The growth conditions and development ofAsterionella formosaHass.,Tabellaria fenestrata(Lyngb.) Kütz.,Fragilaria crotonensisKitt., andOscillatoriaspp. have been studied in Lake Vansjø and Lake Mjøsa for many years. Some batch culture experiments have been performed with dilute phytoplankton populations in filtered water samples to support the field data. The results indicate that the concentrations of phosphate, nitrate, silicate or chelators/Fe were important factors regulating the spatial and temporal distribution of the populations. Based on the assumption that the growth rates were strongly dependent on the external nutrient concentration, S, the growth conditions were divided into three types. The nutrient concentration may be too low to support growth, i.e. the growth rate k ≤ 0, or the population is nutrient growth limited (0展开▼
