Reference : Annual nitrogen budget of the seagrass Posidonia oceanica as determined by in situ up...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
Life sciences : Aquatic sciences & oceanology
Life sciences : Environmental sciences & ecology
http://hdl.handle.net/2268/1108
Annual nitrogen budget of the seagrass Posidonia oceanica as determined by in situ uptake experiments
English
Lepoint, Gilles mailto [Université de Liège - ULg > Département des sciences et gestion de l'environnement > Océanologie >]
Millet, S. [> > > >]
Dauby, Patrick mailto [Université de Liège - ULg > Département des sciences et gestion de l'environnement > Systématique et diversité animale >]
Gobert, Sylvie mailto [Université de Liège - ULg > Département des sciences et gestion de l'environnement > Océanologie >]
Bouquegneau, Jean-Marie mailto [Université de Liège - ULg > Département des sciences et gestion de l'environnement > Océanologie >]
18-Jul-2002
Marine Ecology. Progress Series
Inter-Research
237
87-96
Yes
International
0171-8630
Oldendorf Luhe
[en] seagrass ; nitrogen uptake ; N-15 tracer ; NW Mediterranean
[en] The uptake of nitrate and ammonium by the roots and leaves of Posidonia oceanica were determined between February 1993 and June 1999 by in situ experiments using the isotope 15 of nitrogen (N-15) as a tracer in a nutrient-poor coastal zone of the NW Mediterranean Sea (Revellata Bay, Corsica). Nitrate and ammonium leaf uptakes are recorded at 0.05 and 0.1 muM respectively. The high variability observed cannot be explained solely by the variation of the substrate concentrations in the water column. For leaves, mean specific uptake rates were 43 +/- 45 and 43 +/- 64 mug N g N-1 h(-1). Nitrate and ammonium leaf uptake fluxes (g N m(-2) yr(-1)) seem to have the same importance on an annual basis. :Nitrate uptake occurs mainly in winter and early spring, when nitrate concentrations in the water column are highest. The uptake of N, and mainly of ammonium, is significant throughout the year with maxima at the beginning of spring, but it is insufficient to meet the annual N requirement of the plant. Posidonia root biomass was very high and corresponded to high specific N uptake rates by the roots. Ammonium was incorporated by the roots 6 times faster than nitrate. In the sediment, this uptake capacity is limited by the nutrient diffusion rate, and the root uptake is therefore insufficient to meet the N requirements of the plant. In fact, P. oceanica of Revellata Bay have a complex N budget involving uptake and recycling processes and allowing the plants to meet their N requirements in one of the most nutrient-poor areas of the NW Mediterranean Sea. We calculated that leaf and root would contribute to 40 and 60% of the annual N uptake, respectively, and 60% of the annual N requirement of the plant.
Centre Interfacultaire de Recherches en Océanologie - MARE
Fonds pour la formation à la Recherche dans l'Industrie et dans l'Agriculture (Communauté française de Belgique) - FRIA ; Communauté française de Belgique - CfB
Researchers ; Students
http://hdl.handle.net/2268/1108

File(s) associated to this reference

Fulltext file(s):

FileCommentaryVersionSizeAccess
Open access
MEPS237Lepoint et al.pdfNo commentaryPublisher postprint302.79 kBView/Open

Bookmark and Share SFX Query

All documents in ORBi are protected by a user license.