Researchers from Flinders University in South Australia have found that increasing artificial light at night masks natural cues, which prompts clownfish eggs to hatch.
The problem is exacerbated by urbanisation in coastal areas where artificial light spills out into reefs close to shore.
The Saving Nemo foundation was established by Flinders University and the University of Queensland to breed clownfish and raise awareness of their declining numbers in the wild.
In the latest project, research director Dr Emily Fobert monitored 10 pairs of breeding Amphirprion ocellaris, or false clownfish, of varying sizes.
Half were exposed to low levels of overhead LED light at night, while the other half were exposed normal daylight and darkness.
Although the number of eggs laid didn’t change, none of the eggs exposed to LED lights hatched. The other half had an 80% hatch rate. The research team turned off the artificial nightlights and continued to monitor the fish for 60 days and hatch rates soon returned to 80%.
The results are published in the journal Biology Letters.