An automated bioassay technique using ultrasonic standing waves to monitor effects of pollutants, chemicals and other environmental parameters on aquatic organisms

The effect on aquatic animals of exposure to pollutants has been tested using a novel ultrasonic standing wave generating apparatus. In this procedure, two transducers are placed in a test system and a standing wave at 50 KHz is generated. The receiving transducers are then tuned, so that they are exactly one-half wavelength apart. This creates a three dimensional grid in the system with "nulls" or points of least energy return approximately l" apart. As an organism moves through a "null", the energy return at the receiving transducer mementarily changes and a count is recorded. The printout of the device indicates motor activity in terms of counts per unit time. The effects of chemicals, drugs, and other parameters on activity of aquatic animals has been measured quantitatively.