Abstract: Holometabolous insects exhibit complex life cycles in which both morphology and ecological niche change dramatically during development. In the larval stage, many insects have soft, slow-moving bodies and poor vision, limiting their ability to respond to environmental threats. Artificial light at night (ALAN) is an environmental perturbation known to severely impact the fitness of adult insects by disrupting both temporal and spatial orientation. The impact of ALAN on earlier life stages, however, is largely unknown. We conducted a series of laboratory experiments to investigate how two distinct forms of ALAN affect the development and movement of immature Photuris sp. and Photinus obscurellus fireflies. Although long-term exposure to dim light at night (dLAN), akin to urban skyglow, did not impact overall survivorship or duration of egg, larval, and pupal stages in either species, it did accelerate weight gain in early-instar Photuris larvae. Late-instar Photuris exposed to point sources of ALAN at the start of their nightly foraging period were also significantly more likely to burrow beneath the soil surface, rather than disperse across it. ALAN may therefore impede dispersal of firefly larvae away from illuminated areas, which could have downstream consequences for the reproductive fitness of adults.
Abstract: Sleep is a reversible state that sustains physiological and psychological processes in humans. As well established, individual-level factors, such as stress, smoking, drugs, and caffeine intake, reduce sleep duration and quality. However, studies of the effect of environmental risk factors, such as artificial light at night (ALAN) and noise, on sleep have been infrequent. Using records obtained from the 2017 Social Survey of Israel and combined with ALAN satellite data and various proxies for traffic noise, the present study aimed to determine how the combination of ALAN and traffic noise impact sleep duration and quality in urban areas. The increase of road density at the place of residence reduces average sleep duration by ~4.5% (~18 min.) and increases the frequency of reported sleep difficulties by ~3.5%, all other factors held equal. Similarly, an increase in ALAN exposure reduces average sleep duration by ~3% (~12 min) and increases the frequency of reported sleep difficulties by ~11%. The study also reveals a significant interaction between the two environmental risk factors in question, with the adverse impact of ALAN on sleep quality especially pronounced in high noise exposure areas.
Abstract: Sea turtles in the Gulf of Mexico, which are listed as either threatened or endangered under the US Endangered Species Act, face numerous threats but are particularly susceptible to the negative effects of light pollution on nesting beaches. Light pollution affects the distribution, density, and placement of nests on beaches, and disrupts seafinding in hatchlings emerging from nests; often leading to their death. Rapid urban growth near Gulf Islands National Seashore (GUIS), FL, United States, over the last century has contributed to increased light pollution on its beaches. There is concern that light pollution is causing females to build nests in at-risk locations subject to erosion and flooding, and is causing the observed high rates of hatchling misorientation. From 2015 to 2016, we measured brightness of the night sky, horizon profile, and lunar variables at GUIS at loggerhead (Caretta caretta) nests to assess the effects of brightness on building of at-risk nests and hatchling misorientation. In addition, we quantified the effects of relocating at-risk nests on nest success. We found that contrast in brightness between the landward and seaward directions at GUIS was partially responsible for high rates of hatchling misorientation, and there was a strong moderating influence of lunar fraction and lunar altitude on hatchling misorientation: larger lunar fractions and lower lunar altitudes reduced misorientation. We did not find an effect of artificial light, horizon profile, or lunar fraction on the propensity of loggerheads to build nests in at-risk locations, and found no evidence that relocating nests at GUIS reduced loggerhead nest success. In fact, we found that nest success was improved and hatchling misorientation rates were reduced for relocated loggerhead nests.
Abstract: Photoentrainment of the circadian clock located in the hypothalamic suprachiasmatic nucleus (SCN) is fundamental for the stable regulation of neuroendocrine function underlying physiological functions such as metabolism, sleep, immune responses, and reproduction. Masking by light directly suppresses melatonin secretion independent of the circadian system, with impact on several neuroendocrine axes. This chapter describes recent findings in anatomy and physiology on how light mediates its effects on SCN-regulated timing of the neuroendocrine system, including the hypothalamic-pituitary-adrenal (HPA) axis, the hypothalamic-pituitary-thyroid (HPT) axis, the hypothalamic-pituitary-gonadal (HPG) axis, and melatonin and arginine-vasopressin (AVP) secretion. In modern societies, artificial light at night (ALAN) seems to affect circadian and neuroendocrine systems, and should be considered in the understanding the health problems of the industrialized human population.
Abstract: Knowledge-based economic activities (aka quaternary industries or QIs) are characterized by high concentrations of labour force and potentially high night-time light emissions. Therefore, geographic concentrations of such activities can presumably be identified using information on the amount artificial light at night (ALAN), which different geographic areas emit. Question, however, remains whether the models, incorporating ALAN data, are place-specific or whether such models are sufficiently generic, thus making it possible to apply them, once estimated, to other countries and continents. To answer this question, the analysis is performed in several phases. First, we build separate models for European NUTS3 regions and US counties. Next, we cross-validate these models and use them to predict QI concentrations worldwide. As the analysis shows, cross-validation of the models, applied to the “counterpart” continent, also results in a reasonably good fit, with R2 reaching 0.852, when the US-model is applied to the EU data, and R2 = 0.896, when the EU-model is applied to the US data. Although attempts to use ALAN data for the analysis of different socio-economic phenomena are not new, to the best of our knowledge, this is the study first that uses cross-continent validation of ALAN-based models to determine their generality.