杏吧原创

SHIPPING is making the Pacific Ocean 10 times noisier than it was 30 years ago鈥攁nd this could unsettle marine mammals. Rex Andrew and his team at the University of Washington in Seattle looked at recordings from US Navy hydrophones anchored 40 kilometres off the coast of California. They found that both low-frequency (around 20 to 80 hertz) and mid-frequency (between 200 and 300 hertz) sound was around 10 decibels higher鈥攅quivalent to 10 times louder鈥攖han it was in the 1960s (Acoustic Research Letters Online, vol 3, p 65). The scientists think that ships鈥� propellers are the main cause and alternative means of propulsion may be needed. 鈥淚f we鈥檙e disturbing the habitats of whales,鈥� says Andrew, 鈥渢he implications could be that marine vessels have to lose their props.鈥�