Ocean noise pollution makes fish stressed and disoriented

A study from Newcastle University shows that European sea bass are getting stressed out by noises from offshore construction. Exposure to the noise pollution also make the fish confused and disoriented when faced with a predator.

“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 sea bass’s ability to remain ‘in tune’ with its environment,” explained lead author Ilaria Spiga.

The research team played recordings of piling and drilling sounds to observe the responses of sea bass. The fish fled to an area the scientists referred to as the “safe zone.” When the researchers mimicked the presence of a potential predator, the sea bass became confused and made turns in the water which did not move them to safety.

“Sea bass, along with other bony fishes, rely on a characteristic ‘startle and response’ mechanism to get away from predators,” said Spiga. “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.”

The drilling sounds used in the study were recorded in the English Channel during the installation of a new tidal barrage. The piling sounds were captured from the construction of a new lifeboat station at Swansea Bay. The drilling was continuous noise, while the piling consisted of low frequency sounds that occurred in intense bursts.

Offshore construction, shipping, and some onshore activities can all intensify the noise levels underwater.

“Man-made marine noise could potentially have an adverse effect on reproduction also,” said Spiga. “If fishes actively avoid areas where these sounds are present it could prevent them from entering spawning grounds, or affect communication between individuals.”

Despite the fact that noise is recognized as a pollutant by the European Union’s Marine Strategy Framework Directive, only larger and more complex projects have to be approved by the Marine Noise Registry. The research team is urging officials to expand the reach of legislation by putting limits on the length of time that underwater construction can take place.

The study is published in Marine Pollution Bulletin.

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By Chrissy Sexton, Earth.com Staff Writer