Species that rely on darkness for foraging and foraging are losing their talent for camouflage, thanks to advances in lighting technology used to illuminate the world’s cities and coastlines, a study suggests.
The worldwide spread of energy-efficient broad-spectrum lighting has the potential to disrupt a range of visually-guided ecological processes.
New research shows that these new lighting techniques could significantly improve predators’ ability to distinguish prey species from natural backgrounds.
The magnitude of this effect varies by the color of the organism, which means that certain color changes may be at greater risk.
The study was published in Journal of Applied Ecologyby researchers at the University of Plymouth and Plymouth Marine Laboratory (PML).
It is one of the first to investigate the potential of nocturnal artificial light (ALAN) to influence the mechanisms of camouflage in coastal species.
Oak McMahon, who led the research while studying an MSc in Applied Marine Science and is now a PhD student at the University of Plymouth, said: “This research clearly shows that new lighting techniques will increase prey conspicuousness by reducing efficacy. Their camouflage. Our results suggest that the Littorinid snail species commonly found on our shorelines retain their camouflage when illuminated by old-style lighting. However, when illuminated by modern broad-spectrum lighting, they are more vulnerable to predators is clearly visible and results in risk over a longer period of time.”
This is the latest research by the University and PML, funded by the Natural Environment Research Council, to highlight the growing growth of ALAN and its impact on coastal environments.
In this study, scientists used a well-established model to determine the prominence of three different colored Littorinid snails commonly found on the world’s coastlines.
They compared the species’ performance against three common coastal predators under different forms of lighting. This includes 20th century narrow-spectrum low-pressure sodium (LPS) lighting, three modern broad-spectrum lighting—high-pressure sodium (HPS); light-emitting diodes (LED); and metal halide (MH)—as well as natural light provided by the sun and moon.
Under LPS illumination, all snails were effectively camouflaged. However, when illuminated by LED, MH, sun or moon, yellow snails were significantly more visible compared to brown and olive snails in most cases.
Dr Thomas Davies, Lecturer in Marine Conservation at the University of Plymouth and senior author of the study, said: “As technology has developed, people have moved from narrow spectrum to lighting, allowing us to live and travel in a safe and secure manner. However, it is estimated that , a quarter of the earth between the Arctic Circle and Antarctica is now affected by nighttime light pollution. Some forecasts say that LED bulbs will account for 85% of the global street light market in about five years, and our research highlights that these advances will impact on humans and animals now and in the future.”
Dr Tim Smyth, Head of Marine Biogeochemistry and Observational Sciences at PML and co-author of the study, added: “Over the past century, the ability to illuminate our environment around the clock has transformed the urban landscape and ushered in some Said Urbanocene. The orange glow over cities has shifted from the typical transition from the 1970s and 1980s to energy-efficient broad-spectrum LEDs that even allow us humans to perceive color correctly. This work shows that this advancement has additional implications “The natural world must adapt at an ever-increasing rate to the man-made changes we make to the environment. We need to learn to adapt our technologies to avoid the worst consequences of adopting them. “
What can be done to reduce the impact of artificial lighting on our coastlines
With an estimated 23% of the world’s surface between the Earth’s poles affected by ALAN — a growth rate of 2.2% between 2012 and 2016 — there is an urgent need to address the problem, to say the least.
In this study, the researchers highlight various mitigation methods that planners and environmental managers can use when considering their ecological impacts.
These include reducing the amount of light used, shielding lights to reduce their impact on the surrounding environment, introducing partial nighttime lighting during peak demand periods, and manipulating the lighting spectrum to minimize ecological impact.
The researchers stress that while it may seem intuitive to recommend narrow-spectrum lighting to avoid these effects, the effects of ALAN go beyond camouflage, and that all parts of the visible spectrum may have some ecological impact.