Role of Iron in the Marquesas Island Mass Effect

Type Article
Date 2019-11
Language English
Author(s) Raapoto Hirohiti1, Martinez Elodie2, Petrenko Anne3, Doglioli Andrea3, Gorgues Thomas2, Sauzède Raphaëlle4, Maamaatuaiahutapu Keitapu5, Maes Christophe2, Menkes Christophe6, Lefèvre Jérôme6
Affiliation(s) 1 : UPF, IRD, ILM, Ifremer, Écosystèmes Insulaires Océaniens Tahiti ,French Polynesia
2 : Université Brest, Ifremer, CNRS, IRD, Laboratoire d'Océanographie Physique et Spatiale, IUEM Brest ,France
3 : Aix‐Marseille University, Université de Toulon, CNRS, IRD, OSU PYTHEAS, Mediterranean Institute of Oceanography MIO, UM 110, 13288 Marseille ,France
4 : Sorbonne Université, CNRS, Institut de la Mer de Villefranche, Laboratoire d'Océanographie de Villefranche Villefranche‐sur‐Mer ,France
5 : Université de la Polynésie française, GePaSud Laboratory Tahiti ,French Polynesia
6 : IRD/Sorbonne Universités Nouméa, New Caledonia
Source Journal Of Geophysical Research-oceans (2169-9275) (American Geophysical Union (AGU)), 2019-11 , Vol. 124 , N. 11 , P. 7781-7796
DOI 10.1029/2019JC015275
WOS© Times Cited 3
Abstract

A remarkable chlorophyll‐a concentration (Chl, a proxy of phytoplankton biomass) plume can be noticed on remotely sensed ocean color observations at the boundary separating the equatorial mesotrophic from the subtropical oligotrophic waters in the central South Pacific Ocean. This prominent biological feature is known as the island mass effect of the Marquesas archipelago. Waters surrounding these islands present high macronutrient concentrations but an iron depletion. In this study, the origin of Chl enhancement is investigated using a modeling approach. Four simulations based on identical physical and biogeochemical forcings but with different iron sources are conducted and analyzed. Only simulations considering an iron input from the island sediments present similar patterns (despite being too weak) of vertical and horizontal Chl distributions as compared to biogeochemical‐Argo profiling float and satellite observations. In addition, simulations with no other iron input than the boundary forcings reveal the relative importance of remote processes in modulating the seasonal pattern of Chl around the archipelago through horizontal advection of nutrient‐rich waters from the equator toward the archipelago and vertical mixing uplifting deep nutrient‐rich waters toward the upper lit layer.

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Raapoto Hirohiti, Martinez Elodie, Petrenko Anne, Doglioli Andrea, Gorgues Thomas, Sauzède Raphaëlle, Maamaatuaiahutapu Keitapu, Maes Christophe, Menkes Christophe, Lefèvre Jérôme (2019). Role of Iron in the Marquesas Island Mass Effect. Journal Of Geophysical Research-oceans, 124(11), 7781-7796. Publisher's official version : https://doi.org/10.1029/2019JC015275 , Open Access version : https://archimer.ifremer.fr/doc/00592/70397/