Noise pollution in large cities has long been the subject of many discussions about its detrimental effects on human health.
More recently, the United Nations (UN) has reported its concern about increasing noise pollution at sea as well.
Apparently, this pollution is affecting and endangering the survival of marine species.
The rise in man-made marine cacophony is a problem, especially for mammals, who use sounds to communicate. Marine mammals such as whales and dolphins depend largely on sound for communication, reproduction and perception of the environment.
Sound is, after all, indispensable to the survival of whales. While the complex sounds of humpback whale (and some blue ones) are thought to be mostly used at the stage of sexual selection, the simpler sounds of other animals of the same species are used throughout the year. On the other hand, unlike others, such as sharks, it is thought that smell is not very developed in whales. Thus, given the poor visibility of aquatic environments and given that sound propagates better in the aquatic environment, audible sounds may be of particular importance in their "navigation".
Despite protective measures already in place, sea-floor noise continues to rise and, according to a study by the International Animal Welfare Fund, has doubled with each passing decade.
The UN, through its Environment Program (UNEP), calls on governments and industries to adopt quieter engines and less damaging ship alarms and more restrictive measures to use seismic testing for oil and gas prospecting. Naval sonar, for example, is related to the huge killings of some cetaceans.
The UN also denounces that changes in marine chemical composition contribute to increased ocean noise pollution, as rising seawater acidity levels make it absorb 10% fewer low frequency sounds.
Unless greenhouse gas emissions are reduced, marine acidity levels could reach by 2050 where ship noise reaches 70% greater distances.
To complicate matters further, existing legislation is virtually nil on noise levels at sea. Especially because the International Animal Welfare Fund alleges a difficult legal obstacle: the large amount of noise produced occurs on the high seas, where enforcement is difficult and international waters are difficult.