Tag Archives for Light Pollution

Turn off the porch light: 6 easy ways to stop light pollution from harming our wildlife



Shutterstock

Emily Fobert, Flinders University; Katherine Dafforn, Macquarie University, and Mariana Mayer-Pinto, UNSW

As winter approaches, marine turtle nesting in the far north of Australia will peak. When these baby turtles hatch at night, they crawl from the sand to the sea, using the relative brightness of the horizon and the natural slope of the beach as their guide.

But when artificial lights outshine the moon and the sea, these hatchlings become disorientated. This leaves them vulnerable to predators, exhaustion and even traffic if they head in the wrong direction.



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Getting smarter about city lights is good for us and nature too

Baby turtles are one small part of the larger, often overlooked, story of how light pollution harms wildlife across the land and underwater.

Green Turtle’s Battle For Survival | Planet Earth | BBC Earth.

Today, more than 80% of people – and 99% of North American and European human populations – live under light-polluted skies. We have transformed the night-time environment over substantial portions of the Earth’s surface in a very short time, relative to evolutionary timescales. Most wildlife hasn’t had time to adjust.

In January, Australia released the National Light Pollution Guidelines for Wildlife. These guidelines provide a framework for assessing and managing the impacts of artificial light.

The guidelines also identify practical solutions that can be used globally to manage light pollution, both by managers and practitioners, and by anyone in control of a light switch.



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Bright city lights are keeping ocean predators awake and hungry

The guidelines outline six easy steps anyone can follow to minimise light pollution without compromising our own safety.

Although light pollution is a global problem and true darkness is hard to come by, we can all do our part to reduce its impacts on wildlife by changing how we use and think about light at night.

Light pollution can interfere with clownfish reproductive cycle.
Shutterstock

1. Start with natural darkness. Only add light for a specific purpose

Natural darkness should be the default at night. Artificial light should only be used if it’s needed for a specific purpose, and it should only be turned on for the necessary period of time.

This means it’s okay to have your veranda light on to help you find your keys, but the light doesn’t need to stay on all night.

Similarly, indoor lighting can also contribute to light pollution, so turning lights off in empty office buildings at night, or in your home before you go to sleep, is also important.

2. Use smart lighting controls

Advances in smart control technology make it easy to manage how much light you use, and adaptive controls make meeting the goals of Step 1 more feasible.

Investing in smart controls and LED technology means you can remotely manage your lights, set timers or dimmers, activate motion sensor lighting, and even control the colour of the light emitted.

These smart controls should be used to activate artificial light at night only when needed, and to minimise light when not needed.

3. Keep lights close to the ground, directed and shielded

Any light that spills outside the specific area intended to be lit is unnecessary light.

Light spilling upward contributes directly to artificial sky glow – the glow you see over urban areas from cumulative sources of light. Both sky glow and light spilling into adjacent areas on the ground can disrupt wildlife.

Installing light shields allow you to direct the light downward, which significantly reduces sky glow, and to direct the light towards the specific target area. Light shields are recommended for any outdoor lighting installations.

Step 3: Keep lights close to ground (a) and use shields to light only the intended area (b)
National Light Pollution Guidelines for Wildlife Including Marine Turtles, Seabirds and Migratory Shorebirds, Commonwealth of Australia 2020

4. Use the lowest intensity lighting

When deciding how much light you need, consider the intensity of the light produced (lumens), rather than the energy required to make it (watts).

LEDs, for example, are often considered an “environmentally friendly” option because they’re relatively energy efficient. But because of their energy efficiency, LEDs produce between two and five times as much light as incandescent bulbs for the same amount of energy consumption.



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So, while LED lights save energy, the increased intensity of the light can lead to greater impacts on wildlife, if not managed properly.

5. Use non-reflective, dark-coloured surfaces.

Sky glow has been shown to mask lunar light rhythms of wildlife, interfering with the celestial navigation and migration of birds and insects.

Highly polished, shiny, or light-coloured surfaces – such as structures painted white, or polished marble – are good at reflecting light and so contribute more to sky glow than darker, non-reflective surfaces.

Choosing darker coloured paint or materials for outdoor features will help reduce your contribution to light pollution.

6. Use lights with reduced or filtered blue, violet and ultra-violet wavelengths

Wavelength perception in wildlife – most animals are sensitive to short-wavelength (blue/violet) light.
National Light Pollution Guidelines for Wildlife Including Marine Turtles, Seabirds and Migratory Shorebirds, Commonwealth of Australia 2020

Most animals are sensitive to short-wavelength light, which creates blue and violet colours. These short wavelengths are known to suppress melatonin production, which is known to disrupt sleep and interfere with circadian rhythms of many animals, including humans.

Choosing lighting options with little or no short wavelength (400-500 nanometres) violet or blue light will help to avoid unintended harmful effects on wildlife.

For example, compact fluorescent and LED lights have a high amount of short wavelength light, compared low or high-pressure sodium, metal halide, and halogen light sources.



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The Conversation

Emily Fobert, Research Associate, Flinders University; Katherine Dafforn, Senior Lecturer in Environmental Sciences, Macquarie University, and Mariana Mayer-Pinto, Senior Research Associate in marine ecology, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Lights out! Clownfish can only hatch in the dark – which light pollution is taking away



Some 22% of the worlds’ coastlines are exposed to artificial light at night.
Emily Fobert, Author provided

Emily Fobert, Flinders University

Clownfish achieved worldwide fame following Finding Nemo, but it turns out these fish don’t do so well in the spotlight.

Our research, published in Biology Letters, found when clownfish eggs were exposed to low levels of light at night – as they would be if laid near a coastal town – not a single egg hatched.

This finding adds to the growing body of research on the health affects of light pollution, a rapidly spreading ecological problem.



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Light pollution: the dark side of keeping the lights on

What is light pollution?

Light pollution occurs when artificial light interferes with ecological systems or processes, usually at night.

Natural light at night, produced by the moon, stars, and other celestial bodies, is minimal. A full moon creates only 0.05-0.1 lux, which pales in comparison to the artificial light produced by humans, which can range from around 10 lux from an LED or low-pressure sodium streetlight, up to 2,000 lux from something like stadium lighting.

Clownfish were exposed to artificial light to see what effect it would have on their reproduction.
Emily Fobert, Author provided

Because nearly all organisms on Earth have evolved with a stable day-night, light and dark cycle, many biological events are now highly attuned to the daily, lunar, and seasonal changes in light produced by the reliable movements of the Earth and Moon around the Sun.

But artificial light can mask these natural light rhythms and interfere with the behaviour and physiology of individual creatures, and ecosystems as a whole.

The ocean is not exempt from these problems. Light pollution is spreading to marine habitats through urbanised coastlines and increasing marine infrastructure such as piers, harbours, cruise ships, and tropical island resorts where bungalows extend out into the lagoon, directly above coral reefs.

Why are clownfish at risk?

Clownfish, like many reef fish, are particularly vulnerable to light pollution because they don’t move around much in their adult stage. Clownfish can travel long distances in the first 2 weeks after hatching, but at the end of this period the young fish will settle in a suitable sea anemone that becomes their forever-home.

Once clownfish find a suitable anemone they stay put forever.
Emily Fobert, Author provided

This means that if a fish chooses an anemone on a shallow reef in an area that is heavily lit at night, they will experience chronic exposure to light pollution throughout their life; they won’t just move away.

Clownfish also lay their eggs attached to rock or other hard surfaces, so in areas exposed to light pollution the eggs will experience continuous artificial light (as opposed to many fish that lay and fertilise eggs in open water, so they are immediately carried away by ocean currents).

What we found

To test how artificial light affects clownfish reproduction, we examined the common clownfish (Amphiprion ocellaris) in a lab experiment.

Five breeding pairs of fish experienced a normal 12-hour daylight, 12-hour dark cycle, while another five pairs of fish had their “night” period replaced with 12 hours of light at 26.5 lux, mimicking light pollution from an average coastal town.

For 60 days, we monitored how often the fish spawned, how many eggs were fertilised, and how many eggs hatched. While we saw no difference in spawning frequency or fertilisation rates between the two groups of fish, the impact of the artificial light treatment on hatch rate was staggering. None of the eggs hatched, compared with an average of 86% in the control group.

Clownfish attach their eggs to rocks or other hard surfaces, leaving them at the mercy of their immediate environmental conditions.
Emily Frobert, Author provided



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At the end of the experiment we removed the artificial light and monitored the fish for another 60 days to see how they would recover. As soon as the light at night was removed, eggs resumed hatching at normal rates.

Clownfish, like many reef fish, have evolved to hatch after dusk to avoid the threat of being eaten. Newly hatched baby clownfish, like most coral reef fish, are small (about 5mm long) and transparent. Hatching in darkness likely means they are less visible to predators as they emerge from their eggs.

Our findings show that the presence of artificial light, even at relatively low levels, can disrupt this crucial process, by masking the environmental cue – darkness – that triggers hatching. As many reef fish share similar reproductive behaviours to clownfish, it is likely artificial light will similarly interfere with the ability of other fish species to produce viable offspring.

Healthy, fertilised clownfish eggs did not hatch in the presence of artificial light.
Emily Frobert, Author provided

The larger problem

Light pollution is one of the most pervasive forms of environmental change. An estimated 23% of land surface (excluding the poles) and 22% of coastal regions are exposed to light pollution.

And the problem is only growing. The reach of light pollution across all land and sea is expanding at an estimated rate of 2.2% per year, and this will only increase with the rising global human population.



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Saving Nemo: how climate change threatens anemonefish and their homes

Although research on the ecological impacts of light pollution is arguably only in its infancy, the evidence for negative consequences for a range of insects, birds, amphibians, reptiles, and mammals, including humans, is stacking up.

Our new research adds another species to the list, and highlights the importance of finding ways to manage or reduce artificial light, on land and below the waves.The Conversation

Emily Fobert, Research Associate, Flinders University

This article is republished from The Conversation under a Creative Commons license. Read the original article.