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Valdes V., Carlotti F., Escribano R., Donoso K., Pagano Marc, Molina V., Fernandez C. (2018). Nitrogen and phosphorus recycling mediated by copepods and response of bacterioplankton community from three contrasting areas in the western tropical South Pacific (20 degrees S). Biogeosciences, 15 (20), 6019-6032. ISSN 1726-4170

Fichier PDF disponiblehttp://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers18-11/010074151.pdf[ PDF Link ]

Lien direct chez l'éditeur doi:10.5194/bg-15-6019-2018

En Libre Accès sur HAL https://hal.sorbonne-universite.fr/hal-01908261

Titre
Nitrogen and phosphorus recycling mediated by copepods and response of bacterioplankton community from three contrasting areas in the western tropical South Pacific (20 degrees S)
Année de publication2018
Type de documentArticle référencé dans le Web of Science WOS:000447403800002
AuteursValdes V., Carlotti F., Escribano R., Donoso K., Pagano Marc, Molina V., Fernandez C.
SourceBiogeosciences, 2018, 15 (20), p. 6019-6032. ISSN 1726-4170
RésuméZooplankton play a key role in the regeneration of nitrogen and phosphorus in the ocean through grazing and metabolism. This study investigates the role of the organic and inorganic nitrogen and phosphorus compounds released by copepods on biogeochemical processes and on the microbial community composition during the OUTPACE cruise (18 February-3 April 2015) at three longduration stations (LD). Two LD stations were located in the Melanesian Archipelago region (MA; LD A and LD B) and one in the South Pacific Gyre (SG; LD C), which represent oligotrophic and ultra-oligotrophic regions respectively. At each station, on-board microcosm experiments were performed with locally sampled organisms, comprising a mix of epipelagic copepods fed with their natural food and then incubated along with wild microbial assemblages. In the presence of copepods, ammonium and dissolved organic nitrogen showed a significant increase compared to a control in two situations: in ammonium concentration (rate: 0.29 mu mol L-1 h(-1) after 4 h of incubation) in LD C and in dissolved organic nitrogen concentration (rate: 2.13 mu mol L-1 h(-1) after 0.5 h of incubation) in LD A. In addition, during the three experiments, an enhanced remineralization (ammonification and nitrification) was observed when adding copepods compared to the controls. A shift in the composition of the active bacterial community was observed for the experiments in LD A and LD B, which were mainly characterized by an increase in Alteromonadales and SAR11, respectively, and linked with changes in nutrient concentrations. In the experiment performed in LD C, both groups increased but at different periods of incubation. Alteromonadales increased between 1 and 2 h after the beginning of the experiment, and SAR 11 at the end of incubation. Our results in near in situ conditions show that copepods can be a source of organic and inorganic compounds for bacterial communities, which respond to excretion pulses at different timescales, depending on the initial environmental conditions and on their community composition. These processes can significantly contribute to nutrient recycling and regenerated production in the photic zone of ultra-oligotrophic and oligotrophic oceanic regions.
Plan de classementEcologie, systèmes aquatiques [036] ; Limnologie physique / Océanographie physique [032]
Descr. géo.ZONE TROPICALE ; PACIFIQUE SUD
LocalisationFonds IRD [F B010074151]
Identifiant IRDfdi:010074151
Lien permanenthttp://www.documentation.ird.fr/hor/fdi:010074151

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