Environmental Science
The Effects of Noise Pollution on Marine Mammal Communication
Quick fact
A single container ship can raise ocean noise levels by more than 20 decibels, potentially halving the communication range of whales—meaning they can suddenly 'hear' only a fraction of the distance they normally do.
Why this is interesting
You're floating in the middle of the ocean, and the only way to talk to your friends is by singing a song that travels for miles. But what if a constant roar of machinery drowned out your voice?
Read the full explanation
Understanding The Effects of Noise Pollution on Marine Mammal Communication
Imagine you're at a crowded party. You try to talk to a friend across the room, but the loud music and chatter make it hard for them to hear you. You may have to shout or move closer. Marine mammals face the same problem underwater, but their party is the entire ocean. They use sound to communicate because light doesn't travel far in water, but sound does—a blue whale's call can travel hundreds of miles. When a ship passes overhead, it creates a continuous low-frequency rumble that masks these calls, much like a constant loud vacuum cleaner in your room. This makes it harder for whales to find mates, stay in contact with their young, and navigate.
A deeper explanation
The core mechanism is acoustic masking. Underwater, sound travels about four times faster than in air, and low-frequency sounds (like those from ship engines) travel particularly well. These sounds add to the ambient noise, raising the background level. When background noise increases, the signal-to-noise ratio drops, meaning a whale's call is less distinguishable. To compensate, marine mammals may call louder (the Lombard effect), shift their frequency, or call more often—but this costs energy and may not always work. In extreme cases, very loud noises like sonar can cause physical harm, leading to strandings or even internal injuries. The effect is not just annoyance; it disrupts essential life functions like feeding, breeding, and navigation. This is why noise pollution is now recognized as a significant threat to marine mammal populations worldwide.