It’s May, and beach season is almost here! To humans, swimming in the ocean is a well-deserved vacation, but to marine animals, the ocean is home. Most people know that trash and chemical pollutants can harm ocean wildlife, but did you know that noise pollution is also a problem in the ocean? Read on to learn how animals are affected by ocean noise pollution.
Sound is a pressure wave, meaning that it travels through a medium through compression and rarefaction (pulling apart) of molecules. While humans usually think of sound traveling through air as a medium, sound can also travel in liquids, like water. In fact, sound travels over four times faster in water than it does in air, and sounds in the ocean can be louder and travel greater distances than they would in air. Marine animals use this to their advantage, especially when dark or murky waters make it difficult to see. In the ocean, sound is used to navigate, communicate, find mates, avoid predators, and search for food.
Even small, human-made sounds can be harmful to marine animals; some of the most prevalent and harmful include boats, offshore construction, seismic surveys, and sonar activities. At the very least, these noises can mask the sounds that animals use to survive. Fish have a hard time avoiding predators when masking sounds are present, and mammals such as dolphins and whales change their communication habits. Humpback whales have been known to stop singing or change the frequency of their song in response to boat noise up to 120 miles away, similar to how humans pause conversation or speak louder when a noisy truck passes.
While noise pollution can mask important ocean sounds, it can also harm animals physically. Noise pollution has been linked to both temporary and permanent hearing damage and deafness in fish, dolphins, and whales. Human-made sounds can also cause animals to become stressed or disoriented. When startled by sounds, whales have been known to change their diving behavior, which can cause sickness and even death. Excessively loud noises from seismic surveys and naval sonar exercises have even been known to scare whales to death and cause internal organ damage in other marine animals.
Compared to other forms of ocean pollution, noise is one of the easiest to combat, and lowering sound levels provides some of the best short-term benefits to ocean wildlife. Animals can rebound almost instantly when noise sources are taken away. In the spring of 2020, when 60% of the world was in lockdown, ocean noise went down by 20% and animals returned to habitats that had been abandoned due to noise. For more permanent change, research and outreach groups, such as those in the International Ocean Noise Coalition, are working on increasing public awareness and advocating for governmental regulations to limit noise pollution at the source.
Every small change helps, so consider renting a kayak instead of a jet ski on your next beach vacation. If you are in a boat and see dolphins or whales, slow down or cut the engine to avoid disrupting their communications. They may even spout their blowholes for you!