Unbearable noise harms sea life

It’s always been noisy under the sea but now the noise is going through the roof.

The crash of waves, the shifting of the earth’s crust, the songs of whales are being drowned out by shipping traffic, drilling and dredging and sonar and seismic surveys, studies show.

And it means even the iconic coelacanth is in trouble.

Addressing the 5th African Marine Mammal Colloquium on Wednesday, Ezemvelo KZN Wildlife scientist Dr Jennifer Olbers said this clamour of human activity – and in particular seismic survey noise related to offshore oil and gas exploration – was harming marine life in various ways.

While relatively little research had been done on the issue in South African waters the data from the North Atlantic was abundant, she said.

“The level of undersea noise increased by 10-12 decibels between 1960 and 2004.”

She said it was clear that the present mitigation measures for seismic surveys in South Africa were insufficient and that the department of mineral resources should not rule on environmental assessments of mining projects.

With seismic surveys, air guns towed behind a research vessel fire into the water. The sound vibrations bounce off the sea bed, capturing information about mineral deposits beneath the seabed, and return this information to receivers on the surface.

Olbers said research showed that the excessive undersea noise could directly injure or kill marine animals, immediately or over a period of time, by impairing hearing, triggering the release of stress-related enzymes and damaging tissue.

The commission “cautioned against prioritising the immediate economic benefit of mining activities over the maintenance and protection of the environment”.

Undersea noise increased by 10-12 decibels between 1960 and 2004