The effects of artificial lighting

THE IMPACTS OF LIGHT POLLUTION ON WILDLIFE AND HUMAN POPULATIONS

Emma-Louise Spicer

CURRENCY AND SIGNIFICANCE OF THE ISSUE

• For 2.5 billion years the earth has orbited the sun resulting in a 24 hour cycle of day and night.

• 30% vertebrates nocturnal• 60% invertebrates nocturnal(Hölker, et al, 2010; Gaston, et al, 2014).• Natural lighting during dark periods: moonlight, starlight, diffused light in the

atmosphere • Utilised by species for navigation and orientation, reproduction and feeding (Marlin, 2009; Gallaway, et al, 2010 Falchi, et al, 2011; Gaston et al, 2014)• Artificial lighting during dark periods: street lights, lighting from human

dwellings, vehicle lights, illuminated signs and advertising boards• 20th centaury seen an increase in development and infrastructure(Kuechly, et al, 2012; Pun, et al, 2013; Gaston and Bennie, 2014).).• Approximately 3-6% increase in light emissions per year (Brüning, et al, 2015)

(Holker, et al, 2010)

(APN Photography & Web-Design, 2012)


• Sky glow noted by astronomers as decreased visibility for celestial studies• Disappearance of the Milky Way• Prevalent sky glow in European Countries; including the UK(Kuechly, et al, 2012; Luginbuhl, et al, 2014; International astronomical Union, 2015; Dark- Sky’s Association, 2015)

Two Categories of light pollution: 1) Astronomical pollution: hinders the visibility of the night sky2) Ecological pollution: disrupts ecosystems and species biology (Longcore and Rich, 2004; Kuechly, et al, 2012).

Reason for artificial light: • Improved night time safety and reduced fear of darkness• Night time businesses• Safe navigation during low light periods (Kuechly, et al, 2012).

(Cost.eu Lonne, 2014)

(Space.com, 2013)

LIGHT POLLUTION IN THE UK

(Davis, et al, 2013)


• Lack of awareness concerning consequences of artificial lighting on wildlife populations and human health despite the obvious benefits

• Leading to recent growth in research and evaluation of lighting schemes(Lyytimäki, et al, 2012; Lyytimäki, 2013; Kuechly, et al, 2012).

• Light pollution considered to be a significant current environmental pressure on organisms and ecosystems

• Environmental pressures such as climate change have occurred throughout history allowing adaption of species

• Artificial lighting is considered to be outside the evolutionary experience of species to adapt (Lyytimäki, et al, 2012; Gaston, et al, 2014).

However possible that select species will be able to adapt via evolution, particularly those with short generations (Holker, et al, 2010)

ANALYSIS OF THE MAIN ARGUMENTS• As infrastructure continues to expand as does the level of artificial lighting; however the human benefits

of night time lighting is often prioritised with little consideration for environmental and species biodiversity. (Falchi, et al, 2011; Lyytimäki, 2013; Gaston, et al, 2014).

Poorly designed lighting results in:1. Waste of energy (Gaston, et al, 2014; Pun, et al, 2014)2. Waste of natural resources: USA 66 million metric tonnes of carbon dioxide annually (Gallaway, et al,

2010)3. Waste of finances: • USA $6.9 billion annually due to inappropriate design of lighting (Gallaway, et al, 2010)• £1 billion annually in the UK according to the British Astronomical Association (Winterman, 2012;

Rowan- Robinson, 2012)• Loss of aesthetic appeal of the night sky for astronomy enthusiasts and negative effects on wildlife

species behaviour, reproduction, circadian rhythms and plant growth cycles (Gaston, et al, 2014; Pun, et al, 2014)

ANALYSIS OF THE MAIN ARGUMENTS• Artificial lighting is utilised in shopping areas in order to increase

profits by creating a lively atmosphere to encourage spending (Falchi, et al, 2011).

• Also used as a means of reducing crime levels at night with women often being targeted during dark periods (Kim, et al, 2007; Falchi, et al, 2011).

• Deficiency in studies to suggest night time lighting reduces crime levels; stated light may increase crime levels in some areas as criminals utilise light to select victim and assess risks in the environment (Claudio, 2009; Falchi, et al, 2011; Rowan- Robinson, 2012).

• Artificial lighting is also put into place in order to improve road safety with research stating that night time lighting reduces the extent of road accidents on motorways and overall crash rates; particularly crashes associated with sleep deprivation (Flatly, et al, 2008; University of Wisconsin-Madison, 2008).

Simon Everett Photography Kent, 2015

(The Daily Mail, 2014)

ANALYSIS OF THE MAIN ARGUMENTS• Argued that excessive poorly designed lighting leads to glare and

decreased visibility and thus reduced safety (e.g. car accidents from blinding and in some cases increase in crime). Also nuisance lighting for local residents (Claudio, 2009; International Dark-Sky Association, 2015).

Dark Sky Reserves:• Creation of International Dark Sky Reserves as a means of reducing

environmental impacts and sky glow contribution • Dark Sky reserves in the United Kingdom• 2011 Exmoor• 2013 Brecon Beacons(Gaston, et al, 2014)• Before and after comparisons are required by the use of artificial light

models and radiance maps in order to determine effectiveness of these areas in reducing the contribution of light pollution to the environment. Despite creation of dark reserves skyglow from surrounding lit areas can still effect navigation and connectivity of habitats (Martin and Roby, 2014; Gaston et al, 2014)

• Creating dark corridors for the movements of nocturnal species can have positive effects on species such as bats; although they can be difficult to implement due to human fear of darkness (Fure, 2006; Gaston, et al, 2014).

• This has been implemented in the Olympic park by creation of dark corridors across water ways to aid foraging and movement of Eptesicus serotunus (serotine bat). (Shepherd, 2012)

(International Dark-Sky Association, 2015)

(International Dark-Sky Association, 2015)

• Changing the spectrum• High intensity light (white light) has greater negative effects on biological systems• Lower intensity (red light) has less adverse effects and reduced sky glow• However, can have negative effects on plant physiology and bird migration • Light-emitting diode also being trialled: energy saving and more uniform lighting.

However being utilised with white lighting to improve colour vision for humans (Poot, et al, 2008; Rich and Longcore, 2013; Gaston, et al, 2014)

• Part night lighting • local councils switching off of street lighting to cut financial costs and reduce carbon

emissions (Falchia, et al, 2011; Gaston, et al, 2014)• However, argued part night lighting will only benefit strictly nocturnal species, with

little benefit for crepuscular species (Gaston, et al, 2014)• Potential benefits of releasing trapped invertebrates around street light, reducing

mortalities and preventing disruption to trophic cascades (e.g. moths) (Gaston, et al, 2014)

• However, increased criticism from locals due to fear of rise of crime levels and vehicle accidents with reluctance to venture into dark areas (Lyytimäki, 2013; Chapman, 2014)

(Lyytimäki, 2013)

(Kootenay Local Agricultural Society, 2015)

IMPACTS OF LIGHT POLLUTION ON HUMAN POPULATIONS

• Negative effects on human health by suppression of Melatonin Hormone• Strong antioxidant• Protective hormone• Oncostatic (inhibits the growth of cancer cells)(Pauly, 2004; Falchia, et al, 2011; Stevens, et al, 2013)

• Disruption of circadian rhythms leading to sleep disorders, depression, reproductive disorders and increase in metabolic conditions such as obesity and diabetes (Pauly, 2004; Boyce, 2010; Wysea, et al, 2011; Falchia, et al, 2011;Stevens, et al, 2013).

• Human health particularly effected by blue wavelength, high intensity light, utilised in high intensity outdoor lighting such as high pressure sodium lighting and mercury vapour lighting(Pauly, 2004; Stevens, et al, 2013; Gaston, et al, 2014).

• The international Agency for Cancer Research suggests that shift work and circadian rhythm disruptions can result in higher cancer rates; with increased risk of breast cancer in women based on the “Light-at-Night Theory” (Stevens, 2009; Stevens, 2013).

• Research: insertion of cancer cells into the groins of lab rats with measurements taken of cancer cell growth: results constant light exposure group showed increased growth rate of cancer cells (Pauly, 2004).

(Falchia, et al, 2011)

(CenBlog.org, 2011)

IMPACTS OF LIGHT POLLUTION ON HUMAN POPULATIONS

• Despite the negative effects of high-intensity lighting; research conducted by Chellappa, et al, 2013 on 16 male volunteer, suggests that human cognition is improved when exposed to blue enriched lighting (Chellappa, et al, 2013).

• Artificial lighting can also have positive effects on Seasonal Affected Disorder; particularly blue enriched (Gagnéa, et al, 2011; Boyce, 2014).

• Artificial lighting can have positive affects of cognitive ability of Alzheimer’s disease patients; although suggested only in elderly patients with specific circadian rhythm disorders (Friedmana, et al, 2012; Boyce, 2014)

(Chellappa, et al, 2013)

IMPACTS OF ARTIFICIAL LIGHTING ON WILDLIFE POPULATIONS

• Insects attracted to illumination are subject to energy loss, thus threatening biodiversity of invertebrate prey leading to disruptions of food chains (Holker, et al, 2010; Gaston, et al, 2014).

• However, bats have been reported to feed around low wavelength street lights (Gaston,et al, 2013)

• Light pollution can lead to increased levels of predator competition by extending the hunting period of diurnal feeders (Holker, et al, 2010).

Behavioural changes documented: • Increased tourism in coastal areas leading to negative effects on turtle behaviour and

reproductive success (satellite picture showing coast of Israel): illumination leading to nesting in unsuitable nesting sites or abandonment of nests (Loncore and Rich, 2010; Mazor et al, 2013; Verutes, et al, 2014).

• Concentration of nest sites in order to avoid illumination can lead to skewed sex ratio, decrease in hatchlings and increased mortality (Deda, et al, 2007)

• Increased predation and dehydration risk to hatchlings emerging from the nest at night to navigate to the ocean as well as potential exposure to high temperatures at sunrise (Verutes, et al, 2014).

• Earlier dawn chorus of songbirds such as Blue Tit (Cyanistes caeruleus) and Robin (Erithacus rubecula) and earlier Development of reproductive organs in birds in urban areas, e.g. Black Bird (Turdus merula). (Kempenaers, et al, 2010; Dominoni, et al, 2015).

• Behavioural change in Redshank has also been noted. With changes from tactile to visual foraging in illuminated areas. Thus suggesting that artificial lighting improve nocturnal visibility for the species despite change in behaviour. (Dyer, et al, 2013).

(Mazor, et al, 2013)

(Mazor, et al, 2013)

Earlier dawn chorus, extra pair mating and earlier egg laying dates can lead to deficiencies in food resources during rearing and poor mate choice

Differences in light polluted areas (light blue) in comparison to non-light polluted areas (dark blue). Most noticeable in Robin

(Kempenaers, et al, 2010) (Kempenaers, et al, 2010)

IMPACTS OF ARTIFICIAL LIGHTING ON WILDLIFE POPULATIONS

• Artificial lighting is suggested to have negative effects on the circadian rhythms of fishery populations feeding and migratory behaviour (Gaston, et al, 2014; Bruning et al, 2015)

• Suppression of melatonin and increased stress; however studies on European Perch resulted in decrease melatonin, but no significant differentiation in cortisol levels (Bruning, et al, 2015)

• Moreover, artificial lighting has shown to have negative effects on feeding and migration of Atlantic Salmon; with abnormal swimming direction, speed and distribution of schools observed in caged salon exposed to lighting (Oppedal, et al, 2001; Gaston, et al, 2015)

• Light pollution is believed to be a significant threat to the decline of keystone species such as bats and moths in the United Kingdom and thus is stated to be a significant driver in biodiversity loss (Holker, et al, 2010; Langevelde, et al, 2011;Gaston et al, 2014)

• There has been extensive studies on the effects of artificial light on reproduction, hibernation, predator-prey relationships and navigation across a range of species including bats, birds, reptiles, amphibians and invertebrates and the disruption of plant photoperiod cycles (Holker, et al, 2010; Gaston, et al, 2014).

• However, the impacts of artificial light on the biodiversity of ecosystems as a whole, as well as the conservation of species, requires further evaluation. For example the decline of moth species in the UK and the impacts of increased light pollution remains data deficient.(Gaston, et al, 2014)

(Bruning, et al, 2015)

(WordPress, 2013)

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• Websites

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citizen-science-apps-to-measure-light-pollution/ (Accessed 03/02/15)• Brüning, A., Hölker, F., Franke, S., Preuer, T., and Kloas, W., (2015). Fig. 3. Concentration of cortisol per L tank water in ng/L/kg fish (median + − percentiles).

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2882983/The-great-street-light-switch-75-cent-councils-dimming-lights-save-cash-amid-fears-increased-crime-road-accidents.html (Accessed 03/02/15)• Holker, F., Wolter, C., Perkin, E.K., Tockner, K., (2010) Figure 1. Percentage of extant nocturnal species within different vertebrate classes and orders. Trends in

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• Kempenaers, B., Borgström, P., Loës, P., Schlicht, E., and Valcu, M. (2010). . Figure 2. Effect of Artificial Night Lighting on Reproductive Parameters in the Blue Tit. Current Biology. 20 (19) 1735–1739

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night lights along the coast of Israel. Biological Conservation. 159: 63–72• Mazor, T., Levin, N., Possingham, H.P., Levy, Y., and Rocchinie, D., (2013). Fig. 3. Scatter plot using spatial units (1 × 0.5 km) along the

coast of Israel to show relationships between sea turtle nesting activityBiological Conservation. 159: 63–72.• Ricemm.org, (2013). Graph-Melatonin. (Image online) Available at

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ANY QUESTIONS?