Influence of enhanced CO2 on growth and photosynthesis of the red algaeGracilaria sp. andG. chilensis

Abstract

The influence of elevated CO2 concentrations on growth and photosynthesis ofGracilaria sp. andG. chilensis was investigated in order to procure information on the effective utilization of CO2. Growth of both was enhanced by CO2 enrichment (air + 650 ppm CO2, air + 1250 ppm CO2, the enhancement being greater inGracilaria sp. Both species increased uptake of NO3 − with CO2 enrichment. Photosynthetic inorganic carbon uptake was depressed inG. chilensis by pre-culture (15 days) with CO2 enrichment, but little affected inGracilaria sp. Mass spectrometric analysis showed that O2 uptake was higher in the light than in the dark for both species and in both cases was higher inGracilaria sp. The higher growth enhancement inGracilaria sp. was attributed to greater depression of photorespiration by the enrichment of CO2 in culture.