It's a Less Than Silent World

It's very noisy down there. Diver who have paused and held their breath, listening for a moment to the sounds of a vibrant coral reef, will know the undersea world is anything but silent, as Jacques Cousteau would have had us believe.

New research by a senior oceanographer at the Naval Undersea Warfare Center shows that degraded coral communities do not sound as crackling and vibrant as healthy ones because the reduced biodiversity means less activity. So, one can, in effect, judge a reef's health by its decibel level.

Lauren Freeman and her team from the NUWC monitored acoustics on Hawaii reefs between 2019 and 2020 and compared them to soundscapes from the ocean near Bermuda and off the coast of New England. They found most reefs are full of noise when it's warmer and immediately before the sun sets and when the sun rises.

Sound surveys are far less costly than traditional reef surveys, which require more boats and crews, while diver time is limited, and only small reef areas can be covered.