Noise Pollution is Having a Detrimental Impact on Marine Life: We Must Do Something About It
From cetaceans to shellfish, sound is an integral part of ocean life. Marine animals can usually only see as far as tens of metres at most, they can smell across hundreds, but they can hear across entire ocean basins. Therefore, sound is crucial to many aspects of marine life — like sight is for ours — including hunting, navigation, communication and even finding a safe home.
Marine animals are being exposed to a devastating amount of anthropogenic noises, especially as sound waves travel 4.3 times faster in water than air. Human technology — through the use of ships, seismic surveys, fishing, construction, and oil-drilling — has steadily altered the ocean soundscape. And, since we are responsible for unleashing this increasing, brutal cacophony of noise, we must also find solutions to reduce it, thereby enabling marine mammals to re-establish their use of sound in a healthier ocean.
Until recently, the impacts of noise pollution on marine life haven’t received the same publicity level as other forms of anthropogenic effects, including overfishing and climate change. However, an article published in the journal Science earlier this month, “Soundscape of the Anthropocene Ocean” has provided compelling evidence that it is just as destructive, destroying the quality of life for billions of marine mammals and serving as a significant disruption to ocean ecosystems.
The article involves 25 experts on marine acoustics from across the globe and is currently the most comprehensive synthesis of evidence about the effects of noise pollution. Across the 500 studies that were analysed, it was discovered that the current levels of noise pollution are causing substantial harm to marine mammals such as whales, seals and dolphins, and quantifiable adverse effects on fish and invertebrates.
Climate change further exacerbates this issue. Carbon dioxide emissions from fossil fuels have caused our oceans to become more acidic, resulting in water being able to carry sound further. If we do not do something now, anthropogenic noise will continue to drown out natural soundscapes to the detriment of all marine life.
It is difficult to think of a sea creature that has not been impacted, even baby clownfish that rely on the gurgles and crashing soundscape of the reefs that prevent them from drifting out to open ocean. Nevertheless, as proven by the covid-19 pandemic, hope is not lost. When ocean traffic came to a dramatic halt as much of the world locked down, marine mammals and sharks almost instantly returned to previously noisy areas. This demonstrates that marine life can rapidly recover from anthropogenic noise pollution; we just have to make the necessary changes.
Over the past 50 years, increased overseas shipping has increased low-frequency marine noise by 3200%. As well as this, technological advancements such as sonar navigation which is used by the military, and fishing vessels to locate shoals of fish, construction, offshore windfarms, the operation of oil rigs, as well as the detonation of WW2 bombs in the North Sea, all add to the unnecessary and detrimental marine noise.
Extreme stress is a direct symptom of anthropogenic noise on marine animals, which takes away their ability to effectively use their dominant sense. This leads to them making poor decisions, as evidenced by the increase of mass strandings worldwide and the discovery that the noise from motorboats on the Great Barrier Reef in Australia leads to double the mortality of marine mammals from predators. Their primary sense is sound. Ours is sight. So, it would be like if we were forced to live the rest of our lives with only strobe lights to see.
But what can we do about it?
The lives of all species — including humans — are interconnected. For a healthy planet and our species’ survival, we must care for all the others. As human presence in the ocean has increased, the human noise has also exponentially increased whereas sounds of biological origin have been reduced through hunting, fishing and habitat degradation. While this affects marine animals on multiple levels, unlike other pollutants, the sources can be easily rectified and the effects would decline almost instantly.
The most obvious and one of the most detrimental impacts is the use of military sonar and seismic survey detonations, which have been proven to cause deafness, mass strandings and deaths of marine animals. These are not essential to human quality of life and could be performed only in designated areas, or avoided where possible. Additionally, seismic surveys could be carried out using seabed vibrators rather than sending noise waves through the whole water column.
There are functional solutions too, for example, shipping giant Maersk in 2015 discovered that retrofitting five large container ships with new propeller designs reduced noise and increased fuel efficiency. Quieter propellers should be the top priority, as the study discovered that half of all shipping noise comes from just 15% of vessels. And, while it may be a short term expense, the increased fuel efficiency would make it worth-while for companies and the climate crisis alike.
Electric motors are another possible solution, as are small reductions in speed. Cutting the speeds of noisy vessels in the Mediterranean from 15.6 to 13.6 knots resulted in noise emissions from 2007 to 2013 being reduced by 50%. This is a cost-effective and also a more viable solution.
Along with reducing plastic pollution and climate change pledges, clamping down the human-made ocean audio must be a core component of environmental policy. Cutting noise is possibly the easiest way to make a near-immediate difference in biodiversity and reduce anthropogenic impacts of humans on the environment, thereby resulting in a healthier planet for everyone.
Further Reading and Sources:
Source of Anthropogenic Sound in the Marine Environment: Microsoft Word — TextENDNOTE.doc (mmc.gov)