Article
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

The increasing use of artificial light at night (ALAN) has led to exposure of freshwater ecosystems to light pollution worldwide. Simultaneously, the spectral composition of nocturnal illumination is changing, following the current shift in outdoor lighting technologies from traditional light sources to light emitting diodes (LED). LEDs emit broad-spectrum white light, with a significant amount of photosynthetically active radiation, and typically a high content of blue light that regulates circadian rhythms in many organisms. While effects of the shift to LED have been investigated in nocturnal animals, its impact on primary producers is unknown. We performed three field experiments in a lowland agricultural drainage ditch to assess the impacts of a transition from high-pressure sodium (HPS) to white LED illumination (color temperature 4000 K) on primary producers in periphyton. In all experiments, we compared biomass and pigment composition of periphyton grown under a natural light regime to that of periphyton exposed to nocturnal HPS or, consecutively, LED light of intensities commonly found in urban waters (approximately 20 lux). Periphyton was collected in time series (1–13 weeks). We found no effect of HPS light on periphyton biomass; however, following a shift to LED the biomass decreased up to 62%. Neither light source had a substantial effect on pigment composition. The contrasting effects of the two light sources on biomass may be explained by differences in their spectral composition, and in particular the blue content. Our results suggest that spectral composition of the light source plays a role in determining the impacts of ALAN on periphyton and that the ongoing transition to LED may increase the ecological impacts of artificial lighting on aquatic primary producers. Reduced biomass in the base of the food web can impact ecosystem functions such as productivity and food supply for higher trophic levels in nocturnally-lit ecosystems.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Intrigued by these questions, we mimicked light conditions of light-polluted areas in two field studies, in two contrasting aquatic ecosystems: a subalpine stream (Grubisic et al. 2017(Grubisic et al. , 2018a) and a lowland agricultural drainage ditch (Grubisic et al. 2018b). We focused on primary producers in periphyton, mixed communities of benthic algae, cyanobacteria and heterotrophic microbes, and compared communities that were exposed to ALAN with those that experienced a natural light regime. ...
... This appeared to be a direct effect of nocturnal illumination, rather than a top-down effect driven by grazers. Yellowish high-pressure sodium (HPS) light, one of the traditionally most commonly used in street lighting, had no pronounced effect at similar intensities (Grubisic et al. 2018b). Which mechanisms contributed to the observed biomass decrease under LEDs remain unknown: as white LEDs are typically rich in blue light that is known to entrain circadian rhythms, this may have disrupted circadian regulation and processes it regulates (Fig. 4). ...
Article
Full-text available
Bright night lights have become a symbol of development and prosperity in the modern world. But have you ever wondered how artificial light at night (ALAN) may be affecting living beings in our cities, and how it may be affecting us? As artificial illumination is transforming nocturnal environments around the world, light pollution associated with its use is becoming a topic of increasing interest in the scientific and public communities. Light pollution disrupts natural light regimes in many regions of the world, raising concerns about ecological and health impacts of this novel anthropogenic pressure. Most obviously, ALAN can influence night‐active animals in urban and suburban areas, and most research in this growing field focuses on terrestrial organisms such as bats, birds, and insects. Effects on aquatic ecosystems are much less known. In particular, aquatic primary producers, such as microalgae, cyanobacteria, and plants, have rarely been studied despite their critical positioning in the base of aquatic food webs and the fundamental role that light plays in their ecology. For primary producers, light is a key source of both energy and environmental information; it influences their growth, production, and community structure. ALAN has therefore a large potential to influence their communities and induce bottom‐up changes to aquatic ecosystems and ecosystem functions.
... In terrestrial plants, these effects may be direct (e.g., phenology and dark recovery from stress) or indirect (e.g., plant-animal interactions), and may superimpose on those of other stressors such as chemical pollution (e.g., tropospheric ozone), climate change, habitat fragmentation and the introduction of invasive species (Bennie, et al., 2016). In aquatic primary producers, wavelength-dependent effects that might ultimately affect food availability for higher trophic levels have also been identified (Grubisic, et al., 2018;Grubisic, et al., 2017). There is only one laboratory study reporting ALAN-induced long-term changes in the species composition of aquatic microbial sediment communities, where a "strong street light" scenario was mimicked by LED lights, which finally led to a shift of the system from negative to positive net ecosystem production at night (Hölker, et al., 2015a). ...
... In this regard, it is interesting to observe that slightly higher respiration rates and, correspondingly, lower (more negative) values have been found for the low skyglow treatment. This is consistent with studies suggesting that low light levels at night might be even more impacting than higher ones (Grubisic, et al., 2018). In any case, for conclusiveness, more research is required. ...
Thesis
Full-text available
Freshwater lakes are among the most important ecosystems for both human and other biological communities. They account for about 87% of surface freshwater in the planet, thus constituting a major source of drinking water. They also provide a wide range of ecosystem services that go from the sustenance of a rich biodiversity to the regulation of hydrological extremes; from the provision of a means for recreation to the support of local economies, e.g., through tourism and fisheries, just to cite a few. Lakes are now also widely recognised as natural early warning systems, their responses potentially being effective indicators of local, regional and global scale phenomena such as acidification and climate change, respectively. This is because of their high sensitivity to environmental factors of the most diverse nature that can rapidly alter the course of their evolution. Examples of this are the observed abrupt shifts between alternative stable states in shallow lakes, which led them to become the archetype, go-to example in alternative stable state theory. Therefore, attaining a good scientific understanding of the many processes that take place within these ecosystems is fundamental for their adequate management. Among the tools that serve this purpose, ecological models are particularly powerful ones. Since their introduction in the 1960s, the development of mechanistic ecological models has been driven by their wide spectrum of potential applications. Nevertheless, these models often fall into one of the two following categories: overly simplistic representations of isolated processes, with limited potential to explain real-world observations as they fail to see the bigger picture; or overly complex and over-parameterised models that can hardly improve scientific understanding, their results being too difficult to analyse in terms of fundamental processes and controls. Moreover, it is now well known that an increased complexity in the mechanistic description of ecological processes, does not necessarily improve model accuracy, predictive capability or overall simulation results. To the contrary, a simpler representation allows for the inclusion of more links between model components, feedbacks which are usually overlooked in highly-complex models that partially couple a hydro-thermodynamic module to a biogeochemical one. However, ecological processes are now known to have the potential to significantly alter the physical response of aquatic ecosystems to environmental forcing. For example, steadily increasing concentrations of coloured dissolved organic carbon, a process known as brownification (also browning), as well as the intense phytoplankton blooms that characterise lakes undergoing severe nutrient enrichment, a process known as eutrophication, have been shown to have the potential to alter the duration of the stratified period, thermal structure and mixing regime of some lakes. In this thesis, with the aim of addressing the limitation of partially-coupled models to account for such feedbacks, we further develop a process-based model previously reported in scientific literature. Subsequent studies have already built upon this model in the last few years. In Chapter 2, we do so too by integrating hydro-thermodynamics and biogeochemistry in a reduced complexity framework, i.e., customising the model so that each version only includes the fundamental processes that, brought together, sufficiently describe the studied phenomena. Two case studies served the purpose of testing the adaptability and applicability of the developed model under different configurations and requirements. Limnological data for these two studies were measured at high spatial and temporal resolutions by means of an automated profiling system and recorded as part of two large-scale mesocosm experiments conducted in 2015 and 2016 at the IGB LakeLab in Lake Stechlin, Brandenburg, Germany. Meteorological datasets were also made available to us for both periods by the German Federal Environment Agency. The scope of the first experiment, which we describe in Chapter 3, was that of detecting any changes attributable to eutrophication and browning, in the competition for nutrients and light between four different groups of lake primary producers. These four groups are phytoplankton, periphyton, epiphyton and macrophytes. The model version for this study, therefore, includes equations for all four groups. By tailoring the model to these very specific needs with relative ease, we demonstrate its versatility and hint at its potential. The second experiment, described in Chapter 4, sought to shed light on the largely unknown effects of an increase in the diffuse luminance of the night sky that is due to artificial light at night (artificial skyglow) on lake metabolic rates, i.e., gross primary productivity, ecosystem respiration and net ecosystem productivity (the difference between the first two). For this purpose, an empirical equation for dissolved oxygen concentration was included, the parameters of which were estimated by means of a Markov Chain Monte Carlo sampling method within a Bayesian statistical framework, showing the compatibility, with these statistical methods, of our otherwise fully deterministic model. In Chapter 5, we present a theoretical study on the ecological controls of light and thermal patterns in lake ecosystems. A series of simulations were performed to determine in which cases ecological processes such as eutrophication and brownification may have an observable effect on the physical response of lakes to environmental forcing, which we assessed along a latitudinal gradient. Results show that, in general, across all examined latitudes, and consistent with previous studies, accounting for phytoplankton biomass results in higher surface temperatures during the warm-up phase, slightly lower water temperatures during the cool-down phase, and a shallower thermocline throughout the entire stratified period. This effect is relatively more important in eutrophic lakes where intense blooms are likely. This importance, however, decreases as lakes get browner. Finally, in line with the overall scope of the SMART EMJD, in Chapter 6 we illustrate the case of Ypacaraí Lake, the most important lake in landlocked Paraguay, hoping to provide an example of how interdisciplinary research and international intersectoral collaboration can help bridge the gap between science and management of freshwater ecosystems. This lake presents very special hydro-ecological conditions, such as very high turbidity that can impair phytoplankton growth despite its nutrient-based trophic state indices having consistently fallen within the hyper-eutrophic range in recent years. A strong interest in its complex functioning, through modelling, was taken early on. This led to a collaborative research line being established among several public and private institutions in Italy, Germany and Paraguay. Results so far include: • three concluded UniTN Master theses in Environmental Engineering, partly developed in Paraguay, the first two in collaboration with the “Nuestra Señora de la Asunción” Catholic University (UCNSA) and the third one with the National University of Asunción (UNA); • a collaborative UCNSA-UniTN research proposal submitted for consideration to receive funding through the PROCIENCIA Programme of the National Council of Science and Technology of Paraguay (CONACYT); and • the first multidisciplinary review that has ever been published about the case of Ypacaraí Lake, which highlights the importance of such a collaborative and integrative approach to further advance scientific knowledge and effectively manage this ecosystem.
... Because ALAN is linked closely to human activity (Elvidge et al., 1997), it is assumed to affect freshwater systems and coastal areas disproportionally (Zhao, Li, Li, Zhao, & Wu, 2018). The effects of ALAN on aquatic organisms and communities have been researched in several laboratory (Brüning, Hölker, Franke, Kleiner, & Kloas, 2016;Brüning, Hölker, Franke, Preuer, & Kloas, 2015;Hölker et al., 2015;Kurvers et al., 2018;Perkin, Hölker, Heller, & Berghahn, 2014c;Poulin et al., 2013;Szekeres et al., 2017) and field studies (Becker, Whitfield, Cowley, Järnegren, & Naesje, 2013;Bolton et al., 2017;Brüning, Kloas, Preuer, & Hölker, 2018a;Cullen & McCarthy, 2000;Davies, Duffy, Bennie, & Gaston, 2016;Grubisic et al., 2017;Grubisic, van Grunsven, Manfrin, Monaghan, & Hölker, 2018;Hölker et al., 2015;Ludvigsen et al., 2018;Manfrin et al., 2017Manfrin et al., , 2018Meyer & Sullivan, 2013;Moore, Pierce, Walsh, Kvalvik, & Lim, 2001;Perkin, Hölker, & Tockner, 2014b;Perkin, Hölker, Tockner, & Richardson, 2014a;Riley, Bendall, Ives, Edmonds, & Maxwell, 2012;Riley, Davison, Maxwell, & Bendall, 2013;Szaz et al., 2015;Tabor, Brown, & Luiting, 2004;Underwood, Davies, & Queirós, 2017). However, we found a knowledge gap regarding the status quo of light pollution in and along aquatic systems. ...
... ALAN has several negative consequences on aquatic systems and their surroundings as demonstrated on almost all trophic levels and for a wide variety of consequences. Effects at small scales include changes in community composition and phytophysiology for microorganisms , cyanobacteria (Poulin et al., 2013) and periphyton communities (Grubisic et al., 2017(Grubisic et al., , 2018. Zooplankton is affected by very low levels of ALAN. ...
Article
Full-text available
Freshwater ecosystems are hotspots of biodiversity. They are of major importance for humans because they provide vital ecosystem services. However, as humans tend to settle near freshwaters and coastal areas, these ecosystems are also over‐proportionally affected by anthropogenic stressors. Artificial light at night can occur as a form of environmental pollution, light pollution. Light pollution affects large areas on a worldwide scale, is growing exponentially in radiance and extent and can have diverse negative effects on flora, fauna and on human health. While the majority of ecological studies on artificial light at night covered terrestrial systems, the studies on aquatic light pollution have unraveled impact on aquatic organisms, ecosystem functions as well as land‐water‐interactions. Although monitoring of light pollution is routinely performed from space and supported by ground‐based measurements, the extent and the amount of artificial light at night affecting water bodies is still largely unknown. This information, however, is essential for the design of future laboratory and field experiments, to guide light planners and to give recommendations for light pollution regulations. We analyze this knowledge gap by reviewing night‐time light measurement techniques and discuss their current obstacles in the context of water bodies. We also provide an overview of light pollution studies in the aquatic context. Finally, we give recommendations on how comprehensive night‐time light measurements in aquatic systems, specifically in freshwater systems, should be designed in the future. This article is categorized under: Water and Life > Stresses and Pressures on Ecosystems Water and Life > Conservation, Management, and Awareness Water and Life > Methods Artificial light at night can occur as a form of environmental pollution, light pollution, which also affects aquatic systems. We identify a knowledge gap of insufficient data regarding the status quo of aquatic light pollution and provide a route to fill this gap with in‐situ measurements.
... Although new developments in LED technology provide long-lived and energy efficient lighting infrastructure (Djuretic and Kostic 2018), they have been the focus of many critical assessments claiming that LED might be particularly detrimental because their spectral composition peaks in the blue range to which many nocturnal insects appear sensitive ( (Donners et al. 2018;Eccard et al. 2018;Grubisic et al. 2018;Longcore et al. 2015;Pawson and Bader 2014, but see Macgregor et al. (2019)). Replacing the older street lights with energy saving LEDs can also lead to brighter illumination. ...
... Bats are nocturnal insectivores that use ultrasound echolocation for orientation and hunting (Schnitzler and Kalko 2001). This makes them acoustically conspicuous when using techniques that are sensitive to ultrasound (Griffin 1958). To monitor the presence of bats, a total of four batloggers (https ://www.batlo ...
Article
Full-text available
Artificial light at night (ALAN) is an important driver of change in ecological environments of the 21th century. We investigated the impact on nocturnal insect abundance and bat activity of two LED light colors (warm-white 2700 K, cold-white 6500 K) in a peri-urban environment. Bat activity (predominantly Pipistrellus pipistrellus) was largely driven by prey availability (insects), while insect abundance was responsive to nightly weather conditions (precipitation, temperature). Thus, both insects and bats were not differentially responsive to cold-white or warm-white LEDs. These findings are largely in contrast with literature, particularly for insects. However, as most published experiments on ALAN were conducted in areas that were lit solely for the purpose of the experiment, we would like to bring forward that (1) adaptation to environmental constraints may play a role in peri-urban environments that have been exposed to ALAN for many decades; or (2) impacts of cold-white LEDs on nocturnal insects may be lower than expected, because nocturnal insects adapted to low-light conditions may be put off by cold white light sources (6500 K).
... Despite the surge of interest in the ecological effects of ALAN, most of the evidence collected so far comes from terrestrial habitats, while studies on marine populations and communities are currently limited [20][21][22][23][24][25]. Although a small number of studies have investigated the effects of monochromatic ALAN on cyanobacteria and microalgae, these focused on benthos and periphyton [2,[26][27][28][29][30], while no study so far has investigated the effects of polychromatic LEDs on marine phytoplankton. Due to the continuous expansion of coastal urbanization [31,32], ALAN is a source of pollution that is increasingly relevant for coastal ecosystems [4,21]. ...
... Night-time light irradiance was measured with a LI-200R pyranometer (LI-COR, USA) and was standardized at 0.023 W m −2 for all three ALAN treatments. This irradiance level is within the range of values reported in previous studies on ALAN [26,28,60,61]. With respect to illuminance, our standardized irradiance level corresponds to 8.51 lux for the white light, to 3.4 lux for the red light and 12.81 lux for the green light. ...
Article
Artificial light at night (ALAN) is a disruptive form of pollution, impacting physiological and behavioural processes that may scale up to population and community levels. Evidence from terrestrial habitats show that the severity and type of impact depend on the wavelength and intensity of ALAN; however, research on marine organisms is still limited. Here, we experimentally investigated the effect of different ALAN colours on marine primary producers. We tested the effect of green (525 nm), red (624 nm) and broad-spectrum white LED ALAN, compared to a dark control, on the green microalgae Tetraselmis suesica and a diatom assemblage. We show that green ALAN boosted chlorophyll production and abundance in T. suesica. All ALAN wavelengths affected assemblage biomass and diversity, with red and green ALAN having the strongest effects, leading to higher overall abundance and selective dominance of specific diatom species, some known to cause harmful algal blooms. Our findings show that green and red ALAN should be used with caution as alternative LED colours in coastal areas, where there might be a need to strike a balance between the effects of green and red light on marine primary producers with the benefit they appear to bring to other organisms.
... On the other hand, exposure to white LED light at night (20 lx) declined algal biomass and altered community composition in comparison to unlit stream sections, changing the proportions of diatoms and cyanobacteria, two autotrophic groups characterized by contrasting nutritional quality for invertebrate consumers (Grubisic et al., 2017). In another study, neither HPS nor LED illumination of a similar intensity (20 lx) altered the composition of the algal community, but the transition from HPS to white LEDs reduced algal biomass (Grubisic et al., 2018). Artificial illumination may therefore differentially affect the abundance and composition of algae depending on its spectra, thus changing the quantity and nutritional quality of food (leaves and associated biofilm) available to shredders. ...
... We hypothesized that ALAN would reduce leaf consumption and growth rates in both shredder species compared to dark night conditions through decrease in the nocturnal activity of shredders. We also expected that the LED light would have a stronger impact on the feeding and growth of shredders than HPS, due to decreased algal growth and diminished food quantity and quality (Grubisic et al., 2017(Grubisic et al., , 2018. Given that D. villosus is common in anthropogenic habitats, which are often subjected to relatively high intensities of ALAN (Meyer and Sullivan, 2013;Perkin et al., 2014a), we also assumed that this species might be less sensitive to ALAN than G. jazdzewskii. ...
Article
Full-text available
Artificial light at night (ALAN) is a globally widespread phenomenon potentially affecting ecosystem processes, such as leaf litter breakdown, which is a source of organic matter in fresh waters. Here, we conducted a long-term experiment to test the effects of ALAN (2 lx) differing in spectral composition: white LEDs and high pressure sodium lamps (HPS) on leaf consumption, growth and activity of two macroinvertebrate species of shredders: Gammarus jazdzewskii and Dikerogammarus villosus (Crustacea, Amphipoda), compared to the undisturbed light-dark cycle. We also tested if the nocturnal illumination would influence the algal community colonising leaves, which is an important component of the leaf-shredder diet. We found that LED light increased the consumption of leaves by both species, which was nearly twice as high as in other treatments, and supressed the growth rate of G. jazdzewskii, whereas the growth of D. villosus was not affected by either light type. Moreover, D. villosus reduced its activity when exposed to ALAN of both types. As ALAN-induced changes in shredder growth and consumption were not associated with their increased activity or decreased food quality, we suggest that LED light may be a source of physiological stress for shredders, raising their energy expenditure, which was compensated by increased food intake. We have shown that LED illumination induces greater effects on wildlife than alternative, narrow wavelength spectrum light sources, such as HPS lamps, and may potentially alter the litter breakdown in aquatic ecosystems. It may accelerate the turnover of leaves by shredders, but on the other hand, it may negatively affect the fitness of macroinvertebrates and thus disturb the leaf processing over a longer term.
... Similarly, in freshwater ecosystems, three weeks of exposure to ALAN (white LED, 20 lx) decreased periphyton (the mixture of algae, microbes, cyanobacteria and detritus) biomass and the proportion of Cyanobacteria, while increasing the proportion of Diatoms (Grubisic et al., 2017(Grubisic et al., , 2018a. In addition, it was shown that the replacement of high-pressure sodium (HPS) lamps by white LED at intensities commonly found in urban waters (∼20 lx), induced similar but stronger effects (Grubisic et al., 2018b). Autotrophs within periphyton communities form the base of aquatic food webs and as such constitute a fundamental element in aquatic ecosystems. ...
Article
Full-text available
The present review draws together wide-ranging studies performed over the last decades that catalogue the effects of artificial-light-at-night (ALAN) upon living species and their environment. We provide an overview of the tremendous variety of light-detection strategies which have evolved in living organisms - unicellular, plants and animals, covering chloroplasts (plants), and the plethora of ocular and extra-ocular organs (animals). We describe the visual pigments which permit photo-detection, paying attention to their spectral characteristics, which extend from the ultraviolet into infrared. We discuss how organisms use light information in a way crucial for their development, growth and survival: phototropism, phototaxis, photoperiodism, and synchronization of circadian clocks. These aspects are treated in depth, as their perturbation underlies much of the disruptive effects of ALAN. The review goes into detail on circadian networks in living organisms, since these fundamental features are of critical importance in regulating the interface between environment and body. Especially, hormonal synthesis and secretion are often under circadian and circannual control, hence perturbation of the clock leads to hormonal imbalance. The review addresses how the ubiquitous introduction of light-emitting diode technology may exacerbate, or in some cases reduce, the generalized ever-increasing light pollution. Numerous examples are given of how widespread exposure to ALAN is perturbing many aspects of plant and animal behaviour and survival: foraging, orientation, migration, seasonal reproduction, colonization and more. We examine the potential problems at the level of individual species and populations and extend the debate to the consequences for ecosystems. We stress, through a few examples, the synergistic harmful effects resulting from the impacts of ALAN combined with other anthropogenic pressures, which often impact the neuroendocrine loops in vertebrates. The article concludes by debating how these anthropogenic changes could be mitigated by more reasonable use of available technology – for example by restricting illumination to more essential areas and hours, directing lighting to avoid wasteful radiation and selecting spectral emissions, to reduce impact on circadian clocks. We end by discussing how society should take into account the potentially major consequences that ALAN has on the natural world and the repercussions for ongoing human health and welfare.
... A horizon scan of threats to urban ecosystems listed LEDs and the associated profusion of bright white light [3]. Most of these concerns, however, are based on the experience of the general public that LEDs used in outdoor lighting can only be blue-white -or on studies of instances where the switch to LEDs is in fact to high color temperature whites [4,5]. ...
Article
Full-text available
The introduction and widespread uptake of LEDs as outdoor lighting has caused no small amount of concern amongst conservation biologists. The prevailing impression that LEDs are always blue-white is well founded as adoption of LEDs for streetlights were invariably high color temperatures and with the deterioration of phosphors the blue wavelengths penetrated even more. But LEDs do have characteristics that differentiate them from other light sources and may allow for the reduction of environmental effects of lighting on species and habitats: direction, duration, intensity, and spectrum. Travis Longcore, Assistant Professor at the University of Southern California’s School of Architecture, sheds light on all these aspects.
... Nevertheless, ALAN disturbs the morpho-physio-phenological traits of plants, 8 animals, 9 and microbes. 10 It is important that the shapes of dose−responses are characterized for typical novel entities independently of their lethality at high exposure. ...
... Hölker et al. [24] found that high-pressure sodium lamps (70 W, 2000 K, 96 Lm W −1 ) changed microbial community composition at the sediment surface, increasing the proportions of primary producers such as diatoms and cyanobacteria. Studies on periphyton demonstrate that nocturnal illumination by white LEDs (of around 20 lux) decreased periphyton biomass in both a subalpine stream and a lowland agricultural drainage ditch [25][26][27]. Only few studies of the effects of artificial light on primary producers in lakes are available, however. ...
Article
Full-text available
Eutrophication of lakes is becoming a global environmental problem, leading to, among other things, rapid reproduction of phytoplankton, increased turbidity, loss of submerged macrophytes, and the recovery of these plants following nutrient loading reduction is often delayed. Artificial light supplement could potentially be a useful method to help speeding up recovery. In this study, three common species of submerged macrophytes, Vallisneria natans, Myriophyllum spicatum and Ceratophyllum demersum, were exposed to three LED light treatments (blue, red and white) and shaded (control) for 100 days (from 10 November 2016 to 18 January 2017) in 12 tanks holding 800 L of water. All the three LED light treatments promoted growth of the three macrophyte species in terms of shoot number, length and dry mass. The three light treatments differed in their effects on the growth of the plants; generally, the red light had the strongest promoting effects, followed by blue and white. The differences in light effects may be caused by the different photosynthetic photon flux density (PPFD) of the lights, as indicated by an observed relationship of PPFD with the growth variables. The three species also responded differently to the light treatments, V. natans and C. demersum showing higher growth than M. spicatum. Our findings demonstrate that artificial light supplement in the low-growth winter season can promote growth and recovery of submerged macrophytes and hence potentially enhance their competitiveness against phytoplankton in the following spring. More studies, however, are needed to elucidate if LED light treatment is a potential restoration method in small lakes, when the growth of submerged macrophytes are delayed following a sufficiently large external nutrient loading reduction for a shift to a clear macrophyte state to have a potential to occur. Our results may also be of relevance when elucidating the role of artificial light from cities on the ecosystem functioning of lakes in urban areas.
... Nature and environment are affected negatively as they suffer from skyglow over cities [5][6][7][8]. Even aquatic ecosystems suffer from light pollution as observed [9,10]. However, also impacts on human health cannot be neglected, as sleep deprivation is only one among many issues found [11][12][13]. ...
Article
Full-text available
The aim of this work was to develop an easy and quick technique for characterizing various lighting situations, that is, single lamps or illuminated signs and to quantify impacts on small scales like streets, buildings and near areas. The method uses a DSLR-camera equipped with fisheye-lens and the software Sky Quality Camera, both commonly used as part of night sky imagery in the light pollution community, to obtain information about luminance and correlated colour temperature. As a difference to its usual build-up, observed light emitting sources were captured by pointing the camera towards analysed objects, that is, images were taken via vertical plane imaging with very short exposure times under one second. Results have proven that this technique provides a practical way to quantify the lighting efficacy in a certain place or area, as a quantitative analysis of the direct emission towards the observer and the illumination on surroundings, that is, street surfaces, sidewalks and buildings, was performed. When conducting lamp conversions, the method can be used to characterize the gradient of change and could be a useful tool for municipalities to find the optimal lighting solution. The paper shows examples of different lighting situations like single lamps of different types, also containing various luminaires, illuminated billboards or buildings and impacts of the lighting transition to LEDs in the city of Eisenstadt, Austria. The horizontal fisheye method is interdisciplinary applicable, for example, being suitable for lighting management, to sustainability and energy saving purposes.
... Ecological functions in riparian areas can be similarly affected. Grubisic et al. found that direct LED lighting on aquatic freshwater bodies can interfere with the communities of periphyton, the primary growth of plants, presumably due to the high emission of blue light [157][158][159]. ...
Article
Full-text available
The fundamental change in nocturnal landscapes due to the increasing use of artificial light at night (ALAN) is recognized as being detrimental to the environment and raises important regulatory questions as to whether and how it should be regulated based on the manifold risks to the environment. Here, we present the results of an analysis of the current legal obligations on ALAN in context with a systematic review of adverse effects. The legal analysis includes the relevant aspects of European and German environmental law, specifically nature conservation and immission control. The review represents the results of 303 studies indicating significant disturbances of organisms and landscapes. We discuss the conditions for prohibitions by environmental laws and whether protection gaps persist and, hence, whether specific legislation for light pollution is necessary. While protection is predominantly provided for species with special protection status that reveal avoidance behavior of artificially lit landscapes and associated habitat loss, adverse effects on species and landscapes without special protection status are often unaddressed by existing regulations. Legislative shortcomings are caused by difficulties in proving adverse effect on the population level, detecting lighting malpractice, and applying the law to ALAN-related situations. Measures to reduce ALAN-induced environmental impacts are highlighted. We discuss whether an obligation to implement such measures is favorable for environmental protection and how regulations can be implemented.
... As for different light spectra, the results of Grubisic et al. (2018) on freshwater periphyton assemblages suggest that the current transition from HPS lamps to white LEDs (Kyba, 2018) might increase the ecological impact of artificial light on aquatic primary producers. ...
Article
Full-text available
Artificial light at night (ALAN) has been recently recognized as a globally widespread anthropogenic disturbance, characterized by different intensities and spectra, as well as spatial and temporal variability. Among marine organisms, those living on coastal areas are particularly exposed to artificial light. Some recent studies anticipated a potential for influences of ALAN on microphytobenthos (MPB) on rocky shores, either direct or indirectly mediated by trophic relationships. Here we emphasize the need for further investigations in different habitats, as well as on synergistic interferences with other stressors already impinging on coastal areas. The study of effects of ALAN poses new challenges in MPB research, including those related to the use of instruments for measuring both the light environment and the functioning of microbial photoautotrophs at night, and to the development of common monitoring approaches and manipulative experiments.
... Fieldwork was undertaken by 10 doctoral candidates in Italy (e.g., Brighenti, et al., 2019;Cashman, et al., 2017, Zen et al., 2017, 7 in Germany (e.g. Gaona, et al., 2019;Grubisic, et al., 2018), 6 in the UK (e.g. Faller, et al., 2016), 3 in Poland (e.g. ...
Article
Full-text available
Interdisciplinary science is rapidly advancing to address complex human-environment interactions. River science aims to provide the methods and knowledge required to sustainably manage some of the planet’s most important and vulnerable ecosystems; and there is a clear need for river managers and scientists to be trained within an interdisciplinary approach. However, despite the science community’s recognition of the importance of interdisciplinary training, there are few studies examining interdisciplinary graduate programs, especially in science and engineering. Here we assess and reflect on the contribution of a 9-year European doctoral program in river science: ‘Science for MAnagement of Rivers and their Tidal Systems’ Erasmus Mundus Joint Doctorate (SMART EMJD). The program trained a new generation of 36 early career scientists under the supervision of 34 international experts from different disciplinary and interdisciplinary research fields focusing on river systems, aiming to transcend the boundaries between disciplines and between science and management. We analyzed the three core facets of the SMART program, namely: (1) interdisciplinarity, (2) internationalism, and (3) management-oriented science. We reviewed the contents of doctoral theses and publications and synthesized the outcomes of two questionnaire surveys conducted with doctoral candidates and supervisors. A high percentage of the scientific outputs (80%) were interdisciplinary. There was evidence of active collaboration between different teams of doctoral candidates and supervisors, in terms of joint publications (5 papers out of the 69 analyzed) but this was understandably quite limited given the other demands of the program. We found evidence to contradict the perception that interdisciplinarity is a barrier to career success as employment rates were high (97%) and achieved very soon after the defense, both in academia (50%) and the private/public sector (50%) with a strong international dimension. Despite management-oriented research being a limited (9%) portion of the ensemble of theses, employment in management was higher (22%). The SMART program also increased the network of international collaborations for doctoral candidates and supervisors. Reflections on doctoral training programs like SMART contribute to debates around research training and the career opportunities of interdisciplinary scientists.
... In the last few decades, urbanisation and decreasing energy cost caused a dramatic increase in the extent of artificial lights at night (ALAN) [1]. Light pollution not only hinders astronomical observations, but also influences the natural behaviour of nocturnal animals, affecting foraging, reproduction, communication, and other critical behavioral patterns [2][3][4][5][6]. The mechanism of the effect of light pollution on a cellular level is also widely researched, revealing that increased illumination at night change the circadian rhythm and inhibits melatonin production causing adverse health issues in non-nocturnal species [7][8][9][10]. ...
Article
Full-text available
The measurement of night sky quality has become an important task in night sky conservation. Modern measurement techniques involve mainly a calibrated digital camera or a spectroradiometer. However, panchromatic devices are still prevalent to this day, even in the absence of determining the spectral information of the night sky. In the case of multispectral measurements, colour information is currently presented in multiple ways. One of the most frequently used metrics is correlated colour temperature (CCT), which is not without its limitation for the purpose of describing especially the colour of natural night sky. Moreover, visually displaying the colour of the night sky in a quantitatively meaningful way has not attracted sufficient attention in the community of astronomy and light pollution research—most photographs of the night sky are post-processed in a way for aesthetic attractiveness rather than accurate representation of the night sky. The spectrum of the natural night sky varies in a wide range depending on solar activity and atmospheric properties. The most noticeable variation in the visible range is the variation of the atomic emission lines, primarily the green oxygen and orange sodium emission. Based on the accepted models of night sky emission, we created a random spectral database which represents the possible range of night sky radiance distribution. We used this spectral database as a learning set, to create a colour transformation between different colour spaces. The spectral sensitivity of some digital cameras is also used to determine an optimal transformation matrix from camera defined coordinates to real colours. The theoretical predictions were extended with actual spectral measurements in order to test the models and check the local constituents of night sky radiance. Here, we present an extended modelling of night sky colour and recommendations of its consistent measurement, as well as methods of visualising the colour of night sky in a consistent way, namely using the false colour enhancement.
... First, the key satellite sensors have been panchromatic, providing no information on the spectral composition of artificial light at night (ALAN), and while the bandwidths have been broad, they have also been insensitive to the blue part of the visible spectrum (380 to 450 nm); the Defense Meteorological Program/Operational Line-Scan System (DMSP/OLS) was sensitive from 450 to 1000 nm, and the Suomi-National Polar-Orbiting Partnership/Visible and Infrared Imaging Radiometer Suite-Day/Night Band (SNPP/VIIRS-DNB) and NOAA20 VIIRS-DNB are sensitive from 480 to 920 nm (10). Second, ALAN has been found to affect a wide diversity of biological phenomena, from individual physiology and behavior (including that of humans) to community structure and ecosystem function (11,12), with these responses almost invariably being dependent on the spectrum of emissions and some of the most important (e.g., melatonin suppression) being particularly sensitive to those at blue wavelengths (13)(14)(15). Third, much of the world's outdoor lighting stock has been transitioning from narrow spectrum (e.g., low-pressure sodium) to "broad white" spectrum [using light-emitting diode (LED)] lamps, particularly resulting in increases in emissions in the blue part of the visible spectrum (16,17). Together, these issues mean that satellite-borne imagery may provide a poor or limited quantitative indicator of the exposure to environmental risks associated with ALAN, as shifts toward potentially harmful lower-wavelength emissions are masked by the low sensitivity of the sensors at these wavelengths. ...
Article
Full-text available
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.
... Il est en effet très difficile de comprendre la complexité des interactions et des équilibres dans les interactions faune-flore et lumière-plante-insecte [229], [230] mais il est prouvé que l'ALAN a un impact sur les pollinisateurs nocturnes et diurnes [231]. De nombreux insectes nocturnes, y compris les pollinisateurs comme les papillons de nuit, utilisent le clair de lune pour naviguer et seront désorientés par l'ALAN, ce qui pourrait perturber leur activité de pollinisation [155], [156]. ...
Thesis
Un bref historique des systèmes d'éclairage et une présentation des terminologies et usages qui leurs sont associés sont tout d'abord présentés. Ensuite, une analyse systémique des enjeux de l'Anthropocène et de ce qu'ils impliquent pour la transition sociétale présente le contexte de ce travail. Elle met en avant un impératif de sobriété matérielle et énergétique indispensable pour la mitigation des crises climatiques. S'ensuit un premier bilan à propos des apports et des risques relatifs au développement des nouvelles technologies de l'éclairage. La révolution récente des systèmes d'éclairage, qui a vu la technologie LED être largement adoptée, a permis de faire des progrès considérables en termes d'efficacité énergétique pendant la phase d'utilisation et a ainsi participé à réduire les impacts environnementaux ainsi que les coûts associés aux systèmes d'éclairage. Toutefois, malgré des avancées majeures en termes d'efficacité énergétique, de nombreux questionnements sont apparus au sujet des impacts potentiels des systèmes d'éclairage, sur notre environnement, notre santé, notre bien-être et notre productivité qu'ils soient positifs ou négatifs, ne sont pas considérés et ne doivent plus être négligés. Une large étude bibliographique développe chacun de ces impacts, allant des risques photo-biologiques à la pollution lumineuse en passant par différents aspects sociotechniques liés aux usages de l'éclairage. Enfin une étude des différentes méthodes d'analyse d'impacts existantes ou en développement est réalisée afin d'en identifier les avantages et les limites. Alors que l'Analyse de Cycle de Vie (ACV) est probablement l'outil le plus performant et le plus reconnu pour l'étude des impacts des produits et des services, ses évolutions, l'Analyse de Cycle Vie Sociale (ACV-S) et l'Analyse de Soutenabilité du Cycle de Vie (ASCV) sont encore en plein développement et nécessiteront probablement encore quelques années avant d'être uniformément reconnues et utilisées. Différentes études de cas permettent ensuite de discuter des impératifs de durabilité et d'efficacité à travers notamment l'influence des mix électriques sur les résultats et les conclusions de l'ACV des systèmes d'éclairage. Cette première étude introduit le Megalumen.heure maintenu comme unité fonctionnelle et met en évidence différents profils énergétiques ainsi que la présence d'un point de bascule en France qui tend à voire la phase de fabrication contribuer autant, voire plus, aux impacts potentiels que la phase d'utilisation (de façon similaire aux équipements électroniques ou informatiques). Ce constat incite à ne plus miser seulement sur l'efficacité énergétique, et fait de la durabilité des lampes et la gestion de leur fin de vie un paramètre déterminant qu'il est nécessaire de développer. Dans un second temps, une méthode d'analyse du coût du cycle de vie (CCV) confirme cet impératif de durabilité en définissant un optimum économique de durée de vie environ deux fois supérieur à la moyenne des lampes que l'on trouve actuellement sur le marché. Pour finir ce travail se concentre sur une analyse multicritère d'un usage émergent des systèmes d'éclairage : les serres horticoles. Une ACV est tout d'abord réalisée pour évaluer les performances et les impacts de différentes lampes spécifiques à cet usage. [...]
... Also, it is relevant to remark on the research plans performed at the Westhavelland Nature Park (e.g. Grubisic et al., 2018a;Manfrin et al., 2018). Australia also registered an elevated number of publications with more than five papers per year from 2015 in Melbourne (e.g. ...
Article
Light pollution is the consequence of elevated lighting emitted by human-made artefacts to the lower atmosphere. Recently, there have been major advances in the assessment and mitigation of light pollution impacts on humans and the natural ecosystems. Severe negative impacts of light pollution have been highlighted while very few mitigation measures have been implemented. People (scientists, policymakers or stakeholders) interested in light pollution may not have a holistic perspective of the problem, and also there is a need for incorporating social and natural dimensions. Therefore, the main goal of this paper is to review the literature on light pollution using ISI Web of Science by paying attention to the (i) type of publication, year and journal; (ii) impacts on specific elements; (iii) location and (iv) methods used. Our results indicated that the elevated number of papers come from a diverse range of disciplines, methods, places and scales. It is clear that light pollution is getting enough attention from the scientific community but decisions on the implementation of mitigation measures are left with the stakeholders, ordinary inhabitants, policymakers and politicians. Nevertheless, light pollution is having impacts on the health of humans and the natural ecosystem as perceived by experts and inhabitants having divergent perspectives. Thus, light pollution is multifaceted but difficult to be faced, mitigated and not holistically understood. This review paper groups the total impacts of light pollution on the Earth presents some contradictory results, summarises mitigation measures, and provides specific future research directions.
... On the other hand, ALAN has been shown to reduce biomass in freshwater periphyton (Grubisic et al. 2018b;Dananay and Benard 2018). It has also been shown that ALAN changes the diversity of the biofilm in favour of photosynthetic bacteria in marine (Maggi et al. 2020) and freshwater communities , possibly changing the carbon and nutrient turnover. ...
Technical Report
Full-text available
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.
... Consequently, supplementation with artificial light can be a potentially useful approach for the restoration of eutrophic lakes. Some studies have found that artificial light supplementation could promote not only macrophyte growth (Grubisic et al., 2018) but also phytoplankton growth and then lead to internal P release by increasing alkaline phosphatase activity (APA) (Ma et al., 2018). However, few works have studied about the effects of light on internal P loading. ...
Article
Full-text available
Nutrient loading reduction is an essential approach for controlling eutrophication. In addition to external nutrient loading, internal phosphorus (P) loading is usually considered one of the most important factors determining nutrient levels in water. The underwater light climate plays a pivotal role. However, few studies have been reported on the effect of light intensity on P release, and the existing studies have not drawn a definitive conclusion on whether underwater light has a positive or negative effect on P release. To confirm the effect of underwater light on internal P release, a 1-month microcosm experiment was carried out (18 November–15 December 2020) under three light intensities. The P release flux (F P ) was significantly higher in the control (no light) group than in the low light group during the first 2 weeks ( p = 0.03). No difference among treatments occurred for accumulative F P in the past 4 weeks, although it tended to be higher in the control than in both the low and high light groups ( p > 0.05). Spearman rank correlations showed that photosynthetic photon flux density (PPFD) was positively correlated with DO, pH, phytoplankton chlorophyll a (Chl a Phyt ) and benthic algae chlorophyll a (Chl a Bent ). DO was positively correlated with Chl a Phyt and Chl a Bent . The results indicate that light may promote the growth of phytoplankton and benthic algae, both of which may increase DO and pH. DO inhibits P release from sediment and pH promotes P release from sediment. Lake-scale studies are needed to fully evaluate its effect under natural conditions, as many other factors (e.g., wind or fish disturbance) in natural lakes could regulate P release from sediment.
... Light-emitting diodes (LEDs), a high-efficiency, long-lifetime, and low heat-generating light source (Hölker et al., 2010;Watanabe, 2011;Kozai et al., 2016;Grubisic et al., 2018), have been widely used in the cultivation of terrestrial vegetables, medicinal herbs, and ornamental waterweeds (Sabzalian et al., 2014;Phansurin et al., 2017). In a previous study, Xu et al. (2019) found that LEDs promoted increased growth of three submersed macrophytes (Vallisneria natans, Myriophyllum spicatum, and Ceratophyllum demersum), and red light performed best. ...
Article
Urban lakes are important natural assets but are exposed to multiple stressors from human activities. Submersed macrophytes, a key plant group that helps to maintain clear-water conditions in lakes, tend to be scarce in urban lakes, particularly when they are eutrophic or hypertrophic, and their loss is linked, in part, to impaired underwater light climate. We tested if enhancing the underwater light conditions using light-emitting diodes (LEDs) could restore submersed macrophytes in urban lakes. Twelve mesocosms (1000 L each) were each planted with tape grass (Vallisneria natans) and monitored over three months (22 August-7 November), using a control and three artificial light intensity treatments (10, 50, and 100 µmol m-2 s-1). Compared with the control, the high light treatment (100 µmol m-2 s-1) had higher leaf number, maximum leaf length, and average leaf length (3.9, 5.8, and 2.8 times, respectively). Shoot number, leaf number, leaf dry mass, root dry mass, and photosynthetic photon flux density in the highlight treatment were significantly greater than the control, but root length and phyto-plankton chlorophyll a were not related to plant growth variables and were low in all treatments. Periphyton chlorophyll a increased significantly with the plant growth variables (i.e., shoot number, leaf number, and maximum leaf length) and was high in the light treatments but did not hamper the growth of the macrophytes. These results indicate that LED light supplementation enables the growth of V. natans under eutrophic conditions , at least in the absence of fish as in our experiment, and that the method may have potential as a restoration method in urban lakes. Lake-scale studies are needed, however, to fully evaluate LED light supplementation under natural conditions where other stressors (e.g., fish grazing) may need to be controlled for successful restoration of urban lakes.
... With accelerating urbanisation, the area affected by ALAN and the brightness of light pollution is growing annually [1]. Artificial lights influence the natural behaviour of nocturnal animals by making them disoriented and misled by additional illumination, which affects foraging, reproduction, communication, and other critical behavioral patterns [2][3][4][5][6]. With the mechanism of altering the circadian cycle and inhibiting melatonin production in several species, including human, light pollution has adverse impacts on health and the natural quality of life [7][8][9][10]. ...
Article
Full-text available
The measurement of night sky quality has become an important task in nature conservation. The primary device used for this task can be a calibrated digital camera. In addition, colour information can be derived from sky photography. In this paper, we provide a test on a concept to gather information about the possible sources of night sky brightness based on digital camera images. This method helps to understand changes in night sky quality due to natural and artificial changes in the environment. We demonstrate that a well-defined colour–colour diagram can differentiate between the different natural and artificial sources of night sky radiance. The colour information can be essential when interpreting long-term evolution of light pollution measurements.
... It is still unclear whether the intensity of ALAN in peri-urban areas (PAR <0.1 µmol m −2 s −1 ) has an effect on plant leaf traits. Freshwater ecosystems are particularly exposed to ALAN (Bennie et al., 2015;Grubisic, 2018;Grubisic et al., 2018;Secondi et al., 2017) since lit road networks, urban development and industrial infrastructure are frequently located along river, lake, and sea shores (Reid et al., 2019). ...
Article
• 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.
... µmol m -2 s -1 (corresponding to 6.8-8.5 lux) increased the abundance of photoautotrophs (diatoms and cyanobacteria) in sediments . It has been shown that the ongoing transition from high-pressure sodium light to light emitting diodes (LEDs) for street lighting increases the impact of ALAN on primary producers (Grubisic et al., 2018). The minimum light intensity that supports growth based on aerobic photosynthesis is considered to be between 0.01 µmol m -2 s -1 (approximately 0.5 lux) and 0.1 µmol m -2 s -1 (approximately 7.4 lux), slightly above the maximum light of a full moon on a clear night (0.005 µmol m -2 s -1 , approximately 0.3 lux) (Raven and Cockell, 2006;Grubisic et al., 2017). ...
Article
Artificial light at night (ALAN) is recognized as one of the major anthropogenic pollutants jeopardizing biodiversity at a global scale. Few studies have focused on the impacts of nocturnal light on freshwater ecosystems despite their increasing exposure to light pollution worldwide due to human activities along rivers or lakes. By modifying metabolism, the disruption of natural light regime could modify the leaf palatability and affect the plant-herbivore interactions which can partly determine the structure of macrophyte communities. By experimentally mimicking light conditions from sub-urban areas, we measured the effects of low-level light at night on the leaf traits of an aquatic plant, Ceratophyllum demersum, and herbivory by the snail Lymnaea stagnalis, a generalist feeder. We demonstrate that artificial light at night increases the herbivory rate: leaves of C. demersum that had been exposed to ALAN for three months were 1.6 times more consumed by L. stagnalis than control leaves. The increase in C. demersum palatability to the pond snail when plants were exposed to ALAN was not due to a decrease in dry matter content or to a modification of the biomechanical characteristics of the leaves. Because snails have not been exposed to nocturnal light before or during the herbivory experiment, this increase in leaf palatability, is possibly linked to modifications of primary and/or secondary metabolism. Our results suggest that ALAN is a potential key factor affecting ecological processes in aquatic ecosystems such as trophic networks.
... Зокрема, згідно з літературними даними, штучне нічне освітлення гальмує ріст водних рослин при використанні лише енергозберігаючих LED-ламп, які дають надмірне випромінювання в регуляторній синій частини світлового спектру. Використання нічних ліхтарів інших типів не здійснює суттєвого впливу на показники росту коренів і епікотилів проростків ячменю [15]. ...
Article
Full-text available
Natural light cycles are being eroded over large areas of the globe by the direct emissions and sky brightening that result from sources of artificial night-time light. This is predicted to affect wild organisms, particularly because of the central role that light regimes play in determining the timing of biological activity. Although many empirical studies have reported such effects, these have focused on particular species or local communities and have thus been unable to provide a general evaluation of the overall frequency and strength of these impacts. Using a new database of published studies, we show that exposure to artificial light at night induces strong responses for physiological measures, daily activity patterns and life history traits. We found particularly strong responses with regards to hormone levels, the onset of daily activity in diurnal species and life history traits, such as the number of offspring, predation, cognition and seafinding (in turtles). So far, few studies have focused on the impact of artificial light at night on ecosystem functions. The breadth and often strength of biological impacts we reveal highlight the need for outdoor artificial night-time lighting to be limited to the places and forms—such as timing, intensity and spectrum—where it is genuinely required by the people using it to minimize ecological impacts.
Article
Full-text available
Artificial light at night (ALAN) has been recently recognized as a threat for aquatic systems, but a comprehensive knowledge of its effects is still lacking. A fundamental question is whether and how ALAN might affect temporal variability of communities, thus undermining the stability of mature assemblages or influencing the colonization process. Here we investigated the role of ALAN on temporal variability of total biomass and maximum photosynthetic efficiency of marine autotrophic biofilms colonizing Mediterranean high-shore rock surfaces while controlling for density of their main grazers. Results showed stability in total biomass, but an increase in maximum photosynthetic efficiency from unlit to lit conditions, which suggested a temporal change in composition and/or abundance of different taxa within mature assemblages. The effect was weaker during the colonization process; in this case, density of grazers acted in the opposite direction of ALAN. We suggest that the addition of light at times when it would not be naturally present may affect the temporal variability of a variety of functioning in aquatic systems, depending on species-specific sensitivities to ALAN within microbial assemblages and/or indirect effects mediated by their consumers. We highlight to further investigate the role of this emergent topic in aquatic ecology.
Article
Full-text available
The application of lighting technologies developed in the 20th century has increased the brightness and changed the spectral composition of nocturnal night-time habitats and night skies across urban, peri-urban, rural, and pristine landscapes, and subsequently, researchers have observed the disturbance of biological rhythms of flora and fauna. To reduce these impacts, it is essential to translate relevant knowledge about the potential adverse effects of artificial light at night (ALAN) from research into applicable urban lighting practice. Therefore, the aim of this paper is to identify and report, via a systematic review, the effects of exposure to different physical properties of artificial light sources on various organism groups, including plants, arthropods, insects, spiders, fish, amphibians, reptiles, birds, and non-human mammals (including bats, rodents, and primates). PRISMA 2020 guidelines were used to identify a total of 1417 studies from Web of Science and PubMed. In 216 studies, diverse behavioral and physiological responses were observed across taxa when organisms were exposed to ALAN. The studies showed that the responses were dependent on high illuminance levels, duration of light exposure, and unnatural color spectra at night and also highlighted where research gaps remain in the domains of ALAN research and urban lighting practice.To avoid misinterpretation, and to define a common language, key terminologies and definitions connected to natural and artificial light have been provided. Furthermore, the adverse impacts of ALAN urgently need to be better researched, understood, and managed for the development of future lighting guidelines and standards to optimize sustainable design applications that preserve night-time environment(s) and their inhabiting flora and fauna.
Preprint
Full-text available
Artificial light at night (ALAN) is increasingly recognised as a disruptive form of environmental pollution, impacting many physiological and behavioural processes that may scale up to population and community-level effects. Mounting evidence from animal studies show that the severity and type of the impact depends on the wavelength and intensity of ALAN. This knowledge has been instrumental for informing policy-making and planning for wildlife-friendly illumination. However, most of this evidence comes from terrestrial habitats, while research testing alternative wavelength illumination in marine environments is lagging behind. In this study we investigated the effect of such alternative ALAN colours on marine primary producers. Specifically, we tested the effect of green, red, and natural white LED illumination at night, compared to a dark control, on the growth of a green microalgae as well as the biomass, diversity and composition of a phytoplankton assemblage. Our findings show that green ALAN boosted chlorophyll production at the exponential growth stage, resulting in higher biomass production in the green algae Tetraselmis suesica. All ALAN wavelengths affected the biomass and diversity of the assemblage with the red and green ALAN having the stronger effects, leading to higher overall abundance and selective dominance of specific diatom species compared to white ALAN and the dark control. Synthesis. Our work indicates that the wavelength of artificial light sources in marine areas should be carefully considered in management and conservation plans. In particular, green and red light should be used with caution in coastal areas, where there might be a need to strike a balance between the strong effects of green and red light on marine primary producers with the benefit they bring to other organisms.
Article
Street lights are important light sources that contribute to artificial light at night (ALAN). To date, ecological impacts of individual LED properties (color temperature, dimmability) have been studied, while interactions between light properties or aspects of luminaire design have not been addressed. However, the design of luminaires can influence ALAN impacts as the shape determines the spatial distribution of light and its visibility in the environment. This may cause amplifying or mitigating effects. We assessed the relative individual and interacting effects of two LED luminaire designs and three LED color temperatures (1750 K, 3000 K, 4000 K) on nocturnal insect abundance, bat foraging and feeding activity. We considered a standard LED luminaire shape with focused light emission and a luminaire shape with a diffusor to scatter the light spatially, leading to increased visibility of the light in the environment. During 104 nights, we trapped 51263 nocturnal insects of which 97% were caught at lights and 3% at dark sites. For bats, up to 44.8% fewer acoustic signals were recorded at dark sites. We caught 31% insects at LEDs with1750 K, 34% and 35% at 3000 K and 4000 K, respectively. Thus, color temperatures of 1750 K proved less detrimental than 3000/4000 K. Effects of luminaire shape led to an increase (16%) of trapped insects for luminaires with diffusors compared to the standard shape. In addition, luminaires with diffusors amplified the effects of LED color (+12% insects at 1750 K/3000 K; +25.6% at 4000 K). In contrast, bat foraging activity was independent of the light treatments while bat feeding activity was increased by 21.5% at standard luminaire shapes. Likely, intense straylight at diffused lights negatively affects the target-focused echolocation by deterring the bats. We concluded that ecological impacts of luminaire shape are an important, yet underestimated variable in light-pollution impact research.
Article
Full-text available
The Internet of Things is rapidly entering the lighting domain. An Internet of Lighting is expected to have significant benefits for its users, such as advanced automated lighting and personal lighting control. The OpenAIS project developed an IP-based lighting architecture and realized a large-scale pilot implementation of an IoT lighting system with advanced sensor-driven controls and user control in a real-life office. Two user control apps were developed and deployed in the open office, individual offices, and meeting rooms: a smartphone application for personal lighting control and an app for dedicated room control tablets. This article reports on an extensive study that evaluated peoples’ use and experiences with the lighting system. The results show that people appreciate personal lighting control and that they adjusted the lighting regularly using both the phone application and the control tablets. Furthermore, lighting control was experienced differently in different workplaces. In general, the level of lighting appraisal increased when more control was available. We argue that the flexibility will be a key success factor for improving the lighting experience, that human-in-the-loop control strategies need balanced automated system behavior and user control, and interfaces should support shared lighting control by including the social context.
Article
Artificial light at night (ALAN) causes a wide range of ecological impacts across diverse ecosystems. Most concentrated in urban areas, ALAN poses a particular risk to associated wildlife by disrupting physiology, behaviour and ultimately survival. This risk is predicted to shift as nighttime lightscapes in many cities undergo change. Globally, streetlights are currently being retrofitted with newer technologies that differ in the spectrum and intensity of their emissions, but there is a dearth of in situ urban experiments on the ecological impacts of this change. We monitored timing of dawn and dusk bird song; frequency of owl vocalisations; avian diversity, relative abundance and community composition; small invasive mammal and ground insect activity; and invertebrate relative abundance at 26 residential properties over an 18-month period that coincided with a retrofit from high-pressure sodium (HPS) to white light-emitting diode (LED) streetlights. Initiation time of dawn song was advanced or delayed for two bird species following the retrofit and backyard avian community composition was altered. Avian species richness, relative abundances of three bird species and ground insect activity increased in the presence of LED streetlights. No other retrofit effects were found. Our study suggests that retrofitting streetlights with white LEDs may lead to both positive and negative conservation outcomes for urban wildlife, but direct impacts are relatively small and may be mitigated by changes in lighting characteristics, such as dimming. Streetlight retrofits could provide an opportunity to reduce the impacts of ALAN on urban wildlife if intentionally designed with conservation benefits in mind.
Article
Full-text available
The beneficial effect of sunlight on all forms of life has been well-known to human cultures worldwide throughout history. However, the importance of darkness for survival, successful reproduction and the overall fitness of all organisms is fully appreciated only by physiologists and environmental biologists. Seasonal variations in environmental conditions (i.e., rainfall, temperature, barometric pressure, food availability) significantly affect reproduction and survival but they are of little predictive value. In contrast, daily fluctuations in light levels and the light spectrum are less dramatic in their impact on life, but were highly predictable throughout evolution. Natural selection has thus favored a strategy of monitoring a day’s length as a predictor of changes in external conditions by the development of the molecular circadian clock, which is sensitive to changes in light/darkness during the day and night. Well-synchronized circadian clockwork ensures that behavioral and physiological processes fluctuate with the daily solar cycle and programs the seasonal changes in physiology via the transduction of the photoperiod into hormonal messages. During the last two decades, energy-efficient lighting technology has shifted from “yellow” high-pressure sodium vapor lamps to new “white” light-emitting diodes (LEDs). As a consequence, nighttime light pollution increased, and the sharp difference between day and night has been erased in many parts of the world, which threatens animal ecology and human health. Studies on humans, laboratory mammals and wildlife suggest that the physiological costs of living under artificial light at night (ALAN) may be due to the disruption of circadian and circannual timing. This overview summarizes the recent findings on the effect of the blurred day/night difference on the circadian clock, nighttime melatonin secretion and photoperiodic changes in mammals and suggests that the gradual decline of fitness due to the increasing ALAN measured in the human population may contribute to the changes in mammalian biodiversity in nature.
Article
Full-text available
Plants can undergo external fluctuations in the natural light and dark cycle. The photosynthetic apparatus needs to operate in an appropriate manner to fluctuating environmental factors, especially in light. Yellow-poplar seedlings were exposed to nighttime artificial high-pressure sodium (HPS) lighting to evaluate night light-adaptation strategies for photosynthetic apparatus fitness relative to pigment contents, photosystem II photochemistry, photosynthetic parameters, histochemical analysis of reactive oxygen species, and plant biomass. As a result, seedlings exhibited dynamic changes including the enhancement of accessory pigments, the reduction of photosystem II photochemistry, increased stomatal limitation, downregulation of photosynthesis, and the decreased aboveground and belowground biomass under artificial night lighting. Histochemical analysis with 3,3′-diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) staining indicates the accumulation of in situ superoxide radicals (O2−) and hydrogen peroxide (H2O2) in leaves exposed to the lowest level of artificial night lighting compared to control. Moreover, these leaves exposed to artificial night lighting had a lower nighttime respiration rate. These results indicated that HPS lighting during the night may act as a major factor as repressors of the fitness of photosynthesis and growth patterns, via a modification of the photosynthetic light harvesting apparatus.
Article
Full-text available
A central aim of the “lighting revolution” (the transition to solid-state lighting technology) is decreased energy consumption. This could be undermined by a rebound effect of increased use in response to lowered cost of light. We use the first-ever calibrated satellite radiometer designed for night lights to show that from 2012 to 2016, Earth’s artificially lit outdoor area grew by 2.2% per year, with a total radiance growth of 1.8% per year. Continuously lit areas brightened at a rate of 2.2% per year. Large differences in national growth rates were observed, with lighting remaining stable or decreasing in only a few countries. These data are not consistent with global scale energy reductions but rather indicate increased light pollution, with corresponding negative consequences for flora, fauna, and human well-being.
Article
Full-text available
Artificial light at night (ALAN) is a widespread alteration of the natural environment that can affect the functioning of ecosystems. ALAN can change the movement patterns of freshwater animals that move into the adjacent riparian and terrestrial ecosystems, but the implications for local riparian consumers that rely on these subsidies are still unexplored. We conducted a 2-year field experiment to quantify changes of freshwater-terrestrial linkages by installing streetlights in a previously light-naïve riparian area adjacent to an agricultural drainage ditch. We compared the abundance and community composition of emerging aquatic insects, flying insects, and ground-dwelling arthropods with an unlit control site. Comparisons were made within and between years using two-way generalized least squares (GLS) model and a BACI design (Before-After Control-Impact). Aquatic insect emergence, the proportion of flying insects that were aquatic in origin, and the total abundance of flying insects all increased in the ALAN-illuminated area. The abundance of several night-active ground-dwelling predators (Pachygnatha clercki, Trochosa sp., Opiliones) increased under ALAN and their activity was extended into the day. Conversely, the abundance of nocturnal ground beetles (Carabidae) decreased under ALAN. The changes in composition of riparian predator and scavenger communities suggest that the increase in aquatic-to-terrestrial subsidy flux may cascade through the riparian food web. The work is among the first studies to experimentally manipulate ALAN using a large-scale field experiment, and provides evidence that ALAN can affect processes that link adjacent ecosystems. Given the large number of streetlights that are installed along shorelines of freshwater bodies throughout the globe, the effects could be widespread and represent an underestimated source of impairment for both aquatic and riparian systems.
Article
Full-text available
In this study we investigated the influence of artificial light at night (ALAN) of different intensities (0, 1, 10, 100 lx) and different colours (blue, green, red) on the daily melatonin rhythm and mRNA expression of gonadotropins in roach Rutilus rutilus, a ubiquitous cyprinid, which occur in standing and moderately flowing freshwater habitats of central Europe. Melatonin concentrations were significantly lowered under nocturnal white light already at 1 lx. Low intensity blue, green and red ALAN lowered the melatonin levels significantly in comparison to a dark control. We conclude that ALAN can disturb melatonin rhythms in roach at very low intensities and at different wavelengths and thus light pollution in urban waters has the potential to impact biological rhythms in fish. However, mRNA expression of gonadotropins was not affected by ALAN during the period of the experiments. Thus, suspected implications of ALAN on reproduction of roach could not be substantiated.
Article
Full-text available
Yellow poplar (Liriodendron tulipifera L.) is a widespread hardwood tree of great ecological and economic value. Light pollution caused by excessive and indiscriminate exposure to artificial night light has emerged as a new risk factor due to its adverse effects related to energy waste, sleep disorders, anthropogenic habitat disturbance, and perceptual disorder of daily and seasonal rhythms in wildlife. However, it remains unknown how associations between artificial night light and stomatal behaviors controlled by internal signals are established. After continuous exposure to artificial light at night over 3 years, leaves in the experimental set-up were measured for stomatal movements, starch turnover, endogenous abscisic acid (ABA) levels, and chloroplast ultrastructure during the growing season. Yellow poplar showed dynamic changes in stomatal movement, starch turnover, and endogenous ABA levels in response to day/artificial night light cycle, resulting in reduction of circadian phase-shifting capacity at both dusk and dawn and normal chloroplast development as compared with natural night. Nighttime light exposure may act as a major factor for disorder of circadian and circannual rhythms as well as physiological and ultrastructural repressor in plants, via a modification of the perceived photoperiod. Our study suggests that these dynamic responses can provide advantageous insights that complement the current knowledge on light pollution.
Article
Full-text available
Artificial light at night (ALAN) is recognized as a contributor to environmental change and a biodiversity threat on a global scale. Despite its widespread use and numerous potential ecological effects, few studies have investigated the impacts on aquatic ecosystems and primary producers. Light is a source of energy and information for benthic autotrophs that form the basis of food webs in clear, shallow waters. Artificial night-time illumination may thus affect biomass and community composition of primary producers. We experimentally mimicked the light conditions of a light-polluted area (approximately 20 lux, white LED) in streamside flumes on a sub-alpine stream. We compared the biomass and community composition of periphyton grown under ALAN with periphyton grown under a natural light regime in two seasons using communities in early (up to 3 weeks) and later (4–6 weeks) developmental stages. In early periphyton, ALAN decreased the biomass of auto-trophs in both spring (57% at 3 weeks) and autumn (43% at 2 weeks), decreased the proportion of cyanobacteria in spring (54%), and altered the proportion of diatoms in autumn (11% decrease at 2 weeks and 5% increase at 3 weeks). No effects of ALAN were observed for later periphyton. Further work is needed to test whether streams with frequent physical disturbances that reset the successional development of periphyton are more affected by ALAN than streams with more stable conditions. As periphyton is a fundamental component of stream ecosystems , the impact of ALAN might propagate to higher trophic levels and/or affect critical ecosystem functions.
Article
Full-text available
The natural nighttime environment is increasingly polluted by artificial light. Several studies have linked artificial light at night to negative impacts on human health. In free-living animals, light pollution is associated with changes in circadian, reproductive, and social behavior, but whether these animals also suffer from physiologic costs remains unknown. To fill this gap, we made use of a unique network of field sites which are either completely unlit (control), or are artificially illuminated with white, green, or red light. We monitored nighttime activity of adult great tits, Parus major, and related this activity to within-individual changes in physiologic indices. Because altered nighttime activity as a result of light pollution may affect health and well-being, we measured oxalic acid concentrations as a biomarker for sleep restriction, acute phase protein concentrations and malaria infection as indices of immune function, and telomere lengths as an overall measure of metabolic costs. Compared to other treatments, individuals roosting in the white light were much more active at night. In these individuals, oxalic acid decreased over the course of the study. We also found that individuals roosting in the white light treatment had a higher probability of malaria infection. Our results indicate that white light at night increases nighttime activity levels and sleep debt and affects disease dynamics in a free-living songbird. Our study offers the first evidence of detrimental effects of light pollution on the health of free-ranging wild animals.
Article
Full-text available
The vegan package provides tools for descriptive community ecology. It has most basic functions of diversity analysis, community ordination and dissimilarity analysis. Most of its multivariate tools can be used for other data types as well. The functions in the vegan package contain tools for diversity analysis, ordination methods and tools for the analysis of dissimilarities. Together with the labdsv package, the vegan package provides most standard tools of descriptive community analysis. Package ade4 provides an alternative comprehensive package, and several other packages complement vegan and provide tools for deeper analysis in specific fields. Package https://CRAN.R-project.org/package=BiodiversityR provides a Graphical User Interface (GUI) for a large subset of vegan functionality. The vegan package is developed at GitHub (https://github.com/vegandevs/vegan/). GitHub provides up-to-date information and forums for bug reports. Most important changes in vegan documents can be read with news(package="vegan") and vignettes can be browsed with browseVignettes("vegan"). The vignettes include a vegan FAQ, discussion on design decisions, short introduction to ordination and discussion on diversity methods. A tutorial of the package at http://cc.oulu.fi/~jarioksa/opetus/metodi/vegantutor.pdf provides a more thorough introduction to the package. To see the preferable citation of the package, type citation("vegan").
Article
Full-text available
White light-emitting diodes (LEDs) are rapidly replacing conventional outdoor lighting technologies around the world. Despite rising concerns over their impact on the environment and human health, the flexibility of LEDs has been advocated as a means of mitigating the ecological impacts of globally widespread outdoor night-time lighting through spectral manipulation, dimming and switching lights off during periods of low demand. We conducted a three-year field experiment in which each of these lighting strategies was simulated in a previously artificial light naïve grassland ecosystem. White LEDs both increased the total abundance and changed the assemblage composition of adult spiders and beetles. Dimming LEDs by 50% or manipulating their spectra to reduce ecologically damaging wavelengths partially reduced the number of commoner species affected from seven to four. A combination of dimming by 50% and switching lights off between midnight and 04:00 am showed the most promise for reducing the ecological costs of LEDs, but the abundances of two otherwise common species were still affected. The environmental consequences of using alternative lighting technologies are increasingly well established. These results suggest that while management strategies using LEDs can be an effective means of reducing the number of taxa affected, averting the ecological impacts of night-time lighting may ultimately require avoiding its use altogether.
Article
Full-text available
Ecological light pollution occurs when artificial lights disrupt the natural regimes of individual organisms or their ecosystems. Increasing development of shoreline habitats leads to increased light pollution (e.g., from cottages, docks, automobile traffic), which could impact the ecology of littoral zones of lakes and rivers. Smallmouth bass (Micropterus dolomieu) engage in sole paternal care, guarding their nest continually, day and night, to protect their developing offspring. Any alterations to their behaviour—either directly because of the response to light or indirectly due to changes in nest predator activity and associated response of the bass—could lead to increased energetic demands for fish that have a fixed energy budget and ultimately reduce reproductive success. To examine this issue, tri-axial accelerometer biologgers were externally attached to nesting smallmouth bass during the egg stage to determine whether light pollution (i.e., dock lights with low levels of continuous light and spotlights with high intensity irregular light simulating automobile traffic) altered behaviour of nesting males relative to control fish. Our study revealed that both types of light pollution increased overall bass activity level compared with the control group. The intermittent light treatment group had the highest activity and exhibited large fluctuations between night and day activity levels. Fish in the continual light treatment group displayed statistically higher activity than the control fish but showed limited fluctuations between day and night activity levels. Our results suggest that continuous or intermittent light sources, common in shoreline habitats that have been developed, have the potential to alter the behaviour and thus energy use of nest-guarding fish. This study contributes to the growing body of literature on the ecological consequences of light pollution in aquatic ecosystems.
Article
Full-text available
The circadian clock helps plants measure day length and adapt to changes in the day-night rhythm. We found that changes in the light-dark regime triggered stress responses, eventually leading to cell death, in leaves of Arabidopsis thaliana plants with reduced cytokinin levels or defective cytokinin signaling. Prolonged light treatment followed by a dark period induced stress and cell death marker genes while reducing photosynthetic efficiency. This response, called circadian stress, is also characterized by altered expression of clock and clock output genes. In particular, this treatment strongly reduced the expression of CIRCADIAN CLOCK ASSOCIATED1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY). Intriguingly, similar changes in gene expression and cell death were observed in clock mutants lacking proper CCA1 and LHY function. Circadian stress caused strong changes in reactive oxygen species- and jasmonic acid (JA)-related gene expression. The activation of the JA pathway, involving the accumulation of JA metabolites, was crucial for the induction of cell death, since the cell death phenotype was strongly reduced in the jasmonate resistant1 (jar1) mutant background. We propose that adaptation to circadian stress regimes requires a normal cytokinin status which, acting primarily through the AHK3 receptor, supports circadian clock function to guard against the detrimental effects of circadian stress.
Article
Full-text available
Artificial lights raise night sky luminance, creating the most visible effect of light pollution-artificial skyglow. Despite the increasing interest among scientists in fields such as ecology, astronomy, health care, and land-use planning, light pollution lacks a current quantification of its magnitude on a global scale. To overcome this, we present the world atlas of artificial sky luminance, computed with our light pollution propagation software using new high-resolution satellite data and new precision sky brightness measurements. This atlas shows that more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans. Moreover, 23% of the world's land surfaces between 75°N and 60°S, 88% of Europe, and almost half of the United States experience light-polluted nights.
Article
Full-text available
We used a before-after-control-impact paired design to examine the effects of a switch from low-pressure sodium (LPS) to light emitting diode (LED) street lights on bat activity at twelve sites across southern England. LED lights produce broad spectrum 'white' light compared to LPS street lights that emit narrow spectrum, orange light. These spectral differences could influence the abundance of insects at street lights and thereby the activity of the bats that prey on them. Most of the bats flying around the LPS lights were aerial-hawking species, and the species composition of bats remained the same after the switch-over to LED. We found that the switch-over from LPS to LED street lights did not affect the activity (number of bat passes), or the proportion of passes containing feeding buzzes, of those bat species typically found in close proximity to street lights in suburban environments in Britain. This is encouraging from a conservation perspective as many existing street lights are being, or have been, switched to LED before the ecological consequences have been assessed. However, lighting of all spectra studied to date generally has a negative impact on several slow-flying bat species, and LED lights are rarely frequented by these 'light-intolerant' bat species.
Article
Full-text available
Artificial light at night (ALAN) is gaining recognition as having an important anthropogenic impact on the environment, yet the behavioural and physiological impacts of this stressor are largely unknown. This dearth of information is particularly true for freshwater ecosystems, which are already heavily impacted by anthropogenic pressures. Atlantic salmon (Salmo salar L.) is a species of conservation and economic importance whose ecology and behaviour is well studied, making it an ideal model species. Recent investigations have demonstrated that salmon show disrupted behaviour in response to artificial light; however, it is not yet clear which physiological processes are behind the observed behavioural modifications. Here, two novel non-invasive sampling methods were used to examine the cortisol stress response of dispersing salmon fry under different artificial lighting intensities. Fish egg and embryos were reared under differing ALAN intensities and individual measures of stress were subsequently taken from dispersing fry using static sampling, whereas population-level measures were achieved using deployed passive samplers. Dispersing fry exposed to experimental confinement showed elevated cortisol levels, indicating the capacity to mount a stress response at this early stage in ontogenesis. However, only one of the two methods for sampling cortisol used in this study indicated that ALAN may act as a stressor to dispersing salmon fry. As such, a cortisol-mediated response to light was not strongly supported. Furthermore, the efficacy of the two non-invasive methodologies used in this study is, subject to further validation, indicative of them proving useful in future ecological studies.
Article
Full-text available
Artificial light at night (ALAN) is one of the most obvious hallmarks of human presence in an ecosystem. The rapidly increasing use of artificial light has fundamentally transformed nightscapes throughout most of the globe, although little is known about how ALAN impacts the biodiversity and food webs of illuminated ecosystems. We developed a large-scale experimental infrastructure to study the effects of ALAN on a light-naïve, natural riparian (i.e., terrestrial-aquatic) ecosystem. Twelve street lights (20 m apart) arranged in three rows parallel to an agricultural drainage ditch were installed on each of two sites located in a grassland ecosystem in northern Germany. A range of biotic, abiotic, and photometric data are collected regularly to study the short- and long-term effects of ALAN on behavior, species interactions, physiology, and species composition of communities. Here we describe the infrastructure setup and data collection methods, and characterize the study area including photometric measurements. None of the measured parameters differed significantly between sites in the period before illumination. Results of one short-term experiment, carried out with one site illuminated and the other acting as a control, demonstrate the attraction of ALAN by the immense and immediate increase of insect catches at the lit street lights. The experimental setup provides a unique platform for carrying out interdisciplinary research on sustainable lighting.
Article
Full-text available
Artificial light at night (ALAN) is recognized as a widespread and increasingly important anthropogenic environmental pressure on wild species and their interactions. Understanding of how these impacts translate into changes in population dynamics of communities with multiple trophic levels is, however, severely lacking. In an outdoor mesocosm experiment we tested the effect of ALAN on the population dynamics of a plant-aphid-parasitoid community with one plant species, three aphid species and their specialist parasitoids. The light treatment reduced the abundance of two aphid species by 20% over five generations, most likely as a consequence of bottom-up effects, with reductions in bean plant biomass being observed. For the aphid Megoura viciae this effect was reversed under autumn conditions with the light treatment promoting continuous reproduction through asexuals. All three parasitoid species were negatively affected by the light treatment, through reduced host numbers and we discuss induced possible behavioural changes. These results suggest that, in addition to direct impacts on species behaviour, the impacts of ALAN can cascade through food webs with potentially far reaching effects on the wider ecosystem.
Article
Full-text available
An increasing proportion of the Earth's surface is illuminated at night. In aquatic ecosystems, artificial light at night (ALAN) may influence microbial communities living in the sediments. These communities are highly diverse and play an important role in the global carbon cycle. We combined field and laboratory experiments using sediments from an agricultural drainage system to examine how ALAN affects communities and alters carbon mineralization. Two identical light infrastructures were installed parallel to a drainage ditch before the start of the experiment. DNA metabarcoding indicated that both sediment communities were similar. After one was lit for five months (July-December 2012) we observed an increase in photoautotroph abundance (diatoms, Cyanobacteria) in ALAN-exposed sediments. In laboratory incubations mimicking summer and winter (six weeks each), communities in sediments that were exposed to ALAN for 1 year (July 2012-June 2013) showed less overall seasonal change compared with ALAN-naive sediments. Nocturnal community respiration was reduced in ALAN-exposed sediments. In long-term exposed summer-sediments, we observed a shift from negative to positive net ecosystem production. Our results indicate ALAN may alter sediment microbial communities over time, with implications for ecosystem-level functions. It may thus have the potential to transform inland waters to nocturnal carbon sinks. © 2015 The Author(s) Published by the Royal Society. All rights reserved.
Article
Full-text available
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.
Article
Full-text available
Artificial light at night is profoundly altering natural light cycles, particularly as perceived by many organisms, over extensive areas of the globe. This alteration comprises the introduction of light at night at places and times at which it has not previously occurred, and with different spectral signatures. Given the long geological periods for which light cycles have previously been consistent, this constitutes a novel environmental pressure, and one for which there is evidence for biological effects that span from molecular to community level. Here we provide a synthesis of understanding of the form and extent of this alteration, some of the key consequences for terrestrial and aquatic ecosystems, interactions and synergies with other anthropogenic pressures on the environment, major uncertainties, and future prospects and management options. This constitutes a compelling example of the need for a thoroughly interdisciplinary approach to understanding and managing the impact of one particular anthropogenic pressure. The former requires insights that span molecular biology to ecosystem ecology, and the latter contributions of biologists, policy makers and engineers.
Article
Full-text available
Providing an adequate quantity and quality of food for the escalating human population under changing climatic conditions is currently a great challenge. In outdoor cultures, sunlight provides energy (through photosynthesis) for photosynthetic organisms. They also use light quality to sense and respond to their environment. To increase the production capacity, controlled growing systems using artificial lighting have been taken into consideration. Recent development of light-emitting diode (LED) technologies presents an enormous potential for improving plant growth and making systems more sustainable. This review uses selected examples to show how LED can mimic natural light to ensure the growth and development of photosynthetic organisms, and how changes in intensity and wavelength can manipulate the plant metabolism with the aim to produce functionalized foods.
Article
Full-text available
Assessing the effect of light pollution, Microcystis aeruginosa was grown with and without low levels of night lighting. Significant differences were observed between the treatments in the maximum quantum yield of charge separation, the intracellu-lar chlorophyll a concentration, the functional absorption cross-section of photo-system II, the number of Rubisco per cell and per chlorophyll a, the number of photosystem I per chlorophyll a, and the chlorophyll a fraction not bound to the photosystems and IsiA.
Article
Full-text available
Artificial light at night can be harmful to the environment, and interferes with fauna and flora, star visibility, and human health. To estimate the relative impact of a lighting device, its radiant power, angular photometry and detailed spectral power distribution have to be considered. In this paper we focus on the spectral power distribution. While specific spectral characteristics can be considered harmful during the night, they can be considered advantageous during the day. As an example, while blue-rich Metal Halide lamps can be problematic for human health, star visibility and vegetation photosynthesis during the night, they can be highly appropriate during the day for plant growth and light therapy. In this paper we propose three new indices to characterize lamp spectra. These indices have been designed to allow a quick estimation of the potential impact of a lamp spectrum on melatonin suppression, photosynthesis, and star visibility. We used these new indices to compare various lighting technologies objectively. We also considered the transformation of such indices according to the propagation of light into the atmosphere as a function of distance to the observer. Among other results, we found that low pressure sodium, phosphor-converted amber light emitting diodes (LED) and LED 2700 K lamps filtered with the new Ledtech's Equilib filter showed a lower or equivalent potential impact on melatonin suppression and star visibility in comparison to high pressure sodium lamps. Low pressure sodium, LED 5000 K-filtered and LED 2700 K-filtered lamps had a lower impact on photosynthesis than did high pressure sodium lamps. Finally, we propose these indices as new standards for the lighting industry to be used in characterizing their lighting technologies. We hope that their use will favor the design of new environmentally and health-friendly lighting technologies.
Article
Full-text available
This document describes how to use the shape package for plotting graphical shapes. Together with R-package diagram (Soetaert 2009a) this package has been written to produce the gures of the book (Soetaert and Herman 2009)
Article
Freshwaters are increasingly exposed to artificial light at night (ALAN), yet the consequences for aquatic primary producers remain largely unknown. We used stream-side flumes to expose three-week-old periphyton to LED light. Pigment composition was used to infer community changes in LED-lit and control periphyton before and after three weeks of treatment. The proportion of diatoms/chrysophytes decreased (14%) and cyanobacteria increased (17%) in lit periphyton in spring. This may reduce periphyton nutritional quality in artificially-lit waters.
Article
Christopher Kyba, Andrej Mohar and Thomas Posch seek a standard figure for moonlight illuminance.
Article
1. Light pollution is rapidly increasing and can have deleterious effects on biodiversity, yet light types differ in their effect on wildlife. Among the light types used for street lamps, light-emitting diodes (LEDs) are expected to become globally predominant within the next few years. 2. In a large-scale field experiment, we recorded bat activity at 46 street lights for 12 nights each and investigated how the widespread replacement of conventional illuminants by LEDs affects urban bats: we compared bat activity at municipal mercury vapour (MV) street lamps that were replaced by LEDs with control sites that were not changed. 3. Pipistrellus pipistrellus was the most frequently recorded species; it was 45% less active at LEDs than at MV street lamps, but the activity did not depend on illuminance level. Light type did not affect the activity of Pipistrellus nathusii, Pipistrellus pygmaeus or bats in the Nyctalus/Eptesicus/Vespertilio (NEV) group, yet the activity of P. nathusii increased with illu-minance level. Bats of the genus Myotis increased activity 4Á5-fold at LEDs compared with MV lights, but illuminance level had no effect. 4. Decreased activity of P. pipistrellus, which are considered light tolerant, probably paral-leled insect densities around lights. Further, our results suggest that LEDs may be less repelling for light-averse Myotis spp. than MV lights. Accordingly, the transition from conventional lighting techniques to LEDs may greatly alter the anthropogenic impact of artificial light on urban bats and might eventually affect the resilience of urban bat populations. 5. Synthesis and applications. At light-emitting diodes (LEDs), the competitive advantage – the exclusive ability to forage on insect aggregations at lights – is reduced for light-tolerant bats. Thus, the global spread of LED street lamps might lead to a more natural level of competition between light-tolerant and light-averse bats. This effect could be reinforced if the potential advantages of LEDs over conventional illuminants are applied in practice: choice of spectra with relatively little energy in the short wavelength range; reduced spillover by precisely directing light; dimming during low human activity times; and control by motion sensors. Yet, the potential benefits of LEDs could be negated if low costs foster an overall increase in artificial lighting.
Article
A single solution reagent is described for the determination of phosphorus in sea water. It consists of an acidified solution of ammonium molybdate containing ascorbic acid and a small amount of antimony. This reagent reacts rapidly with phosphate ion yielding a blue-purple compound which contains antimony and phosphorus in a 1:1 atomic ratio. The complex is very stable and obeys Beer's law up to a phosphate concentration of at least 2 μg/ml.The sensitivity of the procedure is comparable with that of the stannous chloride method. The salt error is less than 1 %.
Article
The human presence close to streams and rivers is known to have consistently increased worldwide, therefore introducing dramatic anthropogenic and environmental changes. However, a spatiotemporal detailed analysis is missing to date. In this paper, we propose a novel method to quantify the temporal evolution and the spatial distribution of the anthropogenic presence along streams and rivers and in their immediate proximity at the global scale and at a high-spatial resolution (i.e., nearly 1 km at the equator). We use satellite images of nocturnal lights, available as yearly snapshots from 1992 to 2013, and identify five distinct distance classes from the river network position. Our results show a temporal enhancement of human presence across the considered distance classes. In particular, we observed a higher human concentration in the vicinity of the river network, even though the frequency distribution of human beings in space has not significantly changed in the last two decades. Our results prove that fine-scale remotely sensed data, as nightlights, may provide new perspectives in water science, improving our understanding of the human impact on water resources and water-related environments.
Article
The effect of a range of ecologically relevant broader spectrum street light intensities on the dispersal timing of Atlantic salmon (Salmo salar) fry was investigated to assess the efficacy of a proposed management tool, the dimming of lamp brightness, for reducing the ecological consequences of artificial night light on aquatic ecosystems. Dispersal timing under treatment street light intensities of 8, 4, 2 and 1 lux was compared to that under a control night light intensity of 0.1 lux, representative of approximately half that experienced from a full moon.Dispersal timing was significantly delayed (by 1.4 to 2.2 days), and its diel pattern significantly disrupted under the treatment street light intensities. However, the dose–response for both delay and disruption effects was not linear, with a strong effect apparent at 1 lux, and little or no additional impact seen when the light intensity was increased further. Under control conditions, the mean time of dispersal was 3:58 h after dusk, with very few fry ( Survival to dispersal in aquarium conditions was high (≥97.8%) and comparable in the control and treatment street light intensities. However, in the wild, the period between fry dispersal and the establishment of feeding territories is considered to be of critical importance in the dynamics of salmonid populations and any disruption may significantly increase predation and reduce fitness.The findings of this aquarium‐based investigation suggest that the dimming of lamp brightness has little potential as a successful management strategy to reduce the disruptive impact of street lighting surrounding freshwater ecosystems. We therefore recommend that the best course of action is to maintain and increase natural unlit areas.
Article
Artificial light at night is prevalent in human-dominated landscapes, and streams in these landscapes can be expected to be affected by artificial lights. We hypothesised that artificial light at night would reduce the activity of aquatic insects, resulting in reduced drift rates, lower fish growth rates and lower leaf litter decomposition rates.We tested these hypotheses by installing street lights to reaches in four forested, natural streams of coastal British Columbia each paired with a control reach. Cutthroat trout (Oncorhynchus clarkii) are the top predators in these streams and feed mostly on terrestrial and drifting aquatic invertebrates.We found that the night-time drift of aquatic invertebrates in lit reaches was ˜50% of the drift in dark reaches. However, the density of emerging aquatic insects, the density of insects falling into reaches, leaf litter decomposition rate and the number and growth rate of trout caught were not significantly different between the dark and experimentally lit reaches.We conclude that, while short-term exposure to artificial light during the summer changes invertebrate behaviour, it does not significantly alter other trophic levels in forested headwater streams. Our results suggest that low levels of artificial light do not strongly influence stream ecosystems, but future research should determine whether this is true for all seasons and longer-term exposure to light.
Article
Light is essential for the life of photosynthetic organisms as it is a source of energy and information from the environment. Light excess or limitation can be a cause of stress however. Photosynthetic organisms exhibit sophisticated mechanisms to adjust their physiology and growth to the local environmental light conditions. The cryptochrome/photolyase family (CPF) is composed of flavoproteins with similar structures that display a variety of light-dependent functions. This family encompasses photolyases, blue-light activated enzymes that repair ultraviolet-light induced DNA damage, and cryptochromes, known for their photoreceptor functions in terrestrial plants. For this review, we searched extensively for CPFs in the available genome databases to trace the distribution and evolution of this protein family in photosynthetic organisms. By merging molecular data with current knowledge from the functional characterization of CPFs from terrestrial and aquatic organisms, we discuss their roles in (i) photoperception, (ii) biological rhythm regulation and (iii) light-induced stress responses. We also explore their possible implication in light-related physiological acclimation and their distribution in phototrophs living in different environments. The outcome of this structure-function analysis reconstructs the complex scenarios in which CPFs have evolved, as highlighted by the novel functions and biochemical properties of the most recently described family members in algae.
Article
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.
Article
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.
Article
We measured specific growth rates of Stephanodiscus minutulus, Nitzschia acicularis (diatoms), and Limnothrix redekei (cyanobacterium) under fluctuating and constant light in semi-continuous culture at 10°C, 15°C, and 20°C and under photoperiods of 6 h d−1 and 12 h d−1. Fluctuating light regimes simulated regular vertical mixing in lakes with a ratio of euphotic to mixed depth (zeu : zmix) of 1 and 0.5 on a cloudless day. Light fluctuations at zeu : zmix = 1 decreased the growth rates of S. minutulus, N. acicularis, and L. redekei by 18%, 33%, and 29%, respectively, compared to constant light at the same daily light supply. Temperature had no effect on this decrease. Halving zeu : zmix (simulating deep mixing) had the same effect on growth as halving the photoperiod, demonstrating that these factors are cumulative. We introduce a simple empirical factor to adjust growth rates measured under constant light to account for fluctuating light. This factor is independent of temperature and photoperiod, applies over a range of zeu : zmix, and accurately describes present and published growth rates of several species. We show how to account for temporal variability of the light supply at different temperatures and photoperiods when predicting growth rates of phytoplankton.
Article
1. Regime shifts are commonly associated with the loss of submerged macrophytes in shallow lakes; yet, the effects of this on whole-lake primary productivity remain poorly understood. This study compares the annual gross primary production (GPP) of two shallow, eutrophic lakes with different plant community structures but similar nutrient concentrations. 2. Daily GPP rates were substantially higher in the lake containing submerged macrophytes (586 ± 23 g C m−2 year−1) than in the lake featuring only phytoplankton and periphyton (408 ± 23 g C m−2 year−1; P < 0.0001). Comparing lake-centre diel oxygen curves to compartmental estimates of GPP confirmed that single-site oxygen curves may provide unreliable estimates of whole-lake GPP. The discrepancy between approaches was greatest in the macrophyte-dominated lake during the summer, with a high proportion of GPP occurring in the littoral zone. 3. Our empirical results were used to construct a simple conceptual model relating GPP to nutrient availability for these alternative ecological regimes. This model predicted that lakes featuring submerged macrophytes may commonly support higher rates of GPP than phytoplankton-dominated lakes, but only within a moderate range of nutrient availability (total phosphorus ranging from 30 to 100 μg L−1) and with mean lake depths shallower than 3 or 4 m. 4. We conclude that shallow lakes with a submerged macrophyte–epiphyton complex may frequently support a higher annual primary production than comparable lakes that contain only phytoplankton and periphyton. We thus suggest that a regime shift involving the loss of submerged macrophytes may decrease the primary productivity of many lakes, with potential consequences for the entire food webs of these ecosystems.
Article
Seven marine and freshwater diatoms were grown in a 6:18 L:D cycle with a one hour light break in the middle of the dark period. The freshwater diatom Fragilaria crotonensis showed a depressed growth rate compared to a 7:17 L:D control, while the other species showed no clear response.
Article
The growth rate of the freshwater planktonic diatom Aulacoseira subarctica (O. Müll.) Haworth was significantly depressed when the dark period in a 6:18 light: dark cycle was interrupted by a one hour light break. The degree of depression was sensitive to the length and timing of the light break. A one hour light break was most effective in the middle of the dark period.
Article
The ecological impacts of nighttime light pollution have been a longstanding source of concern, accentuated by realized and projected growth in electrical lighting. As human communities and lighting technologies develop, artificial light increasingly modifies natural light regimes by encroaching on dark refuges in space, in time, and across wavelengths. A wide variety of ecological implications of artificial light have been identified. However, the primary research to date is largely focused on the disruptive influence of nighttime light on higher vertebrates, and while comprehensive reviews have been compiled along taxonomic lines and within specific research domains, the subject is in need of synthesis within a common mechanistic framework. Here we propose such a framework that focuses on the cross-factoring of the ways in which artificial lighting alters natural light regimes (spatially, temporally, and spectrally), and the ways in which light influences biological systems, particularly the distinction between light as a resource and light as an information source. We review the evidence for each of the combinations of this cross-factoring. As artificial lighting alters natural patterns of light in space, time and across wavelengths, natural patterns of resource use and information flows may be disrupted, with downstream effects to the structure and function of ecosystems. This review highlights: (i) the potential influence of nighttime lighting at all levels of biological organisation (from cell to ecosystem); (ii) the significant impact that even low levels of nighttime light pollution can have; and (iii) the existence of major research gaps, particularly in terms of the impacts of light at population and ecosystem levels, identification of intensity thresholds, and the spatial extent of impacts in the vicinity of artificial lights.
Article
The migratory timing and behaviour of wild Atlantic salmon smolts leaving their natal stream was determined using a passive integrated transponder (PIT) antennae system at a study site on a tributary of the River Itchen, England. Experiments compared the downstream migration of smolts under natural control conditions (2000–2006) with two years (2008 and 2009) when the main downstream exit of the study site was subject to street-lit conditions every alternate night (maximum light intensity measured at the stream surface = 14 lx). Migration of smolts under control conditions was significantly (p < 0.01, n = 170) correlated with sunset. By contrast, street lighting resulted in the timing of migration being random (p = 0.11, n = 7; p = 0.76, n = 34, respectively) with respect to time of day. Furthermore, migration of smolts was significantly (p = 0.01, n = 19) correlated with the time of sunset for fish migrating when the lamp had been off, but random (p = 0.36, n = 22) when the lamp had been on (2008 and 2009 data, combined). This alteration in migratory behaviour due to street lighting may impact fitness.