5 surprising effects of light pollution

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Light pollution, though usually considered as a minor problem, has some surprising impacts not only on nature, but also on our health and mood. One interesting example of the effects of light pollution is that it could make our bones more fragile.

Light pollution in New York

Light pollution may have quite a significant impact on both nature and human health (Photo: pixabay.com / Free-Photos)

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Light pollution, when compared to - for example - the pollution of the air, seas and soil may seem as a far less important issue, but in fact, it may have quite a significant impact on both nature and human health. Below are five ways in which the excessive use of artificial lights may affect life on Earth!

1. Light pollution confuses turtles

The life of sea turtles is getting harder and harder as years go by. Not only the global warming, improper fishing techniques and the multiplying amount of plastic pollution in the seas and on the shores make their lives more difficult, but so does light pollution, which, according to a study published in the March 2013 issue of the journal Biological Conservation, is changing the nesting habits of these already rare reptiles. It turned out that turtles started choosing darker spots when laying their eggs due to the light pollution near big cities.

Three species of the sea turtles are listed as vulnerable on the IUCN Redlist, while others are considered endangered or critically endangered, and this means that even smaller challenges can make a big difference in their chances of survival. Unfortunately, light pollution is no minor danger, because it not only deters the nesting animals, but confuses the hatchlings while making the most dangerous journey in their young lives too. Scientists noticed that many of the young reptiles are heading to the wrong direction after hatching due to the confusing artificial light, and even if they somehow turn into the right direction, spending too much time on the shore makes them extremely vulnerable to predators.

2. It may make our bones more fragile and muscles less strong

Light pollution affects many living organisms, and humans are no exception either... According to studies, the huge amount of artificial lights can distract our biological clock, leading to bad sleep quality and perhaps even contributing to mood disorders. Sleep disturbances, of course, can also affect our work performance, family life and relationships.

What's even more interesting is that scientists noticed changes in the muscles and bones of mice that were exposed to artificial light during the night. According to the study published in the journal Current Biology in 2016, the muscles of the mice became weaker, and the bones more fragile when exposed to light for six months. In our cases, the effects of artificial lights are obviously less dramatic, because we can use curtains to make the room darker at night, but it's surprising just in how many ways light pollution can affect mammals. Researchers also noticed that mice recovered after they were switched to natural light.

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3. Light pollution in cities has a negative effect on the behavior of robins

According to researchers of the University of Southampton, light and sound pollution may have a negative effect on the behavior of songbirds living in cities - just like the robins, whose behavior they examined for the research.

Male robins usually protected their territory really aggressively and loudly, but those that lived near places that were exposed to large amounts of light and sound pollution tended to be less aggressive when protecting their territory. This also meant that they were typically below the others in hierarchy. It is not yet known whether noisy and excessively lit places were less valuable in the birds' eyes, or birds living in such places suffer from too much stress, which prevents them from protecting their territories efficiently.

4. Artificial lights can confuse nighttime pollinators

When it comes to pollinator crisis, the hardships of nocturnal pollinators are usually disregarded or ignored - even though nighttime pollinators play a very important role in protecting the health of ecosystems. While pesticides and other hazards may affect both nighttime and daytime pollinators, light pollution is something that has a huge impact on the lives of nocturnal insects.

According to a study published in the journal Nature in 2017, flowers on meadows which were experimentally illuminated with street lamps were visited around two thirds less frequently by pollinators than those that were further away from artificial light. The lack of pollinators had significant effect on the amount of the fruit set. This study was the first to show how the fruit set of plants reduced due to the lack of nighttime pollination.

5. Trees start to produce leaves earlier in big cities

According to a study published in the Proceedings of the Royal Society B journal in 2016, trees start to produce leaves up to 7,5 days earlier in areas polluted with light than those that are placed in places further away from the constant lights of the cities.

This might not seem as a problem at all - after all, we all love spring, and are happy to see the bright green leaves after months of snow and grayness... The truth is, however, that even this seemingly small change in the "timing" of the leaf production can lead to serious consequences in the urban biodiversity.

First of all, cold nights are not uncommon in the first days of spring, and the leaves may freeze in the low temperatures.

Secondly - and this is the more important problem -, insects, such as the winter moth, usually hatch when the first leaves appear on the plants, and while the artificial lights affect the leaf production, they have no influence on when the caterpillars hatch. This means the latter can be more than a week too late, when the leaves - containing big amounts of tannin by that time, thus no longer ideal for them to feed on - appear. As the chances of the insects reduce, so does the food of the birds and small mammals. In the end, almost the whole urban fauna and flora could become more or less affected by the early leaf production...

Anita Diós

June 2018

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