Losing the cover of the darkness

A new study shows how advances in street lighting are reducing the efficacy of coastal species’ camouflage

Species that rely on darkness to forage and feed are losing the gift of camouflage thanks to advances in the lighting used to illuminate the world’s cities and coastlines, a study has shown.

The worldwide proliferation of energy efficient broad spectrum lighting has the potential to disrupt an array of visually guided ecological processes.

New research has demonstrated that these new lighting technologies can significantly improve a predator’s ability to discriminate prey species against a natural background.

The magnitude of this effect varies depending on an organism’s colour, meaning certain colour variations may be at greater risk.

The study, published in the Journal of Applied Ecology, was conducted by researchers at the University of Plymouth and Plymouth Marine Laboratory (PML).It is one of the first to examine the potential for artificial light at night (ALAN) to affect the camouflage mechanisms of coastal species.

“This study clearly indicates that new lighting technologies will increase the conspicuousness of prey species by reducing the efficacy of their camouflage. Our findings revealed that species of Littorinid snails found commonly on our coastlines will remain camouflaged when illuminated by older style lighting. However, when illuminated by modern broad spectrum lighting, they are clearly visible to predators and at far greater long-term risk as a result.”

Oak McMahon, who led the research while studying for an MSc in Applied Marine Science and is now a PhD candidate at the University of Plymouth

An illustration of how a Littorinid snail loses the benefit of camouflage making it more visible under broad spectrum lighting