Photosynthetic parameters Marcel Babin

measured variables Photosynthetic parameters derived from P vs. E (14C) curves (10 depths, 1L) Parameters derived from measurements of variable fluorescence : –discrete samples : PAM (10 depth, 100ml) –in situ measurements: FRRF

P (mg C m -3 h -1 ) PAR (mole Quanta m -2 s -1 ) P max Ek P = P max tanh(PAR /Ek)  c = P / 12 (PAR. a) mole C mole Quanta -1  c max =  / 12 a P vs E curve  a = absorption coefficient m -1 Ek = P max / 

PROSOPE Bruyant, 2002

Photo-physiological parameters might be dependant on phytoplankton community composition (POMME results) 7.27 ± ± ± 0.29 R 2 = 0.73 n = ± ± ± R 2 = 0.91 n = ± ± ± R 2 = 0.72 n = 344 P B max mg C mg Chla -1 h -1 micro nano pico a* m 2 mg Chla -1 BB mg C mg Chla -1 h -1 mole Quanta m -2 s  Cmax mole C mole quanta

Besides P vs E measurements : Absorption, HPLC pigments, and 14C primary production (other approach to test the dependence of carbon fixation efficiency on taxonomic composition) More easy to parameterise than a dependence on environmental variables (T°, Nutrient and light) Potential applications for bio-optical models Main hypothesis to be tested on BIOSOPE : Is the efficiency of carbon fixation dependant on the taxonomic groups (size) which are present (large phytoplankton more efficient than small one)?

Parameters deduced from variable fluorescence measurements on discrete samples and in situ. PSII ox PSII red 0 FoFo FmFm FvFv  PS2 = (F m – F o ) / F m  PS2