The impact of artificial lighting on nature

Silvia Maria Carneiro de Campos - e-mail [email protected]

BRAZIL – S?o Paulo, May 19th, 2017

CAMPOS, Silvia MC ISSN no 2316 – 5650, v. 1 – no. 6 – 2017

Abstract

Humans have been changing nature without taking into account its past and the processes it went through to evolve in the last 400 thousand years, or even what the impact for humans and for other species will be in the future. Since the development of artificial lighting, about 100 years ago, we have been increasing the illumination of the night-time environment to the point that we have modified the organisms and biome's habits in the lighted region. Inappropriate lighting systems are related to health problems because they cause disturbs in the circadian system. The regular movements of the planet determines the environmental cycles that, through its evolution, have stimulated living creatures to develop their internal rhythm. All live organism in the planet has developed photoreceptor and ganglion cells adapted to this circadian rhythm. Artificial lighting negatively impacts on the development of the wild flora and fauna, leading to the extinction of some of these wild species – whether they are arthropods, plants or animals in certain biomes. The present study aims to integrate the available multidisciplinary bibliographic knowledge, in biology, about the visual system in different species in order to identify the specific characteristics required  to create an artificial lighting less harmful to nature.

Keywords: landscape lighting; lighting impact on nature; light pollution; circadian cycle.

1. Light – a window to life.

We know for sure that we are ruled by our own experience, but it is necessary to analyse visual perception properties of other species, in addition to humans, and the impact of light on their development, feeding and reproduction cycles. Like humans, a large number of terrestrial fauna have a visual sensitivity from 400 to 700 nanometres. Aquatic and flying animals are different in this aspect. They have developed specific qualities in their sensory system adapted to each environment; birds and insects have developed a greater sensitivity to the ultraviolet (UV) and the blue spectral range, which is significant given their outdoor life cycle.  Many species have developed a visual sensitivity to the 360 nanometres region of the UV spectrum. Since sunlight is filtered when it enters the water, aquatic animals have developed a greater sensitivity to spectral wavelengths between blue (450) and green (500), because only these wavelengths reach to about 100 metres into the water. There are also species with mechanisms to detect infrared light. Among them are some species of reptiles, insects, and aquatic organisms that live next to underwater hydrothermal vents. Life on Earth is basically organised with the purpose of getting the highest of energy efficiency from the solar radiation. Different wavelengths are used by organisms for different survival functions. It is important to remember that photosynthetic plants and seaweeds are our planets primary producers. Without them, we would not have the energy fixation in organic matter form that provides the support for the rest of the trophic levels. Life is now adapted to the presence of oxygen, and life, as we know it, would not exist without oxygen. It is necessary to understand that all life on Earth developed under the influence of solar light, and all species have evolved their own photoreceptor cells according to the environment the lived in to survive. We first need to understand what the importance of solar light on life on our planet is when it comes to energy production and life.

Light is a form of energy within the electromagnetic spectrum ranging from short wavelength ultraviolet, passing through the region of the spectrum that is light that is visible to humans until it reaches the long wavelength infrared light. Humans are sensitive to a small region of the electromagnetic spectrum, between 400 and 700 nanometres. However, sunlight includes radiation that ranges from 100 to 1400 nanometres. Other species are able to detect these wavelengths beyond the visible spectrum, and include vertebrates and invertebrates that live in the earth, skies, and oceans which have different photobiological and photochemical processes (BARGHINI, 2010).

Considering that light is energy and that it follows the laws of physics, we must observe its behaviour through its diffraction and reflection, consider its behaviour in different media and its relationship with the water and the atmosphere.

Light can be artificially produced by heat at the moment when an object becomes incandescent and produces light energy (photon). This respects the thermodynamic law when it establishes that no energy can be created or destroyed. It is always changed into another form of energy, or it comes from another energy source. This transformation can also be chemical and can modify natural elements to produce  light, what we call bioluminescence.

Photosynthesis is the best example of light to energy transformation; with plants and seaweeds converting sunlight, water, and CO2 into energy vital to all other living beings. (INNES, 2012). "Unlike the past, humans will have to return to the idea that our existence is a gift from the Sun." Famous quote by Nicholas Georgescu-Roegen in The Entrophy Law and the Economic Process (CECHIN, 2010).

It is important  to undertand biological evolution based on thermodynamic principles, where the fundamental objective in life is the competition for the available energy. When struggling for life, the advantage goes to organisms that are more efficient at burning and getting energy. The principle of natural selection tends to favour organism with the most efficient energy conversion ratio (CECHIN, 2010).

Plants are the base of the food chain. With its efficient production, the plant world is the main energy production and food source on earth. All other living beings depend on it.

Table 1: Mayor radiations of biological interest (TN – Translator note)[1]

Source: Data produced by the author (2017) adapted from Hopkins (2000)

2. The Circadian Cycle

The term circadian cycle originates from the Latin "circa diem", that means approximately one day.

The most significant daily variation is the sleep-wake cycle. Specific studies aim to understand this process by the division of these two functions. While in the wake process, the main activity is searching for energy and glucose through feeding, on the other hand, all the growing and regeneration process of living beings happen in the sleep process. These cycles can last 24 hours, they can be less than one day, they can last weeks, months or years. (BRAND?O, 2004).

The circadian periodicity is generally  hereditary and must be considered as a phylogenetic adaptation to the environment structure. Problems in this cycle can cause several problems related to growth and reproduction, as well as interfering in  hormone and nutrient production. We have to consider that all metabolic changes occur due to electric impulses produced in the animal brain, presumably in the suprachiasmatic nucleus located in the hypothalamus, especially through the photoreceptors that send the message about what is light or dark (BRAND?O, 2004). In addition, the visual system converts the light energy its photoreceptors receive into chemical energy, in order to take this information to the brain (INNES, 2012).

Artificial light usage can disturb species development, activity pattern, and hormonal regulatory processes in the circadian cycles of all species (LONGCORE, 2005).

We should always take into consideration that, by lighting up the nighttime environment, we somehow impact the entire ecosystem around us, due to the fact that sleep quality is extremely important in the entire plant and animal kingdom. It is always during the sleep phase that life regenerates.

We know that artificial night lighting affects the human’s natural behaviour, but we must consider that this practice also harms other animal species, causing population distresses and, in some cases, extinction.

3. Light and plants

Through Isaac Newton experiment in 1672, we now know that visible sunlight spectrum can be separated into colours. This spectrum is measured in wavelengths that goes from short waves in violet, and passes by blue, green, yellow and orange until it becomes red. However, our perception is incomplete because human’s visual acuity, and most part of mammals’, can only detect a small amount of electromagnetic radiation that goes from 400 to 700 (nm). Other beings have their photoreceptors adapted to the UV spectrum (ultraviolet radiation), and others to the IR spectrum (infrared radiation) (HOPKINS, 2000).

Figure 1: solar spectrum wavelength range (TN)[2]

Source: Data produced by the author (2017)

The term photosynthesis means "synthesis through the light", at which photosynthetic organisms use the solar light to produce organic composts, especially glucose. Plant stored energy is a source of energy for all other life forms on the planet (HOPKINS, 2000).

In 1804, the phenomenon of photosynthesis was described by the Swiss Nicolas Saussure. He also demonstrated that, when exposed to light, plants consumed carbon dioxide (CO2) and transformed it into oxygen (O2). Later, Julius Von Sachs described the process of luminous light into a chemical light process. From 1900, plant studies have evolved, and the English physiologist Frederick Frost Blackman argued that plant reaction to light was photochemical, but they produced biochemical reactions in the dark, thus keeping a circadian cycle. Plants go through the light phase, called the photochemical phase, at which light is absorbed by the vegetable pigments (chlorophyll) and converted into chemical and caloric energy. In the dark phase, called the biochemical phase, it transforms the energy generated during the day into glucose. The glucose produced during the photosynthesis can become other organic substance, such as starch, protein, lipid, cellulose, pigments, hormones, vitamins, among others. These products are constantly transferred by the plant to its storage places, that can be its root, fruits, bark and seed (FLOSS, 2006). Experiments of the American Physiologist Robert Emerson, in 1940, showed that the most efficient lights for plant photosynthesis are found both in blue and red bands. He also has identified that plant activity drastically decreases only with red light, coming to the conclusion that photosynthesis is a combined system and depends on both colours, that is, it depends on both solar light wave spectrum (PONS, 1986).

Figure 2: The efficiency of the photosynthetic process due to the presence of type a and b chlorophylls. (TN)[3]

Source: Data produced by the author (2017) adapted

Taking into account the effects of artificial lighting on plants, the lighting industry has developed specific equipment to stimulate plant growth in controlled environments. However, recent studies have shown that plants also sleep and that interruptions in their circadian cycle intervene in their breeding season, during their flowering stage, and in their resistance against plague and fungi, damaging their health. It is necessary further studies relating public lighting in wooded area considering photoinhibition phenomena, named by botany as the vegetal physiological stress in large periods of light exposure, which can harm plants photosynthesis. Under a constant light exposure, and adaptation takes place: the plant photosynthesis stabilizes and starts producing harmful substances to its growth.

The circadian cycle influences plants as much as it influences other living beings. The dark phase, at night, is necessary so as the plant can grow, regenerate and make the photosynthesis correctly and with the same efficiency every day (HOPKINS, 2000).

Green algae, which can be found in the first few metres next to the surface, keep their response to blue and red spectrum, but we can notice that red algae are red when they are deeper than 30 metres, where the radiation from 650 to 700 is minimal (BARGHINI, 2010).

4. Fish attraction to the light

The positive phototaxis, also called photopollution, means animal attraction to light sources and it happens in several species. Light is a factor of attraction for fish. Even some fishing companies use this technique to help catching some species.

Most hunting fish look for waters rich in smaller fish, insects and shrimp. According to John Lythgoe studies, every member of this food chain has sensible eyes to the colours green and blue.

As green algae absorb red light, waters have a green appearance where their incidence is high. That explains why fish have developed specialized photoreceptor that goes from blue to green. Some species even have a sensibility to the yellow. All living beings have colour photoreceptor in their eyes adapted to the light from their "natural space", and their main objective is to recognise signs of danger or food. (LYTHGOE, 1988)

To detect changes in light intensities, some species have also sensibility to UV from the ranges of 320 to 380 nanometres, besides having photoreceptors in the blue region from 425 to 490 nanometres and, in the green, next to 530 nanometres.

Therefore, light sources with blue, green and UV spectrum are the ones that most attract some aquatic species, and the less notice is the red light (LYTHGOE, 1988).

Figure 4: Visual range comparison for human and fish

Source: Data produced by the author (2017)

5. Fireflies have disappeared from the cities

The inappropriate lighting usage can lead species to extinction. The most common case is that of the fireflies in the cities. Fireflies are a very popular beetle in nature because they flash subtly when flying. Female fireflies do not fly, so they use their light generated by bioluminescence as sexual objects to attract males.

In cities, the excessive lighting usage confuses male when it is attracted by artificial light sources. It dies burned or by exhaustion and it does not produce new descendant. Some firefly species use termite nest to lay their eggs and grow their maggots. They shine during the night ensuring nearby insect attraction, mostly termite, their biggest food source. It is during its larval phase that fireflies eat to store energy. During its adult stage, the male stop eating and only uses the energy it accumulated during its larval stage (VIVIANI, 2001).

Figure 5: Fireflies maggot’s bioluminescence

Source: Picture by Ary Bassous, Parque Nacional das Emas, GO, Brazil (2014)

Figure 6: Fireflies maggot’s bioluminescence in a termite nest

Source: Picture by Ary Bassous, 1st place in the "wildlife" category (2014)

6. The power of light attraction for insects

Insects are used to polarized light and use the sun and the moon as an instrument of orientation when searching for water and food. Light reflection on the water can be noticed from a far distance by insects. The presence of artificial light confuses the insect and literally becomes an attraction "source". In many cases, a deadly trap.

Insect's photoreceptors are regulated to green, blue, and Ultraviolet spectra. Humans cannot see the ultraviolet, "the light beyond the violet", but insects can. Flowers have some patterns next to their centre that can only be observed by the ultraviolet range. They use it especially to attract the insects responsible for their pollination. (BARGHINI, 2008).

According to the naturalist Edward O. Wilsom, of Havard University, if all humans disappear, the world would fast regenerate to the balanced state it was ten thousand of years ago, but if insects disappear, the environment would collapse and take us to extinction (BARGHINI, 2008).

Red flowers are pollinated by birds and butterflies because insects have a low sensibility to the red colour. However, some plants have mechanisms in their flowers and fruits that make them visible to species sensible to the ultraviolet spectrum (BARGHINI, 2008)

Aedes Aegyoti, for instance, is an insect with adaptation for daylight. But as cities are even more illuminated, there is nothing to prevent them to work also at night like we do. Light excess confuses their circadian cycle and they keep their activity during the night. Well-illuminated human conglomerates, like intermodal transport and all kind of well-illuminated and populated edification, becomes a hunting place for the mosquito. Because the female of this specie is attracted by the smell of animal sweat, when searching for blood to ovulate, sportive sites become more vulnerable to infestations, especially if there is stagnant water nearby.

As insect's peak of vision is the ultraviolet spectrum (UV-A), around 365 nanometres, we should avoid the use of fluorescent sources, mercury vapour lamp and metal halide lamp that emit radiation in this spectrum (BARGHINI, 2008)

Figure 7: Visual range comparison for human and insect

Source: Data produced by the author (2017)

Light is invisible, but not its source. A source's light brightness is a major attraction point for insects, therefore, using a correct luminaire will smooth its power of attraction.

The Luminaire's cut-off turns into an important item for the lighting specification. If the source is well positioned and completely inside the luminaire, we can reduce the phototaxis (BARGHINI, 2008).

By not having a good red spectrum perception, the insect will see less if the source's light spectrum is as close to red as possible (BARGHINI, 2008). Warm light sources, less than 2.700 Kelvins, and amber light are more appropriate to illuminate nighttime environment in landscapes next to humans’ settlements.

We can assume that the red light is a great answer to illuminate landscapes in these cases. But nature is delicate when it comes to the food chain. By trying to keep insects away, we could attract, perhaps, some reptile.

7. The blind snake

There is a Brazilian saying that says that snakes are blind, but it is wrong. Besides having an accurate olfactory system, snakes, like mayor reptiles, have developed photoreceptors sensible to the red spectrum.

Snake's eyes are basically made of rods, red photoreceptors and sensible receptors to infrared, called thermoreceptor.

Figure 8: snake's infrared vision

Source: Data produced by the author (2017)

They have membranes below their eyes which are sensitive to radiation. Signals go to the brain, that also receives these signals in a visual matter, making it possible for snakes to literally see their preys through heat. This device allows snakes to detect their warm-blood preys even when the light is absent (BARGHINI, 2008).

8. Birds’ vision

Vision is the most important sense for birds, once a good vision is important for a safe flight. This animal group has a number of adaptations in their eyes that give them a superior vision acuity when compared to other species.

The eye of the bird resembles that of a reptile. Most birds cannot move their eyes, but their ocular muscles can quickly change their focus and get a much higher reach than those from mammals.

Some group birds have specific changes in their visual system depending on their way of life. Birds of prey have a high quantity of photoreceptors that increase their visual acuity. Their binocular vision allows an accurate distance examination (GOLDSMITH, 2011).

In order to improve their vision, particularly in fog conditions, swallows, gulls and albatrosses are amongst the seabirds with the highest amount of photoreceptor cones from red to yellow. Eye performance in low luminosity condition depends on the distance between the cornea and the retina, therefore, small birds are diurnal because their eyes are not big enough to provide a proper night vision. Night birds have bigger eyes. Their retinas have a large number of photosensitive cones and rods. While humans have about 200,000 photoreceptors per mm2 birds have from 400,000 to 1,000,000 photoreceptors per mm2. Most birds are tetrachromatic, in other words, their cones have a sensibility to four colours. In some birds, the peak of absorption extends to the ultraviolet (UV), making them sensible to UV and able to see colours that are not visible for humans (GOLDSMITH, 2006)

Figure 9: Visual range comparison for human and bird

Source: Data produced by the author (2017)

9. Light impact on migratory birds

In addition to insects, nocturnally migrating birds are the most affected by artificial light (RICH, LONGCORE, 2013). It can cause a direct death to them, or indirect negative effects through the depletion of their energy reserves. 

Studies show an adverse effect on birds’ population, especially on species that migrate at night, due to the increase of artificial light at night. Migratory birds frequently die when they find artificial light in their path. (HEYERS, 2007)

Hundreds of birds, that should be migrating, interrupt their journey to land on oil platforms located on the sea. An excellent study, published at Ecology and Society, from Canada, called “Green light for nocturnally migrating birds” (POOT, H., B. J. Ens, H. de Vries, M. A. H. DONNERS, M. R. Wernand, and J. M. MARQUENIE, 2008) shows a series of experience with different colour and light spectrum and their influence on birds' orientation. People have been studying these problems with oil platforms since the end of the 90s. Thus, this study has identified, after establishing some on-the-spot test prototypes, and also laboratory experiment, that the red light is the one which most intervenes in bird’s magnetic orientation, followed by the white light. Blue and green light spectra were the ones which less hindered birds migrating movement. The blue light was not used in this experiment due to the fact it causes dysfunctions in the human circadian cycle and, therefore, it detrimentally intervenes with workers activities on platforms, focusing his studies on the green light. It was also shown that as bigger the intensity of the installed light is, bigger is its power attraction. So, it is necessary the lowest possible intensity when inspecting tasks in these oil platforms.

This study has started new researches about the effect of artificial lighting on bird’s migration and the development possibility of more suitable equipment with a safer artificial lighting for humans, because of work, but that also lessen its impact on nature.

Dominik Heyers (2007) argues that migratory birds can "see" the direction of Earth's magnetic field, there is a special cryptochrome, a magnetoreceptor that allows their orientation at large distances. It was also observed in some fish, reptiles, sea turtles, dolphins and even bacteria.

Another hypothesis for this green light suggests a better reflection over the roadside vegetation (green), and potentially a lower perturbation in its development and flowering (pons, 1986).

Besides oil platforms, we can mention other big impacts on fauna and flora: seaports, refineries, coastline installations, industrial areas, roads, airports, residential condominium in conservation areas, among others.

The study about ecological consequences of artificial night lighting, published by Rich and Longcore (2006), highlights that migratory birds are not the only one affected by artificial night lighting. When it comes to oil platforms, this study demonstrates the existence of fish and marine mammals’ migratory activities that may be affected by several light source during their journey.

10. Photopollution and sea turtles

Of public domain, the Brazilian Tamar Project, a project aiming to protect sea turtles from extinction in the Brazilian coastline, provides technical material to help using artificial lighting on coastlines, especially in spawning areas. Concerned with possible species extinction, this research institute promotes sea turtle preservation on Brazilian beaches.

Photopollution is an influencing factor in all phase of sea turtles’ live, but especially when they are hatchlings. During spawning, hatchlings rush to the sea, oriented by the sun or moonlight reflected on the water. But when artificial light is used on coastlines, it creates phototaxis, killing them before they reach the water (Tamar Project). According to CONAMA, a Brazilian nongovernmental organization that establishes environmental national policies, the visualization of light sources on the entire Brazilian coastline must be avoided, it must be directed to the inverse direction of the beach and must be the lowest as possible to avoid turtle and other marine mammal’s attraction to the light. It is important to remember that there is a Brazilian environmental protection law that ensures a no-lux practice, in other words, it prohibits lighting on the south Bahia coastline, where Tamar Centre is located.

Besides the positive phototaxis problem, that attracts hatchlings to the light, there is also the negative phototaxis, that prevents adult female turtles to arrive at the coastline to spawn.

Figure 10: comparison of an adequate and inadequate lighting on coastlines.

Source: Data produced by the author (2017) adapted from Witherington and Martin (1996)

Turtle's visual system can also detect the UV spectrum; therefore, it is necessary that the used light sources do not have UV, or have appropriated filters.

Figure 11: Sea turtle's visual reach

Source: Data produced by the author (2017)

11. Sky's polarization

Astronauts see universe black because sun rays travel in a straight line when there is no atmosphere. When we see something, it is because the light was reflected or dispersed.

Colour phenomenon is always associated with a specific wavelength. Ultraviolet, violet and blue waves have a better diffusion in the atmosphere than the red light, in a way that the blue light disperses and reach our eyes easier than the others. The blue light disperses ten times more than the red light (DAWKINS, 2011).

When it is foggy, water particles disperse equality among all wavelengths, creating the perception that the sky is whiter than usual because of colours mixture and addition. That is why we see clouds as white too. Another understanding is that blue becomes even stronger when compared to the zenith, reaching its higher intensity perpendicularly in the sun direction. Different light frequency (colours) travel at different speeds, refracting in different incident angles and causing dispersion. In the sunrise or in the sunset, the red and orange components are the only one notice because the distance that the light has to travel is higher (DAWKINS, 2011).

One of the most interesting aspects of vision is its capacity for perceiving colours. Colours are not a physical reality, they are only a sensation created by our nervous system to understand different light wavelengths during its reflection (INNES, 2012).

We can also detect a phenomenon called polarized light, that is the reflected light from shining or water surfaces.

Animal kingdom embraces an infinity of species, most of them have a common sense: vision. Basically, the vision has the purpose of identifying danger and spotting food, in order to survive and reproduce. However, it is also connected to the environment where different species have developed different methods of using the light.

Light is a physiological stimulus that triggers a pulse, perceived by the cognitive device as a light sensation, which is particular to each individual and is present only in the minds of organisms that can detect it (INNES, 2012).

Animals that have sensitive UV photoreceptors are sensible to these light polarization planes on the water, and they use this system when moving or searching for food. Birds search for water to feed on fish and insects. Insects search for water in order to deposit their eggs. Both species have the needed sensibility to the UV spectrum for their navigation when flying. Amphibians, that shift on water and on earth, also present this sensibility (GOLDSMITH, 1990).

Figure 12: Comparison of UV vision species with Human vision

Source: Data produced by the author (2017) adapted from Goldsmith (1990)

In this sense, by illuminating natural environment, in addition to checking the visual system of affected species, we should also observe source irradiation, that is, check what is the spectrum the artificial source produces, and, every time that ultraviolet incidence exists, it will affect species perception.

Figure 13: Light spectrum of a metal halide lamp (TN)[4]

Source: Data produced by the author (2017)

Positive phototaxis is probably the most devastating known effect on nature: species are attracted or get disoriented by artificial light sources (BARGHINI, 2008).

Artificial light is really a true trap for several species. Sources that produce Ultraviolet radiation, among them, mercury vapour lamp, metal halide lamp and fluorescents are the ones that most cause disturbs in flying species. In many cases, species are lured and die when they get in contact with the lamp heat (Barghini, 2008).

Only out of curiosity, it is worth mentioning the excellent research made by Gabor Horvath from the department of physics and biology at the University of Budapest, in Hungary. He researches and demonstrates birds and insect’s disorientation caused by shiny surfaces, like automobiles painting, gable roofs and facades with reflective films or shiny painting.

Polarized incident light reflection on these surfaces confuses species that are searching for water.

12. Artificial lighting and nature, conclusion.

We do not know exactly what amount of artificial light can be used without harming humans. However, there are significant signs showing that artificial lighting in excess can cause metabolic problems. A flux of 100lux is enough to cease melatonin production in nighttime environment (BARGHINI, 2008).

The question we face now is to know if it is possible to develop light sources that meet human demands without harming our health and the ecosystem around us.

It becomes clear that the public lighting used in cities do not use appropriated sources for plant development, therefore, it is necessary a wide-ranging discussion under the urban point of view about road lighting and landscaping.

Currently applied methodologies, illuminating roads above treetop, is not a healthy option for the plant, and neither efficient in the energetic point of view. On streets, it is easy to identify inappropriate pruning, for the tree's health and survival, in order to block less the lighting.

Interestingly, Professor Alessandro Barghini's study (2008), which describes insect's light source attraction, warns also about the risk of increasing diseases, common in rural and wild areas, in the urban areas of cities. This study was published in 2008 addressing topics such as Chagas disease, caused by the triatomine bug, and, more specifically, diseases caused by the Aedes aegypti mosquito.

After nearly 10 years, the reality shows us that we are facing alarming epidemics, with apparently forgotten diseases; like yellow fever, dengue or diseases transmitted by this mosquito. This only proves that the aspects he pointed out in his these, about the attraction of pathologies linked to tropical forest's insects, need to enter the discussion agenda about public lighting in the cities. We are possibly illuminating outdoor environment in a way that attracts insects with the risk of increasing the pathologies they cause.

"Ceará, a city in northeast Brazil, shows an incidence of 943 cases for every 100 thousand inhabitants. WHO considers an epidemic level of more than 300 cases for every 100 thousand inhabitants.

        News at G1 Ceará, an online Brazilian newspaper, on May 21st, 2017, relating cases of "yellow fever", and considering an alarming increase of a disease almost considered extinct. (available at www.g1.globo.com)

Before making a lighting project on natural environments, it is necessary to make a complete survey of the biome and its surroundings before suggesting an artificial lighting in a landscaping environment.

Each type of plant and animal life has its particularities related to the circadian cycle and a bad planned lighting can cause unintended impacts.

It is certain that, when we make a project for artificial lighting, the lighting proposal has the human visual system as parameters, but we are facing a big variety of visual system and sensors that organize life in a balanced way.

Every life form uses somehow the sun electromagnetic radiation. Whether it is like plants, to generate a direct energy through photosynthesis, or like the animal kingdom, that uses energy for locomotion, guidance and metabolism in several ways, at which the luminous signal is converted into electric signal causing some response in their organism, such as visual, tactile or hormonal.

The Dark Sky organization provides a broad material about light pollution and has been alerting that intense, bad directed artificial lighting sources lead to vision blurring, besides illuminated areas where it was not necessary with the intrusive light. By focusing the light only where it is necessary, and by using light sources with the correct photometry, we can avoid light pollution and reduce the impacts that artificial lighting causes to nature.

The correct choice of the type of technology used in the source also deserves attention. It is desirable to avoid the ultraviolet spectrum in artificial sources, in addition to determining, in the application, which apparent light colour will cause fewer impacts to the biome.

We should take into consideration that all species need to sleep.

More important than knowing how to illuminate, it is knowing when and where not to illuminate.

REFERENCES

BARGHINI, Alessandro. Antes que os Vagalumes Desapare?am ou a Influência da Ilumina??o Artificial sobre o Ambiente. S?o Paulo: Annablume e Fapesp, 2010.

BRAND?O, M. L. As bases biológicas do comportamento: introdu??o à neurociência. S?o Paulo: EPU, 2004.

CECHIN, Andrei. A natureza como limite da economia: a contribui??o de Nicholas Georgescu-Roegen. S?o Paulo: Edusp e Editora Senac, 2010.

FLOSS, E. L. Fisiologia das plantas cultivadas: o estudo do que está por trás do que

se vê. Passo Fundo: Universidade de Passo Fundo, 2006.

GOLDSMITH, Timothy H. What bird see. USA: Scientific American, 2011. Available at www.web.archive.org. Accessed on: May 2017

GRANDA, A. Eyes and their sensitivity to light of differing wavelengths. In Turtles: Perspectives and Research. Warless M, Morlock H. New York: John Wiley and sons; 1979.

HEYERS, Dominic and, Manns M, Luksch H, Gu¨ ntu¨ rku¨n O, Mouritsen H, A Visual Pathway Links Brain Structures Active during Magnetic Compass Orientation in Migratory Birds.

HOPKINS, W. G. Introduction to Plant Physiology. New York: John Wiley & Sons, Inc, 2000.

HORVATH, Gabor. Polarized Light and Polarization Vision in Animal Sciences. Berlin: Springer-Verlag, 2014

INNES, Malcolm. Ilumina??o no Design de Interiores. S?o Paulo: Gustavo Gili 2014

LYTHGOE, John: Light and vision in the aquatic environment. In Sensory Biology

of Aquatic Animals. New Yourk: Atema J, Fay R, Popper A, Tavolga W, 1988.

PONS, Thijs L. Response of Plantago major seeds to the red/farred ratio as influenced by other enviromental factors. Nederlands: Oecologia v. 75, 1986.

POOT, H., B. J. Ens, H. de Vries, M. A. H. DONNERS, M. R. Wernand, and J. M. Marquenie. 2008. Green light for nocturnally migrating birds. Ecology and Society 13(2): 47. [online] URL: https://www.ecologyandsociety. org/vol13/iss2/art47/

RICH, Caterine; LONGCORE, Travis. Ecological consequences of artificial ninght lighting. Washington DC: Island Press, 2005.

SALIES E, LARA P H, PEZETTO F, VERISSIMO L F, ABREU J A, SOARES L A, TOGNIN F, Cartilha de Fotopolui??o Projeto Tamar. Bahia: Funda??o Pró Tamar, 2015.

VIVIANI, Vadim. Fireflies (Coleoptera: Lampyridae) from Southeastern Brazil: Habitats, life history, and bioluminescence. USA: Journal Annals of the Entomological Society of America, v. 94, 2001.

[1]  TN - It is written “colour” at the top of the image on the left margin and “band of wavelength in nanometres” on the right; Written in the vertical, on the left top of the image, is “ultraviolet” and “visible light for humans” at the middle. IR refers to Infrared; In the colours, from the top to the bottom: “Violet, Blue, Green, Yellow, Orange, Red, Distant red, Infrared; At the same line of the Infrared, it is written “bigger than 740”.

[2]  TN – It is written “SOLAR SPECTRUM” at the top of the image; “visible light to humans” at the middle of the image; “Ultraviolet” on the left and “Infrared” on the right.

[3]  TN – It is written “absorption percentage” in the vertical; “wavelength (mm)” in the horizontal; “chlorophyll a” referring to the pink index and “chlorophyll b” to the blue one; from the left to the right, the colours are: “violet, blue, green, yellow, orange, red.

[4]  TN – It is written “metal halide lamp” in the box of the image and wavelength (mm) at the bottom of the image.