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In the harbor, the underwater noise echoes

04 October 2019

There’s a tremendous jumble of sounds below the water surface and shipping is the biggest source of noise that interferes with marine life.
A prestudy from Lighthouse takes a closer look at the noise in ports - a blank space on the map of research.

In recent years, scientists have seriously begun to understand that marine life is disturbed by the noise man is causing in the seas. Reports have been pouring in about how fish and whales can no longer communicate with each other, locate partners or in the worst case - die on the spot of a sudden high noise.

”A noise map has been made of the Baltic Sea showing high levels of noise caused by shipping. There are hardly any silent zones left there”, Torbjörn Johansson, researcher at the IVL Swedish Environmental Institute, says.

In the sea, sounds are heard at longer distances than on land. A large ship can be heard at ten kilometers, sometimes even further away.

”Everyone who dived at some point know this. You hear a buzz, think you’ll be run over, but when you stretch your head above the surface of the water you see that the motorboat is several hundred meters away.”

But most people do not dive. That is why humans haven’t paid much attention to what noise means to marine life, Torbjörn Johansson believes.

”Over the past five years, more research about underwater noise have been published than it has in all previous years.”

Studies have shown that the sounds in the seas have increased significantly over the last 50 years and that shipping is the dominant source of dangerous underwater noise. But measurements have mainly been made in the open seas – not much have been measured . in the coastal areas.

”From ports there are almost no results at all.”

This is a lack of knowledge that some researchers from IVL, SSPA and Chalmers want to cover. Torbjörn Johansson is leading the work in the pre-study study that will summarize what has been done so far and what should be done next.

”A port is a pretty special environment where a lot of noise is made.”

The many hard reflection surfaces in a harbor create echoes. Perhaps a harbor can be likened to a ghetto blaster that is heard far out on the seas.

”We know that underwater noise is a major environmental problem, but not how big it is. Hopefully, the pre-study will lead to research projects where we can make measurements in ports and maybe also do experiments,” Torbjörn Johansson says.

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