Ecophysiological experiments conducted in situ in the Bay of Marennes-Oléron during a spring and neap tide cycle in May 1991 , were designed to get a better representation of 2 important components of the energy budget of the Japanese oyster Crassostrea gigas : clearance rate and selection efficiency. The relationships previously established by Raillard et al. ( 1993) are re-evaluated by integrating the effects of high seston loads, typical of tidal effect within estuaries, on the physiological processes. For the clearance rate, the re-evaluated parameterization includes: - a negative effect of turbidity. - a clogging threshold set to 192 mg/l. Selection efficiency parameterizations are modified by incorporating : - a constant inorganic ingestion for increasing seston load, set to 17 % of the inorganic filtered ration. - an upper selection threshold for the paticulate organic matter set to 160 mg/l. The oyster growth model should be enhanced by integrating theses new equations built-up on realistic field conditions.