@article{fdi:010072713,
  title = {{D}istributions and abundances of sublineages of the {N}-2-fixing cyanobacterium {C}andidatus {A}telocyanobacterium thalassa ({UCYN}-{A}) in the {N}ew {C}aledonian coral lagoon},
  author = {{H}enke, {B}. {A}. and {T}urk-{K}ubo, {K}. {A}. and {B}onnet, {S}ophie and {Z}ehr, {J}. {P}.},
  editor = {},
  language = {{ENG}},
  abstract = {{N}itrogen ({N}-2) fixation is a major source of nitrogen that supports primary production in the vast oligotrophic areas of the world's oceans. {T}he {W}estern {T}ropical {S}outh {P}acific has recently been identified as a hotspot for {N}-2 fixation. {I}n the {N}oumea lagoon ({N}ew {C}aledonia), high abundances of the unicellular {N}-2-fixing cyanobacteria group {A} ({UCYN}-{A}), coupled with daytime {N}-2 fixation rates associated with the <10 mu m size fraction, suggest {UCYN}-{A} may be an important diazotroph ({N}-2-fixer) in this region. {H}owever, little is known about the seasonal variability and diversity of {UCYN}-{A} there. {T}o assess this, surface waters from a 12 km transect from the mouth of the {D}umbea {R}iver to the {D}umbea {P}ass were sampled monthly between {J}uly 2012 and {M}arch 2014. {UCYN}-{A} abundances for two of the defined sublineages, {UCYN}-{A}1 and {UCYN}-{A}2, were quantified using q{PCR} targeting the nif{H} gene, and the nif{H}-based diversity of {UCYN}-{A} was characterized by identifying oligotypes, alternative taxonomic units defined by nucleotide positions with high variability. {UCYN}-{A} abundances were dominated by the {UCYN}-{A}1 sublineage, peaked in {S}eptember and {O}ctober and could be predicted by a suite of nine environmental parameters. {A}t the sublineage level, {UCYN}-{A}1 abundances could be predicted based on lower temperatures (<23 degrees {C}), nitrate concentrations, precipitation, wind speed, while {UCYN}-{A}2 abundances could be predicted based on silica, and chlorophyll a concentrations, wind direction, precipitation, and wind speed. {U}sing {UCYN}-{A} nif{H} oligotyping, similar environmental variables explained the relative abundances of sublineages and their associated oligotypes, with the notable exception of the {UCYN}-{A}2 oligotype (oligo43) which had relative abundance patterns distinct from the dominant {UCYN}-{A}2 oligotype (oligo3). {T}he results support an emerging pattern that {UCYN}-{A} is comprised of a diverse group of strains, with sublineages that may have different ecological niches. {B}y identifying environmental factors that influence the composition and abundance of {UCYN}-{A} sublineages, this study helps to explain global {UCYN}-{A} abundance patterns, and is important for understanding the significance of {N}2 fixation at local and global scales.},
  keywords = {{C}andidatus {A}telocyanobacterium thalassa ; nitrogen fixation ; nitrogenase ; nif{H} ; oligotyping ; {UCYN}-{A} ; {N}ew {C}aledonia ; {W}estern {T}ropical {S}outh {P}acific ; {NOUVELLE} {CALEDONIE} ; {PACIFIQUE} ; {ZONE} {TROPICALE}},
  booktitle = {},
  journal = {{F}rontiers in {M}icrobiology},
  volume = {9},
  numero = {},
  pages = {art. 554 [14 ]},
  ISSN = {1664-302{X}},
  year = {2018},
  DOI = {10.3389/fmicb.2018.00554},
  URL = {https://www.documentation.ird.fr/hor/fdi:010072713},
}