Impacts of Artificial Light at Night on Biological Timings

Abstract

The use of artificial lighting to illuminate the night has provided substantial benefits to humankind. It has also disrupted natural daily, seasonal, and lunar light cycles as experienced by a diversity of organisms, and hence it has also altered cues for the timings of many biological activities. Here we review the evidence for impacts of artificial nighttime lighting on these timings. Although the examples are scattered, concerning a wide variety of species and environments, the breadth of such impacts is compelling. Indeed, it seems reasonable to conclude that the vast majority of impacts of artificial nighttime lighting stem from effects on biological timings. This adds support to arguments that artificial nighttime lighting has a quite pervasive and marked impact on ecological systems, that the rapid expansion in the global extent of both direct illuminance and skyglow is thus of significant concern, and that a widespread implementation of mitigation measures is required.

How ecological communities respond to artificial light at night

“…Experimental lighting inhibited or encouraged the colonization of 39% of all taxa analyzed, including sessile and mobile species, leading to different community composition between lit and control sites. ALAN has also been shown to impact the niche space of species by extending the perceived day length and therefore activity patterns for diurnal species (Gaston et al., ). How significant this might be for community structure will depend on the extent to which species partition time during day and night for activity because of phylogenetic constraints, and the extent to which they do so to avoid or reduce competition or predation (which might mask underlying circadian rhythms).…”

Connecting spectral radiometry of anthropogenic light sources to the visual ecology of organisms

“…These findings are the first to test how different non‐visual photoreceptors are stimulated by numerous anthropogenic light sources and reveal that numerous organisms are at risk for changes to circadian rhythms, seasonal reproduction, hormone cascades and immune function, phenology and migration (Kuenzel et al ., ; Gaston et al ., ; Alaasam et al ., ). We must emphasize that previous research has repeatedly shown that these non‐visual photoreceptors are directly responsible for changes in reproduction, physiology, immunity and phenology (Gaston et al ., ). The non‐visual photoreceptors captured millions of photons from these light sources, indicating that even though the light sources are long wavelength shifted, they will still alter organisms’ physiology and ecology.…”

Moonlight enhances growth in larval fish

“…Artificial light at night (ALAN; Gaston et al. ) may disrupt moonlight effects on pelagic larvae, yet the effects of cloud cover may be context‐dependent, as clouds can amplify the effects of ALAN near urban centers (Kyba et al. ).…”