FN Archimer Export Format
PT J
TI Grazing affects carbon fixation pathways by phytoplankton in coastal marine ecosystems
BT 
AF COLLOS, Y
   DESCOLAS GROS, C
   MORNET, Francoise
AS 1:1;2:2;3:3;
FF 1:;2:;3:PDG-DOP-DCN-AGSAE-CRELA;
C1 Univ Montpellier 2, Lab Ecosyst Lagunaires, UMR 5119, CNRS, F-34095 Montpellier 5, France.
   Univ Montpellier 2, Inst Sci Evolut, UMR 5554, CNRS, F-34095 Montpellier, France.
   IFREMER, CNRS, UMR 10, Ctr Rech Ecol Marine & Aquaculture, F-17137 Lhoumeau, France.
C2 UNIV MONTPELLIER, FRANCE
   UNIV MONTPELLIER, FRANCE
   IFREMER, FRANCE
SI LA ROCHELLE
SE PDG-DOP-DCN-AGSAE-CRELA
IN WOS Ifremer jusqu'en 2018
   copubli-france
   copubli-univ-france
IF 0.475
TC 4
UR https://archimer.ifremer.fr/doc/2005/publication-6437.pdf
LA English
DT Article
DE ;Grazing;Carboxylases;Carbon assimilation;Anaplerotic;Ammonium
AB During parallel sampling of seawater samples in bottles and in free water (1000-2000 m(3) clay ponds), we have measured phytoplankton biomass, Ribulose biphosphate carboxylase (Rubisco), phosphoenol pyruvate carboxylase, and phosphoenol pyruvate carboxykinase activities and major nutrients (ammonium, nitrate, phosphate, silicate). This was done in two ecosystems: one with high grazing pressure due to the presence of oysters and another with low grazing pressure (no oysters). In the ecosystem subjected to high grazing pressure, anaplerotic carbon fixation by phytoplankton in free water was higher in the light period and could represent 25% of total carbon fixation. Incubating samples in bottles led to a major increase in Rubisco activity (80% in 3 h) relative to values measured in free water, a decrease in 5-carboxylases activity (70% in 24 h) due to ammonium exhaustion, as well as disappearance of its diet periodicity. This indicates a contrario that grazers, which are excluded from incubation bottles, drive ecosystems toward heterotrophy in situ by favoring the beta-carboxylation pathway through excretion products such as ammonium. Therefore, incubations in high grazing environments (characterized by a grazing rate near 2 day(-1)) change the way carbon is fixed by unicellular algae within 3 h through a change in the form of nitrogen taken up.
PY 2005
PD DEC
SO Chemistry and Ecology
SN 0275-7540
PU Taylor and Francis
VL 21
IS 6
UT 000234484000009
BP 503
EP 509
DI 10.1080/02757540500439217
ID 6437
ER

EF