Trait shift history: trait shifts in phytoplankton communities induced by grazing and light affect the responses to nutrients

Recent studies on the global primary production showed a decline in cell size and productivity of marine phytoplankton in response to climate warming. Reorganization of phytoplankton communities under global change can change community interactions and energy flows through the whole marine food web. Therefore, being able to predict phytoplankton responses to environmental drivers based on size structure could help to establish an intermediate level of complexity between the almost unachievable goal of reconstructing community behavior from single species and the overly simplistic approach of reducing phytoplankton to a single functional category. Because of strong correlations with other eco-physiological traits phytoplankton size has been considered as an ecologically significant “master” trait. In addition, a major challenge in climate change research on phytoplankton succession is to understand how multiple factors, which drive ecological changes in phytoplankton communities, shape the size distribution of the phytoplankton communities and the way this size alteration affects the performance to another stressor. Therefore, my work highlights the potential of trait based approaches to understand ecological complex processes in phytoplankton communities. It also indicates that cell size can be used as indicator trait predicting phytoplankton responses to several stressors as effect and response trait. However, its use should be based on a good knowledge of the characteristics of the studies communities and interactions between the different trophic levels should not been neglected