@inproceedings{fdi:010072123,
  title = {{O}xygen variability over the southern {S}enegalese shelf [r{\'e}sum{\'e}]},
  author = {{M}achu, {E}ric and {T}all, {A}.{W}. and {C}apet, {X}. and {N}doye, {S}. and {L}azar, {A}. and {B}aurand, {F}. and {A}uger, {P}ierre-{A}ma{\¨e}l and {B}rehmer, {P}atrice},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he shelf of the southern part of the {C}anary upwelling system along {S}enegal and {M}auritania is bordered by an oxygen minimum zone whose center is located at about 400m depth above which is superimposed another minimum shallower than 200m. {A}s a consequence, dynamic upwelling bring hypoxic waters (60 µmol/l or 1.34 ml/l; 15°{C}) over the shelf during the upwelling season from {D}ecember to {M}ay. {A}n oceanographic survey was conducted in the heart of the upwelling season (7th-17th {M}arch 2012) over the southern {S}enegalese coast. {I}ntegrated physical and biogeochemical measurements were acquired and allowed us to measure for the first time to our knowledge an anoxic event in {S}enegalese waters with dissolved oxygen concentrations falling to zero. {V}ery high concentrations of nitrite (11 mmol/m3) mirroring nitrate reduction and nitrate/nitrite deficit to phosphate highlight intense denitrification taking place in this oxygen-depleted water body. {T}he record of this event by 30m depth occurs after a relaxation phase of the upwelling associated with a surface northward advection of warm waters from the south of the plateau. {A} subsurface north-westward advection of water consistent with wind relaxation was recorded near the anoxia event but inertial wave can not be dismissed for driving this northward flow. {A} diatom biomass was measured at 18 mg{C}hl/m3 along the shore two days earlier. {A}pparent {O}xygen {U}tilization and oxygen concentrations support the decay of phytoplankton biomass at the end of the survey. {W}hether the anoxia is due to the local decay of fast sinking dead diatoms or to a specific 3{D} history of the water body is difficult to establish. {H}owever, recently upwelled waters south of {C}ape {V}erde peninsula are advected southward and cover the entire shelf with undersaturated waters. {F}requent occurrence of high phytoplankton biomass along the coast suggests that anoxia and denitrification could occur recurrently in this region during the degradation of organic matter. {T}hese observations take place in a long term monitoring of bottom oxygen concentrations in this very productive coastal region of the world.},
  keywords = {{AFRIQUE} {DE} {L}'{OUEST} ; {SENEGAL} ; {MAURITANIE} ; {CAP} {VERT} ; {CANARIAS} ; {ATLANTIQUE}},
  numero = {},
  pages = {75--76},
  booktitle = {{I}nternational conference {ICAWA} 2016 : extended book of abstract : the {AWA} project : ecosystem approach to the management of fisheries and the marine environment in {W}est {A}frican waters},
  year = {2017},
  ISBN = {978-2-9553602-0-5},
  URL = {https://www.documentation.ird.fr/hor/fdi:010072123},
}