Résumé
Gross primary production (GPP) and respiration (R) in an intertidal
Zostera noltii
(Hornemann, 1832) community were estimated each month from in situ CO
2
flux measurements during the emersion period in the Bay of Morlaix (France). Simultaneously, the Chlorophyll
a
biomass of
Z.
noltii
leaves, associated epiphytes and sediment within the benthic chambers were also monitored. The significant positive exponential relationship established between R and the maximum daily temperature emphasized that temperature was a good predictor of seasonal variation in the community R in
Z.
noltii
bed. In contrast, the amplitude of the fitted curve on GPP was low and represented <25% of the annual mean value (90.9 ± 15.2 mgC m
−2
h
−1
). The Chlorophyll
a
biomass of sediment was high (133.70 ± 22.96 mg m
−2
) but it was likely constituted by detritus which did not contribute much to the community GPP. The Chlorophyll
a
biomass of associated epiphytes was higher in winter and varied over the year inversely with
Z.
noltii
. Therefore, the asynchronous dynamic of primary producers could support a constant rate of production at community scale over the year.