SS3.02 Turbulence and Plankton Dynamics
Date: Wednesday, June 12, 2002
Time: 2:45:00 PM
Location: Saanich
 
O'BrienKR, Dept of Environmental Engineering, University of Western Australia, Perth, Australia, obrien@cwr.uwa.edu.au
Hamilton, D, P, Dept of Environmental Engineering, University of Western Australia, Perth, Australia, hamilton@cwr.uwa.edu.au
Ivey, G, N, Dept of Environmental Engineering, University of Western Australia, Perth, Australia, ivey@cwr.uwa.edu.au
Waite, A, M, Dept of Environmental Engineering, University of Western Australia, Perth, Australia, waite@cwr.uwa.edu.au
 
SIMPLE DETERMINATION OF MINIMUM MIXING REQUIREMENTS FOR GROWTH OF NEGATIVELY BUOYANT PHYTOPLANKTON POPULATIONS
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The population dynamics of negatively buoyant phytoplankton are commonly controlled by the balance between mixing, growth and sedimentation. We use two dimensionless parameters, the Peclet number Pe (ratio of mixing and sedimentation time scales), and the growth number G (ratio of sedimentation and growth time scales) to explore and quantify the balance between mixing, growth and sedimentation. The Peclet number is used to define three 'mixing regimes' where simplified models may be applied to predict phytoplankton distribution, in preference to solving the advection-diffusion equation. Modelling results are used to define 'growth regimes' in terms of Pe and G. These regimes are supported by published data, and can be used to define the minimum turbulent mixing requirements for net population growth of different phytoplankton species. Non-dimensional analysis makes our results applicable to predicting and understanding phytoplankton population dynamics in a range of aquatic systems.