@article{fdi:010071047,
  title = {{A}coustic distribution of discriminated micronektonic organisms from a bi-frequency processing : the case study of eastern {K}erguelen oceanic waters},
  author = {{B}ehagle, {N}olwenn and {C}otte, {C}. and {L}ebourges {D}haussy, {A}nne and {R}oudaut, {G}ildas and {D}uhamel, {G}. and {B}rehmer, {P}atrice and {J}osse, {E}rwan and {C}herel, {Y}.},
  editor = {},
  language = {{ENG}},
  abstract = {{D}espite its ecological importance, micronekton remains one of the least investigated components of the open-ocean ecosystems. {O}ur main goal was to characterize micronektonic organisms using bi-frequency acoustic data (38 and 120 k{H}z) by calibrating an algorithm tool that discriminates groups of scatterers in the top 300 m of the productive oceanic zone east of {K}erguelen {I}slands ({I}ndian sector of the {S}outhern {O}cean). {T}he bi-frequency algorithm was calibrated from acoustic properties of mono-specific biological samples collected with trawls, thus allowing to discriminate three acoustic groups of micronekton: (i) "gas-bearing" ({D}elta {S}v.120-38 < -1 d{B}), (ii) "fluid-like" ({D}elta {S}-v,{S}-120-38 > 2 d{B}), and (iii) "undetermined" scatterers (-1 < {D}elta {S}-v,{S}-120-38 < 2 d{B}). {T}he three groups likely correspond biologically to gas-filled swimbladder fish (myctophids), crustaceans (euphausiids and hyperiid amphipods), and other marine organisms potentially present in these waters and containing either lipid-filled or no inclusion (e.g. other myctophids), respectively. {T}he {N}autical {A}rea {S}cattering {C}oefficient ({NASC}) was used (echo-integration cells of 10 m long and 1 m deep) between 30 and 300 m depth as a proxy of relative biomass of acoustic targets. {T}he distribution of {NASC} values showed a complex pattern according to: (i) the three acoustically defined groups, (ii) the type of structures (patch vs. layers) and (iii) the timing of the day (day/night cycle). {NASC} values were higher at night than during the day. {A} large proportion of scatterers occurred in layers while patches, that mainly encompass gas-bearing organisms, are especially observed during daytime. {T}his method provided an essential descriptive baseline of the spatial distribution of micronekton and a relevant approach to (i) link micronektonic group to physical parameters to define their habitats, (ii) investigate trophic interactions by combining active acoustic and top predator satellite tracking, and (iii) study the functioning of the pelagic ecosystems at various spatio-temporal scales.},
  keywords = {{E}uphausiid ; {K}erguelen ; {M}yctophid ; {S}outhern {O}cean ; {A}coustics ; {KERGUELEN} ; {OCEAN} {ARCTIQUE}},
  booktitle = {},
  journal = {{P}rogress in {O}ceanography},
  volume = {156},
  numero = {},
  pages = {276--289},
  ISSN = {0079-6611},
  year = {2017},
  DOI = {10.1016/j.pocean.2017.06.004},
  URL = {https://www.documentation.ird.fr/hor/fdi:010071047},
}