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Orca Community Blog

Noise pollution in water

Orca

July 6, 2021

NOISY WATER

Finn van der Aar (@saltwaterstories.me)– Marine Scientist  

Often as swimmers, surfers or freedivers we think of pollution in the water as plastics, a tangible thing we can see and try to remove. What we might not think about so much, or even be aware of, is marine noise pollution.
There are so many forms of natural sound in the ocean - made by underwater volcanic eruptions or earthquakes (geophony) or by all the amazing animals below the surface - trills, clicks and whistles (biophony).

On of the world’s most eminent marine biologists Sylvia Earle described acoustic disturbance and sonar caused mortalities “death by a thousand cuts”.

The types of human (anthropogenic) sounds we put into the ocean that are most harmful to marine life come from things like seismic surveys (that are conducted as part of oil and gas exploration or before the development of things like wind farms), drilling/explosives and shipping noise.

THE IMPACT OF NOISE IN MARINE MAMMAL BEHAVIOUR

Baleen whales like humpback and minke whales are more susceptible to the impact of things like seismic and piling noise as the low frequency of these activities overlaps with the frequencies at which they vocalise.

The frequencies used by military sonar (used during war activities or testing) have been shown to have direct correlation with the mass strandings (and ultimately deaths) of marine mammals the world over (even as recently as 2020 along the western European seaboard).
Even just high levels of background noise (like busy shipping routes) has a major affect on marine mammal behaviour. On the west coast of Canada Orcinus orca (our beloved killer whales) spends 18-25% less time feeding when there are high levels of background noise. Highly detrimental to this already dwindling population.

My job is to try to mitigate the damage to marine mammals created by different types of anthropogenic sounds in the ocean. Typically that’s related to marine development - like offshore seismic surveys for the construction of wind farms or inshore work on things like pier construction. I monitor a specific mitigation zone (a spatial area). Sound travels much much faster in water, so the size of the zone increases with the volume of the activity. I’m looking to see that the area is free from marine mammals or to observe the behaviour of any animals that come into the zone after the work has started. All cetaceans (whales and dolphins) are protected under the EU Habitats Directive within the Exclusive Economic Zone (EEZ) of each EU member state, which is why jobs like mine exist!


Photographs taken by Alice Ward from Sea Pea Films

WAYS TO REDUCE NOISE POLLUTION

The one very reassuring things about marine noise pollution (in comparisons to other major issues like ocean acidification or marine plastics) is that once the noise stops, the disturbance disappears - no lingering chemicals, no physical detritus, nothing to be removed or remediated.

In 2017 Canada became the first country in the world to create a financial incentive to industry to reduce noise pollution - Vancouver port offered discounted rates for quieter ships. In some case simply by dropping speed by as little as 3knots, the ship’s noise intensity was cut in half.

Globally there are many ways to reduce marine noise pollution - the use of quieter propellers (already introduced on cruise ships for the benefit of the guests), slower ship speeds, altering marine traffic routes (already in place in Norway) and enforcing the use of quieter equipment for seafloor exploration (already in place in Germany). 


Photographs taken by Alice Ward from Sea Pea Films

ABOUT FINN VAN DER AAR

Finn is passionate about presenting crucial environmental and oceanic research in a way that is actually understandable. Allowing it to have a greater impact in the world. She shares simple and realistic ideas for sustainable living on her Instagram @saltwaterstories.me and website.