Flow visualization in the ocean-implications of laboratory bioluminescence experiments

The objective of this study is to begin to assess the potential of using flow-induced bioluminescence as a method for visualizing oceanic flow fields. The bioluminescence response of dinoflagellates to quantifiable levels of flow stimulus is characterized in laminar and turbulent pipe flow. These results are used in a numerical simulation to predict the spatial extent of the bioluminescent "footprint" associated with supra-threshold levels of flow agitation in a ship's wake. Assuming an ideal multi-spectral sensor, estimates of the ratio of bioluminescent signal to ambient light noise are made for different bioluminescence potentials, flow agitation and ambient light conditions. It was found that the pipe flow experiments are remarkably repeatable, with threshold values for bioluminescence stimulation occurring in laminar flow at about 1 dyn cm/sup -2/. An aircraft carrier moving at 18 kts is estimated to provide supra-threshold levels of hydrodynamic stimulus throughout millions of cubic meters of seawater in its wake. Preliminary multispectral analysis suggests that in littoral waters, for most of the time, nearly all of the stimulated wake can be detected.