Prof. Dr. Ulrike Feudel Institute for Chemistry and Biology of the Marine Environment Carl von Ossietzky University Oldenburg, Germany Title: ``Spatio-temporal patterns in marine systems'' Time: July 16, 2008, 17.15 Uhr Place: Haus 184.108.40.206, Campus Golm, Universitaet Potsdam Abstract: Spatio-temporal patterns in marine systems are a result of the interaction of population dynamics with physical transport processes. These physical transport processes can be diffusion processes in marine sediments and advection of biological species in the water column. We study as a typical example the dynamics of one population of bacteria and its nutrient in sediments, taking into account that the considered bacteria possess an active as well as an inactive state. The nutrients are transported passively by diffusion and actively by bioirrigation. It is shown that under certain conditions both stationary heterogeneous spatial patterns of species (Turing patterns) and spatio-temporal chaos can be generated respectively. The latter emerges as a result of the interplay of Turing and Hopf instabilities. Furthermore, we study the growth of biological species advected by mesoscale hydrodynamic structures in the wake of islands. To this end we consider a time-periodic two-dimensional flow which is characterized by a von Karman vortex street as well as an Ekman flow perpendicular to it. In particular we employ concepts of Lagrangian chaos for the dynamics of particles to show that mesoscale vortices act as incubators for plankton growth leading to localized plankton blooms within vortices.