The ecophysiology team of the Monaco Scientific Centre (CSM), in collaboration with researchers from the Bar-Ilan Institute in Israel, has published the results of its research on light pollution’s effects on coral.

At night, reefs benefit from low light levels provided by the moon and stars. Light exposure is crucial since it influences the species’ behaviour and reproduction. This is particularly the case for corals, which synchronise when they spawn with the phases of the moon. “In recent decades, coastal reefs have been subject to artificial light from city and road lighting, which significantly disrupts the nocturnal rhythms of animals and endangers coastal coral reefs,” says the MSC.

Photosynthesis disrupted

For eight weeks, researchers exposed two species of Red Sea corals (Stylophora pistillata and Turbinaria reniformis) to low levels of light pollution “corresponding to the same levels measured in the Red Sea in the Gulf of Aqaba”. Researchers compared the data with that taken from a group of coral of the same species which had not been exposed to light to study the impacts of artificial light on animals’ physiology.

The results suggested that artificial light at nighttime disrupts algae living in the coral to photosynthesise. “After a few weeks, the corals lose their symbiotic algae — this is called bleaching. The severity of bleaching depends on the intensity of oxidative stress on the corals,” adds MSC.

The Journal of Environmental Pollution published the study. Its results provide a better assessment of the risks to coral as well as the measures that should be applied to reduce this source of pollution.