Noise Pollution Prevents Fish From Finding Home, Disorients Environment in Coral Reef

Busy boats traveling to and from land may be rather disorienting for larval coral reef fish who are simply trying to find their way back home, according to new research from the Universities of Bristol, Exeter and Liege. 

As reef fish are normally attracted by the distinct and boisterous sounds sprouting from the reef, the study found that fish are more likely to swim away from recordings interrupting the natural habitat of their underwater home.

"Natural underwater sound is used by many animals to find suitable habitat, and traffic noise is one of the most widespread pollutants," writes study-author Sophie Holles, a Ph.D. researcher at the University of Bristil, via a press release. "If settlement is disrupted by boat traffic, the resilience of habitats like reefs could be affected."

Background information from the study notes that sound often travels better when underwater than in air, and reefs depend on naturally noisy sounds so that fish can better find their way back home. Waves, wind and tides help bring fish back into swimming groups as well as calls made by various underwater life. 

"Boat noise may scare fish, affecting their ecology," writes co-author of the study, Dr. Steve Simpson, a marine biologist at the University of Exeter. "Since one in five people in the world rely on fish as their major source of protein, regulating traffic noise in important fisheries areas could help marine communities and the people that depend on them."

The study examined coral reef fish larvae. Those in a long plastic tube were able to swim towards or away from a speaker playing back various sounds that research teams put together. Equal numbers of fish moved towards different sections of the tube when hearing ambient sounds. However, when reef noise was played, the fish swam towards the sound. When boat noise was played along with the reef noise, more fish swam way from the sound than reef noise alone.

Researchers believe this directly shows that noise pollution can drastically alter the behavior of environmental life.

More findings regarding the study can be found in Marine Ecology Progress Series.