Underwater Sonar Kills Stuff

“Sound penetrates an animal’s body when immersed in water. Essentially all of acoustic energy goes into a body immersed in water. This effect, which can cause tissue rupture and hemorrhage, has not been adequately addressed in the Navy’s [environmental impact statement]. The implications (of the effect of sound penetration) for marine life are very serious, as described next.”

“The first lethal mechanism involves moderate level sound waves activating the growth of microscopic bubbles in the supersaturated blood and tissue of cetaceans. These bubbles then grow and can cause embolisms, hemorrhaging and localized pressure on the nervous system. Significant oxygen deprivation by blood vessel blockage can kill brain cells and produce stroke. For supersaturated gasses dissolved in cells rather than the blood, activation of bubble formation can rupture the cell walls.”

“The second mechanism for lethal injury involves hemorrhaging caused by acoustic resonance of the LFA [Low Frequency Active] sonar signal in cranial and other airspaces such as lungs and swim bladders. Specifically, the rapid change in pressure (from very high to very low several times per second for the duration of the one-minute LFA sonar blast) can rupture the delicate membranes enclosing the airspace.”

“Animals with air filled lungs and swim bladders are especially vulnerable because of the large difference in impedance between air in the lungs or swim bladders and their body tissues or seawater. Submerged animals exposed to explosions at short range showed hemorrhage in the lungs and ulceration of the gastro-intestinal tract.”