REAL-TIME TRACKING OF MICROORGANISMS

The hardware and software components are described to track multiple flagellates simultaneously in real time. The technique is based on online digitization of four frames taken at 80 ms intervals and stored in a specialized video memory. The outline and position of each organism is determined by chain coding and followed through the recorded series images. The movement vectors of all organisms tracked are stored in the form of deviation angles from the predefined stimulus direction and the distance each organism has moved in the time interval determined by the hardware clock of the computer. This system was used to track phytoplankton organisms and analyse their orientation with respect to light and gravity. Phytoplankton organisms orient in the water column to optimize their vertical position. Both orientation mechanisms and motility are affected by solar ultraviolet radiation.