Let There Be A Little Less Light

These days everyone knows that dumping waste into the ocean is harmful, but when it comes to one specific pollutant, people around the world allow damaging radiation to pour from their homes, shops, and restaurants night after night. I’m referring, of course, to light.

No, your light bulbs are not directly dangerous to animals – little Fido is safe, don’t worry – but it turns out the term “light pollution” is more than just a metaphor. University of Queensland researcher, Tessa Mazor, has shown that light along the Israeli coastline is negatively correlated with nesting behavior of endangered Leatherback and Green sea turtles.1 That is, the more light on the beach, the fewer baby turtles, even after adjusting for other signs of human presence. Since coastal cities are growing rapidly, the animals could conceivably lose their entire nesting habitat to light pollution, no matter how pristine the beaches remain in other respects.

The research article, published in Biological Conservation in 2013, explains that the ecological effects of artificial light are just beginning to be explored. Yet even early studies have shown it to have drastic, often detrimental consequences for local wildlife including bats, birds and fish.1 Remember that the world in which these organisms evolved had only a few, predictable sources of light. At night in particular, their environments must have looked remarkably different than those they are currently confronted with. For sea turtles, it turns out the difference can be deadly.

“Most sea turtle species are nocturnal nesters and thus affected by artificial night-light activity,” Mazor says.2 Even when high light levels do not deter a mother turtle from nesting, her hatchlings can later be disoriented by the environment, have trouble finding their way to the ocean, and ruin their chances of survival.1 With this knowledge Mazor and her team, a collaboration of scientists from Mazor’s own institution and from Hebrew University of Jerusalem, looked at satellite imagery of the Israeli coastline to see if they could predict the presence and concentration of sea turtle nesting sights. The study spanned a period of 14 years and the results are worth shedding some light on.

Picture of Tel Aviv, Israel taken from International Space Station for the European Space Agency. Copyright:ESA/NASA. http://www.esa.int/spaceinimages/ESA_Multimedia/Copyright_Notice_Images

“Tel Aviv by night” taken from International Space Station. Copyright:ESA/NASA. http://www.esa.int/spaceinimages/ESA_Multimedia/Copyright_Notice_Images

“Our findings are one of the first to show that night lights estimated with satellite-based imagery can be used to explain sea turtle nesting activity over a large-scale area,” Mazor boasts.2 She has reason to be proud. This technique will allow for a greater understanding of sea turtle behavior in areas that are hard to reach and on scales that would be impractical to survey. Moreover, this knowledge is likely to have very concrete applications. “Improving our ability to determine [turtles’] nesting patterns can enable us to better direct and target our conservation efforts,” explain the authors.1

More recent research, led by Thomas Davies from the University of Exeter, has found that light pollution is a growing issue even in areas designated for marine protection.3 The findings indicate that legislation meant to protect ocean life may not be effective if the lighting problem is not addressed. Davies’ article, published in Conservation Letters in 2015, explains the necessity of altering public perception of night lighting. Light can of course be necessary for security and human activity, but it may be possible to cut down on the number and intensity of lights and to shield light from the natural landscape. For now, Davies and his team argue that more research like Mazor’s is needed to understand the extent of the impacts of light pollution so we can learn how best to balance human benefit and environmental protection.

Mazor’s team urges us to view their findings as encouraging. Knowing that turtles are deterred by artificial light gives scientists a simple way to track their nesting behavior around the world as well as attempt to reclaim some of their habitat. Most importantly both articles remind us to consider the consequences of all that we introduce to the environment, even those pollutants that don’t seem so dangerous. If artificial light can reduce the survival of wild animals, why not save a little energy, cut down the electricity bill and help some endangered species in the process?

-Bethany Fowler


1Mazor et al. 2013. “Can satellite-based night lights be used for conservation? The case of nesting sea turtles in the Mediterranean.” Biological Conservation (159): 63-72. <http://www.sciencedirect.com/science/article/pii/S0006320712004569>.

2Howell, Elizabeth. “Light Pollution Deters Nesting Sea Turtles.” Live Science. Web. 14 Sept. 2015. <http://www.livescience.com/37278-light-pollution-sea-turtle-nesting.html&gt;.

3Davies et al. 2015. “Stemming the Tide of Light Pollution Encroaching into Marine Protected Areas”. Conservation Letters. doi: 10.1111/conl.12191. <http://onlinelibrary.wiley.com/doi/10.1111/conl.12191/full>.

Image: Nespoli, Paolo. “Tel Aviv by night.” Space in Images. European Space Agency. Web. 14 Sept. 2015. <http://www.esa.int/spaceinimages/Images/2011/ 01/Tel_Aviv_by_night>.

This entry was posted in Conservation Biology Posts, Conservation Editorials 2015. Bookmark the permalink.

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