Last updated January 31, 2018 at 3:47 pm
Noise from motor boats can confuse fish and increase their risk of being eaten.
An experiment to test whether boat noise has long-term effects on the way fish learn, suggests it could be a major – and life-threatening – distraction.
Researchers trained baby damsel fish to recognise the smell of a predator fish, while they played normal reef sounds to half the fish, the other half were played reef and boat noise.
The next day the fish that had been exposed to the reef and boat noise were less able to recognise the predator smell compared to the fish who had heard the normal reef sounds.
It was as if they had failed to learn it at all.
In a follow-up experiment, after being trained to learn the predator smell, the fish were released onto a patch of reef near Lizard Island on the Great Barrier Reef.
The fish that had been exposed to the boat noise were 3.5 times more likely to die within 72 hours of being released.
The boat noise was interfering with the fishes cognitive ability to learn.
Noise pollution is a long-term stress for fish
While direct noise can cause immediate damage to some marine species, increasing mortality of some fish eggs and embryos, noise pollution from boating is an ongoing, chronic stressor for marine species.
This experiment shows that after exposure, noise pollution can still cause ongoing damage.
Half a million motorboats are predicted to cruise on the Great Barrier Reef by 2040. There are already concerns that shipping along the Great Barrier Reef is causing acoustic overload for some migratory whales
The research was carried out by Maue Ferrari from the University of Saskatchewan along with colleagues from James Cook University and the University of Western Australia.
They point out that coral reef communities are already under threat from a wide range of stressors, including global warming, ocean acidification, chemical pollution, overfishing and habitat degradation. They say that noise pollution from boating at least should be a lot easier to detect and control.