Marine Noise Pollution: A Not-So-Silent Killer
When most people think of marine pollution, they picture catastrophic oil spills or seas of discarded plastic. But there is one marine pollutant that needs more recognition — noise. Marine noise pollution is defined as any source of sound created by humans in the marine environment that is capable of harming marine life. According to the World Health Organization, man-made noise is one of the most hazardous forms of pollution and has become widespread both on land and in the ocean.
Many marine organisms rely on sound for survival. Their ability to receive and produce noise is used for communication, finding prey, locating mates and offspring, and avoiding predators. However, humans are changing noise levels in the ocean and disturbing these behaviors. The largest sources of human noise in the ocean are military sonar, pile driving in search of natural resources like oil, and industrial shipping.
Imagine being chased by someone and relying solely on your hearing to escape. If the sound of their steps was drowned out by other loud noises, knowing their location would be practically impossible. This is how prey feel being chased by predators in an environment made louder by human activity.
In addition to disrupting the behaviors of organisms that rely on sound, noise pollution can lead to many negative physiological impacts. Some of the most concerning effects are hearing damage, injuries to other tissues, and changing hormone levels, leading to stress responses and lack of sleep. Effects can be short term, like a temporary shift in hearing threshold (the level below which the ear cannot detect any sound), or more significant, sometimes resulting in death.
An extreme example of these effects is the influence of military sonar on whale populations. Military sonar has been associated with mass whale strandings and deaths — not surprising given the fact that just one low-frequency active sonar loudspeaker can be as loud as a twin-engine fighter jet at takeoff. This overwhelming noise drives whales away from their preferred habitat and can injure or kill them by causing hearing loss, rupturing blood vessels, or driving them to the surface or shore too quickly.
Noise pollution wreaks havoc on individuals, populations, and entire ecosystems. The impacts are even more disastrous if the organism affected plays a large role in the environment, such as an apex predator. Some organisms have started adapting to increased noise, such as whales altering their acoustic frequency in loud environments. But the burden of developing a solution should be placed on humans, not the organisms we harm.
We must implement policies that reduce propeller noise from ships and mitigate the sounds of sonar equipment, pile driving, seismic air guns, and wind turbines. These changes can improve the ocean soundscape and encourage recovery, saving marine organisms from unnecessary suffering.
