Margarita Fernández-Tejedor's main research interests are the ecology and taxonomy of marine phytoplankton, with a special focus on harmful algal blooms (HABs). In addition to the use of this knowledge in basic research on biodiversity, she used the time series on phytoplankton composition and abundance that she produced, together with the associated environmental data, to generate HAB forecast models and to conduct HAB risk evaluation. She is also interested in other applications of phytoplankton research, such as, for example, to define suitable zones for shellfish aquaculture and finding new microalgae strains for their use in aquaculture.