Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 7 4 2010 10.5194/bg-7-1285-2010 http://www.biogeosciences.net/7/1285/2010/ http://www.biogeosciences.net/7/1285/2010/bg-7-1285-2010.html http://www.biogeosciences.net/7/1285/2010/bg-7-1285-2010.pdf 1285 1305 2010-04-21 Influence of consumer-driven nutrient recycling on primary production and the distribution of N and P in the ocean A. Nugraha nugraha@univ-brest.fr P. Pondaven P. Tréguer Université Européenne de Bretagne, Université de Brest, CNRS, IRD, UMR 6539 LEMAR, Institut Universitaire Européen de la Mer (IUEM), Technopôle Brest-Iroise, Place Copernic, 29280 Plouzané, France In this study we investigated the impact of consumer-driven nutrient recycling (CNR) on oceanic primary production and the distribution of nitrogen (N) and phosphorus (P) in the deep ocean. For this purpose, we used and extended two existing models: a 2-box model of N and P cycling in the global ocean (Tyrrell, 1999), and the model of Sterner (1990) which formalised the principles of CNR theory. The resulting model showed that marine herbivores may affect the supply and the stoichiometry of N and P in the ocean, thereby exerting a control on global primary production. The predicted global primary production was higher when herbivores were included in the model, particularly when these herbivores had higher N:P ratios than phytoplankton. This higher primary production was triggered by a low N:P resupply ratio, which, in turn, favoured the P-limited N₂-fixation and eventually the N-limited non-fixers. Conversely, phytoplankton with higher N:P ratios increased herbivore yield until phosphorus became the limiting nutrient, thereby favouring herbivores with a low P-requirement. 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