@article{fdi:010066044,
  title = {{M}esopelagic {N}-2 fixation related to organic matter composition in the {S}olomon and {B}ismarck {S}eas ({S}outhwest {P}acific)},
  author = {{B}enavides, {M}. and {M}oisander, {P}. {H}. and {B}erthelot, {H}. and {D}ittmar, {T}. and {G}rosso, {O}. and {B}onnet, {S}ophie},
  editor = {},
  language = {{ENG}},
  abstract = {{D}initrogen ({N}-2) fixation was investigated together with organic matter composition in the mesopelagic zone of the {B}ismarck ({T}ransect 1) and {S}olomon ({T}ransect 2) {S}eas ({S}outhwest {P}acific). {T}ransparent exopolymer particles ({TEP}) and the presence of compounds sharing molecular formulae with saturated fatty acids and sugars, as well as dissolved organic matter ({DOM}) compounds containing nitrogen ({N}) and phosphorus ({P}) were higher on {T}ransect 1 than on {T}ransect 2, while oxygen concentrations showed an opposite pattern. {N}-2 fixation rates (up to similar to 1 nmol {N} {L}-1 d(-1)) were higher in {T}ransect 1 than in {T}ransect 2, and correlated positively with {TEP}, suggesting a dependence of diazotroph activity on organic matter. {T}he scores of the multivariate ordination of {DOM} molecular formulae and their relative abundance correlated negatively with bacterial abundances and positively with {N}-2 fixation rates, suggesting an active bacterial exploitation of {DOM} and its use to sustain diazotrophic activity. {S}equences of the nif{H} gene clustered with {A}lpha-, {B}eta-, {G}amma- and {D}eltaproteobacteria, and included representatives from {C}lusters {I}, {III} and {IV}. {A} third of the clone library included sequences close to the potentially anaerobic {C}luster {III}, suggesting that {N}-2 fixation was partially supported by presumably particle-attached diazotrophs. {Q}uantitative polymerase chain reaction (q{PCR}) primer-probe sets were designed for three phylotypes and showed low abundances, with a phylotype within {C}luster {III} at up to 10(3) nif{H} gene copies {L}-1. {T}hese results provide new insights into the ecology of non-cyanobacterial diazotrophs and suggest that organic matter sustains their activity in the mesopelagic ocean.},
  keywords = {{PACIFIQUE} {SUD} {OUEST} ; {SALOMON} {MER} ; {BISMARCK} {MER}},
  booktitle = {},
  journal = {{P}los {O}ne},
  volume = {10},
  numero = {12},
  pages = {e0143775 [19 p.]},
  ISSN = {1932-6203},
  year = {2015},
  DOI = {10.1371/journal.pone.0143775},
  URL = {https://www.documentation.ird.fr/hor/fdi:010066044},
}