Phytoplankton blooms are a well described phenomenon. However, while the succession of species is also usually well documented, the mechanisms that drive it still remain unknown to a large extent. Correlations between algal behaviour and biotic and abiotic factors can provide valuable information, but, as long as little continues to be known about the requirements of individual species such correlations remain somewhat speculative. To obtain a better insight, we cultured five key diatom species, from different phases during the 2004 spring bloom, under 5 different nutrient regimes at two grazer related stress levels and at three temperatures. Photosynthetic efficiency, growth rate, individual biovolumes and colony size were measured. The results of this experiment can be linked to data from the 2004 spring bloom and show different life strategies, preferences and reaction patterns that might explain the observed succession during blooms.