FN Archimer Export Format
PT J
TI Diazotrophic Trichodesmium impact on UV-Vis radiance and pigment composition in the western tropical South Pacific
BT 
AF DUPOUY, Cecile
   FROUIN, Robert
   TEDETTI, Marc
   MAILLARD, Morgane
   RODIER, Martine
   LOMBARD, Fabien
   GUIDI, Lionel
   PICHERAL, Marc
   NEVEUX, Jacques
   DUHAMEL, Solange
   CHARRIERE, Bruno
   SEMPERE, Richard
AS 1:1,2;2:3;3:1;4:1;5:;6:;7:;8:;9:;10:;11:;12:;
FF 1:;2:;3:;4:;5:;6:;7:;8:;9:;10:;11:;12:;
C1 Univ Toulon & Var, Aix Marseille Univ, CNRS, IRD,MIO UM 110, F-13288 Marseille, France.
   Ctr IRD Noumea, MIO UM 110, Noumea 98848, New Caledonia.
   Univ Calif San Diego, Scripps Inst Oceanog, La Jolla, CA 92093 USA.
   Univ Polynesie Francaise, Inst Malarme, Ifremer, Inst Rech Dev,EIO, Papeete, French Polynesi, Fr Polynesia.
   Univ Paris 06, UPMC, Sorbonne Univ, CNRS,LOV,Observ Oceanol, F-06230 Villefranche Sur Mer, France.
   Univ Paris 06, UPMC, Sorbonne Univ, Lab Oceanog Microbienne LOMIC,Observ Oceanol,CNRS, F-66650 Banyuls Sur Mer, France.
   Columbia Univ, Lamont Doherty Earth Observ, Palisades, NY USA.
   Ctr Format & Rech Environm Mediterraneens CEFREM, UMR CNRS UPVD 5110, 52 Ave Paul Alduy, F-66860 Perpignan, France.
C2 UNIV TOULON, FRANCE
   IRD, FRANCE
   UNIV CALIF SAN DIEGO, USA
   UNIV POLYNESIE FRANCAISE, FRANCE
   UNIV PARIS 06, FRANCE
   UNIV PARIS 06, FRANCE
   UNIV COLUMBIA, USA
   CEFREM, FRANCE
UM EIO
IN DOAJ
IF 3.951
TC 14
UR https://archimer.ifremer.fr/doc/00457/56824/58659.pdf
   https://archimer.ifremer.fr/doc/00457/56824/58660.pdf
LA English
DT Article
CR BIOSOPE
   DIAPALIS
   OUTPACE
BO L'Atalante
AB We assessed the influence of the marine diazotrophic cyanobacterium Trichodesmium on the bio-optical properties of western tropical South Pacific (WTSP) waters (18-22 degrees S, 160 degrees E-160 degrees W) during the February-March 2015 OUTPACE cruise. We performed measurements of backscattering and absorption coefficients, irradiance, and radiance in the euphotic zone with a Satlantic MicroPro free-fall profiler and took Underwater Vision Profiler 5 (UPV5) pictures for counting the largest Trichodesmium spp. colonies. Pigment concentrations were determined by fluorimetry and high-performance liquid chromatography and picoplankton abundance by flow cytometry. Trichome concentration was estimated from pigment algorithms and validated by surface visual counts. The abundance of large colonies counted by the UVP5 (maximum 7093 colonies m(-3)) was well correlated to the trichome concentrations (maximum 2093 trichomes L-1) with an aggregation factor of 600. In the Melanesian archipelago, a maximum of 4715 trichomes L-1 was enumerated in pump samples (3.2 m) at 20 degrees S, 167 30 degrees E. High Trichodesmium abundance was always associated with absorption peaks of mycosporine-like amino acids (330, 360 nm) and high particulate backscattering, but not with high Chl a fluorescence or blue particulate absorption (440 nm). Along the west-to-east transect, Trichodesmium together with Prochlorococcus represented the major part of total chlorophyll concentration; the contribution of other groups were relatively small or negligible. The Trichodesmium contribution to total chlorophyll concentration was the highest in the Melanesian archipelago around New Caledonia and Vanuatu (60 %), progressively decreased to the vicinity of the islands of Fiji (30 %), and reached a minimum in the South Pacific Gyre where Prochlorococcus dominated chlorophyll concentration. The contribution of Trichodesmium to zeaxanthin was respectively 50, 40 and 20% for these regions. During the OUTPACE cruise, the relationship between normalized water-leaving radiance (nL(w)) in the ultraviolet and visible and chlorophyll concentration was similar to that found during the BIOSOPE cruise in the eastern tropical Pacific. Principal component analysis (PCA) of OUTPACE data showed that nL(w) at 305, 325, 340, 380, 412 and 440 nm was strongly correlated to chlorophyll and zeaxanthin, while nL(w) at 490 and 565 nm exhibited lower correlations. These results, as well as differences in the PCA of BIOSOPE data, indicated that nL(w) variability in the greenish blue and yellowish green during OUTPACE was influenced by other variables associated with Trichodesmium presence, such as backscattering coefficient, phycoerythrin fluorescence and/or zeaxanthin absorption, suggesting that Trichodesmium detection should involve examination of nLw in this spectral domain. 
PY 2018
PD AUG
SO Biogeosciences
SN 1726-4170
PU Copernicus Gesellschaft Mbh
VL 15
IS 16
UT 000443197700002
BP 5249
EP 5269
DI 10.5194/bg-15-5249-2018
ID 56824
ER

EF