Fluctuation of growth and photosynthetic characteristics in Prorocentrum shikokuense under phosphorus limitation: Evidence from field and laboratory

Exploring the complex interaction between algal growth and their photo-physiology is of significant interest as it can further the understanding of harmful algal blooms. To this end, we investigate variations in cell abundance and chlorophyll fluorescence parameters during the algal bloom formation of Prorocentrum shikokuense in the field and batch culture via the pulse amplitude modulated fluorometry. Furthermore, based on the interaction between algal growth and its photo-physiology status, we develop a novel algal growth model incorporating cell growth delay. The model parameters are estimated by fitting the experimental data of P. shikokuense and validated by the experimental data of Symbiodinium sp. The experimental results show that the growth status and photosynthetic parameters of algal cells fluctuate in both field and laboratory experiments and that the photosynthetic parameters have a faster response than growth parameters. According to the experimental and mathematical results, the time delay between the slow growth of algae and the rapid change of photosynthetic parameters may be a physiological mechanism leading to the fluctuations in algal growth. These results are significant for studying the relationship between phytoplankton growth dynamics and photosynthetic parameters and will help resource managers to predict and deepen the understanding of harmful algal blooms.