Effects Of Artificial Light Research Articles

The duration of artificial light defines sexual signalling in the common glow-worm

Artificial light at night is increasing globally, interfering with both sensory ecology and temporal rhythms of organisms, from zooplankton to mammals. This interference can change the behaviour of the affected organisms, and hence compromise the viability of their populations. Limiting the use of artificial light may mitigate these negative effects. Accordingly, we investigated whether the duration of artificial light affects sexual signalling in female glow-worms, Lampyris noctiluca, which are flightless and attract flying males to mate by emitting glow that is interfered by light pollution. The study included three treatments: no artificial light (control), 15 min of artificial light, and 45 min of artificial light. The results show that females were more likely to cease glowing when the exposure to light was longer. Furthermore, small females were more likely to cease their glow, and responded faster to the light, than larger females. These findings suggest that glow-worms can react rapidly to anthropogenic changes in nocturnal light levels, and that prolonged periods of artificial light trigger females to stop sexual signalling. Thus, limiting the duration of artificial light can mitigate the adverse effects of light pollution on sexual signalling, highlighting the importance of such mitigation measures.Significance statementInterest in the effects of artificial light at night on animal behaviour has increased in recent years. With evidence for its negative impact accumulating, potential remedies, such as limiting the duration of light exposure, have emerged. To date, however, knowledge on the effectiveness of these methods has remained very limited. We show that female European common glow-worms, which are wingless beetles that glow to attract flying males to mate, responded to prolonged artificial light exposure by discontinuing their glow. Such non-glowing females are not expected to find a mate, making it difficult for them to reproduce. Hence, our study indicates that the duration of artificial light should be limited to protect this night-active beetle and its opportunities for effective sexual signalling. Because many other nocturnal species also need darkness, this study provides valuable information for the development and use of less disruptive night-time lights.

The effect of artificial light on bat richness and nocturnal soundscapes along an urbanization gradient in an arid landscape of central Peru

The effect of artificial light on bat richness and nocturnal soundscapes along an urbanization gradient in an arid landscape of central Peru

Effects of artificial light at night on the leaf functional traits of freshwater plants

Abstract The increasing use of artificial light at night has led to ecosystem exposure to light pollution worldwide. Aquatic ecosystems are particularly exposed, since lit road networks, urban development and industrial infrastructure are frequently located along river, lake, and sea shores. Although the negative effects of night‐time lighting on the physiology, behaviour, and life‐history traits of animals have been largely documented, there is a large knowledge gap about the responses of plants, especially regarding leaf functioning and resource‐management strategies. Some authors have proposed contrasting hypotheses of mechanistic responses to dim light at night in plants, but empirical results are still lacking. Based on field measurements of nocturnal irradiance in freshwater ecosystems located in peri‐urban areas, we performed a mesocosm experiment using three species of submerged aquatic plants. After 5 months of exposure to realistic dim light at night, four functional traits related to the resource management at the leaf level were measured. Artificial light at night had significant effects on the leaf physiology or chemistry, affecting their resource acquisition rate, but with different response intensities depending on the species. No effect was found on morphological or biomechanical traits for any of the studied species. These results support the hypothesis that plants could interpret dim light at night as a shaded environment and respond accordingly. We demonstrated that the effects of light at night on plants may have been underestimated in previous work. By modifying biotic interactions (e.g., competition and herbivory), these responses can have profound effects on community structure and ecosystem functioning.

Effects of artificial light with different wavelengths and irradiances on the sleep behaviors of Chestnut buntings (Emberiza rutila)

ABSTRACT Artificial light owns a rapid-expanding pattern, which may disrupt the sleep behaviors of birds roosting in illuminated urban areas. Whether the birds’ sleep would variably be affected by light with different wavelengths or intensities has not been broadly explored, and the species in Eastern China have rarely been investigated. The study chose Chestnut buntings that are a common migratory species flying via Eastern China as the subjects and investigated their sleep in response to five light spectrums at three ecologically relevant intensities. It shows that artificial light mainly delayed sleep onset, reduced sleep duration and increased frequency of awakenings, which to the largest degrees resulted in a 3-h delay of sleep onset, 25% reduction of sleep and 0.31 times/h more nocturnal awakenings. Awakening time was delayed at higher light intensity while being advanced in dimmed light. The effect of light spectrums overall ranked from the most to the least as 510 nm green, 580 nm yellow or white, and 470 nm blue or 620 nm orange light; the sleep parameters were affected more with higher light intensities. The study highlights the potential of adjusting spectral compositions of light source to mitigate the disturbance of artificial light to avian sleep.

Effects of artificial light at night on the nest-site selection, reproductive success and behavior of a synanthropic bird

Understanding how artificial light at night (ALAN) impacts wildlife is increasingly important because more and more species are colonizing urban areas. As most of the bird studies on ALAN use controlled light set inside or around nest-boxes, the ecological effect of ALAN resulting from in situ streetlight on birds remains contentious. The barn swallow (Hirundo rustica) often builds open nests on buildings, which are directly exposed to varying intensity of ALAN, and thus provides a good system to examine the effect of in situ ALAN on birds. By examining the nest-site selection, reproductive success and behavior of barn swallows under various ALAN intensity in Taipei City, we found a positive effect of ALAN on their fledging success; nonetheless, such effect was only found in the swallows’ first brood, but not second one. We also found that parent birds in the nests with higher ALAN intensity had higher feeding rates and more extended feeding time past sunset, which were likely stimulated by the increased begging behavior of their chicks. The night-feeding behavior might contribute to the increased fledging success, especially at the early breeding season. Interestingly, despite of the reproductive benefits obtained from ALAN, we found that the barn swallows did not select nest sites regarding ALAN intensity. The weak nest-site selection perhaps result from the complex life history interactions involving ALAN and/or confounding factors associated with ALAN in cities. This study improves our understanding of how urban birds, especially open-nesting ones, respond to in situ ALAN and provides useful information for developing urban conservation strategies.

Assessment of the effect on the human body of the flicker of OLED displays of smartphones

This paper considers the effects on the human body of the flicker of organic light-emitting diode (OLED) displays. Related studies have been conducted due to reports of cases of adverse health effects of the use of artificial lighting. Interest in this problem recently intensified with the development of various new displays and the longer exposure time of people to them. Therefore, the previous studies on the effects of artificial lighting on the human body are described in this paper, and based on them, the dimming technique for liquid-crystal displays and OLED displays of smartphones is explained and the effect of the flicker of OLED displays on the human body is assessed.

Effects of Artificial Light at Night on Avian Provisioning, Corticosterone, and Reproductive Success.

Artificial light at night (hereafter "ALAN") affects 88% of the land area in Europe and almost half of the land area in the USA, with even rural areas exposed to lights from agricultural and industrial buildings. To date, there have been few studies that assess the impacts of ALAN on both wildlife behavior and physiology. However, ALAN may alter energy expenditure and/or stress physiology during the breeding period, potentially reducing reproductive success and resulting in conservation implications. Here, we experimentally exposed adult female and nestling tree swallows (Tachycineta bicolor) to ALAN. We then measured the effects of ALAN compared with control conditions on parental behavior (provisioning rate), nestling physiology (corticosterone levels), and reproductive success (likelihood of all eggs hatching and all nestlings fledging per nest). Our results showed that ALAN-exposed females provisioned their nestlings at lower rates than control females. Although relatively weak, our results also suggested that ALAN-exposed nestlings had reduced baseline and increased stress-induced corticosterone compared with control nestlings. ALAN-exposed nestlings also showed greater negative feedback of circulating corticosterone. We found no support for our prediction that ALAN would reduce nestling body condition. Finally, we found some support for a negative effect of ALAN on the likelihood that all eggs hatched in a given nest, but not the likelihood that all nestlings fledged. Therefore, while it is possible that the behavioral and physiological changes found here result in long-term consequences, our results also suggest that direct ALAN exposure alone may not have substantially large or negative effects on tree swallows. Exposure regimes for free-living birds, such as exposure to a combination of anthropogenic disturbances (i.e., ALAN and noise pollution) or direct and indirect effects of ALAN (i.e., effects on physiology due to direct light exposure and alterations in food availability), may produce different results than those found here.

Sugar industry waste-derived anode for enhanced biohydrogen production from rice mill wastewater using artificial photo-assisted microbial electrolysis cell

Microbial Electrolysis Cell (MEC) is a promising green technology for energy production from wastewater. This study attempts to investigate the biohydrogen production from rice mill wastewater using artificial photo-assisted microbial electrolysis cell (APAMEC) with an inexpensive anode prepared from carbonaceous material disposed by sugar industry. The X-ray diffraction (XRD) and scanning electron microscopic (SEM) analyses confirmed the presence of carbon on the electrode surface. Cyclic Voltammogram analysis indicated that the carbonaceous anode has higher reduction peak at 0.7 V compared to control (plain carbon cloth) electrode. The experimental results showed a maximum hydrogen production of 220 mL on 5th day of fermentation and the production rate observed was 3.6 ± 0.4 mL/l/h. The effect of pH and acid concentration used in the acid hydrolysis of rice mill wastewater and the effect of artificial light on biohydrogen production were investigated. The optimum pH and acid concentration of 6 and 1.5%, respectively, gave better biohydrogen production and COD removal. The results demonstrated that the development of inexpensive anode from the waste disposed by sugar industry would pave the path to scale-up MECs.

Effects of artificial light at night (ALAN) on gene expression of Aquatica ficta firefly larvae.

Artificial light at night (ALAN) is a major driver of firefly population declines, but its physiological effects are not well understood. To investigate the impact of ALAN on firefly development, we exposed larval Aquatica ficta fireflies to ALAN for two weeks. High larval mortality was observed in the periods of 1-68 days and 106-134 days post-treatment, which may represent the short- and long-term impacts of ALAN. We then profiled the transcriptome of larval Aquatica ficta fireflies following two weeks of ALAN exposure. A total of 1262 (1.67% out of 75777 unigenes) were differentially expressed in the treatment group: 1157 were down-regulated, and 105 were up-regulated. Up-regulated unigenes were related to regulation of hormone levels, ecdysteroid metabolic process, and response to stimulus; down-regulated unigenes were related to negative regulation of insulin receptor signaling, germ cell development, oogenesis, spermatid development, and regulation of neuron differentiation. Transcriptome results suggest that the endocrine, reproductive, and neural development of firefly larvae could be impaired by even relatively brief period of ALAN exposure. This report contributes a much-needed molecular perspective to the growing body of research documenting the fitness impacts of ALAN on bioluminescent fireflies.

Impact of artificial light at night on diurnal plant-pollinator interactions

Artificial light at night has rapidly spread around the globe over the last decades. Evidence is increasing that it has adverse effects on the behavior, physiology, and survival of animals and plants with consequences for species interactions and ecosystem functioning. For example, artificial light at night disrupts plant-pollinator interactions at night and this can have consequences for the plant reproductive output. By experimentally illuminating natural plant-pollinator communities during the night using commercial street-lamps we tested whether light at night can also change interactions of a plant-pollinator community during daytime. Here we show that artificial light at night can alter diurnal plant-pollinator interactions, but the direction of the change depends on the plant species. We conclude that the effect of artificial light at night on plant-pollinator interactions is not limited to the night, but can also propagate to the daytime with so far unknown consequences for the pollinator community and the diurnal pollination function and services they provide.

Effects of artificial light at night and predator cues on foraging and predator avoidance in the keystone inshore mollusc Concholepas concholepas.

The growth of Artificial Light At Night (ALAN) is potentially having widespread effects on terrestrial and coastal habitats. In this study we addressed both the individual effects of ALAN, as well as its combined effect with predation risk on the behaviour of Concholepas concholepas, a fishery resource and a keystone species in the southeastern Pacific coast. We measured the influence of ALAN and predation risk on this mollusc's feeding rate, use of refuge for light and crawling out of water behaviour. These behavioural responses were studied using light intensities that mimicked levels that had been recorded in coastal habitat exposed to ALAN. Cues were from two species known to prey on C.concholepas during its early ontogeny: the crab Acanthocyclus hassleri and the seastar Heliaster helianthus. The feeding rates of C.concholepas were 3-4 times higher in darkness and in the absence of predator cues. In contrast, ALAN-exposed C.concholepas showed lower feeding activity and were more likely to be in a refuge than those exposed to control conditions. In the presence of olfactory predator cues, and regardless of light treatment, C.concholepas tended to crawl-out of the waterline. We provide evidence to support the hypothesis that exposure to either ALAN or predation risk can alter the feeding behaviour of C.concholepas. However, predator cue recognition in C.concholepas was not affected by ALAN in situations where ALAN and predator cues were both present: C.concholepas continued to forage when predation risk was low, i.e., in darkness and away from predator cues. Whilst this response means that ALAN may not lead to increased predation mortality in C.concholepas, it will reduce feeding activity in this naturally nocturnal species in the absence of dark refugia. Such results may have implications for the long-term health, productivity and sustainability of this keystone species.

Assessing long‐term effects of artificial light at night on insects: what is missing and how to get there

Abstract Widespread and significant declines of insect population abundances and biomass are currently one of the most pressing issues in entomology, ecology and conservation biology. It has been suggested that artificial light at night is one major driver behind this trend. Recent advances in the gathering and analysis of long‐term data sets of insect population and biomass trends, however, have mostly focused on the effects of climate change and agricultural intensification. We posit here that adequate assessment of artificial night at light that would be required to evaluate its role as a driver of insect declines is far from trivial. Currently its implementation into entomological monitoring programmes and long‐running ecological experiments is hampered by several challenges that arise due to (i) its relatively late appearance as a biodiversity threat on the research agenda and (ii) the interdisciplinary nature of the research field where biologists, physicists and engineers still need to develop a set of standardised assessment methods that are both biologically meaningful and easy to implement. As more studies that address these challenges are urgently needed, this article aims to provide a short overview of the few existing studies that have attempted to investigate longer‐term effects of artificial light at night on insect populations. To improve the quality and relevance of studies addressing artificial light at night and its effect on insects, we present a set of best practise recommendations where this field needs to be heading in the coming years and how to achieve it.

Effects of artificial light on growth, development, and dispersal of two North American fireflies (Coleoptera: Lampyridae)

Holometabolous insects exhibit complex life cycles in which both morphology and ecological niche change dramatically during development. In the larval stage, many insects have soft, slow-moving bodies and poor vision, limiting their ability to respond to environmental threats. Artificial light at night (ALAN) is an environmental perturbation known to severely impact the fitness of adult insects by disrupting both temporal and spatial orientation. The impact of ALAN on earlier life stages, however, is largely unknown. We conducted a series of laboratory experiments to investigate how two distinct forms of ALAN affect the development and movement of immature Photuris sp. and Photinus obscurellus fireflies. Although long-term exposure to dim light at night (dLAN), akin to urban skyglow, did not impact overall survivorship or duration of egg, larval, and pupal stages in either species, it did accelerate weight gain in early-instar Photuris larvae. Late-instar Photuris exposed to point sources of ALAN at the start of their nightly foraging period were also significantly more likely to burrow beneath the soil surface, rather than disperse across it. ALAN may therefore impede dispersal of firefly larvae away from illuminated areas, which could have downstream consequences for the reproductive fitness of adults.

Effects of Artificial Lighting at Night on Predator Density and Salmonid Predation

AbstractPredation of juvenile salmonids within California’s Sacramento–San Joaquin Delta (the Delta) has been identified as a contributing factor to low survival during out‐migration through the system. Artificial lighting at night (ALAN) may contribute to increased levels of salmonid predation by attracting predators and prey, increasing predator reaction distance, and boosting foraging success. To assess ALAN effects on predator (piscivorous fishes) density and the relative predation risk of Chinook Salmon Oncorhynchus tshawytscha smolts in the Delta, we preformed field‐based experiments with introduced ALAN. We used adaptive resolution imaging sonar cameras to generate predator density estimates in light and dark treatments throughout nightly experiments at 30‐min intervals. We simultaneously deployed predation event recorders to estimate the impact of ALAN intensity (lux) on relative predation risk of Chinook Salmon smolts. Early in the night (1–3 h past sunset), predator density and relative predation risk of smolts were unrelated to ALAN. However, late in the night (3–5 h past sunset), ALAN presence increased predator density, and the relative predation risk of juvenile salmonids increased with increasing lux. Predation risk was also positively related to predator density, and increased late‐night predator density under ALAN, coupled with late‐night foraging benefits of ALAN, likely contributed to the lux–risk relationship. The exact mechanism behind this discrepancy between early‐ and late‐night trends is unknown and could be a result of our experimental design or the predator community sampled here. However, if these temporal trends prove robust to future investigations, late‐night lighting reduction campaigns during out‐migration could maximize the human benefits of ALAN while minimizing the negative impacts on salmonids. Overall, our findings align with others and suggest that ALAN increases juvenile salmonid predation. Although many questions remain unanswered, it appears that reducing artificial illumination is a practical management strategy to reduce predation.

Daphnia depth selection in gradients of light intensity from different artificial sources: An evolutionary trap?

AbstractIt is well known that artificial light at night alters the natural patterns of light in space and time, which interrupts a variety of physiological processes of individuals, altering their life history and behavioral adjustments. However, much less is known about the effect of artificial light at night on their fitness. We tested the hypothesis that planktonic animals, such as Daphnia spp., are able to correctly assess light intensity‐ and spectrum‐dependent‐mortality risk due to predation by planktivorous fish and select depths offering the highest possible fitness gain in the vertical gradient of different artificial light sources (halogen, metal‐halide, cool white LEDs, and high pressure sodium lamps) commonly used in street lighting. To test this hypothesis, we compared the virtual distributions of three clones of Daphnia longispina from simulations based on an experimentally parameterized, optimizing individual‐based model with distributions observed in laboratory experiments performed with 5‐d‐old individuals in an experimental apparatus comprised of twin vertical columns. Our hypothesis was confirmed only partially, since the distributions obtained in the experiments overlapped the virtual distributions only in the gradient of LEDs and high pressure sodium light, which suggests that that the strength of the maladaptive response could depend on the type of artificial light (i.e., spectral composition) penetrating the water column. Moreover, the results revealed that the response to the presence of artificial light is clone‐specific, which suggest that it could be a selective factor for microevolutionary changes.

Seasonal variation in the effects of artificial light at night on the occurrence of nocturnally migrating birds in urban areas.

Urban areas often contain large numbers of migratory bird species during seasonal migration, many of which are nocturnal migrants. How artificial light at night (ALAN) and urban landcover are associated with the diurnal occurrence of nocturnal migrants within urban areas across seasons has not been explored. Here, we use eBird bird occurrence information to estimate the seasonal species richness of nocturnally migrating passerines (NMP) within 333 well surveyed urban areas within the contiguous USA. We model the relationship between seasonal NMP species richness and ALAN, proportion of tree canopy cover, and proportion of impervious surface. NMP species richness reached its highest levels during spring and autumn migration and lowest during the winter and summer. Greater tree canopy cover was associated with higher NMP species richness during spring and autumn migration and the summer. A 10% increase in the proportion of tree canopy cover was associated with a 2.0% increase in NMP species richness during spring migration, a 1.8% increase during autumn migration, and a 0.9% increase during the summer. More impervious surface was associated with higher NMP species richness during the winter. A 10% increase in the proportion of impervious surface was associated with a 6.1-9.8% increase in NMP species richness. Higher ALAN was associated with lower NMP species richness during the winter and summer, and higher NMP species richness during spring and autumn migration. A 50% increase in ALAN was associated with a 3.0-3.6% decrease in NMP species richness during the winter, a 1.7% increase during spring migration, a 2.1% decrease during the summer, and a 5.0% increase during autumn migration. These findings highlight the variable effects of ALAN and urban landcover on the seasonal occurrence of NMP species in urban areas, the value of tree canopy cover during migration and the breeding season, and the importance of reducing ALAN during migration.

Study of the vertical temperature profile in a tomato greenhouse equipped with lighting, two screens and a VentilationJet system

The application of Next Generation Growing (NGG, in Dutch “Het Nieuwe Telen”) in Dutch greenhouses has resulted in energy savings, accompanied by the extensive use of screens. The latter has affected the control of greenhouse climate which strongly depends on the air and humidity exchange between the top and bottom greenhouse compartment, as they are separated by the screen itself. When the screens are fully deployed an air exchange/mix system (VentilationJet) that blows dry and cold air from the top compartment into the greenhouse can be used to lower the greenhouse air temperature and relative humidity in a controllable way. The effect of this greenhouse climate control equipment use on vertical air temperature profile as well as on energy use was studied in a commercial greenhouse. Effects of artificial lighting, heating with pipes below the crop, activation of vertical fans and air exchange rate were analyzed during the winter of 2018. It was observed that when significant heat input (radiation) at the top of the crop occurred a vertical temperature gradient up to 2°C exists, with the bottom of the crop being colder than the top. This temperature gradient cannot be reduced by using only vertical air circulation fans but it can be minimized by additional heat input at the bottom; this may result in excess heat that has to be removed through either natural ventilation or with the use of VentilationJet when the screens are deployed. During the studied period about a quarter of the daily gas use for heating took place at the same time as the VentilationJet was removing warm and humid air from the top of the greenhouse.

Pollination and fruit infestation under artificial light at night:light colour matters

Rapid human population growth and associated urbanization lead to increased artificial illumination of the environment. By changing the natural light–dark cycle, artificial lighting can affect the functioning of natural ecosystems. Many plants rely on insects in order to reproduce but these insects are known to be disturbed by artificial light. Therefore, plant–insect interactions may be affected when exposed to artificial illumination. These effects can potentially be reduced by using different light spectra than white light. We studied the effect of artificial lighting on plant–insect interactions in the Silene latifolia–Hadena bicruris system using a field set-up with four different light treatments: red, green, white and a dark control. We compared the proportion of fertilized flowers and fertilized ovules as well as the infestation of fruits by Hadena bicruris, a pollinating seed predator. We found no difference in the proportion of fertilized flowers among the treatments. The proportion of fruits infested by H. bicruris was however significantly higher under green and white light and a significantly lower proportion of fertilized ovules was found under green light. We show that artificial light with different colours impacts plant–insect interactions differently, with direct consequences for plant fitness.

Advances and Current Issues in Adolescent Sleep

Adolescents have unique risks for inadequate sleep. There are constant updates in the understanding of natural biologic tendencies, technological advancements, social constrictions, and medical conditions affecting sleep. This article aims to review and highlight recent advances in these areas. There is a greater understanding of the natural tendencies of adolescent sleep towards circadian phase delay. New research has better delineated the effects of artificial light and school start times, on sleep and circadian phase. There have also been updates about the diagnosis and management of narcolepsy, obstructive sleep apnea, and idiopathic hypersomnia. Greater understanding of how light exposure affects the circadian system allows for more concrete recommendations about managing electronics exposure. Growing evidence suggests that delaying school start times may be beneficial for adolescents. Advances in diagnostic techniques for various disorders may allow greater flexibility and greater accuracy in testing, as well as better evidenced-based care.

Towards a Sustainable Indoor Lighting Design: Effects of Artificial Light on the Emotional State of Adolescents in the Classroom

In recent years, articles have been published on the non-visual effects of light, specifically the light emitted by the new luminaires with light emitting diodes (LEDs) and by the screens of televisions, computer equipment, and mobile phones. Professionals from the world of optometry have raised the possibility that the blue part of the visible light from sources that emit artificial light could have pernicious effects on the retina. The aim of this work is to analyze the articles published on this subject, and to use existing information to elucidate the spectral composition and irradiance of new LED luminaires for use in the home and in public spaces such as educational centers, as well as considering the consequences of the light emitted by laptops for teenagers. The results of this research show that the amount of blue light emitted by electronic equipment is lower than that emitted by modern luminaires and thousands of times less than solar irradiance. On the other hand, the latest research warns that these small amounts of light received at night can have pernicious non-visual effects on adolescents. The creation of new LED luminaires for interior lighting, including in educational centers, where the intensity of blue light can be increased without any specific legislation for its control, makes regulatory developments imperative due to the possible repercussions on adolescents with unknown and unpredictable consequences.