Axenic cultures of the coccolithophorid EtGliarziu

Experiments carried out with the coccolithophorid E~Gliania h~4xkqvi maintained in batch cultures showed that the patterns of photosynthetic carbon metabolism characteristic of this species are: ( I) carbon incorporation into proteins only represents about 20% of total carbon fixation into organic carbon, (2) protein a~.;:k?s in darkness is a significant and growth-dependent process, (3) most of the carbon fixed photosynthetically (45--600/F) fl_ *ws towards the lipid fraction, (4) the relative contribution of lipid-c to ce!lular biomass is directly related to the amount of calcite-L” present as coccoliths, (5) half of the carbon incorporated into polysaccharides during the light period is respired during the night, (6) d:trk “C k~ses durii~g the night generally represent IO13% of gross photosynthesis. and (7) the release of dissolved organic carbon is related to growth stage and accounts for 2-60/o of the total amount of carbon incorporated photosynthetically. Most of these lXIttems of carbon partitioning were validated in natural phytoplunkror~ asser,~blagzs dominated by I:‘. Arrx/e,vi during sampling conducted in the Norwgiart fjords. The results nrr: interpreted and discussed iti &SiIIs of their potential ecological and biogeochemical significance.