A switcheroo!

[Thomas Daniel <danielt@u.washington.edu>]

Garry, by the grace of Danny, has lucked out.  Instead of gene networks
we will hear about the following topic from   Uffe Thygesen of the
Danish Institute of Fisheries Research, who is visiting the good
Professor Grunbaum for a few months.

As always:  1230 W, F  in 114 Kincaid



The colonization of marine snow by zooplankters: A study of fluid motion

and solute distributions

Abstract:

Marine snow are milimeter to centimeter sized aggregates, which are a
main
vehicle for downward transport in the water column. They are also sites
of
elevated biological activity and are subject to colonization by
zooplankters.

In these two talks I will present joint work with Thomas Kiorboe, which
aimed to describe the hydromechanical and chemical fields around marine
snow. We used numerical solution of the Navier-Stokes equations and the
advection-diffusion equation, modelling the aggregate as a solid sphere
which acts as a source of amino acids. We also compared to laboratory
experiments by Helle Ploug.

Our findings lead us to believe that zooplankers locate marine snow
through chemical rather than hydromechanical cues; specifically,
horizontally cruising copepods detect the plume which trails the snow.

In the first talk I will give an overview of the study, emphasising the
motivation and the conclusions. In the second talk I will go a bit more
in
detail with the models and in particular discuss the interpretation and
importance of two different boundary conditions for the solute transport

(Dirichlet vs. Neumann). If time permits, I will also demonstrate the
CFD
software which we developed as part of the study.