@article{fdi:010089530,
  title = {{C}omposition of the sinking particle flux in a hot spot of dinitrogen fixation revealed through polyacrylamide gel traps},
  author = {{A}babou, {F}. {E}. and {L}e {M}oigne, {F}. {A}. {C}. and {C}ornet-{B}arthaux, {V}. and {T}aillandier, {V}. and {B}onnet, {S}ophie},
  editor = {},
  language = {{ENG}},
  abstract = {{D}iazotrophs regulate marine productivity in the oligotrophic ocean by alleviating nitrogen limitation, contributing to particulate organic carbon ({POC}) export to the deep ocean. {Y}et, the characterization of particles composing the sinking {POC} flux has never been explored in such ecosystems. {M}oreover, the contribution of the direct gravitational export of diazotrophs to the overall flux is seldom assessed. {H}ere we explore the composition of the sinking {POC} flux in a hot spot of {N}-2 fixation (the western sub-tropical {S}outh {P}acific) using polyacrylamide gel-filled traps deployed at two stations ({S}05{M} and {S}10{M}) and three depths (170 m, 270 m, 1000 m) during the {TONGA} expedition ({N}ovember-{D}ecember 2019). {I}mage analyses of particles collected in the gels was used to classify them into 5 categories (fecal aggregates, phytodetrital aggregates, mixed aggregates, cylindrical fecal pellets, and zooplankton carcasses). {F}ecal aggregates were the most abundant at both stations and all depths and dominated the flux (average of 56 +/- 28% of the {POC} flux), followed by zooplankton carcasses (24 +/- 19%), cylindrical fecal pellets (15 +/- 14%) and mixed aggregates (5 +/- 4%), whereas phytodetrital aggregates contributed less (<1%). {S}ince {N} isotope budgets show that export is mainly supported by diazotrophy at these stations, these results suggest that the diazotroph-derived {N} has been efficiently transferred to the foodweb up to zooplankton and fecal pellets before being exported, pleading for an indirect export of diazotrophy. {H}owever, random confocal microscopy examination performed on sinking particles revealed that diazotrophs were present in several categories of exported particles, suggesting that diazotrophs are also directly exported, with a potential contribution to overall {POC} fluxes increasing with depth. {O}ur results provide the first characterization of particle categories composing the sinking flux and their contribution to the overall flux in a hot spot of {N}-2 fixation.},
  keywords = {biological carbon pump ; carbon export ; export efficiency ; transfer ; efficiency ; diazotrophs ; {PACIFIQUE} ; {TONGA} {KERMADEC} {ARC}},
  booktitle = {},
  journal = {{F}rontiers in {M}arine {S}cience},
  volume = {10},
  numero = {},
  pages = {1290625 [16 p.]},
  year = {2024},
  DOI = {10.3389/fmars.2023.1290625},
  URL = {https://www.documentation.ird.fr/hor/fdi:010089530},
}