From the drone of a yacht to the sonar blast of a warship, the deafening noises of the military and commercial shipping industries have reached a point where it is seriously threatening whales, said scientists at last week's World Conservation Congress.
Already, the proliferation of these anthropogenic sounds in the ocean's waters have impacted whales' abilities to feed, mate and migrate on their long-established routes — resulting in increased whale beachings, strandings and collisions with ships.
"The noises generated by ships create what I call acoustic smog," says Michel Andre, director of the Laboratory of Applied Bio-Acoustics in Barcelona. To understand how vast and potentially devastating the problem is, Andre and his team have created an interactive website that lets users see and hear the impact of this "acoustic smog" in relation to various whale species. Called Sons de Mar ("sounds of the sea"), you can compare a blue whale's call (measuring 188 decibels and heard at hundreds of kilometres) with the incessant sounds of industrial shipping (180 db heard at hundreds of kilometres) and low-frequency sonar used by the military (240 db heard at hundreds of kilometres). It becomes clear how some forms of this noise pollution may not only confuse whales, but can also be so powerful that "a whale can be killed outright by the shock," says Carl Gustav Landin, who heads the marine program for the International Union for the Conservation of Nature (IUCN).
Needless to say, global warming is compounding the problem. A recent study published in the Geophysical Research Letters found that increasing ocean acidification due to rising temperatures also reduces sound absorption by up to 40 percent, allowing ambient noise to travel that much further.
"Noise pollution in the sea reduces the zone in which whales can feed and hampers their ability to communicate," explains Andre. "There is no place in the world's oceans that is untouched."
::Sons de Mar via AFP
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Pollution Makes Oceans Noisier (LiveScience)