Publications des scientifiques de l'IRD

Martinez Elodie, Rodier Martine, Pagano Marc, Sauzede R. (2020). Plankton spatial variability within the Marquesas archipelago, South Pacific. Journal of Marine Systems, 212, 103432 [13 p.]. ISSN 0924-7963.

Titre du document
Plankton spatial variability within the Marquesas archipelago, South Pacific
Année de publication
2020
Type de document
Article référencé dans le Web of Science WOS:000582806700011
Auteurs
Martinez Elodie, Rodier Martine, Pagano Marc, Sauzede R.
Source
Journal of Marine Systems, 2020, 212, 103432 [13 p.] ISSN 0924-7963
The Marquesas Islands, in the central South Pacific, is a region of enhanced phytoplankton enrichment visible from space and is a hotspot of endemism and biodiversity; however, it has been poorly studied. In situ physical-chemical-biological concomitant observations are almost non-existent and all located close to the main northern island, while ocean dynamics based on satellite observations and numerical modeling show contrasting north/south patterns within the archipelago. Thus, we took the opportunity of the Pakahi I te Moana cruise conducted in 2012 to collect hydrological and plankton samples and investigate biogeochemical spatial patterns, especially north/south, over the archipelago. These data provide the first description of the spatial and vertical distribution of physical, chemical and plankton characteristics over the entire Marquesas archipelago, and give a first hint to improve our understanding of this planktonic enrichment. The whole archipelago appeared to be a macro-nutrient-rich environment. Different patterns in the physical, chemical and biological vertical distributions were observed between the northern vs. southern part of the archipelago, and offshore vs. nearshore stations. Phytoplankton biomasses were higher in the north where stratification was weaker, compared to the south and higher close to the islands than offshore. Phytoplankton all over the archipelago was largely dominated by picophytoplankton; specifically, Prochlorococcus presented a more widespread distribution than previously thought and were present over a large range of nutrient concentrations. Copepods were always the most abundant taxa in the archipelago but showed higher mean relative abundances near the islands. The importance of suspension-feeding zooplankton in the northern islands coincided with the highest biomasses of phytoplankton with a predominance of nano- and micro-phytoplankton. This was consistent with a young community responding to nutrient enrichment by an increase of suspension-feeders animals and bottom-up effect on zooplankton. Opposite to this, small copepods were significantly less abundant in the northern offshore region and the dominance of carnivorous forms coincided with low phytoplankton biomass and strong dominance of picoplankton, suggesting a microbial grazing pathway and more mature communities.
Plan de classement
Limnologie physique / Océanographie physique [032] ; Ecologie, systèmes aquatiques [036]
Description Géographique
PACIFIQUE ; MARQUISES
Localisation
Fonds IRD [F B010079898]
Identifiant IRD
fdi:010079898
Contact