Pervasiveness of Biological Impacts of Artificial Light at Night

Abstract

Artificial light at night (ALAN) and its associated biological impacts have regularly been characterised as predominantly urban issues. Although far from trivial, this would imply that these impacts only affect ecosystems that are already heavily modified by humans and are relatively limited in their spatial extent, at least as compared with some key anthropogenic pressures on the environment that attract much more scientific and public attention, such as climate change or plastic pollution. However, there are a number of reasons to believe that ALAN and its impacts are more pervasive, and therefore need to be viewed from a broader geographic perspective rather than an essentially urban one. Here we address, in turn, 11 key issues when considering the degree of spatial pervasiveness of the biological impacts of ALAN. First, the global extent of ALAN is likely itself commonly underestimated, as a consequence of limitations of available remote sensing data sources and how these are processed. Second and third, more isolated (rural) and mobile (e.g., vehicle headlight) sources of ALAN may have both very widespread and important biological influences. Fourth and fifth, the occurrence and impacts of ALAN in marine systems and other remote settings, need much greater consideration. Sixth, seventh and eighth, there is growing evidence for important biological impacts of ALAN at low light levels, from skyglow, and over long distances (because of the altitudes from which it may be viewed by some organisms), all of which would increase the areas over which impacts are occurring. Ninth and tenth, ALAN may exert indirect biological effects that may further expand these areas, because it has a landscape ecology (modifying movement and dispersal and so hence with effects beyond the direct extent of ALAN), and because ALAN interacts with other anthropogenic pressures on the environment. Finally, ALAN is not stable, but increasing rapidly in global extent, and shifting towards wavelengths of light that often have greater biological impacts.

Tracking Flights to Investigate Seabird Mortality Induced by Artificial Lights

“…Light pollution is an important threat to biodiversity conservation because it can cause cascading effects on ecosystem functioning (Longcore and Rich, 2004;Hölker et al, 2010). Despite the numerous studies and reviews of the field, the underlying factors are far from being understood (Gaston et al, 2014(Gaston et al, , 2021, especially for secretive species. From a conservation point of view, mass mortality events of organisms are one of the most severe ecological consequences of light pollution, involving a wide range of taxa such as moths, sea turtles, passerine birds, and seabirds (Rich and Longcore, 2006).…”

The duration of artificial light defines sexual signalling in the common glow-worm

“…Our finding that extended exposure to artificial light causes female glow-worms to cease glowing suggests that glow-worm reproduction (especially mate searching) would benefit from minimisation of the period of time that an artificial light is turned on, easing the negative anthropogenic impact on these beetles. Glow-worms and flashing fireflies aside, at least 49.5% (with the exact figure depending on the method) of the world's land surface between 59° N and 55° S, not restricted to urban areas, has been estimated to be exposed to either direct or indirect night-time light pollution (Gaston et al 2021). Given that a range of species, from insects to mammals, show adverse responses to light pollution (Dominoni and Nelson 2018), limiting both the amount of nocturnal light sources and the duration of the light is likely to be beneficial.…”

“…Natural environments are increasingly affected by human activity. Indeed, anthropogenic disturbances, such as noise, light pollution, and habitat destruction, have become more common and increased in their intensity (Gaston et al 2015(Gaston et al , 2021Swaddle et al 2015). Many organisms struggle with adapting to such quick environmental changes (Wong and Candolin 2015).…”

11 Pressing Research Questions on How Light Pollution Affects Biodiversity

“…Light corridors and networks (e.g., illuminated roads), as well as light patches (e.g., an illuminated gas station in a dark environment) can impact landscapes by acting as barriers to movement and dispersal, and as population sinks (Degen et al, 2016;Laforge et al, 2019;van Grunsven et al, 2020). Changing the ability of species to move through landscapes may alter foraging and reproductive opportunities for individuals, modifying habitat connectivity and gene flow between populations, disrupting recolonization of habitat patches, and altering metapopulation dynamics (Caplat et al, 2016;Grubisic et al, 2018;Camacho et al, 2021;Gaston et al, 2021).…”

“…ALAN-induced disruptions of those cycles affect the structure and function of multiple levels of biodiversity that are again strongly interconnected (Longcore and Rich, 2004;Hölker et al, 2010b;Gaston et al, 2013). Given the growing global pervasiveness of ALAN (Kyba et al, 2017;Gaston et al, 2021), it is important to understand how multiple levels of biodiversity respond to it directly and indirectly (Figure 1).…”