Something that I had never considered but I actually found quite interesting once I started reading about is that exploration, development, and construction underwater for offshore oil and wind power results in powerful sound waves that can confuse and harm many marine creatures, even those as big as whales. These marine mammals use gentle sound pulses (waves) to communicate. In order to avoid interfering and harming these creatures they are trying a technique using a curtain of bubbles to alter the shape of the noise waves they create. They cannot yet tell how effective this method will be, but there are high hopes as energy is lost from the wave when it passes through the air but how much is lost is questionable. However, it has been determining that a softball-sized bubble would be best; the problem is now how to keep that from just breaking up into smaller bubbles. An experiment was done when construction was needed on the Oakland-Bay Bridge, when air bubbles were used to reduce fish deaths due to burst swim bladders and kidneys. In Germany, where they have been working on constructing a offshore wind farm have found that porpoises have not been swimming within 13 miles of the site. This has resulted in a limit of 160-decibel on sound levels during the construction of the farms and has been considering trying out using bubble curtains. However it should be noted that decibels are different under-water and above: “a sound that is 100 decibels on the surface, just “on the threshold of being uncomfortable” to human ears, is roughly equal to 162 decibels underwater.” There are concerns especially with Shell looking to drill offshore in Alaska. Many of the animals that they are concerned with are ice seals, walruses, baleen, toothed whales, polar bears, and bowhead whales. This has lead to the work that Shell has been doing to try to protect these animals. It is really quite interesting just what an effect noise pollution can create such a problem and that one of the viable options to fix it is in fact bubbles.
http://news.nationalgeographic.com/news/energy/2012/02/120207-bubble-curtains-to-protect-whales/
