I decided to go for a swim into the south pacific off the coast of Guam, and submerged to about 36,000 feet just to listen to how noisy the Mariana Trench is. The Mariana Trench is the deepest part of the ocean and runs roughly in a crest from a north to south direction. The pressure at that depth is about 1,000 times as great as is normal air pressure. Like most people, I assumed that it would be rather quiet down there but it was anything but quiet.
A category 5 typhoon was roaring overhead, underwater mud volcanoes, vents spewing sulfur compounds, baleen whales were blathering away, cargo and merchant ships were passing overhead, and not to mention underwater construction that was many miles away- and it was nothing like quiet.
In a recent study by Robert Dziak, who is a researcher at the National Oceanic and Atmospheric Administration (NOAA), he was quoted as saying “You would think that the deepest part of the ocean would be one of the quietest places on earth”. Boy was he wrong!
His group sent down an underwater microphone almost 7 miles down – more than the height that many commercial passenger jets travel above the ground – and measured many sources of noise. Of course I wasn’t swimming down there – even though I have a very thick skin, I would have been crushed to death, and the air in my SCUBA tank would only have lasted a fraction of a minute.
Some of the sounds that were recorded can be found on the NOAA site.
The Ocean Conservation Research group is an organization that has studied underwater noise created by humans and they found that the ocean may be about 10 times noisier today than it was 50 years ago. For those who like decibels, this is about 10-12 dB higher than 50 years ago.
Other groups such as the Acoustical Society of America have working groups and standards committees that are dedicated to understanding the effects of environmental noise on marine life. The concerns relate to altered migration routes, reproduction, and marine communication and health. Specifically the Acoustical Society of America has the ASC-S3/SC1 Working
Groups. They are Animal Bioacoustics, Effects of sound on fish and turtles, and underwater passive acoustic monitoring for bioacoustics applications. For more information on this, contact the Acoustical Society of America.
And for those who would like nothing better than to spend their July holidays in sunny (and sometimes, rainy) Dublin, Ireland, the fourth international conference on “The Effects of Noise on Aquatic Life” will take place in Dublin, Ireland, July 10-16, 2016 , and “is intended to introduce participants to the most recent research data and regulatory issues related to the effects of man-made noise, and to foster discussion between the participants. Emphasis will be on the cross-fertilization of ideas and findings across species and noise sources. This kind of sharing of material is of exceptional value since there are many commonalities in issues that never get appreciated except at meetings that cross disciplines and ideas.”
