@article{fdi:010068147,
  title = {{B}iogeochemical fluxes and fate of diazotroph-derived nitrogen in the food web after a phosphate enrichment : modeling of the {VAHINE} mesocosms experiment},
  author = {{G}imenez, {A}. and {B}aklouti, {M}. and {B}onnet, {S}ophie and {M}outin, {T}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he {VAHINE} mesocosm experiment in the oligotrophic waters of the {N}oumea lagoon ({N}ew {C}aledonia), where high {N}-2 fixation rates and abundant diazotroph organisms were observed, aimed to assess the role of the nitrogen input through {N}-2 fixation in carbon production and export and to study the fate of diazotroph-derived nitrogen ({DDN}) throughout the planktonic food web. {A} 1-{D} vertical biogeochemical mechanistic model was used in addition to the in situ experiment to enrich our understanding of the dynamics of the planktonic ecosystem and the main biogeochemical carbon ({C}), nitrogen ({N}) and phosphate ({P}) fluxes. {T}he mesocosms were intentionally enriched with similar to 0.8 mu mol {L}-1 of inorganic {P} to trigger the development of diazotrophs and amplify biogeochemical fluxes. {T}wo simulations were run, one with and the other without the phosphate enrichment. {I}n the {P}-enriched simulation, {N}-2 fixation, primary production ({PP}) and {C} export increased by 201, 208 and 87 %, respectively, consistent with the trends observed in the mesocosms (+124, +141 and +261% for {N}-2 fixation, {PP} and {C} export, respectively). {I}n total, 5-10 days were necessary to obtain an increase in primary and export productions after the dissolved inorganic phosphate ({DIP}) enrichment, thereby suggesting that classical methods (short-term microcosms experiments) used to quantify nutrient limitations of primary production may not be relevant. {T}he model enabled us to monitor the fate of fixed {N}-2 by providing the proportion of {DDN} in each compartment (inorganic and organic) of the model over time. {A}t the end of the simulation (25 days), 43% of the {DDN} was found in the non-diazotroph organisms, 33% in diazotrophs, 16% in the dissolved organic nitrogen pool, 3% in the particulate detrital organic pool and 5% in traps, indicating that {N}-2 fixation was of benefit to non-diazotrophic organisms and contributed to {C} export.},
  keywords = {{NOUVELLE} {CALEDONIE} ; {NOUMEA} {LAGON}},
  booktitle = {},
  journal = {{B}iogeosciences},
  volume = {13},
  numero = {17},
  pages = {5103--5120},
  ISSN = {1726-4170},
  year = {2016},
  DOI = {10.5194/bg-13-5103-2016},
  URL = {https://www.documentation.ird.fr/hor/fdi:010068147},
}