added 2 research items
Artificial light at night (ALAN) has been massively deployed worldwide and has become a major environmental pressure for biodiversity, especially contributing to habitat loss and landscape fragmentation. To mitigate these latter, green and blue infrastructure policies have been developed throughout the world based on the concept of ecological networks, a set of suitable interconnected habitats. However, currently, these nature conservation policies hardly consider the adverse effects of ALAN. Here, we promote the integration of darkness quality within the ’green and blue infrastructure’, to implement a ‘dark infrastructure’. Dark infrastructure should be identified, preserved and restored at different territorial levels to guarantee ecological continuities where the night and its rhythms are as natural as possible. For this purpose, we propose an operational 4-steps process that includes 1) Mapping of light pollution in all its forms and dimensions in relation to biodiversity, 2) Identifying the dark infrastructure starting or not from the already identified green/blue infrastructure, 3) Planning actions to pre- serve and restore the dark infrastructure by prioritizing lighting sobriety and not only energy saving, 4) Assessing the effectiveness of the dark infrastructure with appropriate indicators. Dark infrastructure projects have already been created (for example in France and Switzerland) and can serve as case studies for both urban and natural areas. The deployment of dark infrastructure raises many operational and methodological questions and stresses some knowledge gaps that still need to be addressed, such as the exhaustive mapping of light pollution and the characterization of sensitivity thresholds for model species.
This study covers the role of exposure to artificial light at night (ALAN) in shaping the spatial distributions of two species of conservation concern, roosting sites of the Western Snowy Plover and locations of California Grunion spawning runs, along the coast of southern California. Observational data on plover and grunions, derived from community science sources, were obtained along with remotely sensed environmental measurements along the coast of southern California. The study area comprises a 1.5 km wide coastal strip, bounded by the mean low-tide line, and stretching from 10 km north of the northern Ventura County line to 10 km south of the southern Orange County line. These data were used as inputs within three species distribution models: a generalized linear model, Maxent, and random forest. Exposure to ALAN was based on a ground-verified model of night sky illuminance. In the highest performing models, which used random forest modeling, exposure to ALAN was the most important environmental factor influencing distribution of grunion runs and second-most important factor for plover roosts. Significant declines were found in the likelihood of plovers roosting in locations where exposure to ALAN exceeded illuminance levels equivalent to that produced by approximately one half a full moon and for grunion spawning at one full moon. Disruption of behaviors related to reproduction, roosting, and spawning associated with elevated levels of ALAN are likely a result of increased predation risk in illuminated coastal areas. With evidence of ALAN providing significant ecological disturbances to these two managed species, it is therefore recommended that control of nighttime illumination be used, even at naturalistic intensities, to mitigate disturbances to critical reproductive coastal habitats and potentially other environments.
Artificial light at night (ALAN) is closely associated with modern societies and is rapidly increasing worldwide. A dynamically growing body of literature shows that ALAN poses a serious threat to all levels of biodiversity - from genes to ecosystems. Many “unknowns” remain to be addressed however, before we fully understand the impact of ALAN on biodiversity and can design effective mitigation measures. Here, we distilled the findings of a workshop on the effects of ALAN on biodiversity at the first World Biodiversity Forum in Davos attended by several major research groups in the field from across the globe. We argue that 11 pressing research questions have to be answered to find ways to reduce the impact of ALAN on biodiversity. The questions address fundamental knowledge gaps, ranging from basic challenges on how to standardize light measurements, through the multi-level impacts on biodiversity, to opportunities and challenges for more sustainable use.
The physiology and behavior of most life at or near the Earth’s surface has evolved over billions of years to be attuned with our planet’s natural light–dark cycle of day and night. However, over a relatively short time span, humans have disrupted this natural cycle of illumination with the introduction and now widespread proliferation of artificial light at night (ALAN). Growing research in a broad range of fields, such as ecology, the environment, human health, public safety, economy, and society, increasingly shows that ALAN is taking a profound toll on our world. Much of our current understanding of light pollution comes from datasets generated by remote sensing, primarily from two missions, the Operational Linescan System (OLS) instrument of the now-declassified Defense Meteorological Satellite Program (DMSP) of the U.S. Department of Defense and its follow-on platform, the Day-Night Band (DNB) of the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument on board the Suomi National Polar-Orbiting Partnership satellite. We reviewed both current literature and guiding advice from ALAN experts, aggregated from a diverse range of disciplines and Science Goals, to derive recommendations for a mission to expand knowledge of ALAN in areas that are not adequately addressed with currently existing orbital missions. We propose a stand-alone mission focused on understanding light pollution and its effects on our planet. Here we review the science cases and the subsequent mission recommendations for NITESat (Nighttime Imaging of Terrestrial Environments Satellite), a dedicated ALAN observing mission.
This report analyses all artificial interference that can have a negative impact on the visibility of the night sky. These interferences can be logically grouped into three categories according to type. The first category refers to the effect caused by the artificial emission of visible light during the night, also known as ALAN (Artificial Light At Night). The second category refers to the impact that the very large number of communication satellites in Low Earth Orbit will have on astronomical observations. The third category refers to the interference that radio broadcasting, both by terrestrial and satellite sources, have on observations by radio telescopes. The possibility of illuminating our houses and cities during the night time represents great technological progress and is currently an indefeasible asset to our society. However, excessive, ubiquitous and improperly directed illumination has very negative impact on three main aspects: 1. the ability of our citizens to view a pristine, starry sky, 2. the efficiency of scientific observations of cosmic phenomena by amateur and professional astronomers, 3. the bio-environment including human health. These three aspects have been analysed in detail by three ad hoc Working Groups. Their findings and recommendations are summarized in the report. The WorkingGroup on the BioEnvironment compiled 13 recommendations to mitigate the impacts of ALAN on humans, flora, and fauna:
• New infrastructure development in previously natural environments is introducing light pollution to habitats at an unprecedented rate, which has the potential to be devastating for native insect assemblages. • We evaluated insect attraction to three lamp types emitting different spectra of light (white, yellow‐filtered and amber‐filtered ~3000 K LED lamps) and an unlit control in a lowland forest site in the northern Peruvian Amazon previously naïve to artificial illumination. • Lamp type was the only variable included in the most parsimonious models explaining morphospecies richness and abundance for all insects combined and for eight different insect orders. White lamps (3200 K) attracted far more insects, both morphospecies and individuals, including groups containing important vectors of pathogens, bacteria or parasites, than either yellow (2700 K) or amber (2200 K) lamps. • Amber lamps attracted the fewest morphospecies and individuals overall but were the most attractive for a limited group of insects, including elaterid beetles (click beetles) and mycetophilid flies (fungus flies). • While period of night was not a significant predictor of morphospecies richness or abundance, different assemblages of insects were collected during two different sampling periods (18:00–20:00 and 03:00–05:00). • We strongly recommend that new infrastructure development projects introducing ALAN to light‐naïve tropical forests use filtered amber LED lamps with no blue and minimal green light content in outdoor lighted areas. Similarly, operators should develop outdoor lighting plans that include overall reduction of nocturnal lighting and impact mitigation measures. These recommendations should also be used to retrofit existing infrastructure including roads and human settlements. Abstract en español • El desarrollo de nuevas infraestructuras en entornos previamente naturales está introduciendo contaminación lumínica en esos hábitats a una taza sin precedentes, la cual tiene el potencial de ser particularmente devastadora para las comunidades de insectos nativos. • Evaluamos la atracción de insectos a tres tipos de lámparas que emiten diferentes espectros de luz (lámparas LED blancas de ~3000K sin filtro, con un filtro amarillo y con un filtro ámbar para limitar o eliminar los espectros azules de luz emitidos) y un control sin luz en un sitio de bosque bajo en el norte de la Amazonía peruana, previamente sin iluminación artificial. • El tipo de lámpara fue la única variable incluida en los modelos más parsimonicos que explican la riqueza y abundancia de morfoespecies para todos los insectos combinados y para ocho órdenes diferentes de insectos. Las lámparas blancas (3200K) atrajeron muchos más insectos, morfoespecies e individuos, incluyendo grupos conocidos por contener vectores importantes de patógenos, bacterias o parásitos, que las lámparas de color amarillo (2700K) o ámbar (2200K). • Las lámparas ámbar atrajeron la menor cantidad de morfoespecies e individuos en general, pero fueron las luces más atractivas para un grupo limitado de insectos, incluyendo a los escarabajos elatéridos (escarabajos clic) y las moscas micetofílidas (moscas de los hongos). • Si bien el período de la noche no fue un predictor significativo de la riqueza o abundancia de morfoespecies, se colectaron diferentes ensamblajes de insectos durante los dos períodos de muestreo (18: 00‐20: 00 y 03: 00‐05: 00). • Recomendamos enfáticamente que los nuevos proyectos de desarrollo de infraestructura que introduzcan ALAN a bosques sin luces artificiales utilicen luces LED con filtro ámbar sin espectro azul y muy poco espectro verde en áreas iluminadas al aire libre. Del mismo modo, los operadores deben desarrollar un plan de iluminación al aire libre que incluya la reducción general de la iluminación nocturna y métodos de mitigación de impactos. Estas recomendaciones también deben usarse para modernizar la infraestructura existente, incluidas las carreteras y los asentamientos humanos.
From the position of wildlife, the best artificial light at night is no artificial light at night. Recognizing that this is not feasible while maintaining safety and achieving other goals, I have focused on evaluating spectrum as an approach to minimizing impacts to wildlife and, more broadly, to the night sky, ecosystems, and humans. The most useful information needed to compare the effects of one light source with another is the spectral power distribution (SPD) from ultraviolet to infrared. By comparing the visual systems or known behavioral responses of different groups and species of wildlife to those SPDs, we can first predict, then confirm through experiments in the laboratory and field, the extent to which one light affects species more or less than another at the same brightness as perceived by humans. My colleagues and I have tested this approach with insects (Longcore et al. 2015; Donners et al. 2018) and seabirds (Longcore et al. 2018) and published this approach to rapid assessment of different lamp sources (Longcore et al. 2018). Although we did provide the code for designers to bring their own SPDs and be able to produce these assessments with just a web browser and a server (see https://github.com/herf/ecological), there is still a widespread desire to allow another metric of spectral characteristics to stand in for full analysis using a light source’s spectral power distribution.
Exposure to artificial light at night (ALAN) is a significant factor in ecological and epidemiological research. Although levels of exposure are frequently estimated from satellite-based measurements of upward radiance, and the correlation between upward radiance and zenith sky brightness is established, the correlation between upward radiance and the biologically relevant exposure to light experienced from all directions on the ground has not been investigated. Because ground-based exposure to ALAN can depend on local glare sources and atmospheric scattering, ecological and epidemiological studies using upward radiance have relied on an untested relationship. To establish the nature of the relationship between upward radiance and hemispherical scalar illuminance (SI) on the ground and to calibrate future experimental studies of ALAN, we used hemispheric digital photography to measure SI at 515 locations in coastal southern California, and compared those values to co-located satellite-based measures of upward radiance as described by the Visible Infrared Imaging Radiometer Suite (VIIRS) satellite’s Day-Night Band (DNB) sensor and zenith downwards radiance as estimated by the World Atlas of Artificial Night Sky Brightness (WA). We found significant variations in SI within the geographic scale defined by the resolutions of both the DNB and WA, as well as in both luminance and color correlated temperature (CCT) across individual image hemispheres. We observed up to two or more orders of magnitude in ALAN exposure within any given satellite-measured unit. Notwithstanding this variation, a linear model of log(SI) (log(SI modeled )), dependent only on the percent of the image hemisphere obscured by structures along the horizon (percent horizon) and log(WA) accounted for 76% of the variation in observed log(SI). DNB does not perform as well in alternative models and consequently future studies seeking to characterize the light environment should be built on WA data when the high temporal resolution of DNB measurements are not needed.
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.
This paper presents examples of the latest imaging data of the Earth at night from multiple CubeSat platforms. Beginning in 2012, with AeroCube-4, The Aerospace Corporation has launched multiple CubeSat platforms in different orbits equipped with a common suite of CMOS sensors. Originally designed as utility cameras to assist with attitude control system studies and star sensor development, we have been using these simple camera sensors to image the Earth at night since 2014. Our initial work focused on observing nighttime urban lights and global gas flare signals at higher resolution than is possible with the VIIRS sensor. To achieve optimum sensitivity and resolution, orbital motion is compensated for via the use of on-board reaction wheels to perform point-and-stare experiments, often with multiple frame exposures as the sensor moves in orbit. Ground sample distances for these systems range from approximately 100 to 130 meters for the narrow-field-of-view cameras, to 500 meters for the medium-field-of-view cameras. In our initial work, we demonstrated that CMOS sensors flown on AeroCube satellites can achieve a nighttime light detection sensitivity on the order of 20 nW-cm-2-sr-1. This resolution and sensitivity allows for detection of urban lighting, road networks, major infrastructure illumination, natural gas flares, and other phenomena of interest. For wide-area surveys, we can also program our cameras to observe regions of interest and co-add pixels to reduce the data bandwidth. This allows for a greater number of frames to be collected and downloaded. These results may then be used to task later satellite passes. Here, we present new examples of our nighttime Earth observation studies using CubeSats. These include: 1) detecting urban growth and change via repeat imaging, 2) investigating the utility of color observations, 3) spotting major sources of light pollution, 4) studying urban-wildland interface regions where lighting may be important to understanding wildlife corridors, 5) imaging lightning and cloud cover at night using wide-area imaging, 6) observations of the very bright lights of fishing boats, and 7) observing other interesting natural phenomenon, including airglow emissions, and the streaking caused by proton strikes in the South Atlantic Anomaly. Our ongoing work includes utilizing a diversity in overpass times from multiple satellites to observe nighttime scenes, imaging high-latitude cities not optimally accessed by the international space station's cameras, and building a catalogue of observations of rapidly developing megacities and global infrastructure nodes. Data from CMOS sensors flown in common on 5 different AeroCubes in 4 different orbits have been collected. Our results show that enhanced CubeSat sensors can improve mapping of the human footprint in targeted regions via nighttime lights and contribute to better monitoring of: urban growth, light pollution, energy usage, the urban-wildland interface, the improvement of electrical power grids in developing countries, light-induced fisheries, and oil industry flare activity. Future CubeSat sensors should be able to contribute to nightlights monitoring efforts by organizations such as NOAA, NASA, ESA, the World Bank and others, and offer low-cost options for nighttime studies.
Light sources attract nocturnal flying insects, but some lamps attract more insects than others. The relation between the properties of a light source and the number of attracted insects is, however, poorly understood. We developed a model to quantify the attractiveness of light sources based on the spectral output. This model is fitted using data from field experiments that compare a large number of different light sources. We validated this model using two additional datasets, one for all insects and one excluding the numerous Diptera. Our model facilitates the development and application of light sources that attract fewer insects without the need for extensive field tests and it can be used to correct for spectral composition when formulating hypotheses on the ecological impact of artificial light. In addition, we present a tool allowing the conversion of the spectral output of light sources to their relative insect attraction based on this model.
For many decades, the spectral composition of lighting was determined by the type of lamp, which also influenced potential effects of outdoor lights on species and ecosystems. Light‐emitting diode (LED) lamps have dramatically increased the range of spectral profiles of light that is economically viable for outdoor lighting. Because of the array of choices, it is necessary to develop methods to predict the effects of different spectral profiles without conducting field studies, especially because older lighting systems are being replaced rapidly. We describe an approach to predict responses of exemplar organisms and groups to lamps of different spectral output by calculating an index based on action spectra from behavioral or visual characteristics of organisms and lamp spectral irradiance. We calculate relative response indices for a range of lamp types and light sources and develop an index that identifies lamps that minimize predicted effects as measured by ecological, physiological, and astronomical indices. Using these assessment metrics, filtered yellow‐green and amber LEDs are predicted to have lower effects on wildlife than high pressure sodium lamps, while blue‐rich lighting (e.g., K ≥ 2200) would have greater effects. The approach can be updated with new information about behavioral or visual responses of organisms and used to test new lighting products based on spectrum. Together with control of intensity, direction, and duration, the approach can be used to predict and then minimize the adverse effects of lighting and can be tailored to individual species or taxonomic groups. The intersection of response curves and lamp spectra describes potential impacts of nighttime lighting on insects, sea turtles, Newell's Shearwater, and juvenile salmon, as well as their average, compared with equal brightness in lux of daylight (D65; 6500K) within the range 350–780 nm.
Currently light pollution is a significant problem for our public lands and its impact has only worsened over the past several decades. Affordable measurement techniques are not well developed so this study was the first extensive trial of a new method for light pollution monitoring in the US. Existing methods are very expensive and require high levels of technical skill or are inexpensive and yield limited data. This study used a digital camera with a hemispherical fisheye lens to capture the entire night sky in a single long-exposure image. The amount and quality of data generated from these images after processing with Sky Quality Camera (a proprietary light pollution monitoring software from Slovenia) is comparable to much more expensive setups at a fraction of the cost.
This poster documents the analysis of point detections of lighted boats off the Pacific Coast of the United States. The patterns observed in the 2016-2017 period are consistent with the boats being part of the light-induced squid fishery. We show variation in the distribution of boats through the year and in response to the weekend closure of the squid fishery. The boat distributions also show the effectiveness of established Marine Protected Areas in excluding this fishery from protected zones.
Light pollution has been of increasing concern as it relates to protected areas. As such, natural resource managers need information on the distribution, intensity, and dynamics of nighttime lights in protected areas. We examine the extent of nighttime light brightness from 1992 to 2012 in the Mediterranean Coast Network (Santa Monica Mountains National Recreation Area, Channel Islands National Park, and Cabrillo National Monument) using the Defense Meteorological Satellite Program (DMSP) Operational Linescan System, which has provided global annual nighttime light imagery at 0.9 km pixel resolution. Nighttime lights appeared stable in Santa Monica Mountains National Recreation Area, decreased in Cabrillo National Monument, and are extremely low in Channel Islands National Park. However, the mean brightness values in Santa Monica Mountains National Recreation Area and Cabrillo National Monument were very high compared to all other National Parks. Indeed, both were comparable to the two National Parks in the USA with the highest mean brightness values (Cuyahoga Valley National Park, Hot Springs National Park). Monitoring night light extent, intensity, time series, and change detection using remote sensing should be a standard practice for all protected areas managed by the National Park Service due to the no-cost nature of the data and ease at which analyses can be undertaken. The DMSP data and calibrated products can be used to monitor long-term changes in light distribution and intensity while the higher-resolution Visible Infrared Imaging Radiometer Suite data can be used to show changes in light distribution and density throughout the year and can be used to test how policy or ordinance changes impact light pollution.
A consequence of the explosive expansion of human civilization has been the global loss of biodiversity and changes to life-sustaining geophysical processes of Earth. The footprint of human occupation is uniquely visible from space in the form of artificial night lighting – ranging from the burning of the rainforest to massive offshore fisheries to omnipresent lights of cities, towns, and villages. This article describes a novel approach to assessing global human impact using satellite observed nighttime lights. The results provide reef managers and governments a first-pass screening tool for reef conservation projects. Sites requiring restoration and precautionary actions can be identified and assessed further in more focused investigations. We hope to create a mental picture for others to see and encourage participation in maintaining and restoring the natural world.
Ecologists have long studied the critical role of natural light in regulating species interactions, but, with limited exceptions, have not investigated the consequences of artificial night lighting. In the past century,the extent and intensity of artificial night lighting has increased such that it has substantial effects on the biology and ecology of species in the wild. We distinguish “astronomical light pollution”, which obscures the view of the night sky, from “ecological light pollution”, which alters natural light regimes in terrestrial and aquatic ecosystems. Some of the catastrophic consequences of light for certain taxonomic groups are well known, such as the deaths of migratory birds around tall lighted structures, and those of hatchling sea turtles disoriented by lights on their natal beaches. The more subtle influences of artificial night lighting on the behavior and community ecology of species are less well recognized, and constitute a new focus for research in ecology and a pressing conservation challenge.
Humans have radically transformed the physical characteristics of the nighttime hours in ways that would have been unimaginable only a hundred years ago (Figure 1, Longcore and Rich 2004). The cost of industrial development, affluence, and mass consumption has been the loss of natural patterns of darkness over vast expanses of the Earth's sur-face, both on land and at sea (Cinzano et al. 2001). Those concerned with the nighttime environment, whether scientists or advocates, regulators or lighting manufacturers, in the private or public sector, together face the challenge of restoring the night sky and natural patterns of light and dark in a global economy. We are motivated by an affinity for the night sky (Mizon 2002), respect for our natural heritage, concern for our own health (Stevens and Rea 2001, Pauley 2004), and a desire to protect the night for the other living beings with which we share the planet. Astronomers were the first to express concern about the widespread proliferation of artificial night lighting, and they rightfully raised the alarm about the degradation of the night sky (Riegel 1973). Concern about the effects of artificial lighting on wildlife and plants has been a relatively recent phenomenon (Verheijen 1985, Upgren 1996, Outen 1998). This is not to say that scientists were not interested in the effects of light on other species. Naturalist William Beebe was fascinated with the ability of ultraviolet lights to attract juvenile fish, as documented in a sketch from an expedition in 1935 (Figure 2). But Beebe's observations were not motivated by concern that lights had widespread ecological consequences. A substantial and growing body of research on the eco-logical effects of artificial night lighting is now available (see Rich and Longcore 2006). New scientific articles that extend this knowledge are being published at a steady rate (e.g., Oro et al. 2005, Baker and Richardson 2006, Miller 2006). Sufficient information is now available to devise policies to mitigate and avoid the range of profound, adverse consequences on other Figure 1. The view of Los Angeles from the Mount Wilson Observa-tory showing the extent of night lighting. 166 species caused by artifi-cial light at night. Urban planners and open space managers can incorporate this knowledge to better pro-tect nature at night. Here we provide examples of three general types of impacts on wildlife: direct mortality, altered reproductive behaviors, and disrupted interac-tions between species. These examples give an indication of the breadth of this problem and of the opportunities for solutions. Lights that kill Anyone with a porch light knows that lights can kill. Many insects are attracted to their deaths at lights; in Germany alone, the estimate of total insect deaths at streetlights in a summer is 100 billion (Eisenbeis 2006). Migratory birds are attracted to the lights on tall towers when weather conditions are adverse. In North America, an estimated 4–5 million birds are killed per year in collisions with towers, their guy wires, and each other. Most of these are Neotropical migrants, birds that migrate to Central and South America, which are already under severe population stress (Banks 1979, Shire et al. 2000, Longcore et al. 2007). Based on past patterns, we have calculated that two species of federal conservation concern, blackpoll warbler and bay-breasted warbler, suffer losses of over 100,000 individuals each year (Longcore et al. 2007). Over 10,000 individuals of an additional 20 species of conservation concern are killed annually. A change in lighting type would probably eliminate up to 80% of this mortality (Gehring and Kerlinger 2007), and the U.S. Federal Communications Commission is considering such a change based on expert testimony from us, other groups, and the U.S. Fish and Wildlife Service. Although they are not afforded the same attention as birds, the mortality of insects can be significant. In a study along a forested stream, a single streetlight installed on the bank attracted and killed as many caddisflies as emerged from the stream along an entire 200 meter stretch (Scheibe 1999). This process is described by Professor Gerhard Eisenbeis as the "vacuum cleaner effect," vividly evoking the image of lights sucking insects out of the surrounding habitat (Eisenbeis 2006). Beachfront lighting and sky glow threaten the survival of hatchling sea turtles and affect the nest site choice of female turtles (Witherington 1992, Salmon et al. 2000).