During photosynthesis, marine algae tend to let off a little gas. The bubbles, made of oxygen and nitrogen, “ring” in the 2 to 20 kiloHertz range as they assume a spherical shape, and the intensity of the sound correlates with the amount of algae in the area, Simon and Lauren Freeman of the US Naval Undersea Warfare Center and their colleagues report Wednesday (October 3) in PLOS One. Algae grow on coral reefs, so measuring the intensity of the ringing could provide a quick, easy, and noninvasive way to assess the health of the reefs, the researchers report.
S.E. Freeman et al., “Photosynthesis by marine algae produces sound, contributing to the daytime soundscape on coral reefs,” PLOS One, 13:e0201766, 2018.