Does nutrient supply play a role in the control of picoplankton community structure?

Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, SpainMargalef´s mandala (1978) represents one of the first attempts to integrate the role of turbulence and nutrient supply into a trait-based eco-physiological framework to predict the environmental selection of different phytoplankton functional groups. Due to methodological limitations at the time, the smaller-sized picoplankton groups were not included in the original diagram. Moreover, because of the difficulties to measure turbulence in the field, the validation of Margalef’s model has been limited to laboratory experiments and studies in the field where proxies for nutrient supply were used. However, stratification, turbulence and mixing are not equivalent from a physical perspective, neither in their effects on phytoplankton. We have collected simultaneous estimates of nitrate diffusive fluxes, derived from measurements of dissipation rates of turbulent kinetic energy by using a microstructure profiler, and picoplankton abundance and cell properties in more than 200 stations located in different hydrographic regimes. We found that the contribution of eukaryotes to total picoautotrophic biomass increases with nutrient supply, whereas cyanobacteria show the opposite pattern. As in the classical microphytoplankton succession, nutrient supply is an important driver of picophytoplankton community structurePeer Reviewe