Article (Scientific journals)
Field measurements of inorganic nitrogen uptake by epiflora components of the seagrass Posidonia oceanica (Monocotyledons, Posidoniaceae)
Lepoint, Gilles; Jacquemart, Julien; Bouquegneau, Jean-Marie et al.
2007In Journal of Phycology, 43 (2), p. 208-218
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Keywords :
N-15 tracer; corallines; eutrophication; Mediterranean sea; nitrogen; seagrass; stable isotopes
Abstract :
[en] Crustose corallines, crustose and erect brown algae, and sessile animals are major components of the epiphytic community of the Mediterranean seagrass Posidonia oceanica (L.) Delile. Production, biomass, and specific composition of this epiphyte-seagrass association are impacted by anthropogenic increase of nutrient load in this oligotrophic area. In this context, nitrogen uptake by P. oceanica and its epiflora was measured using the isotope N-15 at a 10 m depth in the Revellata Bay (Corsica, Mediterranean Sea). Epiflora components showed various seasonal patterns of biomass and abundance. The epiphytic brown algae appeared at the end of spring, later than the crustose corallines, and after the nitrate peak in the bay. Because of their later development in the season, epiphytic brown algae mostly rely on ammonium for their N needs. We hypothesize that the temporal succession of epiphytic organisms plays a crucial role in the N dynamics of this community under natural conditions. The epiphytic brown algae, which have a growth rate one order of magnitude greater than that of crustose corallines, showed lower N-uptake rates. The greater N-uptake rates of crustose corallines probably reflect the greater N requirements (i.e., lower C/N ratios) of red algae. We determined that the epiflora incorporated ammonium and nitrate more rapidly than their host. Nevertheless, when biomass was taken into account, P. oceanica was the most important contributor to N uptake from the water column by benthic macrophytes in this seagrass bed.
Research center :
MARE - Centre Interfacultaire de Recherches en Océanologie - ULiège
Disciplines :
Aquatic sciences & oceanology
Phytobiology (plant sciences, forestry, mycology...)
Author, co-author :
Lepoint, Gilles  ;  Université de Liège - ULiège > Département des sciences et gestion de l'environnement > Océanologie
Jacquemart, Julien;  Université de Liège - ULiège > Sciences de la Vie > Algologie, mycologie et systématique expérimentale
Bouquegneau, Jean-Marie ;  Université de Liège - ULiège > Département des sciences et gestion de l'environnement > Océanologie
Demoulin, Vincent ;  Université de Liège - ULiège > Département des sciences de la vie > Algologie, mycologie et systématique expérimentale
Gobert, Sylvie  ;  Université de Liège - ULiège > Département des sciences et gestion de l'environnement > Océanologie
Language :
English
Title :
Field measurements of inorganic nitrogen uptake by epiflora components of the seagrass Posidonia oceanica (Monocotyledons, Posidoniaceae)
Publication date :
April 2007
Journal title :
Journal of Phycology
ISSN :
0022-3646
eISSN :
1529-8817
Publisher :
Blackwell Publishing, Oxford, United Kingdom
Volume :
43
Issue :
2
Pages :
208-218
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
Commentary :
The definitive version is available at www.blackwell-synergy.com
Available on ORBi :
since 15 December 2008

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