Relationship of CO2 concentrations to photosynthesis of intertidal macroalgae during emersion

In order to assess the ecological impacts of the atmospheric CO2 increase o n the intertidal macroalgae during emersion, the photosynthesis of Enteromo rpha linza (a green alga), Ishige okamurae (a brown alga) and Gloiopeltis f urcata (a red alga) was investigated in air as a function of CO2 concentrat ions 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 p oint and K-[mCO2] increased with increasing desiccation, showing that desic cation lowers the CO2 affinity of the intertidal macroalgae. It was conclud ed that E. linza, I. okamurae and G. furcata, while exposed to air, can ben efit from atmospheric CO2 rise, especially when the algae have lost some wa ter.