| Plankton patterns as observed in satellite images of the ocean are a result of the interaction of population dynamics with physical transport processes. We study the planktonic biological activity in the wake of an island which is close to an upwelling region providing nutrients for the growth of the plankton. Our results are based on the numerical analysis of a simple kinematic flow mimicking the hydrodynamics in the wake coupled to a three component plankton model. We show that the mesoscale hydrodynamic structures can under certain conditions either act as a barrier blocking the transport of nutrients or facilitating transport of nutrients leading to an enhanced primary production. Using finite size Lyapunov exponents to visualize stable and unstable manifolds embedded in the flow we study the transport of nutrients which are essential for the growth of plankton. In particular we show that in a special case mesoscale vortices act as incubators for plankton growth leading to localized plankton blooms within vortices in the wake of an island. The mechanism of the emergence of these localized plankton blooms relies on the intricate interplay of hydrodynamic and biological time scales. Furthermore we show that mesoscale hydrodynamic structures play an important role for dominance patterns of species competing for the same nutrients. |
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