When cetaceans are startled by loud noise, they exhibit unusual diving behavior and suffer something similar to a human diver getting the bends
Oceans and seas are becoming noisier with more vessels, increased seismic surveys for oil and gas, off-shore construction and recreation, and a new generation of military sonars cacophony is intensifying threats to marine mammals that use sound to communicate, forage for food and find mates Ship noise in the Pacific Ocean has doubled every decade over the past 40 years Airguns used in seismic surveys generate "colossal" sounds peaking at up to 259 decibels and can be repeated every 10 seconds for months. These sounds travelled more than 3,000 km from the source. There are 90 seismic survey ships in the world a quarter of them are in use on any given day estimated 300 naval sonar systems worldwide more than 235 decibels. Pings this loud are over one billion times more intense than the 145 decibel upper limit deemed safe for humans blue whales are vulnerable to noise and ship strikes now evidence linking loud underwater noises with some major strandings of marine mammals |
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