Critical Thinking

1. THE IMPACTS OF LIGHT POLLUTION ON
WILDLIFE AND HUMAN POPULATIONS
Emma-Louise Spicer

2. 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)

3. CURRENCY AND SIGNIFICANCE OF THE
ISSUE
• 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 sky
2) 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)

4. LIGHT POLLUTION IN THE UK
(Davis, et al, 2013)

5. CURRENCY AND SIGNIFICANCE OF THE
ISSUE
• 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)

6. 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)

7. 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)

8. 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)

9. • 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)

10. 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)

11. 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)

12. 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)

13. 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)

14. 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)

15. REFERENCES
• Aubé, M., and Roby, J., (2014) Sky brightness levels before and after the creation of the first International Dark Sky Reserve, Mont-Mégantic
Observatory, Québec, Canada. Journal of Quantitative Spectroscopy and Radiative Transfer. 139: 52–63
• Chellappa, S.L., Steiner, R., Blattner, P., Oelhafen, P., Götz, T and Cajochen, C., (2011) Non-Visual Effects of Light on Melatonin, Alertness and
Cognitive Performance: Can Blue-Enriched Light Keep Us Alert? Plos One. 6(1) e16429. doi:10.1371/journal.pone.0016429.
• Claudio, L., (2009). Switch On the Night: Policies for Smarter Lighting. Environmental Health Perspect. 117 (1) 29-31.
• Dwyer, R.G., Bearhop, S., Campbell, H.A., and Bryant, D.M., (2013) Shedding light on light: benefits of anthropogenic illumination to a nocturnally
foraging shorebird. Journal of Animal Ecology. 82 (8) 478-485
• Brüning, A., Hölker, F., Franke, S., Preuer, T., and Kloas, W., (2015). Spotlight on fish: Light pollution affects circadian rhythms of European perch
but does not cause stress. Science of The Total Environment. 511 (1) 516–522.
• Boyce, P.R., (2010). The Impact of Light in Buildings on Human Health. Indoor and Built Environment. 19 (1) 8–20.
• Dominoni, D.M., Van't Hof, T.J., and Partecke, J., (2015). Social cues are unlikely to be the single cause for early reproduction in urban European
blackbirds (Turdus merula). Physiology & Behavior. 142 (1) 14–19.
• Falchi, Fl, Cinzano, P., Elvidge, C.D., Keith, D.M., and Haim, A, (2011). Limiting the impact of light pollution on human health, environment and
stellar visibility. Journal of Environmental Management. 92 (10) 2714–2722.
• Fischer, T.W., Zmijewski, M. A, Zbytek, B., Sweatman, T. W., Slominski, R. M., Wortsman, J., Slominski A., (2006). Oncostatic effects of the indole
melatonin and expression of its cytosolic and nuclear receptors in cultured human melanoma cell lines. International journal of Oncology 29: 665-
672.
• Friedmana, L., Spira, A.P.,Hernandez, B., Mathera, C., Sheikh, J., Ancoli-Israelc, S., Yesavagea, J.A., Zeitzera, J.M., (2012) Brief morning light
treatment for sleep/wake disturbances in older memory-impaired individuals and their caregivers. Sleep Medicine. 13 (5) 546–549.
• Gallaway, T., Olsen, R.N., and Mitchell, D.M., (2010) The economics of global light pollution. Ecological Economics. 69 (3) 658–665.
• Gagné, A.M., Lévesque, F., Gagné, P., and Hébert. M., (2011) Impact of blue vs red light on retinal response of patients with seasonal affective
disorder and healthy controls. Progress in Neuro-Psychopharmacology and Biological Psychiatry. 35 (1) 227–231

16. • Gaston, K.J. and Bennie, J, (2014). Demographic effects of artificial nighttime lighting on animal populations. Environment and Sustainability Institute. 22: 323- 330.
• Gaston, K.J. Davies, T.W., Bennie, J. and Hopkins, J., (2014). Reducing the ecological consequences of night-time light pollution: options and developments. Journal of Applied Ecology. 49 (6)1256–
1266.
• Gaston, K.J., Gaston, S., Bennie, J and Hopkins, (2014). Reducing the impacts of artificial light. British Wildlife. 332-339.
• Gaston, K.J. Davies, T.W., Bennie, J. and Hopkins, J., The ecological impacts of nighttime light pollution: a mechanistic appraisal. Biological Reviews. 88, (4) 912–927
• Holker, F., Wolter, C., Perkin, E.K., Tockner, K., (2010) Light pollution as a biodiversity threat. Trends in Ecology & Evolution. 25 (12) 681–682
• Kempenaers, B., Borgström, P., Loës, P., Schlicht, E., and Valcu, M. (2010). Artificial Night Lighting Affects Dawn Song, Extra-Pair Siring Success, and Lay Date in Songbirds. Current Biology. 20
(19) 1735–1739
• Kim, S, Ulfarsson, G.F. and Hennessy, J.T., (2007) Analysis of light rail rider travel behavior: Impacts of individual, built environment, and crime characteristics on transit access. Transportation
Research Part A: Policy and Practice. 41 (6) 511–522.
• Kuechly, H.U. Kyba, C.M, Ruhtz, T., Lindemann, C., Wolter, C., Fischer, J., and Hölker, F., (2012). Aerial survey and spatial analysis of sources of light pollution in Berlin, Germany. Remote
Sensing of Environment. 126: 39–50
• Longcore, T. and Rich, R., (2004) Ecological light pollution. Frontiers in Ecology and the Environment. 2: 191–198.
• Lyytimäki, J. (2013). Nature’s nocturnal services: Light pollution as a non-recognised challenge for ecosystem services research and management. Ecosystem Services
• 3: 44-48.
• Lyytimäki, J.,Tapio, P., and Assmuth, T., (2012). Unawareness in environmental protection: The case of light pollution from traffic. Land Use Policy. 29 (3) 598–604
• Marlin, C., (2009). Starlight: a common heritage. International Astronomical Union. 5 (260) pp 449-456.
• Mazor, T., Levin, N., Possingham, H.P., Levy, Y., and Rocchinie, D., (2013). Can satellite-based night lights be used for conservation? The case of nesting sea turtles in the Mediterranean.
Biological Conservation. 159: 63–72.
• Langevelde, F.V., Ettema, J.A., Donners, M.,. WallisDeVries, M.F., Groenendijk, D. Effect of spectral composition of artificial light on the attraction of moths. Biological Conservation.
144 (9) 2274–2281.
• Luginbuhl, C.B., Boley, P.A., and Davis, D.R., (2014). The impact of light source spectral power distribution on sky glow. Journal of Quantitative Spectroscopy and Radiative Transfer. 139: 21–26.
• Oppedal F., Juell, J.E., and Tarranger G. L. (2001). Artificial light and season affects vertical distribution and swimming behaviour of post-smolt Atlantic salmon in sea cages. Journal of Fish
Biology. 58, (6) 1570–1584,
• Pauly, S.M., (2004) Lighting for the human circadian clock: recent research indicates that lighting has become a public health issue. Medical Hypotheses. 63, (4) 588–596
• Poot, H., Ens, B.J. de Vries, H., Donners, M. A. H., Wernand, M. R. and Marquenie. J. M. (2008). Green light for nocturnally migrating birds. Ecology and Society 13(2): 47.

17. • Pun, C.S.J., So, C.W. Leung, W.Y., and Wong, C.F., (2014). Contributions of artificial lighting sources on light pollution in Hong Kong measured through a night sky brightness monitoring
network. Journal of Quantitative Spectroscopy and Radiative Transfer. 139: 90–108.
• Stevens, R.G. (2009) Light-at-night, circadian disruption and breast cancer: assessment of existing evidence. International Journal of Epidemiology. 38 (4) 963-970
• Stevens, R.G., Brainard, G.C., Blask, D.E.,Lockley, S.W., and Motta, M.E., (2013). Adverse Health Effects of Nighttime Lighting: Comments on American Medical Association Policy
Statement. American Journal of Preventive Medicine. 45 (3) 343–346.
• Verutes, G.M., Huang, C., Estrella, R.R. and Loyd, K., (2014). Exploring scenarios of light pollution from coastal development reaching sea turtle nesting beaches near Cabo Pulmo, Mexico.
Global Ecology and Conservation. 2, December 2014, Pages 170–180
• Wysea, C.A., Selman C., Page M.M., Coogan A.N. and Hazlerigg D.G., (2011) Circadian desynchrony and metabolic dysfunction; did light pollution make us fat?. Medical Hypotheses. 77 (6),
1139–1144
• Websites
• International astronomical Union, (2015) Controlling light pollution IAU Commission 50 at work. (online) Available at http://www.iau.org/public/themes/light_pollution/ (Accessed 28/1/15).
• International Dark-Sky Association, (2015). International Dark Sky Reserves (online) Available at http://www.darksky.org/night-sky-conservation/87-international-dark-sky-reserves
(Accessed 05/02/15)
• International Dark-Sky Association, (2015). Light pollution—what is it and why is it important to know? (online) Available at http://www.darkskiesawareness.org/faq-what-is-lp.php
(Accessed 28/1/15).
• PDF files
• Deda, P Elbertzhagen, I., Klussmann,M., (2007). Light pollution and The impacts on biodiversity, species and their habitats. (pdf) Convention on the Conservation of Migratory Species of
Wild Animals. Available at http://www.starlight2007.net/pdf/proceedings/P_Deda.pdf (Accessed 07/02/15)
• Fure, A., (2006). Bats and lighting. (pdf) Surrey The London Naturalist. Available at http://www.furesfen.co.uk/bats_and_lighting.pdf (Accessed 05/02/15).
• Rowan-Robinson, M. (2012) The campaign for dark skies. The British Astronomical Association (pdf) Available at http://astro.ic.ac.uk/public/mrr/starsntides/stars71.pdf (Accessed 03/02/15).
• Shepherd, P. (2012). Delivering the Olympic Park Biodiversity Action Plan. (pdf) London. Olympic Delivery Authority. Available at file:///C:/Users/emmal_000/Downloads/307-bio-action-
plan-dei.pdf (Accessed 05/02/15)
• University of Wisconsin-Madison, 2008. Summary of a Literature Review on Bridge Lighting. (pdf) University of Wisconsin-Madison Available at
http://www.topslab.wisc.edu/workgroups/tsewg/Bridge%20Lighting%20References%20for%20WISDOT%20DRAFT%20v2.pdf (Accessed 02/02/15)

18. • Reports
• Flatley, D, Reyner, L.A. , and Horne, J.A., (2008). Sleep-related crashes on sections of different road types in the UK (1995-2001). Great Britain. London. Department of the
Environment, Transport and the Regions.
• Books
• Boyce, P.R., (2014) Human Factors in Lighting. Third Edition. Boca Raton. CRC Press.
• Newspaper Reports
• Chapman, J. (2014) The great street light switch-off: 75 per cent of councils dimming lights to save cash amid fears of increased crime and road accidents. The Daily Mail.
(online) 22 December 2014. Available at http://www.dailymail.co.uk/news/article-2882983/The-great-street-light-switch-75-cent-councils-dimming-lights-save-cash-amid-fears-
increased-crime-road-accidents.html (Accessed 02/02/15)
• Winterman, D. (2012) Light pollution: Is there a solution?. BBC News. (online) Available at http://www.bbc.co.uk/news/magazine-16470744 (Accessed 03/02/15)
• Images
• APN Photography & Web-Design, (2015) Shoot The Cityscapes. (image online) Available at http://www.apnphotographyschool.com/tips-tricks/night-photography-tips-11-
awesome-ideas-for-amazing-low-light-shots/ (Accessed 29/1/15)
• BlogsPlos, (2013) Two new citizen science apps to measure light pollution (image online) Available at (http://blogs.plos.org/citizensci/2013/05/10/two-new-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). Science of The
Total Environment. 511 (1) 516–522.
• CenBlog.org, (2011) melatonin.png (image online) Available at http://cenblog.org/the-haystack/files/2011/06/melatonin.png (Accessed 07/02/15)
• Cost.eu Lonne, (2014) Sky Glow Vienna, Austria (image online) Available at http://www.cost-lonne.eu/gallery/cities-at-night-2/ (Accessed 29/1/15)
• Davies, T.W., Bennie, J. Inger, R., and & Gaston, K.J., (2013) Artificial light alters natural regimes of night-time sky brightness. Scientific Reports. 3: 1722
• Daily Mail (2014) Three-quarters of councils are dimming or extinguishing lights. (image online) Available at http://www.dailymail.co.uk/news/article-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 Ecology &
Evolution. 25 (12) 681–682

19. • International Dark-Sky Association, (2015). Certified International Dark Sky Reserves (image online) Available at
http://www.darksky.org/night-sky-conservation/87-international-dark-sky-reserves (Accessed 05/02/15).
• International Dark-Sky Association. (2015). Glaring lights can actually reduce visibility. (image online) Available at
http://www.darkskiesawareness.org/faq-what-is-lp.php (Accessed 03/02/15)
• Kempenaers, B., Borgström, P., Loës, P., Schlicht, E., and Valcu, M. (2010). Figure. 1. Effect of Artificial Night Lighting on the Start of the Dawn
Chorus in Five Songbird Species. Current Biology. 20 (19) 1735–1739
• 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
• Kootenay Local Agricultural Society, (2015). Light Colour (image online) Available at http://www.growinginthekootenays.ca/daylighthours.html
(Accessed 05/02/15).
• Lyytimäki, J. (2013). Fig.1 Proposed vicious circle of shifting baseline related to nocturnal nature. Ecosystem Services. 3: 44-48.
• Mazor, T., Levin, N., Possingham, H.P., Levy, Y., and Rocchinie, D., (2013). Fig. 2. The satellite images used in this study for calculating 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 http://ricemm.org/wp-content/uploads/2013/05/graph_melatonin_en.png
(Accessed 07/02/15)
• Simon Everett Photography Kent. Night Shoot at Bluewater (image online) Available at http://www.simoneverettphotographykent.co.uk/night-
shoot-bluewater/ (Accessed 03/02/15).
• Space.com, (2013) Milky Way Galaxy: Facts About Our Galactic Home (image online) Available at http://www.space.com/19915-milky-way-
galaxy.html (Accessed 29/1/15)

20. ANY QUESTIONS?