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Three Surprising Creatures Affected by Light Pollution

Photo by Toby Hudson via Flickr (CC 2.0).

Every year we see lots of new research on the effect of artificial light at night on various types of wildlife. Many of us know of the impact of light pollution on wildlife such as moths, migrating birds and sea turtles, but there are others you might not be as familiar with. Here are three such examples.

1. Coral

As if coral didn’t have it bad enough – coral bleaching, ocean acidification and bottom-trawling – new research suggests that light pollution can threaten coral reproduction.

Researchers looked at the corals of the Great Barrier Reef and found that the Reef’s annual coral spawning is dependent on an intricate mix of conditions, with moonlight playing a vital role. But, artificial light competes with moonlight and can prevent corals from spawning.

Even though corals don’t have a brain, they have a spread-out nervous system that allows them to transmit signals in response to sensing changes in light conditions on a cellular level. The study suggests that the release of sex cells in corals is triggered by a protein similar to the photosensitive melanopsin molecule. In mammals, melanopsin plays an important role in synchronizing circadian rhythms with the daily light-dark cycle.

The effects of light on the timing of spawning are especially important because sexual reproduction is vital to reef survival. This discovery could help guide reef and marine ecosystem protection plans.

2. Wallabies

Photo by Tatiana Gerus via Flick (CC 2.0)
Photo by Tatiana Gerus via Flick (CC 2.0)

New research finds that mother wallabies exposed to artificial light at night gave birth about a month later than those living under only the natural light of the moon and stars.

The wallabies’ mating schedule is very specific. They mate in October and the decreasing daylight at that time of year triggers the pregnant females to produce melatonin, a hormone related to regulating sleep-wake cycles. In turn, melatonin causes their progesterone levels to rise, which helps get the fetus ready to be born exactly six weeks after the solstice, a time when day length and temperature are ideal.

Unfortunately, artificial light in the wallabies’ nighttime environment thwarts their ability to detect decreasing daylight. This diminished their melatonin production, delaying births on average by an entire month. According to the study, “These results suggest that urban light pollution could have profound impacts on desynchronizing seasonal physiological processes in wildlife.”

3. Fireflies

Photo by Mike Lewinski via Flick (CC 2.0)
Photo by Mike Lewinski via Flick (CC 2.0)

The familiar glowing patterns of fireflies are a crucial part of their mating rituals. Each species of firefly has a characteristic pattern of flashing light that helps its male and female individuals recognize each other. The males fly and flash, while the usually stationary females respond with their own flashes.

A recent study suggests that light pollution may disrupt this carefully conducted ritual. The researchers subjected ‘big dipper’ fireflies (Photinus pyralis) to artificial light, and found that the females didn’t flash back at the male as often as those not exposed to light, resulting in fewer of those females mating.

But, the researchers found that the firefly areas subjected to the artificial light at night didn’t not appear to have lower populations then those that were not, at least in the short term. Further research may reveal how firefly populations are affected in the long term by exposure to artificial light.

The Light Pollution and Wildlife Research Keeps Coming

New studies are regularly published linking exposure to artificial light at night to harmful effects on various wildlife species. We are just beginning to uncover the complex ways that light pollution wreaks havoc on the environment. Fortunately, light pollution easily can be solved with good lighting design. We just need people to understand. Learn how you can help!