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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 2.28.0.108, 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.

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