Ecological and Organismic Effects of Light Pollution

Abstract

Since the invention of the electric light bulb in 1879, a significant portion of the planet has been transformed from experiencing a natural pattern of light and dark determined by the sun, moon, stars and occasional other transient lights to being subjected to intermittent and perpetual illumination from human civilisation that is unprecedented in the history of Earth. The pervasiveness of this phenomenon and its exponential growth has measurable and significant consequences for living organisms. The results of recent research have extended knowledge about the geographic scope and specific impacts of artificial night lighting on animal behaviour, physiological processes and ecological interactions across a range of taxa and its broader ecosystem effects. Key Concepts Artificial lighting alters natural patterns of light and dark over large areas of Earth's surface. Most species have circadian rhythms that are entrained by cycles of light and dark that can be affected by artificial lighting. Organisms vary widely in their perception of intensity and wavelengths of light; what is perceived as ‘dark’ by humans may be bright to another species. Many species specialise in activities in particular lighting conditions (either day versus night or illumination levels during a month or during the course of a night) and this temporal partitioning can be disrupted by artificial lighting. Nocturnal processes of repair and recovery, including production of essential hormones such as melatonin, can be interrupted by artificial night lighting. Decisions to forage at night are related to lighting levels; species weigh the risk of predation against need to seek food. Additional light at night tends to favour predators, except when groups of prey species, such as a flock of birds or a school of fish, exhibit a communal vigilance for predators. Artificial lighting can interfere with spatial orientation of organisms, resulting in direct mortality or unnecessary movements (e.g. migrating birds, hatchling sea turtles, insects at lights). Adverse effects of artificial night lighting can be reduced through careful consideration of need, spectrum, intensity, direction and duration of light used.

Capitalizing on opportunistic citizen science data to monitor urban biodiversity: A multi-taxa framework

“…These night-time lights data have previously been used to track human population at many different scales (Zhang and Seto 2013). We acknowledge that although we use VIIRS night-time lights as a proxy for urbanization, species are differentially impacted by ambient light pollution (e.g., Longcore and Rich 2016), and it may be difficult to distinguish between whether species are responding to urbanization or night-time lights itself (i.e., ambient light pollution). Species respond differently to the intensity, direction, and duration of ambient light (Longcore and Rich 2016); most of which is not captured in the measurement of VIIRS night-time lights.…”

Enlightening Butterfly Conservation Efforts: The Importance of Natural Lighting for Butterfly Behavioral Ecology and Conservation

“…Unnatural lighting likely affects many biological functions as well as leading to numerous ecological consequences [ 10 , 12 , 13 , 69 , 70 , 71 , 72 ]. I focus on five biological functions: (1) Phenology and Circadian Rhythms; (2) Attraction and Orientation; (3) Foraging; (4) Predation; and (5) Reproduction.…”

“…The emphasis in this arms race literature has been on the effects of temperature altering this developmental race; however, recent research has shown that anthropogenic lighting is altering the phenology of plants and trees as well [ 115 ]. Trees in unnaturally brighter areas budded seven days sooner than plants in areas without anthropogenic lighting [ 115 ] and this is likely across many different species of plants [ 10 , 13 , 70 ]. Thus, anthropogenic lighting is likely affecting the timing of both plant development and larvae development in unequal ways, which could lead to major disruptions in the coevolution between host plants and their insect larvae.…”

“…Thus, the natural light conditions that forest canopy provide have been greatly reduced by human activities [ 9 ]. This alarming change in natural lighting conditions has direct ecological consequences including loss of biodiversity and risk of species extirpation and extinction [ 10 , 11 , 12 , 13 ].…”

“…Previous research has documented the effects of changes to natural light conditions on wildlife ranging from changes in predation, reproduction, phenology, migration and orientation, community level interactions, behavior, communication, and physiology [ 10 , 13 , 14 , 15 , 16 , 17 ]. However, our understanding of how changes in natural light conditions affect butterfly behavior and conservation status remains largely unknown.…”