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LED lighting increases the ecological impact of light pollution irrespective of color temperature


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Recognition of the extent and magnitude of night-time light pollution impacts on natural ecosystems is increasing, with pervasive effects observed in both nocturnal and diurnal species. Municipal and industrial lighting is on the cusp of a step change where energy-efficient lighting technology is driving a shift from ''yellow'' high-pressure sodium vapor lamps (HPS) to new ''white'' light-emitting diodes (LEDs). We hypothesized that white LEDs would be more attractive and thus have greater ecological impacts than HPS due to the peak UV-green-blue visual sensitivity of nocturnal invertebrates. Our results support this hypothesis; on average LED light traps captured 48% more insects than were captured with light traps fitted with HPS lamps, and this effect was dependent on air temperature (significant light 3 air temperature interaction). We found no evidence that manipulating the color temperature of white LEDs would minimize the ecological impacts of the adoption of white LED lights. As such, large-scale adoption of energy-efficient white LED lighting for municipal and industrial use may exacerbate ecological impacts and potentially amplify phytosanitary pest infestations. Our findings highlight the urgent need for collaborative research between ecologists and electrical engineers to ensure that future developments in LED technology minimize their potential ecological effects.
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Ecological Applications, 24(7), 2014, pp. 1561–1568
Ó2014 by the Ecological Society of America
LED lighting increases the ecological impact of light pollution
irrespective of color temperature
Scion, P.O. Box 29-237, Fendalton, Christchurch, New Zealand
Scion, 49 Sala Street, Rotorua, New Zealand
Abstract. Recognition of the extent and magnitude of night-time light pollution impacts
on natural ecosystems is increasing, with pervasive effects observed in both nocturnal and
diurnal species. Municipal and industrial lighting is on the cusp of a step change where energy-
efficient lighting technology is driving a shift from ‘‘yellow’’ high-pressure sodium vapor lamps
(HPS) to new ‘‘white’’ light-emitting diodes (LEDs). We hypothesized that white LEDs would
be more attractive and thus have greater ecological impacts than HPS due to the peak UV-
green-blue visual sensitivity of nocturnal invertebrates. Our results support this hypothesis; on
average LED light traps captured 48%more insects than were captured with light traps fitted
with HPS lamps, and this effect was dependent on air temperature (significant light 3air
temperature interaction). We found no evidence that manipulating the color temperature of
white LEDs would minimize the ecological impacts of the adoption of white LED lights. As
such, large-scale adoption of energy-efficient white LED lighting for municipal and industrial
use may exacerbate ecological impacts and potentially amplify phytosanitary pest infestations.
Our findings highlight the urgent need for collaborative research between ecologists and
electrical engineers to ensure that future developments in LED technology minimize their
potential ecological effects.
Key words: biodiversity; high-pressure sodium lamp; light pollution; spectra; street lighting;
Since the invention of the first practical incandescent
light bulb in the late 1870s, night-time light pollution has
now become almost ubiquitous in the populated regions
of developed countries (Bogard 2013). The extent of
artificial light pollution continues to expand swiftly
(;6%annual increase, range 0–20%[Ho
¨lker et al.
2010a]), especially in newly industrialized economies.
Several aspects of light pollution are clear: (1) there is
extensive evidence that artificial lighting that exceeds
natural background levels has significant ecological and
biological impacts (Longcore and Rich 2004, Rich and
Longcore 2005, Ho
¨lker et al. 2010b, Davies et al. 2012,
Gaston et al. 2013, Le Tallec et al. 2013, Perkin et al.
2014), (2) the spectral composition of light pollution can
alter the magnitude of these impacts (van Langevelde et
al. 2011, Davies et al. 2013), and (3) the spectral
composition of light pollution has changed, and will
continue to change over time with the advent and
subsequent adoption of more energy-efficient lighting
technologies (Schubert and Kim 2005).
The current trend in global lighting is a shift from
‘‘yellow’’ sodium lamps toward a new generation of
broad spectrum, energy-efficient, ‘‘white’’ light-emitting
diodes (LEDs) for municipal and industrial lighting
(Schubert and Kim 2005, Anonymous 2012). The
biological effect of a shift toward a more ‘‘white-light
night’’ (sensu Gaston et al. 2012) has not been studied in
detail, but direct evidence of biological impacts is
mounting (Stone et al. 2012), and comparisons of visual
pigment absorbance spectra with the emission spectra of
municipal light sources suggests indirectly that such
impacts may be widespread among terrestrial animals
(Davies et al. 2013).
Gaston et al. (2012) proposed that the ecological
consequences of light pollution could potentially be
reduced by avoiding critical regions within the spectrum.
Currently available municipal and industrial-scale white
LED lights are based on monochromatic blue LEDs
Manuscript received 6 March 2014; revised 29 May 2014;
accepted 12 June 2014. Corresponding Editor: M. P. Ayres.
coated by a single yellow, or multiple yellow-green,
phosphor coatings that absorb blue light and reemit
longer wavelength emissions (Krames et al. 2007). The
phosphor coating can be manipulated to produce a
range of white LEDs that differ in the proportion of
blue (435–495 nm) wavelengths emitted. This range of
white LEDs is normally referred to by their color
temperature (degrees Kelvin [K]) with higher tempera-
tures having a greater proportion of emitted blue light.
Given the peak UV, blue, and green photoreceptors of
many invertebrates (Briscoe and Chittka 2001), we
hypothesize that low color temperature LED lights will
have less ecological impact than high color temperature
LED lights due to the lower intensity blue spectral
To test this hypothesis we first compared the relative
attraction of flying invertebrates to 4000 K white LEDs
and high-pressure sodium lamps at a scale equivalent to
current industrial/municipal site-lighting practices.
This comparison provided an assessment of the
potential impact of white LEDs on nocturnal inverte-
brates if adopted for industrial and municipal lighting.
We then compared the relative attraction of flying
invertebrates to different color temperature white
LEDs at an experimental scale to identify opportunities
for minimizing the ecological impact of white LED
lighting. For both experiments we used the attraction
of nocturnal flying invertebrates as a proxy measure of
ecological impact.
Data collection: Comparison of LED and HPS
industrial-scale lighting
An industrial-scale lighting comparison of white
LEDs and high-pressure sodium (HPS) lamps was
conducted using five replicate pairs of 4000 K white
LEDs and HPS lamps (see Appendix, Table 1). The key
difference in the spectral composition of the LED and
HPS lamps was that the LED had greater relative
intensity from the blue-green portion of the spectra than
the HPS lamp (Fig. 1). An A2-sized sheet of Perspex
(Evonik Industries, Darmstadt, Germany) mounted 0.5
m below and directly between each pair of LED and
HPS lamps was used to sample flying invertebrates
attracted to the lights (see Appendix, Fig. 1). Each night,
an A2-sized sheet of Tanglefoot-coated (Contech,
Victoria, British Columbia, Canada) Mylar (Fuji Xerox,
Connecticut, USA) was attached to both sides of the
Perspex pane to snare flying invertebrates. Mylar sheets
were identified as ‘‘facing’’ and ‘‘away,’’ depending on
their orientation with respect to the location of the lamp
that was activated on that particular night. Trapping
was conducted between 21:00 and 00:00 on 10 suitable
nights from 21 January and 3 February with each
sampling location randomly assigned to either LED or
HPS lighting on the first night. The active light in each
pair was then alternated on subsequent nights. This
resulted in a final design of five independent replicates
(sampling locations) that compare the two light treat-
ments that were sampled on 10 different nights. The 10
sampling occasions cannot be considered as truly
independent, hence tests for the influence of repeated
measures were performed (see Analysis: Comparison of
LED and HPS industrial-scale lighting). Suitable nights
were considered to be nights with a forecast air
temperature at 21:00 of at least 158C. Actual air
temperature at 22:00 that was recorded at the study site
at an elevation of 10 m was used for analyses (see
Analysis: Comparison of LED and HPS industrial-scale
lighting). All LED and HPS comparisons were conduct-
ed at the PanPac wood processing facility, Hawkes Bay,
New Zealand. Pairs of lights were established on the
edge of industrial buildings at the site. The site is
bordered by an extensive Pinus radiata plantation forest
to the west and by coastal grassland to the east with the
ocean located ,1 km to the east. Insects are known to
disperse into the site from the forest as they are attracted
by the bright site lighting.
Data collection: Comparison of LED color temperature
The attraction of flying invertebrates to white LEDs
with six different color temperatures (see Appendix,
FIG. 1. Relative spectral emission of (a) high-pressure
sodium (HPS) lamp (Sunlux ACE, NH-360 FLX; EYE
Lighting, Wacol, Queensland, Australia) and (b) light-emitting
diode (LED) 4000 K color temperature high bay lamp
(LUXEON M, LXR7-SW40; Koninklijke Philips, Amsterdam,
The Netherlands). Emission spectra are normalized to the
spectrum with the maximum intensity and were kindly provided
by each manufacturer.
S. M. PAWSON AND M. K.-F. BADER1562 Ecological Applications
Vol. 24, No. 7
Table 1, Fig. 2) were compared to a control treatment
(18-ohm resister that matched the power consumption
and heat output of the tested LEDs) in a completely
randomized block design with three replicates (see Plate
1). Each of the three blocks consisted of a linear transect
with seven sampling points located at 20-m intervals.
Within each block, the six color treatments (and control)
were initially assigned at random to one of the seven
sampling points. On subsequent nights the individual
color treatments were then rotated sequentially to
account for any potentially confounding spatial effects
that may have occurred due to the location of the
sampling point along the transect within the block.
LEDs were powered by 12-V DC batteries and the
experiment was conducted over four hours each night
(20:00 to 00:00) on seven non-consecutive days between
30 January and the 26 February 2013. Delays in
sampling were due to periods of unsuitable weather
when invertebrate flight activity was minimal.
LEDs were mounted in a heat sink housing (Makers-
LED, Aimes, Iowa, USA) and the attraction of flying
invertebrates to lights was quantified using A3 Perspex
catching panes installed 30 cm in front of each LED.
Tanglefoot-coated Mylar sheets were attached to the
Perspex to sample flying invertebrates attracted to the
light. Unimpeded light was visible to the sides of the
Tanglefoot-coated Mylar sheets, however a portion of
light emitted during the study did have to pass through
the Mylar sheet, potentially altering the spectral compo-
sition. To test for this the spectral emission of LEDs with
and without a Tanglefoot-coated Mylar sheet were
compared (Fig. 2). This showed that there was some
absorption of light in the 600þnm wavelengths (red and
infrared), but this change should not have biased our
results, as most insects are not sensitive to changes in the
far red portion of the spectra (Briscoe and Chittka 2001).
In the highly attractive blue-green portion of the spectra,
the Tanglefoot coated Mylar sheet did not impact the
relative proportion of light emitted.
The input current of individual LEDs was adjusted
(via a potentiometer attached to a LuxDrive BuckPuck
Driver [LED Dynamics, Randolph, Vermont, USA]) to
produce a uniform power output of 12 61 mW (mean
6SD) for each color temperature (see Appendix, Table
1). To measure power output for calibration the
emission from individual LEDs was collimated using a
25.4 mm focal length 1-inch diameter (1 inch ¼2.54 cm)
lens that was focused on a Coherent J-50MB-HE
thermopile sensor (Coherent, Santa Clara, California,
USA). Power output was averaged over 10-s intervals,
using a Coherent FieldMaxII-TO.
All LED color temperature trials were conducted on the
boundary of the Synlait facility, Rakaia, Christchurch,
New Zealand. Each of the three independent blocks was
established on areas of long grass (intermittently mown)
or gravel. The area is surrounded by introduced exotic
pastoral grass with shelter belts of Pinus radiata. There are
no substantial areas of non-productive ecosystems in the
immediate vicinity of the site.
Analysis: Comparison of LED and HPS industrial-scale
Total number of flying invertebrates (pooling panes
that were ‘‘facing’’ and ‘‘away’’) were standardized by
the nightly trapping duration to account for the
variation in trapping times ranging from 3.7 to 4.2
hours. This standardization procedure changed the
scale of the response variables from a discrete to a
continuous scale and thus allowed the use of linear
mixed effects models (R package nlme [Pinheiro et al.
2014]). The fixed term of the model contained light
type, air temperature, wind speed, and their interac-
tions as explanatory variables. Trapping date nested in
light type and sampling location were modeled as
random terms to account for the hierarchical design
and repeated measures. Plots of the standardized
residuals vs. fitted values and for each of the
explanatory variables were used for graphical model
validation. The validation plots indicated heterosce-
dasticity, which was modeled using a power variance
structure that incorporated the fitted values as a
variance covariate and light type as grouping variable
(i.e., allowing for stratified variance modelling). The
significance of the fixed model terms was assessed via
backward selection using likelihood ratio tests (Zuur et
al. 2009). The final models showed high correlation
between the intercept and the slopes of the fixed
factors. To overcome this issue the models were
refitted using centered air temperature and wind speed
Analysis: Comparison of LED color temperature
We applied generalized linear mixed models (GLMM)
with Poisson errors and log link fit by Laplace
approximation (R package lme4 [Bates et al. 2014]) to
analyze the trap catch data. The total number of flying
invertebrates caught per trap was compared against
color temperature, location (sampling point within
transect), and their interaction as fixed terms within
the model. Block and trapping date were modeled as
random effects. Overdispersion was detected (ratio of
residual deviance to residual degrees of freedom .1)
and accounted for by incorporating a per-observation-
TABLE 1. Results of the optimal linear mixed-effects model
results for standardized invertebrates catches at lights
equipped with light-emitting diode (LED) or high-pressure
sodium (HPS) lamps.
Parameter Estimate SE df tP
Intercept 21.65 2.77 50 7.81 ,0.001
Light 8.55 2.55 42 3.35 0.002
Temp 5.61 0.99 42 5.67 ,0.001
Light 3temp 2.53 1.10 42 2.30 0.027
Notes: Sample size n¼5 blocks. Abbreviations are light, light
type; temp, air temperature; and wind, wind speed.
level random effect. The GLMM was followed by a
multiple comparison test using Tukey contrasts to allow
pairwise comparisons between color temperatures (R
package multcomp [Hothorn et al. 2008]). Plots of the
Pearson residuals vs. fitted values and against the
response variable(s) were applied for graphical model
validation. The significance of the fixed model terms was
assessed via backward selection using Akaike’s infor-
mation criterion (AIC; Zuur et al. 2009). The AIC was
favored over the likelihood ratio test, as used for the
comparison between LED and HPS lamps (see Analysis:
Comparison of LED and HPS industrial-scale lighting).
Our rationale for using the AIC is that it includes a
penalty for the number of parameters, which discour-
ages over-fitting of the model (in this case 36 parameters
were associated with the color temperature 3location
interaction term). When DAIC 2, we considered the
FIG. 2. Relative spectral emission of ‘‘white’’ LED of differing color temperatures. Emission spectra were measured using an
OceanOptics USB2000 fiber-coupled spectrometer (Ocean Optics, Dunedin, Florida, USA) with an integration time of 100 ms.
Emission spectra are normalized to the maximum spectral intensity in the 400–500 nm range, as insects are most attracted to this
portion of the visible spectrum. The shape and form of the curve in the blue-green region is almost identical between naked LEDs
and operational LEDs where measurements were taken behind the Perspex and Tanglefoot-coated Mylar.
FIG. 3. Number of flying invertebrates (standardized by the
3.7–4.2 h trapping duration) caught in light traps equipped with
LED or HPS light. Values are means 6SE, n¼5 replicates.
** P,0.01.
S. M. PAWSON AND M. K.-F. BADER1564 Ecological Applications
Vol. 24, No. 7
competitive models to provide similar goodness of fits
and opted for the model with fewer parameters.
Standardization of trapping times was not required for
the comparison of color temperatures as the sample
duration varied by less than 10 minutes between
treatments. All analyses were conducted in R version
2.15.3 (R Development Core Team 2013).
Comparison of LED and HPS industrial-scale lighting
In total 7300 invertebrates were caught including,
3811 Diptera, 1376 Trichoptera, 994 Coleoptera, 409
Hymenoptera, 308 Hemiptera, 173 Ephemeroptera,
111 Psocidae, and less than 100 Lepidoptera, Neurop-
tera, Thysanoptera, Araneae, Plecoptera, Isoptera,
Orthoptera, and Blattodea. Sampling panes equipped
with LED lamps attracted 48%more flying inverte-
brates on average than HPS lamps (Fig. 3, Table 1).
Insect attraction to light was significantly affected by
air temperature (Table 1), we observed a precipitous
decline in catch numbers during a single night when
air temperatures were favorable for flight (;208C).
This coincided with a strong easterly wind blowing
from the ocean. The prevailing wind directions at the
study site were from west and southwest suggesting
that flying invertebrates from nearby forested land
would have to fly into a headwind to reach the
experimental site.
Comparison of LED color temperatures
In total 12 860 invertebrates were caught, including
8879 Diptera, 1674 Lepidoptera, 1089 Thysanoptera,
450 Coleoptera, 379 Hymenoptera, 144 Neuroptera,
and ,100 Hemiptera, Psocoptera, Trichoptera, Ara-
neae, Ephemeroptera, Collembola, and Mantodea (in
decreasing order of abundance). When considering the
pooled catch of all flying invertebrate taxa (removing
Araneae, Collembola, and Acarina) LED lamps at-
tracted significantly more flying invertebrates than
control traps irrespective of color temperature (Fig. 4,
Table 2). However, the difference between control and
LED lamps was taxon dependent, strong effects were
observed in Diptera and Lepidoptera and no effect
observed for Thysanoptera, Hymenoptera, and Cole-
optera (Fig. 4). Irrespective of taxa, the LED color
temperature had no significant effect on invertebrate
attraction (Fig. 4).
Light pollution is recognized as a global threat to the
conservation of biological diversity that could drive
reductions in the quality of provisioning, regulating and
PLATE 1. Image showing one experimental block with five of the six different color temperature LEDs. Note the dark spot
between the 4th and 5th light as the location of the just visible control treatment. The 6th color temperature is not visible and is to
the left of the image. Individual lights were placed 20 m apart with different blocks placed 200 m apart. Photo credit: S. M. Pawson,
cultural ecosystem services (Ho
¨lker et al. 2010b). There
is increasing evidence that existing light pollution has
significant ecological effects (Rich and Longcore 2005,
Gaston et al. 2012, 2013, Perkin et al. 2014). However,
the spatial extent, density, and spectral composition of
light pollution is predicted to change (Gaston et al.
2012). Continued urban expansion will result in a
concomitant encroachment of light pollution into areas
that are currently naturally lit, however, spectral
changes may alter the type of impacts that these new
areas experience, e.g., changed species interactions
(Davies et al. 2013).
FIG. 4. Effect of LED color temperature on flying invertebrates trap catch over a 4-h sampling period; C is the control trap,
values below the bars indicate the color temperature in Kelvin (n¼3 blocks, values are means 6SE). Different lower case letters
indicate statistically significant differences at a¼0.05 (multiple comparison procedure using Tukey contrasts).
TABLE 2. Results of a backward selection applied to the
generalized linear mixed effects model for LED color
temperature and trap position.
Dropped term AIC
None 608.69
Color temperature 3location 595.11
Color temperature 658.01
Notes: AIC stands for Akaike’s information criterion.
The most parsimonious model, which only contained LED
color temperature as explanatory variable (i.e., the model with
the interaction term and the factor location dropped).
S. M. PAWSON AND M. K.-F. BADER1566 Ecological Applications
Vol. 24, No. 7
White LED lighting for both municipal and indus-
trial applications is predicted to increase dramatically
in the next decade (Anonymous 2012). Gaston et al.
(2012) have referred to this anticipated shift from high-
pressure sodium (HPS) lights to LEDs, as the
formation of a ‘‘white-light night.’’ Our results suggest
that a white-light night shift could significantly increase
the ecological impacts of light pollution as white LEDs
attracted 48%more flying invertebrates than existing
HPS lamps. Our study only accounts for the absolute
loss of individuals from the population of nocturnal
flying invertebrates attracted to LED lights. However,
the true extent of white LED light pollution will require
an assessment of ecological effects across multiple
ecological levels, e.g., species, populations, and com-
munities to address varying complexity in the potential
interactions (as suggested by Fox [2013]). In addition
further research is required to understand the land-
scape-scale influence of LED lights at broader spatial
scales. As discussed by Davies et al. (2013), light
pollution may affect visually guided behaviors of both
individuals and of interactions between species or
ecological guilds, e.g., predator avoidance and/or prey
detection, navigation, pollination, and foraging, may
be influenced by light pollution. However, the magni-
tude of such potential effects may prove to be
dependent on both habitat structure (e.g., forest
canopy vs. open grassland) and the spatial arrangement
of habitat.
Manipulating LED color temperature is one poten-
tial intervention that could minimize the ecological
impacts of white LEDs as it reduces the intensity of
blue spectral emissions that are attractive to inverte-
brates. However, our results show that the attraction of
nocturnal flying invertebrates to currently available
phosphor coated white LEDs does not vary with LED
color temperature. This effect was strongly observed in
Diptera and Lepidoptera as they were the most
numerous taxa attracted to the LEDs (Fig. 4).
However, there was no observed effect of white LED
lights for Hymenoptera, Thysanoptera, and Coleop-
tera. Given the low sample size for these three
taxonomic groups it is difficult to draw absolute
conclusions as these individuals may represent acci-
dental by-catch in the hour before dusk that it took to
install the sticky sheets, as opposed to actual nocturnal
flight activity.
Our general finding for all taxa (Fig. 4) is contrary to
our initial hypotheses, and implies that careful
selection of currently available off-the-shelf color
temperatures is unlikely to mitigate the potential
ecological impacts of a broad-scale shift to white
LED lighting for municipal and industrial applica-
tions. One potential explanation for this is that current
low color temperature white LEDs still emit a
proportion of blue-green spectra (Fig. 2). It may be
possible to overcome this issue using longpass optical
filters, or alternatively by selecting specific monochro-
matic LEDs (with narrow spectral wavelengths) that
avoid the highly attractive blue-green spectra, however
this has yet to be tested.
In addition to their direct ecological impacts light
pollution from white LEDs is likely to exacerbate
existing domestic, e.g., midge swarms and industrial
infestations of sanitary and phytosanitary pests that are
known to be highly attractive to white lighting (Pawson
et al. 2009, Goretti et al. 2011). The potential nuisance
impact of such unwanted domestic pest species is an
additional factor that should be considered in the
selection of municipal lighting. However, more impor-
tant is the potential for white LED lighting to increase
phytosanitary and biosecurity risks that could lead to
additional indirect ecological impacts. For example,
white light is more attractive than light emitted from
HPS lamps to gypsy moth (Lymantria dispar); an
invasive, polyphagous, forest pest (Walliner et al.
1995). The potential ecological impacts from the
establishment of gypsy moth in new regions are severe,
e.g., defoliation affecting productivity (Sharov et al.
2002) and local extinction of other Lepidoptera
(Wagner and Van Driesche 2010), and ships infested
with egg masses are a known pathway that is actively
monitored by a number of countries, including
Australia and New Zealand (MacLellan 2011). Thus a
transition to white LEDs at, or near, ports may elevate
the risk of egg masses moving on a transoceanic
pathway, which potentially increases the risk of
establishment in new regions.
Although we have shown that the color temperature
of existing yellow phosphor white LEDs cannot be used
to reduce their ecological impact on flying inverte-
brates, other options may reduce the effects of white
LEDs in the future. Gaston et al. (2012) highlight the
potential of white LEDs derived from a combination of
monochromatic LED light sources, e.g., red, blue, and
green, that together would form a white light. This may
provide greater ability to avoid certain spectral
emissions to reduce the effects of light pollution.
However, before multiple primary LEDs (e.g., RGB
emitters) can become a reality for large-scale illumina-
tion there are significant technological breakthroughs
required for both green and red LEDs (Krames et al.
2007). Alternatively, longpass filters could be used to
remove specific spectral emissions as was previously
suggested to reduce the attractiveness of mercury vapor
and high-pressure sodium lamps to particular pest
species (e.g., gypsy moth; Walliner et al. 1995).
Practically such filters may have limitations as they
would significantly alter color rendering and may
increase per unit costs and energy consumption per
unit of light emitted.
Phosphor-coated white LED lamps have the potential
to increase the impacts of light pollution dramatically.
Given the strong impetus for their adoption in municipal
and industrial applications, it is imperative to fully
understand the potential long-term impacts of white
LED lights on ecological communities, populations, and
species. A comprehensive assessment of overall impacts
and knowledge about the influence of each region of the
visible spectrum will allow technologists to work with
ecologists to focus future developments in lighting
technology that balance the needs of illumination with
reduced ecological impact.
The authors acknowledge Paul Fielder and Zachary Treamer
from LED Dynamics for advice on LED binning and the
supply of specific LED components. Rob Eagle of PanPac and
Simon Causer of Synlait milk products for access to their
respective facilities to conduct experiments. Sebastian Horvath
for the analysis of LED spectral frequencies and the calibration
of power output from different color temperature LEDs. Jess
Kerr, Brooke O’Connor, Liam Wright, Tia Uaea, Thornton
Campbell, Krystal Jansen, and Arild Roberts for the establish-
ment of field trial sites and Sarah Cross for assistance in
identifying and counting insect samples.
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S. M. PAWSON AND M. K.-F. BADER1568 Ecological Applications
Vol. 24, No. 7
... On a similar subject, Miller (2006) investigated the effects of light pollution on the singing behavior of American robins. To assess future steps in lighting design, Pawson and Bader (2014) aimed to evaluate LED color and lighting type based on ecological impact. And on the human health side of things, Patel (2019) tested whether light pollution is associated with lower or insufficient sleep. ...
... References Statistics (Butt, 2012;Falchi et al., 2019;Gallaway et al., 2010;Hale et al., 2013;Herdiwijaya et al., 2020;Horton et al., 2019;Kamrowski et al., 2014Kamrowski et al., , 2012Kanianska et al., 2020;Katz and Levin, 2016;Kuechly et al., 2012;La Sorte et al., 2022;Lacoeuilhe et al., 2014;Miller, 2006;Moore et al., 2000;Ouyang et al., 2017;Pawson and Bader, 2014;Rabaza et al., 2010;Rodríguez et al., 2017;Schirmer et al., 2019;Ś ciężor and Kubala, 2014;Steinbach et al., 2015;Sun et al., 2020;Xue et al., 2020;Yin et al., 2020;Zielińska-Dabkowska et al., 2020) Physics Aube et al., 2005;Cinzano and Falchi, 2012;Falchi et al., 2016;Kocifaj, 2007;Lawler et al., 2022;Liu and Wu, 2021) Image Processing Jechow, 2019;Katz and Levin, 2016;Li et al., 2017;Liu et al., 2018;Ye et al., 2021;Yuan et al., 2019) L.S. Riza et al. spectra measurements with the Konica Minolta Spectroscope type CS-2000, pictures that reflect the overall brightness relationship in the region with a digital camera, chroma measurements of light sources and optical values such as luminance and color temperature with a digital colorimeter, and measurements of luminance using luminance meters at Dalian, China. Lim et al. (2018) measured vertical pane illuminance using Chroma Meter CL-200A and surface luminance levels using LMK Luminance Meter. ...
... Schirmer et al. (2019) housed male and female C57BL/6 J mice and studied activity changes with respect to changes in nighttime light brightness (< 0.01, 6, 20, 32 lux every 4 weeks) in the enclosure using Clocklab software to control and monitor the experiment. Pawson and Bader (2014) experimented with 5 replicate pairs of LED and HPS lamps to compare which attracted more insects. The insects were caught using Perspex A2 catching pane and Tanglefoot-coated mylar. ...
One of the most pressing issues facing astronomy today is the growing threat of light pollution. Light pollution affects not only astronomical observations but also sustainability in the social and environmental sense. Light pollution has been reported to cause environmental changes by altering the circadian rhythm of organisms such as birds. In this work, we conducted a systematic review of data analyses on light pollution in the literature to assist researchers and those interested in light pollution. The results of the systematic review can be divided into four distinct phases, which are research objective, data collection, data preprocessing, and data analysis. Simple popularity for each phase shows the most popular approaches are measurement as a research objective at 47.46%, ground-based sensors for data collection at 31.91%, image preprocessing at 51.61%, and statistics & machine learning for data analysis at 64.29%. The most popular combination of each phase is a measurement objective with ground-based sensors for data collection without data preprocessing or analysis. This implies that a not insignificant number of studies seek to obtain ground measurements without further analysis of the data. Data analysis as an integral part of the effort for understanding light pollution needs to be used efficiently and effectively by all stakeholders in the pursuit of sustainability.
... The effect of ALAN on the development behavior of plant species has been widely studied. In their research about the ecological impact of ALAN on wild plants, Bennie and colleagues reported that ALAN could affect plants' germination, growth, flowering, phototropism, tissue repair, leaf retention, bud break, and increased disease susceptibility (11). Light, especially sunlight, has always been understood for its importance in enhancing photosynthesis, a natural process always necessary for the growth and nourishment of plant species. ...
... However, it has been identified that some other methods, such as flowering, germination, etc., are more sensitive to specific spectral compositions of visible light (8). For example (11,53, 54) explained the way plants respond to the spectral content of the light by associating the red portion of the light spectrum (625-760 nm) with flowering and the blue amount (360-480 nm) with induced seeds germination. Also, he associated the broad range of the light spectrum (360-760 nm) with photosynthesis or the decomposition of carbonic acid. ...
... Also, ALAN encourages continued growth, thus preventing some trees from developing dormancy in winter seasons, resulting in poor endurance of the harsh winter conditions (13,55). Previous research establishes that ALAN exposure on some urban plants can elongate their leaf retention in winter and initiate early commencement of bud burst in the spring, thereby exposing them to the risk of frostiness and pathogens (11,55). Photoperiodism is the seasonal and light-mediated process that influences leaf shape, surface hairiness (pubescence), and pigment formation in plant species. ...
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This paper attempts to realize the balance between humans and ecology in designing the nighttime light environment of urban parks by clarifying the influence of nighttime artificial light on the ecosystem of urban parks. Firstly, we reviewed the effects of nighttime artificial light on individual predation and reproduction of animals and personal growth and reproduction of plants. Secondly, we discuss the impact of individual changes caused by artificial lighting on ecosystem function at the ecosystem and analyze its advantages and disadvantages. The results showed that nighttime artificial light had a double-sided impact on the ecosystem, which would hurt the ecosystem function, but had a positive effect on the green space, which lacked natural light and had high plant density. This paper focuses on the areas with increased application of artificial lighting and rich species of animals and plants in night cities, such as urban forest parks and urban green spaces. It discusses how to reduce the intrusion of artificial lighting on ecosystems and how to make better use of the positive effect of artificial light.
... Light-based fisheries that use intense nocturnal illumination to attract and capture fish and squid also pose a threat to stormpetrels (Montevecchi, 2006(Montevecchi, , 2022Nguyen and Winger, 2018). While the influence of lighthouses is expected to decrease (Montevecchi, 2006), anthropogenic lighting along coasts, from fishing boats, and from other vessels is intensifying and increasing (Hung et al., 2021;Nguyen & Winger, 2018;Pawnson & Bader, 2014). Intense LED lights (lightemitting diode) are replacing incandescent sources (Hung et al., 2021;Pawnson & Bader, 2014;Rodríguez et al., 2017a), resulting in exponential increases in coastal lighting (Yamashita et al., 2012). ...
... While the influence of lighthouses is expected to decrease (Montevecchi, 2006), anthropogenic lighting along coasts, from fishing boats, and from other vessels is intensifying and increasing (Hung et al., 2021;Nguyen & Winger, 2018;Pawnson & Bader, 2014). Intense LED lights (lightemitting diode) are replacing incandescent sources (Hung et al., 2021;Pawnson & Bader, 2014;Rodríguez et al., 2017a), resulting in exponential increases in coastal lighting (Yamashita et al., 2012). ...
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The Leach's Storm-Petrel is a small seabird that forages in the deep ocean and has multiple colonies along the coast of Newfoundland, Canada. Their population is currently declining sharply, and light attraction may be a contributing factor. To determine if light attraction influences strandings, I investigated where, when, why, and which birds are stranding during the breeding season in Newfoundland using data from systematic single-site monitoring, social media, and personal communications. To assess when, where, and which birds were stranding, I created a map of strandings across the island and a graph to inform the peak stranding period whilst determining the percent of stranded adults versus fledglings. To determine why storm-petrels are stranding, I compared the number of birds that were collected each morning at the Bay de Verde fish plant when the lights were turned on versus off. Turning the lights off significantly reduced strandings by a factor of five. As well, most birds stranded along the Avalon Peninsula from September through October and were almost exclusively fledglings. These results emphasize the need for widespread reduction and modification of anthropogenic light across the province.
... 4000 K contain much blue spectrum in it is considered not appropriate for conservation. The use of LED lighting could be altered with high pressure sodium lamp, or warm white LED lamp which has long wavelength (Pawson & Bader 2014.) The second lighting is accentuation lighting. ...
... The incompatibility of this perimeter illumination using LED strip lamps concerning environmental issues is the application which is not hidden or integrated to features at parks and the use of blue colored light. The use of blue as the color of choice has a very bad impact, especially on the perimeter and under the bridge area (Pawson & Bader, 2014). The use of bollard lamps in the perimeter area is still considered adequate and can be used because the wrapping material used around the lamp is opaque glass so that it can still be tolerated, and the color of the lamp used is warm white or around 3600 K. ...
... However, in the past, lighting was applied without restraint as there was a lack of awareness about its impact, and today, our current use of lighting needs to be questioned because research carried out in the last 20+ years indicates that artificial light at night (ALAN) in cities and the light pollution this generates, especially from new lighting technology such as LEDs, can have negative, lasting consequences on the entire environment [1]. Cities, in this context, play a key role because incorrectly designed nighttime illumination(s) may adversely affect human health and well-being, resulting in road accidents and collisions [2], reduced pedestrian safety [3], lowered life quality [4], lack of sleep [5] and other health-related consequences [6]. ...
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Although sustainability and sustainable development are both considered necessary practices in various fields today, a recent analysis showed that the Sustainable Development Goal SDG11: Sustainable Cities and Communities established by the United Nations does not address urban illumination and its impact. This oversight is of concern because research carried out in the last 20+ years indicates artificial light at night (ALAN) in cities, and the light pollution this generates can have negative consequences on human health and well-being and the entire environment, including ecosystems and the flora and fauna that inhabit them. By applying a literature review, analysis and synthesis method, this work offers a new perspective on lighting and a timeline of key events that established ALAN and light pollution awareness in different disciplines and professional groups connected to urban illumination. It also identifies three fundamental aspects which require further transdisciplinary research and the translation of this knowledge into practice in order to enable the development of sustainable cities and communities at night. Finally, it presents in detail a new, theoretical environment-centred design framework for responsible urban illumination, with four iterative design phases, in order to help guide various stakeholders in cities, along with a four-level pyramid model that can be applied to urban illumination in the form of principles, processes, practices, and tools. This framework is especially relevant for those urban planners, architects, and landscape designers, who are unfamiliar with the subject in order to present the most effective and appropriate lighting design approach and methods that should be taken into consideration with the design of a given urban nighttime environment/situation.
... The sensitivity of biological traits to different wavelengths of light varies greatly, and spectral response curves have been derived for some key impacts (13,15). The shifts in spectra of artificial nighttime lighting and especially the increased emissions at blue wavelengths commonly associated with LED street lighting have been found to have substantial biological impacts (26)(27)(28). Here, we focus on how the Europe-wide changes in the spectral composition of emissions have influenced three exemplars, the suppression of melatonin production, the visibility of stars, and the phototaxic response of insects. ...
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The nighttime environment of much of Earth is being changed rapidly by the introduction of artificial lighting. While data on spatial and temporal variation in the intensity of artificial lighting have been available at a regional and global scale, data on variation in its spectral composition have only been collected for a few locations, preventing variation in associated environmental and human health risks from being mapped. Here, we use imagery obtained using digital cameras by astronauts on the International Space Station to map variation in the spectral composition of lighting across Europe for 2012-2013 and 2014-2020. These show a regionally widespread spectral shift, from that associated principally with high-pressure sodium lighting to that associated with broad white light-emitting diodes and with greater blue emissions. Reexpressing the color maps in terms of spectral indicators of environmental pressures, we find that this trend is widely increasing the risk of harmful effects to ecosystems.
... It is less clear whether sodium lights (HPS and LPS) or LED are more attractive. Some studies found a higher attraction of sodium lights(Huemer et al. 2010;Eisenbeis and Eick 2011;), others found a higher attraction of LED(Pawson and Bader 2014;Wakefield et al. 2017). As described in chapter 3.1.1, ...
Technical Report
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Review on the current knowledge of the impact of artificial light on marine and coastal habitats with special focus on the Waddensea and intertidal areas.
... La combinación de la información de las imágenes satelitales de día y de noche será relevante porque diversos estudios han encontrado que las luces de noche son fuente de contaminación (Levin et al., 2020) y pueden estar amenazando la biodiversidad de las especies (Pauwels et al., 2019). En este contexto, se están dando diversas iniciativas para usar luces más ecológicas; por ejemplo, se viene recomendando el uso de LED (Pawson & Bader, 2014). En concreto, mientras sigamos utilizando los mismos sistemas para iluminarnos en la noche, las imágenes satelitales tomadas durante la noche serán útiles para estimar el PIB. ...
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The expansion of human activity into natural habitats often results in the introduction of artificial light at night, which can disrupt local ecosystems. Recent advances in LED technology have enabled spectral tuning of artificial light sources, which could in theory limit their impact on vulnerable taxa. To date, however, experimental comparisons of ecologically friendly candidate colors have often considered only one type of behavioral impact, sometimes on only single species. Resulting recommendations cannot be broadly implemented if their consequences for other local taxa are unknown. Working at a popular firefly ecotourism site, we exposed the insect community to artificial illumination of three colors (blue, broad-spectrum amber, red) and measured flight-to-light behavior as well as the courtship flash behavior of male Photinus carolinus fireflies. Firefly courtship activity was greatest under blue and red lights, while the most flying insects were attracted to blue and broad-spectrum amber lights. Thus, while impacts of spectrally tuned artificial light varied across taxa, our results suggest that red light, rather than amber light, is least disruptive to insects overall, and therefore more generally insect friendly.
With rapid urbanization, the use of external lighting to illuminate cities for night-time activity is on the rise worldwide. Many studies have suggested the excessive use of external lighting causes light pollution, which harms human health and leads to energy wastage. Although more awareness has been raised, there are not many regulations and guidelines available. As one of the cities most affected by light pollution in the world, Hong Kong has started exploring this issue within the general and business communities. However, studies that quantitatively evaluate the problem of light pollution in this city are lacking. This study aimed to assess light pollution quantitatively through measurement and numerical modelling. To achieve this, measurement protocols were developed, and site measurements were carried out in one of the known problem areas, Sai Yeung Choi Street in Mong Kok district. Through this exercise, both vertical and horizontal illuminances on the street level and the light distribution along the street were determined. An average level of 250 lx for the vertical illuminance was found, which was 3–4 times higher than the recommended brightness for normal activity. The light environment of the measured area was also modelled with the simulation program DIALux. This effort complemented the measurements by providing a means to increase the resolution on the light variation and to visualize light pollution in a 3D environment. The simulation results were verified by correlating the numerical model with measurements. The correlated model was exercised in a subsequent sensitivity study to predict possible outcomes with changing lighting pattern and lighting lumen level. This study serves to quantify this issue, which helps with the further development of effective solutions.
Technical Report
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Description Fit linear and generalized linear mixed-effects models. The models and their components are represented using S4 classes and methods. The core computational algorithms are implemented using the 'Eigen' C++ library for numerical linear algebra and 'RcppEigen' ``glue''.
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Among anthropogenic pressures, light pollution altering light/dark cycles and changing the nocturnal component of the environment constitutes a threat for biodiversity. Light pollution is widely spread across the world and continuously growing. However, despite the efforts realized to describe and understand the effects of artificial lighting on fauna, few studies have documented its consequences on biological rhythms, behavioral and physiological functions in nocturnal mammals. To determine the impacts of light pollution on nocturnal mammals an experimental study was conducted on a nocturnal primate, the grey mouse lemur Microcebus murinus. Male mouse lemurs (N = 8) were exposed 14 nights to moonlight treatment and then exposed 14 nights to light pollution treatment. For both treatments, chronobiological parameters related to locomotor activity and core temperature were recorded using telemetric transmitters. In addition, at the end of each treatment, the 14(th) night, nocturnal and feeding behaviors were explored using an infrared camera. Finally, throughout the study, body mass and daily caloric food intake were recorded. For the first time in a nocturnal primate, light pollution was demonstrated to modify daily rhythms of locomotor activity and core temperature especially through phase delays and increases in core temperature. Moreover, nocturnal activity and feeding behaviors patterns were modified negatively. This study suggests that light pollution induces daily desynchronization of biological rhythms and could lead to seasonal desynchronization with potential deleterious consequences for animals in terms of adaptation and anticipation of environmental changes.
Limitations of linear regression applied on ecological data. - Things are not always linear additive modelling. - Dealing with hetergeneity. - Mixed modelling for nested data. - Violation of independence - temporal data. - Violation of independence spatial data. - Generalised linear modelling and generalised additive modelling. - Generalised estimation equations. - GLMM and GAMM. - Estimating trends for Antarctic birds in relation to climate change. - Large-scale impacts of land-use change in a Scottish farming catchment. - Negative binomial GAM and GAMM to analyse amphibian road killings. - Additive mixed modelling applied on deep-sea plagic bioluminescent organisms. - Additive mixed modelling applied on phyoplankton time series data. - Mixed modelling applied on American Fouldbrood affecting honey bees larvae. - Three-way nested data for age determination techniques applied to small cetaceans. - GLMM applied on the spatial distribution of koalas in a fragmented landscape. - GEE and GLMM applied on binomial Badger activity data.
Artificial lighting is a key biodiversity threat and produces 1900 million tonnes of CO2 emissions globally, more than three times that produced by aviation. The need to meet climate change targets has led to a global increase in energy‐efficient light sources such as high‐brightness light‐emitting diodes (LEDs). Despite the energetic benefits of LEDs, their ecological impacts have not been tested. Using an experimental approach, we show that LED street lights caused a reduction in activity of slow‐flying bats ( Rhinolophus hipposideros and Myotis spp.). Both R. hipposideros and Myotis spp. activities were significantly reduced even during low light levels of 3.6 lux. There was no effect of LED lighting on the relatively fast‐flying Pipistrellus pipistrellus, Pipistrellus pygmaeus and Nyctalus/Eptesicus spp. We provide the first evidence of the effects of LED lights on bats. Despite having considerable energy‐saving benefits, LED lights can potentially fragment commuting routes for bats with associated negative conservation consequences. Our results add to the growing evidence of negative impacts of lighting on a wide range of taxa. We highlight the complexities involved in simultaneously meeting targets for reduction of greenhouse gas emissions and biodiversity loss. New lighting strategies should integrate climate change targets with the cultural, social and ecological impacts of emerging lighting technologies.
1. Population declines among insects are inadequately quantified, yet of vital importance to national and global biodiversity assessments and have significant implications for ecosystem services. 2. Substantial declines in abundance and distribution have been reported recently within a species-rich insect taxon, macro-moths, in Great Britain and other European countries. These declines are of concern because moths are important primary consumers and prey items for a wide range of other taxa, as well as contributing to ecosystem services such as pollination. 3. I summarise these declines and review potential drivers of change. Direct evidence for causes of moth declines is extremely limited, but correlative studies and extrapolation from closely related taxa suggest that habitat degradation (particularly because of agricultural intensification and changing silviculture) and climate change are likely to be major drivers. There is currently little evidence of negative population-level effects on moths caused by chemical or light pollution, non-native species or direct exploitation. 4. I make suggestions for future research with a focus on quantifying impacts of land management practices, light pollution and climate change on moth population dynamics and developing evidence-based measures that can be incorporated into agri-environment schemes and other policy initiatives to help reverse the widespread decline of moths in Great Britain and beyond.
1. There is a growing concern that artificial light might affect local insect populations and disrupt their dispersal across the landscape. In this study, we investigated experimentally the effect of artificial light on flying insects in the field, with an emphasis on aquatic insects. We asked whether lights prevented the ability of insects to disperse across the landscape, a process that is crucial in col-onising restored habitats. 2. We set up six, c. 3.5 m high downward facing high-pressure sodium streetlights along a perma-nently connected oxbow in the Spree River of eastern Germany. We collected insects using 12 flight intercept traps, each with trays at three different heights (0.5, 1.5 and 2.5 m), placed at distances 0, 3, 40 and 75 m from the lights and 5, 8 and 80 m from water. The number of emerging aquatic insects in the study area was measured with six emergence traps. We emptied the traps 22 times between June and September 2010; the lights were on for 11 of these nights and off for the other 11. 3. In total, we caught almost 27 times as many insects at traps 0 m from the lights when the lights were on than when they were off. Most insects caught when the lights were on were aquatic, with Diptera being the most common order. Furthermore, the proportion of aquatic insects caught at traps 0, 3 and 40 m from the lights when they were on was significantly higher than when they were off. On lit nights, more aquatic insects were captured per hour and m 2 (area in which flying insects were intercepted) at traps 0 m from the lights than emerged from per square metre per hour from the Spree River. 4. Our results suggest that adult aquatic insects can be negatively affected by artificial light and that city planners should take this into account when designing lighting systems along rivers.
During the last decades, artificial night lighting has increased globally, which largely affected many plant and animal species. So far, current research highlights the importance of artificial light with smaller wavelengths in attracting moths, yet the effect of the spectral composition of artificial light on species richness and abundance of moths has not been studied systematically. Therefore, we tested the hypotheses that (1) higher species richness and higher abundances of moths are attracted to artificial light with smaller wavelengths than to light with larger wavelengths, and (2) this attraction is correlated with morphological characteristics of moths, especially their eye size. We indeed found higher species richness and abundances of moths in traps with lamps that emit light with smaller wavelengths. These lamps attracted moths with on average larger body mass, larger wing dimensions and larger eyes. Cascading effects on biodiversity and ecosystem functioning, e.g. pollination, can be expected when larger moth species are attracted to these lights. Predatory species with a diet of mainly larger moth species and plant species pollinated by larger moth species might then decline. Moreover, our results indicate a size-bias in trapping moths, resulting in an overrepresentation of larger moth species in lamps with small wavelengths. Our study indicates the potential use of lamps with larger wavelengths to effectively reduce the negative effect of light pollution on moth population dynamics and communities where moths play an important role.