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Noise Pollution

Sound that causes disturbance or harm to the environment.

Sound is important in the marine environment.
 
Some Background:
Sound can travel further than light.
Light usually fails to penetrate around 200m breath the surface, but sound can travel thousands of kilometres in the right frequencies.
Sound is faster in the water than in air.
Sound is about 4.5x faster in seawater than in the air or 1500ms although, there are many factors affecting it's speed, ph, salinity and temperature among others.
Sound can travel further than light.
Light usually fails to penetrate around 200m breath the surface, but because water is denser than air, sound can travel thousands of kilometres in low frequencies.
 
 
 
 
How marine organisms use sound:
 
The qualities of sound in a marine system make it the perfect medium for sensing the environment, and it shows. Animals all over the world have adapted to use sound as an important sense.
 
  • Dolphins use echolocation to find food.
  • Larval stages of fish use sound to find reefs and orientate themselves
  • Whales sing to find mates and communicate over thousands of kilometres.
  • Coral reefs have a dawn chorus of their own, much like birds on land.

What Makes Noise?

Natural sources:
 
The natural environment is full of different sounds already, produced by earthquakes, moving ice, waves, rain, ocean spray and many more. 
Human Sources:
The problems with man made noise are dictated by it's characteristics: frequency, location, constancy and intensity. Many anthropogenic activities produce noise including shipping, fishing, naval sonar, research, construction, leisure activities and more.

How Man Made Noise Affects Marine Organisms

Audibility

When animals hear noise, it can change their behaviour. It may scare them away from the area resulting in changes to the trophic structure and the ecosystem or induce stress, causing accelerated ageing, sickness and lower reproductive rates.

Masking

Masking is when noise covers over the other sounds in the oceans. If animals cannot hear signals made by other organisms, they will not be able to communicate with each other, to forage for food, reproduce or detect potential predators.

Physical Injury

Noise at loud volumes can cause direct harm, like temporary or permanent deafness. There are also strong links however,  between high energy sounds like naval sonar and whale beachings or mass standings with symptoms resembling decompression sickness.