For the history of life on Earth organisms have relied on the light of the sun, moon, and stars to find their way and schedule their lives. While the beginning of electric lighting in the late 19th century may have benefited humans, it has caused problems in the natural world. Among the impacts of artificial light at night(ALAN), light pollution lures migrating birds to cities with shocking consequences, contributes to the alarming decline in insect populations, and convinces sea turtle babies to amble(缓行)away from the water instead of towards it. 

Now, a new study from the University of Plymouth adds another disappointing finding about how ALAN is affecting the creatures with whom we share the planet: Light pollution from coastal cities can trick corals(珊瑚)into reproducing outside of the optimum times when they would normally reproduce. 

Using a combination of light pollution data and spawning(产卵)observations, researchers were able to show for the first time that corals exposed to ALAN are spawning one to three days earlier and closer to the full moon compared to those on unlit corals. "That shift may reduce the survival and fertilization success of gametes(配子)and genetic connectivity between nearby lit and unlit coral systems," they explain.

"Corals are among the most biodiverse, economically important, and threatened ecosystems on the planet," write the authors of the study.

"Climate change has led to mass bleaching(褪色)events. Habitat destruction, fisheries, and pollution have reduced corals substantially since the 1950s," they write, adding, "The complete loss of corals is anticipated over the next 100 years."

If we want to reduce the harm ALAN is causing, we could perhaps look to delay the switching-on of night-time lighting in coastal regions to ensure the natural dark period between sunset and moonrise when coral reproduction remains undisturbed.