All-night lights change the behavior of fish, even into the next generation

Scientists have shown that light pollution—especially light in the blue spectrum—can alter the behavior of fish after only a few nights, and have knock-on effects for their offspring. The team studied how female zebrafish responded after being exposed to artificial light at night, known as ALAN, which is considered to be the main source of the world’s light pollution. Fish were exposed to varying wavelengths of ALAN over nine nights, which caused them to swim less, stick closer together, and spend more time near the wall of the aquarium.

Artificial light at night (ALAN) pollutes the environment by adding luminescence to places that would otherwise be dark at nighttime. ALAN exists outdoors through the lights that brighten streets, buildings, and industrial areas all night; and ALAN exists indoors through the devices that hold our attention into the evening. ALAN is known to impact most organisms by disrupting the natural rhythms of biological processes, which are coordinated by cycles of light and dark.

The study also revealed that the impacts of light pollution did not end in the individual, but were passed down to offspring. After exposure to ALAN, the study’s female zebrafish were allowed to breed and the team raised their offspring under natural light conditions. After 15 days the researchers tested the swimming behaviors of larvae using specialized automated tracking software designed to quantify activity levels of the tiny fish. Offspring of exposed mothers showed decreased daytime movement despite themselves never being exposed to lights at night.

Source: Eurek Alert!