Bright lights at night aren’t just keeping you from seeing the stars: the growing glow of artificial lights also impact animals. And now, scientists have uncovered that it's not just the land-based life forms that we're messing with when we keep the lights on — light that leaks into the high seas may be keeping marine life from settling down too, writes Kate Wheeling for Science.

A new study conducted in the Menai Strait northwest of Wales found that light from oil rigs, passing ships and harbors may be preventing some species from casting anchor. At the same time, the light may draw species that cause chaos for humans and underwater environments, like barnacles.

“Species are responding to cues sometimes that are orders of magnitude dimmer than what we can see, and that means that there’s a whole range of variation out there that we just don’t intuitively notice as humans,” urban ecologist Travis Longcore, who was not involved with the study, tells Wheeling. “To us it’s just dark, but there are many, many, many shades of dark.”

In the study, ecologist Thomas Davies of the University of Exeter submerged 36 plastic panels and lit them up once the sun went down, writes Wheeling:

“They exposed some panels to light from cool, white LEDs that emitted either 19 lux or 30 lux—about the same brightness of streetlights. The control panels were exposed only to artificial light known as “sky glow,” ambient humanmade light scattered in the sky and reflected back to the sea surface by the atmosphere. Because artificial light in the Menai Strait is rare, Davies says, the sky glow in the region would likely have amounted to less light than what occurs during the full moon.”

After a few months, Davies and his team found that the more light a panel was exposed to, the fewer filter feeders decided to make their homes there. These animals, such as the sea squirt and sea bristle, suck plankton and nutrients from the water and keep the ecosystem healthy. And many of the ecosystems these animals live in, like coral reefs, are already stressed by pollution and climate change. On the other hand, the brighter panels attracted more sea worms and barnacles, the latter of which can cost countries around the world more than $303 million a year in damages, writes Wheeling.

Scientists are only beginning to understand how light affects underwater ecosystems and they’ll need a lot more research to figure out what to do about it. But now that researchers know how light disrupts these environments, they can start planning the next step.

h/t Science