Carbon sequestration by a few marine algae: observation and projection

CO2sequestration by the marine planktonic microalgaeNannochloropsis salinaandIsochrysis galbanaas well as macroformsGracilaria corticata, Sargassum polycystumandUlva lactucawas estimatedunder laboratory conditions.The green seaweedU. lactucaregistered 100% utilization of CO2towards carbon fixation from the ambient water up to 15 mg/l and beyond that it declined to 60%.The microalgae were able to utilize 27.7% of dissolved CO2at 15 mg/l, but did not show any effecteither for carbon fixation or for emission at lower and higher levels. Gross primary productivityof these algae were also not affected by increase in the CO2levels. It is estimated that the seaweedbiomass along the Indian coast is capable of utilizing 9052 tCO2/d against emission of 365tCO2/d indicating a net carbon credit of 8687 t/d.