Introduction to the project VAHINE: VAriability of vertical and tropHIc transfer of diazotroph derived N in the south wEst Pacific
Sophie Bonnet1,2,Thierry Moutin1,Martine Rodier3,Jean-Michel Grisoni4,Francis Louis4,5,Eric Folcher6,Bertrand Bourgeois6,Jean-Michel Boré6,and Armelle Renaud6Sophie Bonnet et al. Sophie Bonnet1,2,Thierry Moutin1,Martine Rodier3,Jean-Michel Grisoni4,Francis Louis4,5,Eric Folcher6,Bertrand Bourgeois6,Jean-Michel Boré6,and Armelle Renaud6
1Aix Marseille Université, CNRS/INSU, Université
de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM110 13288,
Marseille, France
2Institut de Recherche pour le Développement, AMU/
CNRS/INSU, Université de Toulon, Mediterranean Institute of Oceanography
(MIO) UM110, 98848 Noumea, New Caledonia
3Institut de Recherche pour le Développement,
Université de la Polynésie française, Institut Malardé,
Ifremer, UMR 241 Ecosystèmes Insulaires Océaniens (EIO), IRD Tahiti,
PB 529, 98713 Papeete, Tahiti, French Polynesia
4Observatoire Océanologique de Villefranche-sur-Mer,
UMS 829, Villefranche-sur-Mer, France
5Centre National de la Recherche Scientifique, UMR 7093,
Observatoire Océanologique de Villefranche-sur-Mer, Laboratoire
d'Océanographie de Villefranche-sur-Mer, Villefranche-sur-Mer,
France
6Institut de Recherche pour le Développement, 98848 Noumea, New Caledonia
1Aix Marseille Université, CNRS/INSU, Université
de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM110 13288,
Marseille, France
2Institut de Recherche pour le Développement, AMU/
CNRS/INSU, Université de Toulon, Mediterranean Institute of Oceanography
(MIO) UM110, 98848 Noumea, New Caledonia
3Institut de Recherche pour le Développement,
Université de la Polynésie française, Institut Malardé,
Ifremer, UMR 241 Ecosystèmes Insulaires Océaniens (EIO), IRD Tahiti,
PB 529, 98713 Papeete, Tahiti, French Polynesia
4Observatoire Océanologique de Villefranche-sur-Mer,
UMS 829, Villefranche-sur-Mer, France
5Centre National de la Recherche Scientifique, UMR 7093,
Observatoire Océanologique de Villefranche-sur-Mer, Laboratoire
d'Océanographie de Villefranche-sur-Mer, Villefranche-sur-Mer,
France
6Institut de Recherche pour le Développement, 98848 Noumea, New Caledonia
Correspondence: Sophie Bonnet (sophie.bonnet@univ-amu.fr)
Received: 07 Dec 2015 – Discussion started: 18 Jan 2016 – Revised: 27 Mar 2016 – Accepted: 16 Apr 2016 – Published: 11 May 2016
Abstract. On the global scale, N2 fixation provides the major external source of reactive nitrogen to the surface ocean, surpassing atmospheric and riverine inputs, and sustains ∼ 50 % of new primary production in oligotrophic environments. The main goal of the VAriability of vertical and tropHIc transfer of diazotroph derived N in the south wEst Pacific (VAHINE) project was to study the fate of nitrogen newly fixed by diazotrophs (or diazotroph-derived nitrogen) in oceanic food webs, and how it impacts heterotrophic bacteria, phytoplankton and zooplankton dynamics, stocks and fluxes of biogenic elements and particle export. Three large-volume ( ∼ 50 m3) mesocosms were deployed in a tropical oligotrophic ecosystem (the New Caledonia lagoon, south-eastern Pacific) and intentionally fertilized with ∼ 0.8 µM of dissolved inorganic phosphorus (DIP) to stimulate diazotrophy and follow subsequent ecosystem changes. VAHINE was a multidisciplinary project involving close collaborations between biogeochemists, molecular ecologist, chemists, marine opticians and modellers. This introductory paper describes in detail the scientific objectives of the project as well as the implementation plan: the mesocosm description and deployment, the selection of the study site (New Caledonian lagoon), and the logistical and sampling strategy. The main hydrological and biogeochemical conditions of the study site before the mesocosm deployment and during the experiment itself are described, and a general overview of the papers published in this special issue is presented.
e main goal of the VAHINE project was to study the fate of N2 fixation in the ocean. Three large-volume (~ 50 m3) mesocosms were deployed in a tropical oligotrophic ecosystem (the New Caledonia lagoon, south-eastern Pacific). This introductory paper describes the scientific objectives of the project in detail as well as the implementation plan: the mesocosm description and deployment, the selection of the study site, and the logistical and sampling strategy.
e main goal of the VAHINE project was to study the fate of N2 fixation in the ocean. Three...