SPECIES ASSEMBLIES AND SEASONAL SUCCESSION OF DINOFLAGELLATES

Seasonality of dinoflagellate blooms and dinoflagellate assemblies are not random. Yet, bloom events and the specific appearance of species is difficult to predict and sometimes appears stochastic. Nevertheless, it has been established that both abiotic and biotic factors determine species assemblies, as well as the available species pool. The physical environment, especially nutrients and mixing/light depth largely determines when and where dinoflagellates are present. As a response to the environemnt, adaptive strategies (C, S, R) have evolved, allowing different species to be favored in different conditions. Based on functional traits, with cell size being a so called master trait, species can be categorized into different life-forms, which in turn can be predicted for different conditions. Among biotic factors, mortality due to natural enemies, including both grazers and parasites are involved in species succession. In addition both competition among dinoflagellates and with other phytoplankton groups can determine which species occur. Finally, life-cycle transitions, especially for cystproducing (meroplanktonic) species can be used to explain fine-scale species replacement. The latter together with species-specific parasite infections provide promise to untangle the processes behind apparently stochastic events.