@article{fdi:010053875,
  title = {{N}utrient control of {N}-2 fixation in the oligotrophic {M}editerranean {S}ea and the impact of {S}aharan dust events},
  author = {{R}idame, {C}. and {L}e {M}oal, {M}organe and {G}uieu, {C}. and {T}ernon, {E}. and {B}iegala, {I}sabelle and {L}'{H}elguen, {S}. and {P}ujo-{P}ay, {M}.},
  editor = {},
  language = {{ENG}},
  abstract = {{A} better understanding of the factors controlling {N}-2 fixation is a pre-requisite for improving our knowledge on the contribution of {N}-2 fixation process in the nitrogen cycling. {T}race-metal clean nutrient/dust addition bioassays (+{P}, +{PF}e, +dust) were performed at three stations located in the western, central and eastern {M}editerranean {S}ea, in summer 2008 as part of the {BOUM} cruise. {T}he main goals were (1) to investigate the nutrient factor(s) limiting {N}-2 fixation (uptake of {N}-15(2)) and (2) to evaluate the potential impact of a {S}aharan dust event on this biological process during the stratification period. {I}nitially, surface waters at the three stations were {DIP}-depleted (<10 n{M}) while the {DF}e concentrations were relatively high (from 1.2 to 2.3 n{M}) most likely due to atmospheric iron accumulation in the surface mixed layer. {A}t all stations, {S}aharan dust input relieved the ambient nutrient limitation of the diazotrophic activity as demonstrated by the strong stimulation of {N}-2 fixation (from 130% to 430 %). {T}he highest dust stimulation of {N}-2 fixation was recorded at the station located in the eastern basin. {T}he response of diazotrophic activity to nutrient additions was variable between the sampled stations suggesting a spatial variability of the factor controlling {N}-2 fixation over the whole basin. {A}t all stations, {N}-2 fixation was not limited by {F}e nor co-limited by {P} and {F}e. {A}t the western station, {N}-2 fixation was {DIP} limited while at the eastern one, {N}-2 fixation was first {DIP} limited, then was limited by one or several chemical element(s) released by dust. {O}ur results demonstrated that a {S}aharan dust input was able to relieve these successive on going limitations. {V}ery interestingly, at the station located in the central basin, {N}-2 fixation was not limited by the availability of {P} yet it was strongly stimulated by dust addition (x3.1). {A} chemical element or a combination of several, released by the added dust may have been responsible for the observed stimulations of {N}-2 fixation. {T}hese results indicated that {S}aharan dust pulses to the surface {M}editerranean waters, in addition to {P} and {F}e, could be a source of chemical(s) element(s) that are necessary for metabolic processes and therefore influence rates of {N}-2 fixation.},
  keywords = {},
  booktitle = {},
  journal = {{B}iogeosciences},
  volume = {8},
  numero = {9},
  pages = {2773--2783},
  ISSN = {1726-4170},
  year = {2011},
  DOI = {10.5194/bg-8-2773-2011},
  URL = {https://www.documentation.ird.fr/hor/fdi:010053875},
}