FN Archimer Export Format PT J TI Lack of P-limitation of phytoplankton and heterotrophic prokaryotes in surface waters of three anticyclonic eddies in the stratified Mediterranean Sea BT AF TANAKA, T. THINGSTAD, T. F. CHRISTAKI, U. COLOMBET, J. CORNET-BARTHAUX, V. COURTIES, C. GRATTEPANCHE, J. -D. LAGARIA, A. NEDOMA, J. ORIOL, L. PSARRA, S. PUJO-PAY, M. VAN WAMBEKE, France AS 1:1;2:2;3:3;4:4;5:1;6:5,6;7:3;8:3,7;9:8;10:9,10;11:7;12:9,10;13:11; FF 1:;2:;3:;4:;5:;6:;7:;8:;9:;10:;11:;12:;13:; C1 Univ Aix Marseille 2, Lab Oceanog Phys & Biogeochim, Ctr Oceanol Marseille, CNRS,OSU,UMR 6535, F-13288 Marseille 09, France. Univ Bergen, Dept Biol, N-5006 Bergen, Norway. Univ Lille , CNRS, ULCO, LOG,UMR 8187, F-62930 Wimereux, France. Univ Clermont Ferrand, Lab Microorganismes Genome & Environm, F-63177 Aubiere, France. Univ Paris 06, Observ Oceanol, UMS 2348, F-66651 Banyuls Sur Mer, France. CNRS, Observ Oceanol, UMS 2348, F-66651 Banyuls Sur Mer, France. Hellen Ctr Marine Res, Iraklion 71003, Crete, Greece. Inst Hydrobiol, Biol Ctr ASCR, Vvi, Ceske Budejovice 37005, Czech Republic. Univ Paris 06, Observ Oceanol, Lab Oceanog Microbienne, UMR 7621, F-66651 Banyuls Sur Mer, France. CNRS, Observ Oceanol, Lab Oceanog Microbienne, UMR 7621, F-66651 Banyuls Sur Mer, France. Univ Aix Marseille 2, Lab Microbiol Geochim & Ecol Marines, Ctr Oceanol Marseille, CNRS,OSU,UMR 6117, F-13288 Marseille, France. C2 UNIV AIX MARSEILLE, FRANCE UNIV BERGEN, NORWAY UNIV LILLE, FRANCE UNIV CLERMONT FERRAND, FRANCE UNIV PARIS 06, FRANCE CNRS, FRANCE HELLEN CTR MARINE RES, GREECE INST HYDROBIOL, CZECH REPUBLIC UNIV PARIS 06, FRANCE CNRS, FRANCE UNIV AIX MARSEILLE, FRANCE IF 3.859 TC 77 TU Aix-Marseille université Centre national de la recherche scientifique Université Lille 1 - Sciences technologies Université Pierre et Marie Curie Université du Littoral Côte d'Opale UR https://archimer.ifremer.fr/doc/00133/24395/22406.pdf LA English DT Article CR BOUM BO L'Atalante AB We investigated the identity of the limiting nutrient of the pelagic microbial food web in the Mediterranean 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 ammonium, 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, 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. PY 2011 SO Biogeosciences SN 1726-4170 PU Copernicus Gesellschaft Mbh VL 8 IS 2 UT 000287796800021 BP 525 EP 538 DI 10.5194/bg-8-525-2011 ID 24395 ER EF