Title :

Lack-of P-limitation of phytoplankton and heterotrophic prokaryotes in surface waters of three anticyclonic eddies in the stratified Mediterranean Sea

Author(s) :

Tanaka, Tsuneo [Auteur]
Institut méditerranéen d'océanologie [MIO]
Thingstad, T. F. [Auteur]
University of Bergen [UiB]
Christaki, Urania [Auteur]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Colombet, J. [Auteur]
Laboratoire Microorganismes : Génome et Environnement [LMGE]
Cornet, Veronique [Auteur]
Institut méditerranéen d'océanologie [MIO]
Courties, Claude [Auteur]
Grattepanche, J.D. [Auteur]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Lagaria, Anna [Auteur]
Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 [LOG]
Nedoma, Jiri [Auteur]
Oriol, Louise [Auteur]
Laboratoire d'Océanographie Microbienne [LOMIC]
Psarra, S. [Auteur]
Pujo-Pay, Mireille [Auteur]
Laboratoire d'Océanographie Microbienne [LOMIC]
van Wambeke, France [Auteur]
Laboratoire de MicrobiologiE de Géochimie et d'Ecologie Marines [LMGEM]

Journal title :

Biogeosciences

Pages :

525-538

Publisher :

European Geosciences Union

Publication date :

2011-02-28

ISSN :

1726-4170

HAL domain(s) :

Planète et Univers [physics]/Océan, Atmosphère

English abstract : [en]

We investigated the identity of the limiting nutrient of the pelagic microbial food web in the Mediter-ranean Sea using nutrient manipulated microcosms during summer 2008. Experiments were carried out with surface waters ...
Show more >We investigated the identity of the limiting nutrient of the pelagic microbial food web in the Mediter-ranean Sea using nutrient manipulated microcosms during summer 2008. Experiments were carried out with surface waters at the center of anticyclonic eddies in the Western Basin, the Ionian Basin, and the Levantine Basin. In situ, the ratio of N to P was always higher in both dissolved and particulate organic fractions compared to the Redfield ratio , suggesting a relative P-starvation. In each experiment, four different treatments in triplicates (addition of ammo-nium, phosphate, a combination of both, and the unamended control) were employed and chemical and biological parameters monitored throughout a 3-4 day incubation. Temporal changes of turnover time of phosphate and ATP, and alkaline phosphatase activity during the incubation suggested that the phytoplankton and heterotrophic prokaryotes (Hprok) communities were not P-limited at the sites. Furthermore, Correspondence to: T. Tanaka (tsuneo.tanaka@obs-vlfr.fr) statistical comparison among treatments at the end of the incubation did not support a hypothesis of P-limitation at the three study sites. In contrast, primary production was consistently limited by N, and Hprok growth was not limited by N nor P in the Western Basin, but N-limited in the Ionian Basin, and N and P co-limited in the Levantine Basin. Our results demonstrated the gap between biogeochemical features (an apparent P-starved status) and biological responses (no apparent P-limitation). We question the general notion that Mediterranean surface waters are limited by P alone during the stratified period.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Internationale

Popular science :

Non

Collections :

• Laboratoire d'Océanologie et de Géosciences (LOG) - UMR 8187

Source :

Harvested from HAL