It's getting noisy underwater too

Washington: A new study by Scripps Institute of Oceanography has revealed that Ocean Noise has increased tenfold since the 1960s.

Oceanologists Sean Wiggins, John Hildebrand from Scripps and Mark McDonald from Whale Acoustics, Colorado, studied declassified US Navy documents.

They then came to the conclusion that global shipping has contributed a lot to increased undersea noise pollution.

They said with populations increasing around the globe in recent decades, the underwater world had also become a noisier place, adding that the effects of greater noise on marine life was still unknown.

For their study, the duo deployed listening devices at various locations around the world and compared the data against acoustic recordings made by the US Navy in 1964-66.

The device consists of an underwater microphone called a hydrophone and a housing compartment that houses disk drives and electronics to make up key elements of a High-Frequency Acoustic Recording Package (HARP).

Findings revealed a tenfold increase in underwater ocean noise off Southern California’s coast as compared with the 1960s in the same area off San Nicolas Island, one of the Channel Islands more than 160 miles west of San Diego.

They said the noise levels in 2003-2004 were about 10 to 12 decibels higher than in 1964-1966, an average noise increase rate of three decibels per decade.

The reasons could be due to the vast increase in the global shipping trade, the number of ships plying the world’s oceans and the higher speeds and propulsion power for individual ships, said Hildebrand.

The research is published in the August issue of the Journal of the Acoustical Society of America (JASA) and supported by the US Navy and the Office of Naval Research.