@article{fdi:010067664,
  title = {{H}eterotrophic bacterial production and metabolic balance during the {VAHINE} mesocosm experiment in the {N}ew {C}aledonia lagoon},
  author = {{V}an {W}ambeke, {F}. and {P}freundt, {U}. and {B}arani, {A}. and {B}erthelot, {H}. and {M}outin, {T}. and {R}odier, {M}artine and {H}ess, {W}. {R}. and {B}onnet, {S}ophie},
  editor = {},
  language = {{ENG}},
  abstract = {{S}tudies investigating the fate of diazotrophs through the microbial food web are lacking, although {N}-2 fixation can fuel up to 50% of new production in some oligotrophic oceans. {I}n particular, the role played by heterotrophic prokaryotes in this transfer is largely unknown. {I}n the frame of the {VAHINE} ({VA}riability of vertical and trop{HI}c transfer of diazotroph derived {N} in the south w{E}st {P}acific) experiment, three replicate large-volume (similar to 50 m(3)) mesocosms were deployed for 23 days in the new {C}aledonia lagoon and were intentionally fertilized on day 4 with dissolved inorganic phosphorus ({DIP}) to stimulate {N}-2 fixation. {W}e specifically examined relationships between heterotrophic bacterial production ({BP}) and {N}-2 fixation or primary production, determined bacterial growth efficiency and established carbon budgets. {BP} was statistically higher during the second phase of the experiment ({P}2: days 15-23), when chlorophyll biomass started to increase compared to the first phase ({P}1: days 5-14). {P}hosphatase alkaline activity increased drastically during the second phase of the experiment, showing adaptations of microbial populations after utilization of the added {DIP}. {N}otably, among autotrophs, {S}ynechococcus abundances increased during {P}2, possibly related to its capacity to assimilate leucine and to produce alkaline phosphatase. {B}acterial growth efficiency based on the carbon budget (27-43 %), was notably higher than generally cited for oligotrophic environments and discussed in links with the presence of abundant species of bacteria expressing proteorhodopsin. {T}he main fates of gross primary production (particulate {C} dissolved) were respiration (67 %) and export through sedimentation (17 %). {BP} was highly correlated with particulate primary production and chlorophyll biomass during both phases of the experiment but was slightly correlated, and only during {P}2 phase, with {N}-2 fixation rates. {H}eterotrophic bacterial production was strongly stimulated after mineral {N} enrichment experiments, suggesting {N}-limitation of heterotrophic bacteria across the experiment. {N}-2 fixation rates corresponded to 17-37% of the nitrogen demand of heterotrophic bacteria. {O}ur results suggest that most of the diazotroph-derived nitrogen fuelled the heterotrophic bacterial community through indirect processes generating dissolved organic matter and detritus, like mortality, lysis and grazing of both diazotrophs and non-diazotrophs.},
  keywords = {{NOUVELLE} {CALEDONIE} ; {PACIFIQUE} ; {NOUMEA} {LAGON}},
  booktitle = {},
  journal = {{B}iogeosciences},
  volume = {13},
  numero = {11},
  pages = {3187--3202},
  ISSN = {1726-4170},
  year = {2016},
  DOI = {10.5194/bg-13-3187-2016},
  URL = {https://www.documentation.ird.fr/hor/fdi:010067664},
}