A NOTE ON THE MODELING OF THE ALGAL BLOOMS IN THE VAAL RIVER - THE SILICON EFFECT

In a recent article published in this journal, the authors described t he basis of a mathematical model aimed to simulate the total planktoni c biomass in a river. Taking only two fundamental environmental variab les, light and temperature, into account, they developed a simple mode l that is able to give a good qualitative description of the winter al gal bloom in the Vaal River (South Africa). However, some discrepancie s between the simulated amplitude of certain algal blooms and field me asurements were observed. In the present study, it is shown that this problem may, to a large extent, be solved by updating the model in ord er to take the Si uptake by diatoms into account.