Light brightness data near sea turtle nests as measured from the horizon and zenith using a Sky Quality Meter.

A Sky Quality Meter (SQM) is a photometer designed to measure night sky brightness. SQMs have been used to interpret light fields for various purposes, including studies of relationships between directional light brightness and sea turtle hatchling orientation. This article reports SQM data collected on a sea turtle nesting beach at Delray Beach, Florida (USA) on 17 August 2020. Three hundred-and-sixty light brightness data were collected by eight consecutive readings in each of the four horizontal directions and the zenith at nine sites. The data also include landward photographic images captured at the nine light-measurement sites. The dataset supports the usefulness of the instrument for biological light-field measurements and refute blanket criticisms on inconsistent measurements that would justify discarding initial readings and averaging over a time series.

The effect of natural and artificial light at night on nocturnal song in the diurnal willie wagtail.

Artificial light at night (ALAN) has rapidly and drastically changed the global nocturnal environment. Evidence for the effect of ALAN on animal behaviour is mounting and animals are exposed to both point sources of light (street and other surrounding light sources) and broadscale illuminance in the form of skyglow. Research has typically taken a simplified approach to assessing the presence of ALAN, yet to fully understand the ecological impact requires consideration of the different scales and sources of light concurrently. Bird song has previously been well studied for its relationship with light, offering an opportunity to examine the relative impact of different sources of light on behaviour. In this study, we combine correlational and experimental approaches to examine how light at night affects the nocturnal song behaviour of the largely diurnal willie wagtail (Rhipidura leucophrys). Observations of willie wagtails across urban and rural locations in southeastern Australia demonstrated that nocturnal song behaviour increased with the intensity of moonlight in darker rural areas but decreased in areas with high sky glow. In addition, willie wagtails were half as likely to sing at night in the presence of localized light sources such as streetlights in urban and rural areas. Experimental introduction of streetlights to a previously dark area confirmed this relationship: willie wagtail song rates declined when lights were turned on and returned to their original rates following streetlight removal. Our findings show that scale, as well as intensity, are important when considering the impact of light at night as moonlight, sky glow, and localized sources of artificial light have different effects on nocturnal song behaviour.

Effect of light pollution on self-reported sleep quality and its components: Comparative assessment among healthy adult populations in a rural and an Urban area of West Bengal, India.

BACKGROUND: Light pollution is inappropriate or excessive use of artificial light. Nighttime sky radiance is an effective measure to study its effects on individual sleep quality. OBJECTIVES: The study is aimed to measure the effect of light pollution on the sleep quality and compare among people residing in selected rural and urban areas of West Bengal, India. METHODS: A comparative cross-sectional study was conducted during September-October 2018 in 10 villages of Barasat II block and 10 wards of Kolkata Municipal Corporation. Two hundred and sixty-three participants from urban and 249 participants from rural areas were selected through multi-stage sampling. Data regarding sleep quality and other selected factors were geotagged along with the radiance data. Multi-level linear regression models were built. RESULTS: The mean age of the participants from rural and urban areas were respectively 37.65 (±10.77) years and 38.10 (±11.02) years. Gender-wise the participants were distributed almost evenly in urban and rural areas. Among the urban and rural population, the observed mean global Pittsburgh Sleep Quality Index scores were 12.63 (±3.04) and 9.23 (±2.27), respectively. Poorer sleep quality was observed to be statistically significant with increasing level of exposure. Multi-level models show that, at an exposure of >40.0 nW/cm2/sr the adjusted coefficient was 11.52 (95% confidence interval [CI]: 9.65, 13.40) in the overall model and 12.84 (95% CI: 12.31, 13.37) for urban participants. CONCLUSION: The disturbance in sleep is associated with higher levels of night-time radiance of the sky strongly observed among the urban population.

Quantifying the erosion of natural darkness in the global protected area system.

The nighttime light environment of much of the earth has been transformed by the introduction of electric lighting. This impact continues to spread with growth in the human population and extent of urbanization. This has profound consequences for organismal physiology and behavior and affects abundances and distributions of species, community structure, and likely ecosystem functions and processes. Protected areas play key roles in buffering biodiversity from a wide range of anthropogenic pressures. We used a calibration of a global satellite data set of nighttime lights to determine how well they are fulfilling this role with regard to artificial nighttime lighting. Globally, areas that are protected tend to be darker at night than those that are not, and, with the exception of Europe, recent regional declines in the proportion of the area that is protected and remains dark have been small. However, much of these effects result from the major contribution to overall protected area coverage by the small proportion of individual protected areas that are very large. Thus, in Europe and North America high proportions of individual protected areas (>17%) have exhibited high levels of nighttime lighting in all recent years, and in several regions (Europe, Asia, South and Central America) high proportions of protected areas (32-42%) have had recent significant increases in nighttime lighting. Limiting and reversing the erosion of nighttime darkness in protected areas will require routine consideration of nighttime conditions when designating and establishing new protected areas; establishment of appropriate buffer zones around protected areas where lighting is prohibited; and landscape level reductions in artificial nighttime lighting, which is being called for in general to reduce energy use and economic costs.

Cuantificación de la Erosión de la Oscuridad Natural en el Sistema Global de Áreas Protegidas Resumen El ambiente de luz nocturna de la mayor parte de la Tierra se ha transformado por la introducción de la luz eléctrica. Este impacto continúa esparciéndose con el crecimiento de la población humana y de la extensión de la urbanización. Esto tiene consecuencias profundas sobre la fisiología y el comportamiento de los organismos y afecta a la abundancia y la distribución de especies, a la estructura de la comunidad y probablemente a los procesos y funciones de los ecosistemas. Las áreas protegidas juegan un papel importante en el amortiguamiento de una amplia gama de presiones antropogénicas para la biodiversidad. Usamos una calibración de un conjunto de datos satelitales globales de luces nocturnas para determinar que tan bien desempeñan este papel con respecto a la iluminación nocturna artificial. En un nivel global, las áreas que están protegidas tienden a ser más oscuras en la noche que aquellas que no lo están, y además, con la excepción de Europa, las declinaciones regionales recientes en la proporción del área que está protegida y permanece oscura han sido menores. Sin embargo, muchos de estos efectos resultan de una mayor contribución a la cobertura total del área protegida por parte de la pequeña proporción de áreas protegidas individuales que son muy grandes. Por esto en Europa y América del Norte, una alta proporción de áreas protegidas individuales (>17%) ha exhibido niveles altos de iluminación nocturna en todos los años recientes y en varias regiones (Europa, Asia, América Central y América del Sur) proporciones altas de áreas protegidas (32-42%) han tenido incrementos significativos de iluminación nocturna. Limitar y revertir la erosión de la oscuridad nocturna en las áreas protegidas requerirá una consideración rutinaria de las condiciones nocturnas cuando se designen y establezcan nuevas áreas protegidas; un establecimiento de zonas de amortiguamiento apropiadas donde se prohíba la iluminación alrededor de las áreas protegidas; y una reducción de los niveles de paisaje en la iluminación nocturna artificial, la cual se pide en general para reducir el uso de energía y los costos económicos.