Relationship of CO2 concentrations to photosynthesis of intertidal macroalgae during emersion

In order to assess the ecological impacts of the atmospheric CO2 increase on the intertidal macroalgae during emersion, the photosynthesis of Enteromorpha linza (a green alga), Ishige okamurae (a brown alga) and Gloiopeltis furcata (a red alga) was investigated in air as a function of CO2 concentrations and water loss. Their photosynthesis was not saturated at the present atmospheric CO2 level (350 mu l l(-1) or 15.6 mu M), the CO2 compensation point and K-[mCO2] increased with increasing desiccation, showing that desiccation lowers the CO2 affinity of the intertidal macroalgae. It was concluded that E. linza, I. okamurae and G. furcata, while exposed to air, can benefit from atmospheric CO2 rise, especially when the algae have lost some water.