Fixation of Elemental Nitrogen by Marine Blue-green Algae

Abstract

Three blue-green algae, Calothrix scopulorum, Nostoc entophytum, and Oscillatoria brevis, isolated from the upper littoral and supralittoral fringe of the sea-shore were obtained in pure culture and tested for fixation of elemental nitrogen. Appreciable fixation by Calothrix and Nostoc was detected, a proportion of the total nitrogen fixed being liberated into the culture medium. There was no evidence of fixation by Oscillatoria. This appears to be the first evidence that blue-green algae isolated in pure culture from marine habitats fix nitrogen.