Diatom biochemistry with respect to nutrient concentrations and the quality of light

Abstract

Experiments were conducted to determine whether a relationship exists between the composition and metabolism of phytoplankton cells, and the chemistry of their environment.

The study was designed to simulate in the laboratory natural conditions as occur in upwelling zones of the sea.

Two diatom species If^alasslosLra pseudonana and SReleronema cojtatum were cultured in nutrient enriched and nutrient deficient seawater medium to create conditions comparable to newly upwelled water and 'aged' water respectively. Such conditions occur in upwelling areas of the world's oceans where oil rich deposits of possibly planktonic origin have been discovered. Differences in the biochemical constituents of the algae cultured in these specific conditions have been examined with a view to establishing background information of relevance to oil generation.

The major findings of the study included:

1 Increased carbohydrate and lipids, storage materials, relative to
protein and amino acids, as nutrient concentrations decreased.
2 Silicon uptake diminished in phosphate-deficient cultures.
3 Mucilage material built up around stationary phase cells.
4 The frustules of silicon limited SReletonema cells showed structural abnormalities. This was not the case in Ifialassiosira cells.
5. The rate of photosynthesis decreased in nutrient deficient cultures, and there was a reduction in the number of chromatophores per cell.

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