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Title:Influence of turbulent advection on a phytoplankton ecosystem with nonuniform carrying capacity
Authors:McKiver W.J. and Neufeld Z., 2009
Abstract: In this work we study a plankton ecosystem model in a turbulent flow. The plankton model we consider contains logistic growth with a spatially varying background carrying capacity and the flow dynamics are generated using the two-dimensional (2D) Navier-Stokes equations. We characterize the system in terms of a dimensionless parameter, y=TB/TF, which is the ratio of the ecosystem biological time scales TB and the flow time scales TF. We integrate this system numerically for different values of y until the mean plankton reaches a statistically stationary state and examine how the steady-state mean and variance of plankton depends on y. Overall we find that advection in the presence of a nonuniform background carrying capacity can lead to very different plankton distributions depending on the time scale ratio y. For small y the plankton distribution is very similar to the background carrying capacity field and has a mean concentration close to the mean carrying capacity. As y increases the plankton concentration is more influenced by the advection processes. In the largest y cases there is a homogenization of the plankton concentration and the mean plankton concentration approaches the harmonic mean, <1/K^−1>. We derive asymptotic approximations for the cases of small and large y. We also look at the dependence of the power spectra exponent, B, on y where the power spectrum of plankton is proportional to k^−B. We find that the power spectra exponent closely obeys B=1+2/y as predicted by earlier studies using simple models of chaotic advection.
ICHEC Project:Collective search strategies in turbulent flows
Publication:Physical Review E (2009) 79:061902
URL: http://dx.doi.org/10.1103/PhysRevE.79.061902
Status: Published

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