Acoustical investigation of phytoplankton

Abstract

The existence of gas vacuoles and the dispersion of sound in water containing phytoplankton is demonstrated under natural conditions by measurement of acoustic reverberation and sound velocity, using phase, resonance, and other methods. The volume of vacuoles ranges from 0.1-30% of the cell body volume. Two types of gas cavities are observed: one is diminished elastically under compression, while the other is decreased irreversibly. However, the volume is restored in a few hours with exposure to light. The sound velocity has been measured over the frequency range 10-30 kHz, in water containing phytoplankton cells at a volume concentration of 10-4. The sound velocity increased on average by 0.1% over this frequency range. © 1996 International Council for the Exploration of the Sea.