By Lewis Smith
Sea bass are being stressed out to such an extent by building works that they are getting easier for predators to catch, a study suggests.
Noise from piling and drilling for new structures at sea, such as tidal barrages, has been found to disconcert the fish and to change their behaviour.
In a study conducted with captive European sea bass scientists played back the sounds of pile driving and drilling to the fish.
The bass, Dicentrarchus labrax, suffered a higher heart rate when exposed to the noises and when a predator was detected they were less able to swim out of range than in quiet conditions.
"Over the last few decades, the sea has become a very noisy place. The effects we saw were subtle changes, which may well have the potential to disrupt the seabass's ability to remain 'in tune' with its environment,” said lead researcher Ilaria Spiga, of Newcastle University.
Sea bass, along with other bony fishes, rely on a characteristic 'startle and response' mechanism to get away from predators. Exposure to underwater noises can make it harder for fishes to detect and react to predators. It could also impair their own ability to detect food.
"Man-made marine noise could potentially have an adverse effect on reproduction also. If fishes actively avoid areas where these sounds are present it could prevent them from entering spawning grounds, or affect communication between individuals."
Among the measures proposed by the research team to reduce the threat to sea bass is to drill rather than pile drive when feasible. Piling was found to have a more traumatic effect on the fish than drilling in the playback tests.
They also called for time limits to be placed on noisy building work at sea to give fish a break from the sounds and give them time to recover.
In their study, published in the journal Marine Pollution Bulletin, they concluded: “This study provides further direct evidence that the behaviour and physiology of D. labrax is affected by exposure to elevated levels of noise, and that the effects differ significantly from ambient noise. Even a moderate increase in sound level had an effect on physiology.”