@article{fdi:010096081,
  title = {{D}issolved organic matter ({DOC}, {CDOM}, {FDOM}) in the western {T}ropical {S}outh {P}acific : depth- and subregion-resolved variability, and hydrothermal influence},
  author = {{T}edetti, {M}arc and {G}uigue, {C}. and {M}ahieu, {L}. and {M}artinot, {P}. {L}. and {B}enavides, {M}ar and {D}upouy, {C}{\'e}cile and {N}unige, {S}. and {P}ulido-{V}illena, {E}. and {D}imier, {C}. and {T}illiette, {C}. and {B}onnet, {S}ophie and {G}uieu, {C}. and {L}ef{\`e}vre, {D}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he {W}estern {T}ropical {S}outh {P}acific has recently been identified as a global hotspot for microbial dinitrogen fixation and shallow hydrothermal activity, yet the dynamics of dissolved organic matter ({DOM}) in this ecosystem remains understudied. {D}uring the {TONGA} cruise (2019), we investigated the distribution of dissolved organic carbon ({DOC}), chromophoric {DOM} ({CDOM}) and fluorescent {DOM} ({FDOM}) from {M}elanesian waters to the {S}outh {P}acific {G}yre, including the {L}au {B}asin/{T}onga-{K}ermadec {V}olcanic {A}rc. {DOC} concentration, {CDOM} absorption [a{CDOM}(254)], the {CDOM} spectral slope ({S}275-295) and tyrosine-like fluorescence decreased from surface to deep waters across subregions. {I}n contrast, apparent oxygen utilization ({AOU}), nutrients, a{CDOM}(350), specific {UV} absorbance ({SUVA}254), humic-like fluorescence, humification ({HIX}) and combustion ({COX}) indices increased with depth. {T}hese distributions reveal 1) the production of labile, low molecular weight {DOM} by phytoplankton, and photobleaching in the photic layer, and 2) the production of higher molecular weight, bio-refractory {DOM} from the remineralization of sinking particulate organic carbon and {DOC} in deeper waters. {A}lso, the tryptophanlike fluorescence peaks at depth could be associated with the presence of sinking {T}richodesmium spp. {R}egional variations in {DOM} characteristics were less pronounced than water-mass-related differences but revealed subtle trends along the west-east gradient, with overall higher {DOC}, {CDOM} and {FDOM} levels in the {M}elanesian and {L}au {B}asin/{A}rc subregions compared to the {S}outh {P}acific {G}yre. {A}t 200-m depth near the {A}rc, the release of hydro-thermal fluids altered the {DOM} composition close to the vent, with significant increases in a{CDOM}(254) and tyrosine-like material, and significant decreases in {HIX} and {COX} indices. {W}e further show an indirect, large-scale impact of shallow hydrothermal vents on the {DOM} stock in the 0-50-m surface layer, driven by the iron fertilization-induced stimulation of planktonic activity in the photic zone. {T}he increased {DOM} stocks were observed mostly in the {L}au {B}asin/{A}rc subregion but extending to {M}elanesian waters and the western edge of {S}outh {P}acific {G}yre. {C}ollectively, these processes shape the optical properties and biogeochemical behavior of {DOM}, highlighting the importance of hydrothermal systems in the oceanic carbon cycle.},
  keywords = {{DOC} ; {CDOM} ; {FDOM} ; {S}outh {P}acific ; {H}ydrothermal vents ; {D}iazotrophs ; {T}onga ; {PACIFIQUE} ; {MELANESIE} ; {TONGA} ; {ZONE} {TROPICALE} ; {PACIFIQUE} {SUD} {OUEST}},
  booktitle = {},
  journal = {{P}rogress in {O}ceanography},
  volume = {242},
  numero = {},
  pages = {103664 [20 p.]},
  ISSN = {0079-6611},
  year = {2026},
  DOI = {10.1016/j.pocean.2025.103664},
  URL = {https://www.documentation.ird.fr/hor/fdi:010096081},
}