Noise pollution

NOISE POLLUTION
For millions of years, the oceans have been filled with sounds from natural sources such as the squeaks, moans and clicks of whales and dolphins, the snapping of shrimp, the sound caused by wind upon the surface and even the occasional rumble from earthquakes. Over  millions of years, the ocean's marine species have developed into what they are today, with their own specializedacute hearing abilities, communication skills and echo location abilities at natural sound levels.  Hearing is generally as important to many marine creatures as sight is for humans. (Image below from: NASA, Jet Propulsion Laboratory)
The oceans, once referred to as the "The Silent World" by Jacques Cousteau,  has now become an increasingly noisy place since the industrial age. It is estimatedthat the ambient ocean noise has increased ten decibels (ten times increase in sound) between 1950 and 1975 (Ross, D. 1993).
Many underwater realms have become very noisy. An increase in motorboats, primarily commercial shipping traffic, exploration and extraction of oil and other minerals, sonar and even coastal jet ski traffic are contributing to the increased level of underwater noise. "If youcould lay down under the shipping lanes at Great South Channel (off Cape Cod) and spend the day there, you would get the impression of being on the tarmac at Logan Airport," said Christopher W. Clark, who runs the Bioacoustics Research Program at Cornell University. 
Sound travels four times faster in water (1,230 meters/sec.) than in air (340 meters/sec.) because water molecules are packed tightertogether. This results in sound that will also travel farther under water. High intensity sound in the oceans can travel for thousands of miles. In this regard it is important to remember that since water has a much greater density than does air that sound waves travel though water at much higher energy levels and are hence louder.
The effects of noise pollution are not as easy to notice as arethe other more obvious and visible pollutants like oil spills and marine debris. To what extent these manmade sounds are negatively impacting the oceans is not fully known.  The current high noise pollution levels are so recent that many individual marine mammals and fish alive today were born before the problem even arose. The long term impact is simply not yet  known.
We know that whales anddolphins use sound to communicate with each other over vast distances.  Other marine species use sound to find food and choose mates as well as  warn others of potential dangers.  Whales communicate at very low frequencies, below 1000 Hertz. This is the same frequency that resonates from many human-caused activities. Man-made sounds are drowning out the calls of mates, calves and other pods thatthese mammals depend on. High sound levels cause grey whales to deviate from their migration paths, the deviation being greater as sound intensity increases (Tyack P. L., Clark C.W., 1998).
 More recently, new sources of marine sound pollution have been added to the mix. The one source having the most immediate and obvious negative effect has been the development and subsequent testing of"Low-frequency Active (LFA) Sonar"  with a potential worldwide deployment by the U.S. Navy and NATO. There have been several tests that have directly resulted in large losses in marine life.  
During March of 2000, at least 17 whales stranded themselves in the Bahamas and the population of beaked whales in this region disappeared.  A federal investigation identified testing of a U.S. Navy active sonarsystem as the cause. According to an article posted by the Natural Resources Defense Council, "More than a dozen harbor porpoises were found dead on the beach near the San Juan Islands soon after the Navy tested active sonar in the Haro Strait in May. Videotape shows a pod of orca whales in the foreground behaving erratically as the Shoup, a U.S. Navy vessel, emits loud sonar blasts. Recent tests on...