[Nitrogen fixation and primary production in Western Mediterranean].
Nitrogen fixation, nitrate assimilation and primary production ((13)C/(15)N method) were investigated during one year and half in the northwestern Mediterranean Sea. Nitrogen fixation was detectable all over the year with rates ranged from 2 to 17 nmol N l(-1) d(-1)(d). Highest values being obtained during spring associated with the phytoplankton bloom. High rates (4-8 nmol N l(-1) d(-1)(d)) were also measured during summer, when primary productivity was very low. Then, diazotrophy process supplies significant new nitrogen during summer oligotrophic periods. This new nitrogen input can balance the annual nitrogen biogeochemical budget in the Mediterranean Sea and should explain the high nitrate/phosphate ratio observed in deep waters.
Garcia
Nicole
N
Laboratoire d'océanographie et de Biogéochimie, Centre d'océanologie de Marseille, CNRS, Université de la Méditerranée, 163, av. de Luminy, case 901, 13288 Marseille cedex 9, France. nicole.garcia@com.univ-mrs.fr
Raimbault
Patrick
P
Gouze
Emma
E
Sandroni
Valérie
V
D008522:Mediterranean Sea; D009566:Nitrates / Q000032:analysis / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D009586:Nitrogen Fixation; D010710:Phosphates / Q000032:analysis; D010839:Phytoplankton / Q000378:metabolism; D012621:Seasons
D009566:Nitrates; D010710:Phosphates; D009584:Nitrogen