There is too much noise in the oceans
Human activities cause various forms of acoustic pollution in the oceans, at the expense of many marine animals, which use sounds to communicate, orientate themselves, and escape dangers – some of them can indeed perceive the presence of other animals or of obstacles up to hundreds of kilometres away. That is the case with dolphins and whales, but also with smaller clownfishes, which reach barrier reefs where they spend their life thanks to the many sounds produced by the creatures living there.
Since the second half of the twentieth century man is able to listen to the sounds of the oceans: since then, many biologists have studied the impact of noises of human origin on the life of fishes, such as those caused by ships, certain modalities of fishing, oil platforms, or military exercises.
The negative effects of these types of noise concern marine mammals in particular, such as whales and dolphins, an article published in Science reports – which states that «there is clear evidence of the fact that noise compromises the hearing abilities of marine animals and that it causes physiological and behavioural changes».
Many animals have adapted to acoustic pollution, whales for instance have learnt to avoid the main navigation routes, but when human activities – such as military drills – cause strong and sudden noises, sea animals can become deaf.
In some cases, however, certain noises of human origin are permanent, and push animals to abandon a certain area. This is what happened around the islands of the Broughton archipelago, in Canada, where there are many salmon farms: to keep seals, who eat them, away, farmers used devices that produce disturbing sounds, but this caused a decline in the local population of killer whales, which hunted the very same seals.
Several solutions against acoustic pollution already exist: in this regard Steve Simpson, marine biologist at the University of Exeter and one of the authors of the article published in Science, said to the New York Times that «noise is more or less the easiest problem to solve in oceans», because «we know exactly what causes it, where it is and how to stop it». Specifically, it would be necessary to make certain ships slow down, modify some navigation routes so that they don’t come too close to precise areas of the ocean, and substitute the loudest propellers with more silent ones – already available for sale.
In the next years there will probably be more noise in the oceans following the development of mining activities on the ocean floors. Until now, international agreements for the safeguard of marine ecosystems haven’t taken into account acoustic pollution and its impact on the ocean; this is why scientists believe that the adoption of soundproof technologies should go hand in hand with new forms of exploitation of the sea.