The University of Maine Maine In-situ Sound & Color Lab
School of Marine Sciences
Turbulence Effects on Plankton: A New Cartoon

One approach toward understanding effects of turbulence on small organisms is to place them in a much simpler flow than fully developed turbulence that still retains key characteristics of turbulence. The prevailing simplification, often generated in the gap between two counter-rotating cylinders, has been Couette flow in which shear and vorticity have no spatial gradients. We reassess that simplification in light of recent advances in understanding of turbulence and find it wanting in several important respects. The typical planktonic condition is to be in or near a dissipation-scale vortex and in a gradient of diffusing vorticity. Among the simplest vortices that follow the Navier-Stokes equations is Burgers vortex. We use its steady and unsteady forms with established energy spectra to assess likely biological consequences. It appears that diffusing vorticity is an underappreciated generator of relative fluid motion and nutrient exchange and also a factor of potential importance to processes of encounter, coagulation and chemosensing. We are examining these effects further through a combination of numerical and analog modeling that explicitly includes vortices and spatially varying vorticity.

Jumars, P.A., L. Karp-Boss, K. Dorgan, L.J. Fauci, E. Boss, and J.H. Trowbridge, 2008. Turbulence Effects on Plankton: A New Cartoon. 2008 Ocean Sciences Meeting, Orlando, FL, March 2-7.

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