@article{fdi:010066761,
  title = {{A}coustic micronektonic distribution is structured by macroscale oceanographic processes across 20-50 degrees {S} latitudes in the {S}outh-{W}estern {I}ndian {O}cean},
  author = {{B}ehagle, {N}olwenn and {C}otte, {C}. and {R}yan, {T}. {E}. and {G}authier, {O}. and {R}oudaut, {G}ildas and {B}rehmer, {P}atrice and {J}osse, {E}rwan and {C}herel, {Y}.},
  editor = {},
  language = {{ENG}},
  abstract = {{M}icronelcton constitutes the largest unexploited marine biomass worldwide. {I}t is one of the most conspicuous and ecologically important components of the still poorly known mesopelagic ecosystem. {A}coustic data were collected from both fishing and research vessels along 18 transects for a total of 47 682 linear kilometers to investigate large-scale distribution of micronekton over a long latitudinal gradient (20-50 degrees {S}) and two contrasted seasons (summer and winter) in the {S}outh-{W}estern {I}ndian {O}cean. {A}coustic backscatter at 38 k{H}z was used as a proxy of mid-water organisms' abundance (0-800 m depth). {T}wo consistent features were diel vertical migration of backscatters and vertical distribution of micronekton in three distinct layers, namely the surface ({SL}), intermediate ({IL}) and deep ({DL}) layers. {S}atellite remote sensing data was used to position oceanic fronts, and hence define water masses, from the tropical to low {A}ntarctic zones. {A} key finding of this study was the significant correlation observed between abundance and distribution of acoustic backscatter and position relative to these front and water masses. {T}otal backscatter peaked in the subtropical zone, with low abundances in the colder {P}olar {F}rontal {Z}one. {T}he high overall abundances in subtropical waters resulted mainly from high backscatters in the {IL} and {DL} that contrasted with low {SL} values, especially during the day (2-11%). {T}he warmer the waters, the higher {SL} backscatter was, with the highest absolute and relative (38-51% of the total abundance) values observed at night in the {T}ropical {Z}one and the lowest abundance in the {A}ntarctic {Z}one. {N}o significant seasonal pattern was found, but {SL} backscatters were very low in winter compared to summer in the {P}olar {F}rontal {Z}one. {M}oreover, the {N}orthern winter shift of the fronts induced a {N}orthern latitudinal shift of the peak in abundance from summer to winter. {T}he present study highlights the value of building large acoustic databases collected from both research and fishing vessels. {T}he method provides unique opportunities to gather basic information on micronekton and is an essential step to describe oceanic zones of relevant biological interest in terms of trophic ecology.},
  keywords = {{M}esopelagic ; {A}coustics ; {M}id-water organisms ; {W}ater masses ; {S}outhern {O}cean ; {OCEAN} {INDIEN} ; {ZONE} {TROPICALE} ; {ANTARCTIQUE} ; {AUSTRAL} {OCEAN}},
  booktitle = {},
  journal = {{D}eep-{S}ea {R}esearch {P}art {I} : {O}ceanographic {R}esearch {P}apers},
  volume = {110},
  numero = {},
  pages = {20--32},
  ISSN = {0967-0637},
  year = {2016},
  DOI = {10.1016/j.dsr.2015.12.007},
  URL = {https://www.documentation.ird.fr/hor/fdi:010066761},
}