Time for international action
Since for many years our knowledge of the effects of marine noise appeared to be patchy compared to aspects like ocean warming and acidification, or pollution due to toxic substances and plastic, the topic was largely neglected. “Although Europe and individual countries have it on their agendas, to date there haven’t been any international protection efforts,” comments van Opzeeland. One exception is the European Union’s Marine Strategy Framework Directive, which clearly lists noise mitigation as a goal. In view of their compelling analysis, the authors call for greater international cooperation. Further, they stress the need to consider the many pressures on marine life as a whole, since, while climate change and litter are difficult to control locally, noise is less so.
“Of course, not all sources of noise in the sea, such as the expansion of wind power and commercial shipping, can be done away with completely,” adds van Opzeeland. “Nevertheless, various measures can be implemented to effectively reduce marine noise.” In the North and Baltic Seas, for instance, bubble curtains have been used for some time at wind turbine construction sites to dampen the echo of the piles being driven into the ground. In the eastern Mediterranean, reducing ships’ maximum speed by ca. two knots has led to a roughly 50 percent drop in noise. And, according to the authors, the explosions and air-gun shots used in natural resource exploration can be avoided using devices that send strong vibrations from the seafloor down into the depths. “Accordingly, with our study we also wanted to offer hope. The current trend can be reversed. The oceans don’t necessarily have to become louder. Our study shows just how serious the problem is. But it also shows that noise levels can be reduced, especially through international collaboration.
Please find polar sounds in our public media library (see Topics).