Raapoto H. auteur aut IRD Martinez Elodie auteur aut IRD Petrenko A. auteur aut IRD Doglioli A. auteur aut IRD Gorgues Thomas auteur aut IRD Sauzede R. auteur aut IRD Maamaatuaiahutapu K. auteur aut IRD Maes Christophe auteur aut IRD Menkès Christophe auteur aut IRD Lefevre Jérôme auteur aut IRD text journalArticle eng text/pdf reformatted digital access 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. specialized PACIFIQUE MARQUISES 032 036 020 124 11 7781-7796 2019 2169-9275 https://www.documentation.ird.fr/hor/fdi:010077333 10.1029/2019jc015275 2169-9275 [F B010077333] https://www.documentation.ird.fr/hor/fdi:010077333 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers20-09/010077333.pdf IRD - Base Horizon / Pleins textes 2020-01-07 2025-02-24 fdi:010077333 fre