What is underwater light and sound pollution?


Light and sound are introduced into the marine environment from a variety of human activities, including coastal construction and development, shipping, oil and gas extraction, marine renewable energy, military operations, and tourism and commerce involving boat traffic.

Light and sound pollution are problematic because they change the sensory conditions to which marine organisms have adapted over time.

Sound travels four times faster in seawater than in air due to water’s greater density, and many species rely on sound for communication and survival. Here’s a fish chorus recorded off the west coast of Australia. And here are recordings of humpback whale songs that are transmitted over vast distances in deep ocean layers and re-sung by other whales, much like viral posts on social media.

On the other hand, light attenuates rapidly underwater with depth, and the relative darkness of pre-industrial oceans made light a useful tool for survival. Some organisms developed bioluminescent properties, illuminating the darkness to confuse predators or attract mates. Others rely on light from the moon for navigation or to synchronize spawning events and maximize reproductive success.

Human-made light and sound are relatively recent phenomena compared with the timeline over which sensory adaptations evolved, and have intensified in recent decades. While the technological advances that led to light pollution have significantly improved life for humans over the last hundred+ years (electricity, combustion motors, etc), they now pose significant challenges for marine organisms.