmental and Applied Biology, School of Life Sciences, University of Dundee at SCRI, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, Scotland, UK, Karen Brown, Plant Research Unit, Division of Environmental and Applied Biology, School of Life Sciences, University of Dundee at SCRI, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, Scotland, UK, Maggie Mackay, Plant Research Unit, Division of Environmental and Applied Biology, School of Life Sciences, University of Dundee at SCRI, Scottish Crop Research Institute, Invergowrie, Dundee DD2 5DA, Scotland, UK, John Beardall, School of Biological Sciences, Monash University, Clayton, VIC 3800, Australia, Mario Giordano, Department of Marine Science, Università Politecnica delle Marche, 60131 Ancona, Italy, Espen Granum, Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK, Richard C. Leegood, Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK, Kieryn Kilminster, School of Plant Biology, University of Western Australia, M090 35 Stirling Highway, Crawley, WA 6009, Australia, Diana I. Walker, School of Plant Biology, University of Western Australia, M090 35 Stirling Highway, Crawley, WA 6009, Australia
- Edited by Geoff Gadd, University of Dundee, Kirk Semple, Lancaster University
- Hilary Lappin-Scott, University of Exeter
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- Book:
- Micro-organisms and Earth Systems
- Published online:
- 06 July 2010
- Print publication:
- 13 October 2005, pp 247-272
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- Chapter
- Export citation
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Summary
INTRODUCTION
Primary productivity in the ocean amounts to the net assimilation of CO2 equivalent to about 50 Pg (petagram, i.e. 1015 g) C year–1, while on land this is approximately 60 Pg C year-1 (Field et al., 1998). Almost all of this primary productivity involves photosynthesis, and in the ocean it occurs only in the top few hundred metres, even in waters with the smallest light attenuation (Falkowski & Raven, 1997). About 1 Pg C of marine primary productivity involves benthic organisms, i.e. those growing on the substratum (Field et al., 1998), in the very small fraction of the ocean which is close enough to the surface to permit adequate photosynthetically active radiation (PAR) to allow photolithotrophic growth. This depth at which photosynthetic growth is just possible varies in time and space, and defines the bottom of the euphotic zone (Falkowski & Raven, 1997). The remaining ∼49 Pg C is assimilated by phytoplankton in the water column (Field et al., 1998). This chapter will concentrate on the planktonic realm, while acknowledging the importance of marine benthic primary producers and their interactions with micro-organisms (e.g. Dudley et al., 2001; Raven et al., 2002; Raven & Taylor, 2003; Cooke et al., 2004; Walker et al., 2004).
The global net primary productivity of the oceans is less than that on land, despite about 70 % of the Earth being covered in ocean and primary productivity over considerable areas of land being limited by water supply.