Previous results of a computer model suggested a number of possible interactions between semidiurnal internal tides and phytoplankton. One extension considers a phytoplankton grid (swimming speed 1-2 m h-1) that is initially distributed at sunset in the upper layer of a water column characterized by a relatively deep mean thermocline depth (25 m) . The organisms undergo a diurnal vertical migration while the water column is simultaneously disturbed by successive semidiurnal internal tides....