The effect of diatom populations on silica concentrations of Lakes Sorell and Crescent, Tasmania, and the utilisation of tripton as a source of silica

Lakes Sorell and Crescent are very alike in most physico-chemical features but differ markedly in silica concentrations. The small diatom crops of Sorell have little effect on silica levels which average 12·2 mg l-1 but in Crescent large crops of Diatoma and Synedra maintain low silica concentrations and often cause complete depletion. Silica is supplied to Crescent from Sorell but derivation of a budget is complicated by artificial regulation of Crescent inflow and outflow and lack of sufficient hydrological data. Cultural studies show that silica may frequently limit the Crescent diatom population and that, at least when dissolved silica is scarce, the diatoms may utilise the abundant triptonic silica of the lake.