Photosynthetic CO₂ Fixation by a Marine Green Macroalga, Enteromorpha prolifera (MÜLLER) J. AGARDH

Abstract

Experiments on photosynthetic CO₂ fixation by E. prolifera were carried out outdoors in 500l FRP tanks with a surface area of 1 m² each. When a cultivation tank containing sea water was aerated with CO₂ gas (1lmin^-1), the pH of the sea water decreased to 6.5 whereas the growth of this alga was stimulated as much as 1.5-1.7 times. Maximal CO₂ fixation rate (12 g-C m^-2 day^-1), photosynthetic efficiency (4 %) and CO₂ fixation efficiency (9 %) were induced through CO₂ aeration at a rate of 74 g-C day ^-1. Photosynthetic CO₂ fixation rate during outdoor cultivation of this alga was maximal under solar radiation of 10-15 MJ m^-2 day^-1. Based on these results, the annual CO₂ fixation rate of this alga in the Shikoku district was estimated to be 2 kg-C m^-2.