Low Levels Of Light Pollution Research Articles

Living on the edge: urban fireflies (Coleoptera, Lampyridae) in Morelia, Michoacán, Mexico.

Fireflies (Coleoptera, Lampyridae) are a globally threatened group of insects due to habitat loss and fragmentation, light pollution, climate change and pesticides. However, against all odds, some firefly populations persist in urbanized environments where all four of these factors are present simultaneously. In this work, we compiled several data sources to document the diversity of fireflies in the urbanized area of Morelia, characterize their current habitats, and determine the main stressors affecting these bioluminescent insects. We found seven genera and 26 species of fireflies (19 nocturnal, seven diurnal) associated with 32 urban, peri-urban and extra-urban areas; at least, 14 are new records for Michoacán, and the list for the state now includes nine genera and 41 species. Five additional sites were documented as extinction sites. We compared the characteristics of these five sites with those of the sites with extant populations. We found that in Morelia, fireflies are mainly associated with areas that have high to moderate proportions of vegetation cover, are near water bodies, have very gentle to moderate slopes, and are exposed to low levels of light pollution. In contrast, the extinction sites showed high proportions of artificial surfaces and high levels of light pollution. Because some fireflies are considered bioindicators of ecosystem integrity as they are associated to specific habitats, are highly diverse and due to their sensitivity to environmental changes, we consider that sites from Morelia's urban core and extinction sites show the highest levels of environmental degradation, threatening most fireflies and other insects living in the urban core with local extinction. At the same time, our results also suggest that implementing conservation strategies and sustainable planning for the urban development of Morelia in the short term could allow fireflies and other vital elements of the city's insect communities to persist for future generations. Restoration and conservation of green areas and nighttime environments are essential for biodiversity and human health, especially in intra-urban zones.

Life history traits modulate the influence of environmental stressors on biodiversity: The case of fireflies, climate and artificial light at night

AbstractAimArtificial light at night (ALAN) is an unprecedented stressor recently introduced in the abiotic milieu of natural landscapes. As such, understanding how ALAN and other natural stressors act in concert to shape the spatial distribution of biodiversity is a core goal in conservation ecology. Here, we aim at understanding how ALAN and climate interact with life history traits and courtship signalling systems to dictate the composition of firefly communities in a global biodiversity hotspot.LocationAn extensive elevational gradient in the Atlantic rain forest (Brazil) currently known as the hottest hotspot of fireflies on Earth.MethodsWe used multivariate species distribution models to understand how species traits and courtship signalling systems interact with climate and ALAN to determine species abundance within firefly communities. We also investigated how species‐specific responses to climate and ALAN scale up to determine compositional changes in firefly communities along the elevational gradient.ResultsWe found that climate shapes communities by filtering species according to their body size and trophic position. ALAN dictates the dominant courtship signalling system within communities by affecting the abundance of species that use bioluminescence or a combination of bioluminescence and pheromones in courtship. We also found that associations between beta‐diversity and ALAN were non‐stationary, being higher in regions under low levels of light pollution. This suggests that even incipient increases in ALAN within protected areas can yield fast changes in the composition of firefly communities.Main ConclusionsFirefly responses to climate and ALAN are modulated by traits associated with different facets of their life histories. Given the alarming changes in both stressors predicted for the foreseeable future, our findings indicate that firefly communities are vulnerable to compositional changes even within protected areas.

Avoidance of different durations, colours and intensities of artificial light by adult seabirds

There is increasing evidence for impacts of light pollution on the physiology and behaviour of wild animals. Nocturnally active Procellariiform seabirds are often found grounded in areas polluted by light and struggle to take to the air again without human intervention. Hence, understanding their responses to different wavelengths and intensities of light is urgently needed to inform mitigation measures. Here, we demonstrate how different light characteristics can affect the nocturnal flight of Manx shearwaters Puffinus puffinus by experimentally introducing lights at a colony subject to low levels of light pollution due to passing ships and coastal developments. The density of birds in flight above the colony was measured using a thermal imaging camera. We compared number of flying shearwaters under dark conditions and in response to an artificially introduced light, and observed fewer birds in flight during ‘light-on’ periods, suggesting that adult shearwaters were repelled by the light. This effect was stronger with higher light intensity, increasing duration of ‘light-on’ periods and with green and blue compared to red light. Thus, we recommend lower light intensity, red colour, and shorter duration of ‘light-on’ periods as mitigation measures to reduce the effects of light at breeding colonies and in their vicinity.

The impact of atmospheric aerosol particles on the brightness of the night sky

This paper analyses the impact of various types of aerosols, both of natural and anthropogenic origin, on the brightness of the night sky glow in southern Poland. The particles of particulate matter, related to the combustion of solid fuels in the winter, the volcanic or desert dust, as well as mists and haze, are considered as the artificial light scattering sources. Measurements of the brightness of the cloudless and moonless night sky were done in 2009–2016, both within the city of Krakow and in suburban areas, as well as in mountainous ones. The strong linear correlation between the brightness of such sky and the concentration of particulate matter is shown. The acoustic sounding of the atmosphere (SODAR) has indicated the possibility of a relationship between the brightness of the night sky and the amount of such particulates, which accumulate in atmospheric boundary layers. The usefulness of the theoretical model of horizontal transport of dust in the atmosphere (FAPPS) for forecasting the brightness of the night sky glow is also pointed out. A clear effect of the Saharan origin dust clouds on the brightness of the night sky glow is shown. This brightness, in the conditions of a low level of light pollution, is associated with the forecasted optical density of such clouds. It is also demonstrated, that with the thickening of mist, the impact of distant light sources on the brightness of the night sky decreases, but the one of a nearby sources becomes more significant. The conclusion states that anthropogenic particulate matter has the greatest impact on the brightness of the cloudless night sky glow in winter. In areas heavily polluted with light, fogs and mist are particularly important. In areas with low levels of light pollution, the clear impact of desert dust is visible.

The use of socio-economy in species distribution modelling: Features of rural societies improve predictions of barn owl occurrence

Variation of habitats and resources important for farmland birds seems to be only partly captured by ordinary statistics on land-use and agricultural production. For instance, densities of rodents being prey for owls and raptors or structures of rural architecture providing nesting sites for many species are central for bird diversity but are not reported in any official statistics. Thus, modelling species distributions, population abundance and trends of farmland birds may miss important predictive habitat elements. Here, we involve local socio-economy factors as a source of additional information on rural habitat to test whether it improves predictions of barn owl occurrence in 2768 churches across Poland. Barn owls occurred in 778 churches and seemed to prefer old churches made of brick located in regions with a milder climate, higher share of arable land and pastures, low road density and low levels of light pollution. Including data on local unemployment, the proportion of elder citizens, commune income per citizen, the share of citizens with high education and share of farmers among working population improved the model substantially and some of these variables predicted barn owl occurrence better than several land-use and climate data. Barn owls were more likely to occur in areas with high unemployment, a higher proportion of older citizens in a local population and higher share of farmers among working population. Importantly, the socio-economy variables were correlated with the barn owl occurrence despite all climatic, infrastructure and land-use data were present in the model. We conclude that the socio-economy of local societies may add important but overlooked information that links to spatial variation in farmland biodiversity.

Artificial light at night does not alter heart rate or locomotor behaviour in Caribbean spiny lobster (Panulirus argus): insights into light pollution and physiological disturbance using biologgers.

Light pollution is a rapidly growing threat to biodiversity, with many unknown or poorly understood effects on species and ecosystems spanning terrestrial and aquatic environments. Relative to other taxa, the effects of artificial light at night on aquatic invertebrates are poorly understood, despite the abundance and integral significance of invertebrates to marine and freshwater ecosystems. We affixed heart rate and acceleration biologgers to adult Caribbean spiny lobster (Panulirus argus), an ecologically, culturally and economically significant species in the western Atlantic ocean, to test the effect of artificial light at night on this species' physiology and behaviour relative to appropriate controls. The experiment was conducted in a simulated reef mesocosm in The Bahamas with incandescent lighting used to illuminate it at 1 lux, approximating light levels offshore of urban areas. In the conditions tested here, artificial light at night was found to have no effect on heart rate or locomotor activity in P. argus. We observed a dissociation between activity and heart rate at both short-term and long-term temporal scales. Lobsters were more active at night and nocturnal activity was higher in trials closer to new moon; however, heart rate did not vary with diel or lunar cycle. There was less than 8% difference between daytime and night time average heart rate despite the average percentage of time spent active almost tripling in nights versus days, to 19.5% from 7.2%, respectively. Our findings suggest P. argus may have some resilience to low levels of light pollution, which warrants further research on aspects of this species' life history, performance and fitness in the face of this potential anthropogenic disturbance.

Overnight measurements of the sky brightness as a method for assessing the cloudiness

Determining the state of cloudiness at night is always a problem, especially at low levels of light pollution. This paper presents an innovative method of assessing the cloudiness of the night sky solely on the basis of all-night measurements of the brightness of the sky using generally available SQM meters. Using the numerical method of calculating the discrete derivative of the overnight brightness of the night sky from time it is possible not only to distinguish a cloudless sky from a cloudy one, but even to distinguish the high level clouds from medium and low level ones. Full Text: PDF ReferencesKyba C.C.M., Ruhtz T., Fischer J., Hölker F., Cloud Coverage Acts as an Amplifier for Ecological Light Pollution in Urban Ecosystems, PLoS ONE, vol. 6, no. 3, 2011, e17307. CrossRef Ściężor T., The impact of clouds on the brightness of the night sky, to be published in Journal of Quantitative Spectroscopy and Radiative Transfer, 2020 CrossRef Ściężor T., Kubala M., Kaszowski W., Light Pollution of the Mountain Areas in Poland, Archives of Environmental Protection, Vol.38, No.4, 2012, pp. 59-69. CrossRef Crawford D.L., Photometry: terminology and units in the lighting and astronomical sciences, The Observatory, vol. 117, 1997, pp. 14-18. DirectLink Ściężor T., Kubala M., Particulate matter as an amplifier for astronomical light pollution, Monthly Notices of the Royal Astronomical Society, vol. 444, no. 3, 2014, pp. 2487-2493. CrossRef

REMOTE SENSING OF LIGHT POLLUTION IN BOSNIA AND HERZEGOVINA

The study deals with the problem of light pollution in Bosnia and Herzegovina in the period 2013-2017. Remotely sensed data were obtained from the Suomi NPP satellite, which is scanning the earth's surface at night. The findings and geospatial trends of light pollution in the mentioned time period are discussed on the national and municipal levels. Some areas with very high and low levels of light pollution were exposed.

Long-term dim light during nighttime changes activity patterns and space use in experimental small mammal populations

Artificial light at night (ALAN) is spreading worldwide and thereby is increasingly interfering with natural dark-light cycles. Meanwhile, effects of very low intensities of light pollution on animals have rarely been investigated. We explored the effects of low intensity ALAN over seven months in eight experimental bank vole (Myodes glareolus) populations in large grassland enclosures over winter and early breeding season, using LED garden lamps. Initial populations consisted of eight individuals (32 animals per hectare) in enclosures with or without ALAN. We found that bank voles under ALAN experienced changes in daily activity patterns and space use behavior, measured by automated radiotelemetry. There were no differences in survival and body mass, measured with live trapping, and none in levels of fecal glucocorticoid metabolites. Voles in the ALAN treatment showed higher activity at night during half moon, and had larger day ranges during new moon. Thus, even low levels of light pollution as experienced in remote areas or by sky glow can lead to changes in animal behavior and could have consequences for species interactions.

Systematic measurements of the night sky brightness at 26 locations in Eastern Austria

We present an analysis of the zenithal night sky brightness (henceforth: NSB) measurements at 26 locations in Eastern Austria focussing on the years 2015–2016, both during clear and cloudy to overcast nights. All measurements have been performed with ‘Sky Quality Meters’ (SQMs). For some of the locations, simultaneous aerosol content measurements are available, such that we were able to find a correlation between light pollution and air pollution at those stations. For all locations, we examined the circalunar periodicity of the NSB, seasonal variations as well as long-term trends in the recorded light pollution. The latter task proved difficult, however, due to varying meteorological conditions, potential detector ‘aging’ and other effects. For several remote locations, a darkening of the overcast night sky by up to 1 magnitude is recorded – indicating a very low level of light pollution –, while for the majority of the examined locations, a brightening of the night sky by up to a factor of 15 occurs due to clouds. We present suitable ways to plot and analyze huge long-term NSB datasets, such as mean-NSB histograms, circalunar, annual (‘hourglass’) and cumulative (‘jellyfish’) plots. We show that five of the examined locations reach sufficiently low levels of light pollution – with NSB values down to 21.8 magSQM/arcsec2 – as to allow the establishment of dark sky reserves, even to the point of reaching the ‘gold tier’ defined by the International Dark Sky Association. Based on the ‘hourglass’ plots, we find a strong circalunar periodicity of the NSB in small towns and villages ( < 5.000 inhabitants), with amplitudes of up to 5 magnitudes. Using the ‘jellyfish’ plots, on the other hand, we demonstrate that the examined city skies brighten by up to 3 magnitudes under cloudy conditions, which strongly dominate in those cumulative data representations. Nocturnal gradients of the NSB of 0.0–0.14 magSQM/arcsec2/h are found. The long-term development of the night sky brightness was evaluated based on the 2012–17 data for one of our sites, possibly indicating a slight ( 2%) decrease of the mean zenithal NSB at the Vienna University Observatory.

Lunar Phase Modulates Circadian Gene Expression Cycles in the Broadcast Spawning Coral Acropora millepora.

Many broadcast spawning corals in multiple reef regions release their gametes with incredible temporal precision just once per year, using the lunar cycle to set the night of spawning. Moonlight, rather than tides or other lunar-regulated processes, is thought to be the proximate factor responsible for linking the night of spawning to the phase of the Moon. We compared patterns of gene expression among colonies of the broadcast spawning coral Acropora millepora at different phases of the lunar cycle, and when they were maintained under one of three experimentally simulated lunar lighting treatments: i) lunar lighting conditions matching those on the reef, or lunar patterns mimicking either ii) constant full Moon conditions, or iii) constant new Moon conditions. Normal lunar illumination was found to shift both the level and timing of clock gene transcription cycles between new and full moons, with the peak hour of expression for a number of genes occurring earlier in the evening under a new Moon when compared to a full Moon. When the normal lunar cycle is replaced with nighttime patterns equivalent to either a full Moon or a new Moon every evening, the normal monthlong changes in the level of expression are destroyed for most genes. In combination, these results indicate that daily changes in moonlight that occur over the lunar cycle are essential for maintaining normal lunar periodicity of clock gene transcription, and this may play a role in regulating spawn timing. These data also show that low levels of light pollution may have an impact on coral biological clocks.

Low levels of light pollution may block the ability of male glow-worms (Lampyris noctiluca L.) to locate females

Light pollution has been proposed as a factor in the decline of Lampyris noctiluca because it has the potential to interfere with reproductive signaling and has been shown to impact the ability of males to locate light lures in a suburban environment. To compare and test the replicability of this effect in a natural setting and population, imitation females were set out under light polluted and control conditions at varying light pollution intensities in an undisturbed British chalk grassland. Very low levels of light pollution were found to interfere with phototaxis: no males were attracted at either 0.3 or 0.18 lux background lighting versus 33 males collected at paired dark controls. These background illumination levels are much lower than that of 1.5 lux which is recommended by local city councils in Britain to light footpaths. A survey of female L. noctiluca numbers and distribution showed a trend towards female clumping that was not statistically significant. We also found no evidence of light interfering with female signaling behavior.

Mice exposed to dim light at night exaggerate inflammatory responses to lipopolysaccharide

The mammalian circadian system regulates many physiological functions including inflammatory responses. Appropriately timed light information is essential for maintaining circadian organization. Over the past ∼120 years, urbanization and the widespread adoption of electric lights have dramatically altered lighting environments. Exposure to light at night (LAN) is pervasive in modern society and disrupts core circadian clock mechanisms. Because microglia are the resident macrophages in the brain and macrophages contain intrinsic circadian clocks, we hypothesized that chronic exposure to LAN would alter microglia cytokine expression and sickness behavior following LPS administration. Exposure to 4 weeks of dim LAN elevated inflammatory responses in mice. Mice exposed to dimly lit, as compared to dark, nights exaggerated changes in body temperature and elevated microglia pro-inflammatory cytokine expression following LPS administration. Furthermore, dLAN mice had a prolonged sickness response following the LPS challenge. Mice exposed to dark or dimly lit nights had comparable sickness behavior directly following the LPS injection; however, dLAN mice showed greater reductions in locomotor activity, increased anorectic behavior, and increased weight loss than mice maintained in dark nights 24h post-LPS injection. Overall, these data suggest that chronic exposure to even very low levels of light pollution may alter inflammatory responses. These results may have important implications for humans and other urban dwelling species that commonly experience nighttime light exposure.

Effect of artificial night lighting on temporally partitioned spiny mice

Abstract We studied the effect of ecological light pollution on a rocky desert community, focusing on 2 spiny mouse congeners, nocturnal Acomys cahirinus (common spiny mouse) and diurnal Acomys russatus (golden spiny mouse). We hypothesized that in response to artificial illumination A. cahirinus will decrease its activity and A. russatus will increase its activity, and thus temporal overlap and interspecific competition could increase. Our study took place in 4 field enclosures: the 1st and 3rd months were controls with natural light, and in the 2nd month artificial illumination, simulating low levels of light pollution, was set for the first 3 h of the night. We implanted temperature-sensitive radiotransmitters to monitor mouse activity, and individual identification tags with automonitored foraging patches were used to track foraging behavior. A. cahirinus decreased activity and foraging with artificial lighting, restricting movement particularly in less-sheltered microhabitats, probably because of inc...

Quantitative genetics of bud phenology, frost damage, and winter survival in an F2 family of hybrid poplars

We studied the quantitative genetics of bud phenology, fall frost damage, and winter survival in an F2 family (no. 822) of Populus hybrids derived from a cross between two full-sub F1 hybrids (P. trichocarpa (Torr. & Gray×P. deltoides Bartr.). Field traits studied included the timing of bud set (BSF) in Minnesota and Oregon, the timing of bud flush (BFF) in Oregon, as well as fall frost damage (FDF) and winter survival (WSF) in Minnesota. We conclude that Family 822 has substantial genetic variability for all field traits, BSF and BFF are under moderate to strong genetic control (H 2 i =0.48–0.80), FDF and WSF are under low to moderate genetic control (H 2 i =0.27–0.40), and late bud set is associated with increased frost damage and decreased winter survival. In a warm greenhouse, we measured the timing of bud set and the number of new leaves on trees growing under either an 8-h photoperiod (BSSD and NLSD) or a natural photoperiod (NP) from August to December (BSNP and NLNP). We found that BSSD, NLSD, and NLNP are under moderate genetic control (H 2 i =0.53–0.70), but the heritability of BSNP could not be determined because few trees set bud in the warm greenhouse under the NP. By comparing results from the greenhouse experiments with results from the field, we conclude that the genetic correlation between BSSD and BSF (0.53–0.60) is relatively modest and that NPs in the fall are relatively ineffective at promoting bud set under warm greenhouse temperatures, although bud set readily occurred in the field. Although, low levels of light pollution in the greenhouse might have affected BSNP, results from both greenhouse and field experiments suggest that genetic differences in photoperiodic responses play a modest role in explaining genetic differences in the timing of bud set under natural field conditions. Therefore, genetic differences in responses to other environmental factors, such as temperature, deserve greater attention.