Sound production in two species of eelgrass

There have been numerous anecdotal reports that a species of the aquatic plant known as eelgrass (Zostera marina) makes an audible bubbling sound that can be heard on warm, sunny days in estuarine waters at low tide. This champagne-like fizzing sound results from the expiration of oxygen by the plant during photosynthesis and can be heard as airborne sound by listening closely to the surface of the water. The author recorded this sound in July of 2014 in the shallow mudflats of Puget Sound in Washington. Recordings were made of both airborne and underwater sounds. On the same day in the same general area, the author also recorded similar bubbling from a different, non-native species of eelgrass (Zostera japonica). The sounds of the two species were compared, revealing clear and distinct sound signatures for each. These recordings suggest that sound production in the two species of eelgrass is strongly present and may provide opportunities for further research.