Light pollution poses developmental risks to clownfish

AFP-Jiji PARIS (AFP-Jiji) — Popularized by Disney’s “Finding Nemo,” the common clownfish may not see its eggs hatch if they are exposed to artificial light at night, researchers reported Wednesday.

“Clownfish, and likely other coral reef fish species living in areas exposed to light pollution, might not be able to produce viable offspring,” Emily Fobert of Flinders University in Australia told AFP.

A wide range of animals and plants across the globe are exposed to light pollution, but scientists have only begun to study its impact on their development and behavior.

An estimated 23 percent of land surface — excluding the poles — is today exposed to so-called “artificial light at night” (ALAN).

“The correct functioning of most natural systems fundamentally relies on light days and dark nights,” Fobert said.

“But the presence of ALAN can mask these natural light rhythms, and interfere with the behavior and physiology of individual organisms.

“It can impact ecological systems as a whole,” she added.

Most research on light pollution has focused on terrestrial wildlife.

But marine species are exposed too: 22 percent of the world’s coastal regions experience some degree of artificial illumination, Fobert said.

Because it typically travels great distances in its larval phase just after hatching, the clownfish was a good subject for experiments testing the impact of light pollution.

“Baby clownfish don’t stay in the anemone where they were born — they can disperse and find a new home, ten to hundreds of kilometers away from their parents,” Fobert explained.

Once they choose a habitat, they remain for life.

“If they settle to an area that is exposed to light pollution, they most likely won’t be able to move away,” she said.

Clownfish eggs are often attached to the side of shallow-water rocks, which means — in an area, say, near a harbor with LED lights that penetrate seawater — embryos will be constantly exposed as they develop.

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