@article{fdi:010078902,
  title = {{E}nhancement of phytoplankton biomass leeward of {T}ahiti as observed by {B}iogeochemical-{A}rgo floats},
  author = {{S}auzede, {R}. and {M}artinez, {E}lodie and {M}aes, {C}hristophe and {F}ommervault, {O}. {P}. and {P}oteau, {A}. and {M}ignot, {A}. and {C}laustre, {H}. and {U}itz, {J}. and {O}ziel, {L}. and {M}aamaatuaiahutapu, {K}. and {R}odier, {M}artine and {S}chmechtig, {C}. and {L}aurent, {V}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he {S}outh {P}acific {S}ubtropical {G}yre ({SPSG}) is a vast and remote oceanic system where the variability in phytoplankton biomass and production is still largely uncertain due to the lack of in situ biogeochemical observations. {T}he {SPSG} is an oligotrophic environment where the ecosystem is controlled predominantly by nutrient depletion in surface waters. {H}owever, this dynamic is altered in the vicinity of islands where increased biological activity occurs (i.e. the island mass effect, {IME}). {T}his study mainly focuses on in situ observations which show evidence of an {IME} leeward of {T}ahiti (17.7 degrees {S} - 149.5 degrees {W}), {F}rench {P}olynesia. {P}hysical and biogeochemical observations collected with two {B}iogeochemical-{A}rgo profiling floats are used to investigate the dynamics of phytoplankton biomass. {D}ata from the first float, drifting from {A}pril 2015 to {N}ovember 2016 over > 1000 km westward of {T}ahiti, describe the open ocean conditions. {T}he second float, deployed leeward of {T}ahiti in {O}ctober 2015, stayed within 45 {I}an off {T}ahiti for three months before it stopped communicating. {I}n the oligotrophic central {SPSG}, our observations show that the deepening of the deep chlorophyll maximum ({DCM}) from winter to summer is light-driven and that the wintertime increase in chlorophyll a concentration in the upper layer is likely to be due to the process of photoacclimation, consistent with previous observations in oligotrophic environments. {I}n contrast, leeward of {T}ahiti, the {DCM} widens toward the surface during late spring in association with a biological enhancement in the upper layer. {U}sing {B}iogeochemical-{A}rgo data, meteorological data from {T}ahiti, {H}ybrid {C}oordinate {O}cean {M}odel outputs and satellite-derived products (i.e., horizontal currents and associated fronts), the physical mechanisms involved in producing this biological enhancement leeward of {T}ahiti have been investigated. {T}he {IME} occurs during a period of strong precipitation and in a zone of weak currents downstream of the island. {W}e conjecture that the land drainage induces a significant supply of nitrate in the ocean upper layer (down to similar to 100 m) while a zone of weak currents in the southwestern zone behind {T}ahiti allows an accumulation zone to form, hence increasing phytoplankton growth up to 20 km away from the coastlines. {A} bio-optical-based community index suggests that the composition of the phytoplankton community differs leeward of {T}ahiti from that in the open ocean area, with more microphytoplankton within the {IME}, which is associated with an increase in the carbon export to the deeper ocean.},
  keywords = {{P}hytoplankton biomass ; {B}iogeochemical-{A}rgo floats ; {I}sland mass effect ; {S}outh {P}acific {S}ubtropical {G}yre ; {TAHITI} ; {PACIFIQUE}},
  booktitle = {},
  journal = {{J}ournal of {M}arine {S}ystems},
  volume = {204},
  numero = {},
  pages = {103284 [16 ]},
  ISSN = {0924-7963},
  year = {2020},
  DOI = {10.1016/j.jmarsys.2019.103284},
  URL = {https://www.documentation.ird.fr/hor/fdi:010078902},
}