Latz, M. I. Scripps Institution of Oceanography,
Rohr, J. I. SPAWAR Systems Center,

In order to examine the effect of turbulence at the small length scales of individual plankton, luminescent dinoflagellates were subjected to several laboratory flow fields with fully characterized hydrodynamic conditions, with bioluminescence used as an essentially instantaneous measure of organism response. Experiments with fully developed pipe flow indicate that for shear stress levels greater than 1 N/m^2, the response of individual cells is nearly constant, and independent of the laminar or turbulent nature of the flow. Moreover, as the Kolmogorov scale becomes significantly smaller than the cell size, there is no conspicuous increase in bioluminescence. Computational and experimental studies of a laminar developing flow field in a nozzle substantiate that cells respond only in the portion of the boundary layer where suitable levels of shear stress are present. In jet flow, the transition from laminar to turbulent conditions causes a dramatic increase in bioluminescence due to an abrupt increase in the magnitude of shear stress and the volume of mixing. Bioluminescence studies can contribute to the understanding of how shear and turbulence affect plankton at the temporal and spatial scales appropriate for oceanic flows.
Day: Tuesday, Feb. 2
Time: 11:45 - 12:00pm
Location: Hilton of Santa Fe
Code: SS02TU1145H