EXPLORATORY STUDIES ON THE PHYSIOLOGY AND ECOLOGY OF A PSYCHROPHILIC MARINE DIATOM(1).

The effect of light, of 2 wavelengths, and of 3 temperatures on the uptake and evolution of O2 by the antarctic marine diatom, Fragilaria sublinearis, has been examined with mass spectrometry. The responses of this organism to light, in terms of O2 exchange, were qualitatively similar to those recorded by Hoch et al. with the blue-green Anacystis nidulans. In addition, distinctive temperature optima were indicated for O2 , production and uptake, which help to explain the psychrophilic character of the diatom. The possibility of varying rates of O2 uptake in the light being associated with photoassimilation of organic substrates has been discussed.