Coral reefs are known for stunning visuals. But sound is just as important to the creatures that live here, and a new study shows that the sound quality here has taken a turn for the worse. Degraded coral reefs are quieter than they were five years ago, which could mean bad news for younger fish trying to find a home.
Young fish find their ways to coral reefs, like the Great Barrier Reef off the coast of Australia, through the cacophony of sound that emanates from these environments. Reef dwellers like snapping shrimp, damselfish, and clownfish all chirp and chatter away. The noisier a reef is, the healthier it is.
These animals make sounds for any number of reasons, just like people. They make sounds when hunting, when trying to avoid being hunted, and when trying and win a mate’s favour. Below, a clownfish hunts a smaller clownfish while making a series of aggressive sounds.
Sound travels well underwater, meaning that juvenile fish often follow reef sounds to figure out how to get to environments for which they’re best suited.
However, research undertaken in the last three years at the Northern Great Barrier Reef show that coral bleaching has left the reefs far quieter than before. A degraded soundscape means that the Great Barrier Reef is attracting 40 percent fewer fish than before the bleaching began.
“It’s heartbreaking to hear. The usual pops, chirps, snaps and chatters of countless fish and invertebrates have disappeared. The symphony of the sea is being silenced,” says Tim Gordon, a marine biologist at the University of Exeter who worked on the study, in a press statement.
Coral, an animal its own right, provides a living ecosystem for a wide range of creatures. Fewer fish could mean that the carefully maintained ecosystem falls out of sync even where it hasn’t been bleached. Clownfish, for example, eat algae that grow on coral. Eating these algae allows coral growth to continue, so even if the reef has been damaged it can recover.
“If fish aren’t hearing their way home anymore, that could be bad news for the recovery prospects of reefs. Fish play critical roles on coral reefs, grazing away harmful algae and allowing coral to grow. A reef without fish is a reef that’s in trouble,” says Harry Harding from the University of Bristol.
Without these sounds, researchers found, coral reefs just become less attractive places for fish, which is the last thing the reefs of the world need at this point. They’ve only just come out of global three-year bleaching events, which occurred for a number of manmade reasons including ocean acidification through warming temperatures.
Source: University of Exeter
Previously published by Popular Mechanics USA