Silica incorporation in the diatom coscinodiscus granii as affected by light intensity

Abstract

Changes in the silicate concentration of the culture medium at growth-saturating concentrations had little effect on the silica content of cells of Coscinodiscus granii Gough at a given light intensity. However, there was a highly significant inverse relationship between silica content and light intensity. At a silicate concentration of 250 pmol l-1, the total silica content fell from 207 pmol cell 1 at a light intensity of 14 pmol m 2 s 1 to 29 pmol cell -1 at 150 pmol m-2 s-1. The corresponding fall in the frustule silica was from 9-2 fmol pm-2 to 1-8 fmol pm-2. The total silica content of diatom cells cannot be explained solely in terms of silicate uptake and duration of uptake is the most obvious modifying factor. It is suggested that under conditions inducing low growth rates (low light intensities) the cells are exposed to silica absorption for a longer period than cells under conditions inducing high growth rates (high light intensities) and that this results in the higher cellular silica content. © 1985 Taylor & Francis Group, LLC.