@article{fdi:010071969,
  title = {{E}ffect of light on {N}-2 fixation and net nitrogen release of {T}richodesmium in a field study},
  author = {{L}u, {Y}. {Y}. and {W}en, {Z}. {Z}. and {S}hi, {D}. {L}. and {C}hen, {M}. {M}. and {Z}hang, {Y}. and {B}onnet, {S}ophie and {L}i, {Y}. {H}. and {T}ian, {J}. {W}. and {K}ao, {S}. {J}.},
  editor = {},
  language = {{ENG}},
  abstract = {{D}initrogen fixation ({NF}) by marine cyanobacteria is an important pathway to replenish the oceanic bioavailable nitrogen inventory. {L}ight is the key to modulating {NF}; however, field studies investigating the light response curve ({NF}-{I} curve) of {NF} rate and the effect of light on diazotrophderived nitrogen ({DDN}) net release are relatively sparse in the literature, hampering prediction using models. {A} dissolution method was applied using uncontaminated {N}-15(2) gas to examine how the light changes may influence the {NF} intensity and {DDN} net release in the oligotrophic ocean. {E}xperiments were conducted at stations with diazotrophs dominated by filamentous cyanobacterium {T}richodesmium spp. in the western {P}acific and the {S}outh {C}hina {S}ea. {T}he effect of light on carbon fixation ({CF}) was measured in parallel using the {C}-13 tracer method specifically for a station characterized by {T}richodesmium bloom. {B}oth {NF}-{I} and {CF}-{I} curves showed a {I}-k (light saturation coefficient) range of 193 to 315 mu {E}m(-2) s(-1), with light saturation at around 400 mu {E}m(-2) s(-1). {T}he proportion of {DDN} net release ranged from similar to 6 to similar to 50 %, suggesting an increasing trend as the light intensity decreased. {A}t the {T}richodesmium bloom station, we found that the {CF}/{NF} ratio was light-dependent and the ratio started to increase as light was lower than the carbon compensation point of 200 mu {E}m(-2) s(-1). {U}nder low-light stress, {T}richodesmium physiologically preferred to allocate more energy for {CF} to alleviate the intensive carbon consumption by respiration; thus, there is a metabolism tradeoff between {CF} and {NF} pathways. {R}esults showed that shortterm (< 24 h) light change modulates the physiological state, which subsequently determined the {C}/{N} metabolism and {DDN} net release by {T}richodesmium. {R}eallocation of energy associated with the variation in light intensity would be helpful for prediction of the global biogeochemical cycle of {N} by models involving {T}richodesmium blooms.},
  keywords = {{PACIFIQUE} ; {MER} {DE} {CHINE}},
  booktitle = {},
  journal = {{B}iogeosciences},
  volume = {15},
  numero = {1},
  pages = {1--12},
  ISSN = {1726-4170},
  year = {2018},
  DOI = {10.5194/bg-15-1-2018},
  URL = {https://www.documentation.ird.fr/hor/fdi:010071969},
}