However, an experimental demonstration of the effects of skyglow in a controlled fashion at a larger scale or at ecosystem level remained elusive so far. Finally, the amplitude of diel vertical migration of zooplankton can be affected by skyglow, as shown in a seminal experiment conducted in small enclosures deployed in an urban lake 30. Another recent study suggests that low skyglow-like ALAN levels disrupt the migration of Talitrus saltator (commonly known as sandhoppers), that normally use celestial light at night for orientation 29. For example, the remarkable sensitivity of the circadian system of several taxa in lab studies, including common freshwater fish 27, 28, indicate that skyglow could influence wild animals over large areas. Skyglow is dramatically amplified during overcast conditions 20, 24 and can then reach extreme night sky brightness values and illuminances of more than 1 lx 20, 21, 22, 23, which is much brighter than moonlight 25.Īlthough it is suspected that ecological impacts of skyglow are significant 5, 6, 7, 26, experimental studies are scarce. In urban areas, skyglow for clear sky condition can exceed the natural night sky brightness by factors of several tens to hundreds 20, 21, 22, 23 resulting in ground illuminances (in the horizontal plane) on the order of 0.01–0.1 lx. Skyglow extends over large areas 18 and can be sensed over large distances ranging from several tens to hundreds of km away from the light sources 19, 20. It causes the diffuse glow above illuminated areas such as a large city (Fig. Because humans tend to settle near water bodies 12, aquatic environments are particularly affected by ALAN, but are currently understudied compared to terrestrial ones 9, 13, 14, 15.Īrtificial skyglow 16 is a form of light pollution which is caused by ALAN being scattered within the atmosphere and redirected back towards the Earth surface 17. Impacts of ALAN on life were also recognized early on 4, but detailed investigation of the impact of ALAN on life only began during the last two decades 5, 6, 7, 8 showing effects on species level ranging from microorganisms 9 to mammals 10 as well as on important ecosystem services such as pollination 11. However, long aware of the artificially increasing brightness of night skies, astronomers have recognized negative aspects of ALAN, pointing to the ‘dark side’ of light emissions by coining the term light pollution 3. ALAN makes it possible to extend human activities (both indoor and outdoor) into the night, and is asociated with wealth and safety, rendering public perception of ALAN overwhelmingly positive 2. Similar content being viewed by othersĮmissions of artificial light at night (ALAN) have dramatically increased since the early twentieth century, and current growth rates of lit area and light intensities on Earth exceed 2% per year at the global scale 1. Our method can be adapted to other outdoor and indoor skyglow experiments, urgently needed to understand the impact of skyglow on ecosystems. The illumination system was enabled by optical modeling with Monte-Carlo raytracing and validated by measurements. Spatially diffuse and homogeneous surface illumination that is adjustable between 0.01 and 10 lx, resembling rural to urban skyglow levels, was achieved with white light-emitting diodes at a large-scale lake enclosure facility. Here we present the first experimental setup to mimic skyglow at ecosystem level outdoors in an aquatic environment. However, testing the impact of skyglow at large scales and in a controlled fashion under in situ conditions has remained elusive so far. Artificial skyglow, a form of light pollution with large range, is hypothesized to have environmental impact at ecosystem level. Light pollution is an environmental stressor of global extent that is growing exponentially in area and intensity. Scientific Reports volume 11, Article number: 23478 ( 2021) Design and implementation of an illumination system to mimic skyglow at ecosystem level in a large-scale lake enclosure facility
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