This week marks Dark Sky Week, an event first thought up by an American high-schooler but now an international affair which aims to focus on the impacts that light pollution can have on many aspects of our lives and our environment.
From ancient times the night sky has been an important part of many parts of human life from religion to navigation but in more modern eras the significance of darkness has become more apparent. Our night and day rhythm is necessary for both plants and animals to thrive and even for our own our own physical and mental well
But in what ways does light pollution impact our wildlife? Here’s just a few critters struggling due to our obsession with artificial night lighting.
Environmental cues are key to many animal behaviours and natural light cues play a vital role in both daily and seasonal cycles. In sea turtles, artificial lighting at nesting sites is a prominent example of how unnatural light cues can result in higher mortality rates.
Under natural conditions, both mother turtles and hatchlings can locate the sea based on light reflections on the ocean’s surface however with addition of household or tourist lighting near nesting sites turtles become lost. Often ending up going in circles, turtles die due to exhaustion or dehydration and for hatching the longer they remain on the beach the higher the chance of becoming someone’s snack.
Corals already face a number of threats including warming waters and ocean acidification but just to add another factor, research carried out in the Great Barrier reef suggests that light pollution may also threaten coral survival.
Coral reproduction takes places under very specific conditions and sex cells from the corals appear to be released by proteins which are photosensitive. Where the right darkness conditions can’t be found due to the introduction of artificial lights corals simply cannot spawn.
As our urban areas sprawl so too do our lights and our impacts on migratory bird fly paths. As well as causing navigation issues for night flying birds that use moonlight as a direction guide, artificial lights can disrupt migratory timing and cause birds wait too long to start their long journey. This can either expose them to harsher conditions or mean they miss mating seasons or preferred nesting spots.
Unnecessary illuminations such as floodlights, festival lighting or simply excessive outdoor lights on homes or businesses can intensify this disorientation effect. Where strong beams are used birds can become stuck in the shaft of light and often end up circling until they are overcome with exhaustion.
Though light pollution is often associated with urban areas the issues and impacts of light pollution are not restricted to towns and cities. In countryside and rural areas increased light sources at night can also affect wildlife and this has been particularly noted for bats.
As nocturnal creatures bats are adapted to dark conditions and avoid lit areas. With an increase in artificial light in their habitats, bats will expend excess energy to avoid lighting. This can impact hunting routes or mating and where lighting has been installed near roosting sites this can have serious consequences on all types of bat activity and affect both diurnal and seasonal rhythms.
How can we fix this?
The best place to start is always at home. Check your own outdoor lighting isn’t excessive or left on unnecessarily. Consider timers, sensor lights or adding light shields that focus light only where it’s needed rather than up into the sky.
You can try to get others involved, raise awareness or be a spokesperson for your neighbourhood to try and reduce street or commercial lighting in the area.
Why not become a citizen scientist and help record issues near you that can be used for conservation or wildlife studies. By recording light pollution problems you can help highlight local issues and the scale of its impacts on our environment
International Dark Sky Week runs from the 4th-10th of April 2016. You can find your local Dark Sky Park, local events and lots more on the impacts of light pollution at darksky.org
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